Neuroscience & Mental Health Flashcards

Question

How is the development of the spinal chord influenced?

Answer 1

Dorso-ventral patterning occurs due to signalling molecules. Those produced by the notorchord influence the cell to become a motor neurone (thus the formation of the basal plate). The ectoderm also produces signals to prevent motor neurone function production. Due to concentration gradients, this forms an alar plate.

Answer 2

The brain develops from the most anterior tip of the neural tube. Differential growth of the neural tube gives rise to three bulges called primary vesicles. This is the prosencephalon (future forebrain), mesencephalon (future midbrain) and rhombocephalon (future hindbrain).

Answer 3

The three primary vesicles give rise to 5 secondary vesicles. The forebrain divides into the telencephalon and diencephalon. The mesencephalon (midbrain) remains, and the rhombocephalon divides into the pons and medulla.

Answer 4

Further development and reduction of the internal space (forming the ventricular system). There are two lateral vesicles in the developing hemispheres, the third vesicle bisects the diencephalon. The aqueduct goes through the midbrain, and the fourth ventricle is in the hindbrain.

Answer 5

Flexures known as the cephalic, pontine and cervical flexures between the prosencephalon, mesencephalon and rhombocephalon respectively.

Answer 6

The brainstem has a similar structure to the spinal chord except that the fourth ventricle opens up in the brainstem. This means that the alar plates are more lateral to the basal plates than dorsal to them.

Answer 7

There is a layer of grey matter cortex over the while cerebral hemispheres. To get the grey matter cells there, they have to undergo a large amount of migration from the germinal later. To do this, cells attach themselves to the process of special radial glial cells. Cells move up towards the hemispheres in waves of proliferation. This continues until there is the typical six-layered structure of the cortex. The timing of this migration and proliferation is very important.

Answer 8

Traffic accidents, fall and sports. They tend to occur in men more frequently than in females, with the cervical cord often affected.

Answer 9

Grey matter consists of cell bodies of interneurones and motor neurones. Damage may affect a few motor neurones, and may not be disastrous. White matter contains interneurones and ascending/descending tracts. Damage is likely to have severe consequences as function below legion will also be impaired.

Answer 10

All spinal nerves, except the first, exit below their corresponding vertebrae. In the cervical segments, there are 7 cervical vertebrae and 8 cervical nerves . C1-C7 nerves exit above their vertebrae whereas the C8 nerve exits below the C7 vertebra. Therefore, each subsequent nerve leaves the cord below the corresponding vertebra. This means there are 8 cervical nerves, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal (although coccyx is made of 3-4 fused vertebrae).

Answer 11

Dorsal roots contain axons of sensory neurones. Ventral roots contain the axons of motor neurones.

Answer 12

L2 at the conus medularis.

Answer 13

By a pial thread called the filum terminale.

Answer 14

The lumbar cistern, containing the lumbar and sacral spinal chord (chorda equina)

Answer 15

The cervical enlargement corresponds roughly to the brachial plexus, which includes spinal segments C5-T1. The lumbosacral enlargement corresponds to the lumbosacral plexus nerves, comprises of segments L2 to S3, and is found about the vertebral levels of T9 to T12.

Answer 16

Loss of bladder and bowel function - can be due to spina bifida.

Answer 17

Loss of lower limb function as well as incontinence (paraplegia)

Answer 18

Loss of upper and lower limb function and incontinence (quadriplegia)

Answer 19

Cannot breathe unassisted, as the phrenic nucleus controls the diaphragm (innervated by C3, C4 and C5)

Answer 20

Three layers of the meninges including dura mater, arachnoid mater and pia mater. CSF flows between pia mater and arachnoid mater (subarachnoid space). Spinal meninges have an extradural space containing a fat and venous plexus. The pia mater also has lateral projections called denticulate ligaments which extend to the dura mater and help stabilise the spinal.

Answer 21

Dorsal columns pathway, spinothalamic pathway and lateral corticospinal pathway.

Answer 22

Touch, proprioception and vibration

Answer 23

Pain and temperature

Answer 24

If primary axon enters below T6, it will travel up the fasciculus gracilis; if primary axon enters above T6, it travels in the fasciculus cutaneous (more medial).

Answer 25

If primary axon enters below T6, it will travel up the fasciculus gracilis; if primary axon enters above T6, it travels in the fasciculus cuneatus (more lateral) of the DORSAL COLUMNS. The primary axons synapse with a secondary neurone at the medulla forming the internal arcuate fibres. These fibres decussate at the lemniscus, and continue ascending on the contralateral side forming a pathway called the medial lemniscus. The secondary axons terminate at the ventral posterolateral nucleus (VPL) of the thalamus, where they synapse with tertiary neurones. The tertiary neurones ascend via the posterior limb of the internal capsule, ending at the primary sensory cortex.

Answer 26

In the SPINOTHALAMIC pathway, primary neurones enter the spinal chord, and then ascend one or two levels before synapsing in the substantia gelatinosa with secondary neurones. The primary neurone tract is called Lissaeur's tract. The secondary axons decussate and ascend in the anterior lateral portion of the spinal chord. The tracts ascend all the way to the VPL of the thalamus, where it synapses with tertiary neurones. These then ascend via the posterior limb of the internal capsule to the primary sensory cortex.

Answer 27

Dorsal column pathway decussates in the medulla (at the lemniscus); Spinothalamic pathway decussates a few levels superiorly to where the primary axon enters the spinal chord (much lower down).

Answer 28

1) loss of neural tissue 2) vertical level of lesion 3) transverse plane (which tracts are affected)

Answer 29

A disorder in which a cyst or cavity forms within the spinal chord.

Answer 30

20% of O2 consumption, 10-20% of cardiac output and 66% of liver glucose.

Answer 31

The vertebral arteries, which join to make the Basilar artery; and the internal carotid arteries.

Answer 32

The Basilar artery splits into the Posterior cerebral arteries. The posterior communicating arteries join this to the middle cerebral artery, which is continuous with the internal carotid. From the middle cerebral artery comes the anterior cerebral artery. The anterior communicating artery connects the two anterior cerebral arteries.

Answer 33

It bifurcates at about the level of the laryngeal prominence, into internal and external common carotid.

Answer 34

Through the transverse foramina at the base of the skull.

Answer 35

Cerebellar veins drain into the venous sinuses. The venous blood circulates to the back of the head, and moves naturally through the lateral sinus and sigmoidal sinus to become continuous with the internal jugular vein.

Answer 36

A stroke is a cerebrovascular accident; a rapidly developing focal disturbance of brain function of presumes vascular origin which lasts for more than 24 hours.

Answer 37

Due to an infarction (85%) or haemorrhage (15%).

Answer 38

A rapidly developing focal disturbance of brain function of presumed vascular origin that completely resolves within 24 hours.

Answer 39

The degenerative changes which occur in tissue following occlusion of an artery.

Answer 40

The lack of sufficient blood flow to nervous tissue resulting in permanent damage if blood flow is not restored quickly.

Answer 41

100,000 annually - 3rd commonest cause of death.

Answer 42

Paralysis of the contralateral leg more commonly than arm, and also the face. Frontal lobe function is affected, hence disturbance of intellect, judgement and executive function.

Answer 43

'classic stroke' presenting with contralateral hemiplegia in the arm more often than leg, contralateral hemisensory deficits, hemianopia and aphasia.

Answer 44

Visual deficits, like homonymous hemianopia. Receptive aphasia.

Answer 45

A stroke of a penetrating artery providing blood to the brain's deep structures. Usually associated with hypertension.

Answer 46

An artery supplying the brain (not meninges) ruptures leading to disturbance of brain function.

Answer 47

``` Epidural haemorrhage (artery ruptures between skull and dura) usually due to trauma. Subdural haemorrhage (vein ruptures between dura mater and brain) usually due to shearing forces. Subarachoind haemorrhage (blood vessel ruptures between arachnoid mater and pia mater) usually due to an aneurysm. ```

Answer 48

55ml/100g tissue/min (15% of CO)

Answer 49

A myogenic response. Increased pressure leads to increased stretch of vascular smooth muscle. This causes increased contraction before blood reaches the brain which decreases CBF.

Answer 50

Neural and Chemical factors

Answer 51

- Sympathetic innervation produces vasoconstriction, but only operates when arterial blood pressure is high - Parasympathetic innervation produces slight vasodilation - Central cortical neurones release a variety of vasoconstrictor neurotransmitters such as catecholamines. - Dopaminergic neurones produce vasoconstriction as they innervate penetrating arterioles and pericytes around capillaries. Pericytes are brain macrophages with diverse function, and can be found associated with capillaries.

Answer 52

Metabolically active cells release factors and effect surroundings. CO2, pH, NO, K+, adenosine and anoxia are vasodilatory factors.

Answer 53

Those that lie outside the blood-brain barrier.

Answer 54

Choroid plexus secretes CSF into the lateral ventricles.

Answer 55

It consists of endothelial cells with tight junctions. Capillaries are also non-fenestrated and surrounded by astrocyte end-feet.

Answer 56

Median eminence of hypothalamus Subfornican organ Organum vasculosum of the lamina terminalis

Answer 57

Total osmolarity is the same. Important difference between specific molecules e.g CSF has less calcium. This means that the pH of the fluids are slightly different, with the CSF being slightly more acidic.

Answer 58

The compartment of the forebrain that contains the thalamus and hypothalamus.

Answer 59

Although the thalamus exists in two halves, the separate nuclei in each half communicate with each other. It has ipsilateral connection with the forebrain.

Answer 60

EACH thalamus is divided into two halves: smaller posterior half, larger anterior half.

Answer 61

Specific nuclei: connect with the primary cortical areas Association nuclei: have more diffuse connections with the association cortex Intralaminar nuclei: are nuclei which are embedded in the lamina dividing the thalamus

Answer 62

- Ventral Lateral Nucleus: connected with the motor cortices for co-ordination and planning - Ventral Anterior Nucleus: connected with the motor cortices for planning and inhibition of unwanted movement - Ventral Posterolateral Nucleus: connected with primary somatosensory cortex for touch and proprioception information about the body - Ventral Posteromedial Nucleus: connected with primary somatosensory cortex for touch and proprioception information about the brain - Lateral geniculate nucleus: connected with visual system sending information to primary visual cortex - Medial geniculate nucleus: connected with the auditory nucleus, acting as a relay between inferior colliculus and primary auditory cortex.

Answer 63

- The anterior, lateral dorsal, and dorsomedial nuclei connect with part of the limbic system (cingulate and prefrontal cortex) The lateral posterior, and pulvinar nuclei connect with the association cortex at the parieto-temporo-occipital junction and the prefrontal cortex.

Answer 64

- They form part of the reticular activating system; responsible for the control of the level of arousal of the brain by modulating the level of activity of the cerebral cortex - They receive input from the reticular formation of the brainstem, and then project diffusely throughout the cortex

Answer 65

It is a fine sheet of neurotissue lying over the lateral surface of the thalamus like a net, giving good access to the thalamic nuclei, but does not have any direct connections with the cortex itself. It receives input from the reticular formation of the brainstem (therefore a part of the RAS) and indirectly regulates the flow of information within the reticular activating system to the cortex.

Answer 66

Results in contralateral hemianaesthesia, followed by burning pain often accompanied by mood swings.

Answer 67

Inferior and anterior to the thalamus, posterior to the optic chasm and pituitary infundibulum.

Answer 68

Paraventricular and Supraoptic neurones that contain oxytocin and vasopressin.

Answer 69

- autonomic nervous system - endocrine system - controlling behaviour

Answer 70

The olfactory system and limbic system.

Answer 71

- eating and drinking via appetite sensors - expression of emotion - sexual behaviour - circadian rhythm - memory

Answer 72

Polydipsia and polyuria; Amennorhea. Later present with liable emotions, rage, inappropriate sexual behaviour, memory loss, hyperphagia. Temperature fluctuations; decreased thyroid function; decreased adrenal cortex and gonadal function

Answer 73

The ability to determine the positioning of joints and the length of muscle to appreciate the body's organisation in space.

Answer 74

Touch and proprioception are realised by mechanoreceptors. Temperatures by thermoreceptors, and pain by nociceptors.

Answer 75

Plexuses are naked nerve endings on skin Peritirichal endings are those wrapped around hair follicles Merkel ending in epidermis Pacinian corpuscules is suited to detecting vibration as it around a group of cells End bulb Meissiner's corpuscles Ruffini endings

Answer 76

1. degree of specialisation 2. location 3. physiological properties

Answer 77

- activation threshold, which determines sensitivity - slow or fast adapting. Slow adapting is where APs are produced from when stimulus starts to until it ends. Fast adapting produce APs as soon as the stimulus starts but stops quickly afterwards, some may have a burst of firing when stimulus stops.

Answer 78

Slow adapting are found in systems where the parameter needs to be constantly monitored e.g joints and muscles Fast adapting are used for monitoring stimulus that move or change quickly and that that persist but do not require monitoring.

Answer 79

The area that can trigger the sensory neurone. The larger the receptive field, the lower the acuity. Density varies over the body and receptive fields overlap. There are smaller and more receptive fields in the fingertip than trunk.

Answer 80

The frequency of firing of the neurones, related to a logarithmic scale.

Answer 81

The capacity of an exited neurone to reduce the activity of its neighbours. This sharpens the spacial profile of excitation in response to a localised stimulus. Only neurones which are most stimulated and least inhibited will fire

Answer 82

An alphabetical system refers to neurones based on diameter. A is largest diameter. The roman numeral system classifies by conduction velocity. 1 is fastest. The two systems correlate.

Answer 83

Sensory information comes from the trigeminal nerve, which synapses with secondary neurones in the PONS, where they decussate and join with the other axons from the dorsal columns at the medial lemniscus.

Answer 84

Somatosensory cortex has a somatotrophic arrangement known as the homunculus. Information arrives into the S1 area of the somatosensory cortex where it is analysed before being further analysed at the S2 area/

Answer 85

It is located in the postcentral gyrus which is just posterior to the central sulcus.

Answer 86

Primary Motor Cortex / M1 / Broadmann's area 4 Premotor Cortex / Broadmann's area 6 Supplementary Motor Area / Broadmann's area 6

Answer 87

On the frontal lobe, on the pre central gyrus just anterior to the central sulcus.

Answer 88

Homunculus layout

Answer 89

The premotor cortex and supplementary motor area have reciprocal connection, and both independently provide reciprocal connections to M1.

Answer 90

It is involved in planning internally driven voluntary movements. It involves many muscle groups, rather than highly specific movements.

Answer 91

Premotor area is necessary to prepare M1 for the motor act. Especially involved in planning externally driven movement such as reacting to visual cues.

Answer 92

a) Lack of spontaneous movements and speech | b) Slow complex movements as M1 neurones take longer to get into actions without sufficient facilitations from PMA.

Answer 93

1) Strategy - planning of movements requires somatosensory cortex, prefrontal cortex and motor association cortices. It also involves feedback information via the basal ganglia and thalamus. 2) Tactics - identify sequence of muscles to execute movement, involves primary motor cortex with feedback from cerebellum and thalamus 3) Execution - requires activation of motor neurone pools as well as spinal chord and brainstem.

Answer 94

The Corticospinal (Pyramidal) tract: - Lateral corticospinal tract - Anterior corticospinal tract The Subcorticospinal (Extrapyramidal) tract: - Rubrospinal tract - Reticulospinal tract - Vestibulospinal tract

Answer 95

Originates from pyramidal cells in LAYER V of the primary motor cortex, integrating inputs from the somatosensory cortex. Axons protect through the cerebral white matter and into the POSTERIOR LIMB of the Internal Capsule where they continue down into the brainstem. Fibres travel via CEREBRAL PEDUNCLES in the medulla where they form column-like structures called pyramids. At the medulla 80% decussate to form the lateral corticospinal tract, while 20% remain uncrossed to form the anterior corticospinal tract. Axons project into the ventral horns, where they connect with the lower motor neurones, which provide innervation for voluntary muscles.

Answer 96

Information for voluntary, fine movements - mainly for the arms and legs.

Answer 97

Supporting voluntary movement (still beyond voluntary control), controlling axial muscles, helping to control posture, and locomotion in automatic movements. They receive substantial input from the basal ganglia, cerebellum and BRAINSTEM NUCLEI.

Answer 98

It passes through the superior cerebellar peduncles to the RED NUCLEUS in the midbrain, and finally to the spinal nerves, carrying information important for muscle tone and posture.

Answer 99

Runs from the VESTIBULAR NUCLEI located in the lower pons and medulla, to the spinal nerves, carrying information about balance.

Answer 100

Runs from the RETICULAR NUCLEI of the pons and medulla to the spinal nerves, carrying information about somatic motor control and autonomic functions.

Answer 101

Cerebral palsy

Answer 102

A nerve cell that goes from the spinal cord to a muscle. All spinal nerves have a lower motor neurone component as they are mixed nerves. Only some cranial nerves have a lower motor neurone component.

Answer 103

1) Weakness 2) Spasticity - increased tone in affected muscles 3) Hyperrelexia - increased muscle stretch reflexes 4) Babinski sign - Abnormal plantar reflex where scratching lateral margin of foot from heel towards toe causes plantar extension as opposed to normal plantar flexion.

Answer 104

1) Weakness 2) Muscle Wasting 3) Tongue fasciculations 4) Nasal speech 5) Dysphagia 6) Hyporeflexia 7) Fibrillations

Answer 105

Nociceptors

Answer 106

- Visceral pain by spinothalamic AND dorsal columns | - Somatic pain by spinothalamic

Answer 107

- Polymodal (can respond to a variety of stimuli) - Free nerve endings - High threshold (compared to touch receptors) - Slow adapting

Answer 108

- A(delta) (group III) is a mechano or thermoreceptor produces sharp pain - C fibres (group IV) are chemoreceptors (bradykinin and histamine) produces dull aching pain

Answer 109

- VPL and VPM nucleus of the Thalamus --> S1 and S2 cortex - Brainstem for perception of pain - Periaqueductal Grey area of the midbrain to inhibit pain

Answer 110

Primary neurones synapse with secondary neurones straight away in the dorsal horn. The secondary neurones decussate at the spinal chord. As neurones enter the spinal chord as you travel up, they are added in a specific somatotropin organisation. More axons added medially. Axons synapse with tertiary neurones in the VPL nucleus in the thalamus.

Answer 111

Carried by the trigeminal nerve (fibres from trigeminal nucleus in the medulla). The axon continues down in the medulla until it reaches the trigeminal nucleus, where it synapses with a secondary nucleus which decussates and joins the spinothalamic tract. It then joins the VPM nucleus of the thalamus.

Answer 112

The thalamus sends information of pain to the appropriate part of S1, which localises and realises the intensity of the stimulus. Pain sensation is perceived by sub-cortical areas: - collateral branches from the spinothalamic tract reaches the reticular formation to increase awareness of stimuli - other branches reach intralaminar nuclei, hypothalamus, forebrain and limbic system to modulate mood, emotion and motivation.

Answer 113

- Peripheral local inhibition | - Central descending inhibition

Answer 114

This occurs in the dorsal horn. Before a primary nociceptive neurone synapses with a secondary neurone in the dorsal root it ALSO synapses with an interneurone. A mechanoreceptor also synapses with this neurone. The mechanoreceptor will send excitatory signals to the interneurone, which synapses with the same secondary neurone of the spinothamic tract sending inhibitory signals. The primary nociceptive neurone sends inhibitory signals to this interneurone. This results in a dampening down of pain sensation when mechanoreceptors are also activated. This is why rubbing a itchy or painful area reduces pain sensation.

Answer 115

This is caused by a group of neurones surrounding the aqueduct in the midbrain - the periaqueductal grey matter. If their stimulation is sufficient from the rest of the brain, they feed impulses down the reticular formation of the medulla into the dorsal horn. There they synapse with secondary projection neurones entering the spinothalamic pathway inhibiting them.

Answer 116

- Syringomyelia is damage in the cerival region which disrupts fibres from crossing over. Patients present with cuts and bruises on hands due to loss of nociception - Charcot joints is a hereditary condition caused by a lack of development of nociceptors, resulting in a loss of joint pain, leading to overuse and inflammation - Wind-up dorsal horn happens when chronic stimulation leads to lowered pain threshold and continuous sensation despite removal of noxious stimuli - Thalamic syndrome is a disorder there is damage to the thalamus, leading to pain hypersensitivity, and poorly localised central pain that doesn't respond to local pain killers - Psychological (neuropathic pain) is where the physical stimulus cannot be found.

Answer 117

- Caudate and putamen - Internal (medial) and external (lateral) part of Globus Pallidus - Subthalamic nucleus - Pars reticulata and Pars compacta of the substantia nigra in the midbrain.

Answer 118

Cortex -> Striatum -> Globus Pallidus -> VL nucleus of Thalamus -> Supplementary Cortex Area

Answer 119

Axons from cerebral cortex -> Putamen and Caudate nucleus. From putamen there are two pathways: 1) Direct: -> Globus Pallidus internal and Substancia Nigra pars reticulata 2) Indirect: Globus Palidus external -> Subthalamic nuclei -> internal There are then outputs from the Globus pallidus internal and Substancia Nigra pars reticulate to the THALAMUS (-> motor cortices) The GPi and SNr INHIBIT the thalamus (and thus motor cortex). The putamen inhibits the GPi which in turn releases the thalamus from inhibition.

Answer 120

Input (excitatory) to the putamen or caudate nuclus from substancia nigra pars compacta

Answer 121

Neuronal degradation of the substania nigra means reduced dopamine in the striatum (less excitation) -> decreased inhibition of the globus pallidus -> increased inhibitory output to the thalamus -> decreased fasciculations of the motor cortex.

Answer 122

Bradykinesia, Hypomimic face, Akinesia (difficulty in initiating movements), Rigidity, Tremor at rest, Parkinson's gait.

Answer 123

huntingtin gene on chromosome 4 defect leads to degradation of the inhibitory pathway neurones (GABAergic) in the straitum, selective to the indirect pathway. Less inhibitory output to the thalamus -> thalamic neurones firing randomly and inappropriately -> chorea

Answer 124

- two hemispheres separated by a vermis | - three lobes horizontally: anterior, posterior and floculonodular lobes

Answer 125

The cerebellum is a highly folded layer of grey matter, underneath which exists myelinated nerve fibres and cerebellar nuclei. The cortex itself can divided into three layers: 1. Molecular layer (top) 2. Purkinje cells 3. Granular cell layer

Answer 126

1) Moss fibres enter at granular layer from pontine nuclei and synapse with the purkinje cells 2) Climbing fibres enter at the Purkinje cell layer and originate from the contralateral inferior olive (medulla)

Answer 127

1) Fibres from dentate nuclei - motor planning and voluntary movements - projections to thalamus and red nucleus 2) Fastigal - involved in balance, has projections to the vestibular and reticular nuclei 3) Interposed - also involved in balance, but projections to the thalamus and red nuclei.

Answer 128

1) Mossy fibres from the spinocerebellar pathway (proprioceptive info) go through the inferior cerebellar peduncle. 2) Climbing fibres from the inferior olive go through the inferior cellebelar peduncle 3) Mossy fibres from the pons bringing information from cerebellar cortex enter through middle cerebellar peduncle.

Answer 129

Vestibulocerebellum, Spinocerebellum and Cerebrocerebellum

Answer 130

Lives in the flocculonodular lobe, and has inputs and outputs to the vestibular nuclei and vestibular nerve via the inferior peduncle. - Regulation of gait, posture and equilibrium - Coordination of head movements with eye movements. (vestibulo-oculo reflex)

Answer 131

Is the vermis and adjacent strips. Contains the fastigal and interposed nuclei. Spinal afferent tracts from axial portions of the body, trigeminal, visual and auditory inputs project into vermis. Spinal afferents from the limbs project into the immediate nuclei. - Speech co-ordination - Adjustments of muscle tone and coordination of limb movements

Answer 132

The lateral lobe contains the dentate nucleus. - Co-ordination of skilled movements, tactics of skilled movements - Cognitive function, attention, language and emotional processing

Answer 133

VESTC: Ataxia, Romberg sign (instability when eyes are closed), and Nystagmus (involuntary eye movement) SPINOC: Hypotonia, Dysarthria (slurred speech) CEREBROC: Dysmetria (inappropriate force and distance for target-directed movements), Dysdiadochokinesia (inability to coordinate movements and inability to perform rapid alternating movements) GENERAL: Intention tumour, scanning speeches

Answer 134

MND is a group of neurological disorders that selectively affect motor neurones causing progressive weakness of many neurones. It affects upper and lower motor neurones.

Answer 135

Most causes are sporadic. However, familial MND accounts for about 10% of cases.

Answer 136

- Stumbling due to leg muscles - Difficulty holding objects due to weakness - Slurring speech or swallowing difficulties - Cramps and muscle twitching (fascinations)

Answer 137

Amyotrophic Lateral Sclerosis is the degeneration of the corticospinal tract and chromatolysis with associated disconnection of neurones from target muscles fibres. Staining reveals mosaic patterns with decrease in myosin ATP and muscle atrophy is observed.

Answer 138

- excitatory post-synaptic potential (EPSP) is when the cell membrane is made less negative and this closer to the threshold potential - inhibitory post-synaptic potential (IPSP) is when the cell membrane is made more negative, making it closer to the threshold potential

Answer 139

Temporal summation is when an action potential is achieved due to increased frequency of impulses Spatial summation is where an action potential is achieved due to input from multiple presynaptic cells

Answer 140

The NMJ is a specialised synapse between the motor neurone and the motor end plate (muscle fibre cell membrane)

Answer 141

The AP arrives at the pre-synaptic bouton, causing Ca2+ channels to open leading to Ca2+ before ACh release into the cleft. Specialised foldings of the muscle fibre membrane will pick up the ACh and act on receptors ACh binds to nicotinic acetylcholine receptors, causing ion channels to open, allowing Na+ influx

Answer 142

At rest, miniature packets of ACh are released into the synapse causing minute end-plate potentials (MEPPs), which are not powerful enough to cause an AP. Arrival of the AP triggers the release pf 200-300 quanta, producing numerous MEPPs, which sum to produce a depolarisation to -20mV (endplate potential)

Answer 143

A lower motor neurone is a motor neurone whose cell body lies in the ventral horn of the spinal chord or cranial nerve nuclei and that directly innervates the muscle via its axon.

Answer 144

- alpha-motor neurone (70micrometeres in diameter) innervate the muscle fibres (extrafusial fibres - big mass of muscle) directly to cause constriction - gamma-motor neurones (30micrometeres in diameter) innervate the intrafusal fibres (small mass at the centre of the muscle). They have a role in keeping muscle fibres taut but do not adjust lengthening/shortening of muscle, also important in stretch perception.

Answer 145

All the alpha neurones innervating a single muscle (as opposed to a motor unit)

Answer 146

A single motor neurone together with all the muscle fibres that it innervates, it is the smallest functional unit that produces force.

Answer 147

During development, lots of motor neurones innervate a single muscle fibre, but one outcompetes the rest.

Answer 148

Type I/Slow: Smallest diamater axons, small dendritic tress, slowest conduction velocity but low fatiguability (60 minutes) therefore used to maintain postural muscles Type I/Fast: large diameter axons, long dendrtotic trees, fast conduction velocity. Type IIA are less fatiguable than IIB, and produce moderate tension. Type IIB are more fatiguable (6 mins) and produce high tension.

Answer 149

1) Recruitment. Smaller units (Slow/Type1) are recruited first -> Type IIA -> Type IIB. Derecruitment in opposite order. As more force is required, more motor units are recruited allowing for fire control. 2) Rate coding. Motor units can fire at frequencies (generally start at 8Hz) and increase as more force is needed. Summation occurs when units fire at frequency too fast to allow muscle to relax between arriving potentials.

Answer 150

Type of growth factors which prevent neuronal death, and promote growth of neurones after injury.

Answer 151

- 'feeds' it to keep it alive. loss of innervation causes hypertrophy, despite maintaining vasculature. - has an effect on its properties, esp regarding if muscle is to be slow or fast twitch.

Answer 152

An automatic and often inborn response to a stimulus that involves a nerve impulse passing inwards from a receptor to a nerve centre and then outwards to an effector without reaching the level of consciousness.

Answer 153

1. Sensory receptor 2. Sensory neurone 3. Integrating centre 4. Motor neurone 5. Effector

Answer 154

Patella tendon reflex: 1) Stretch sensed muscle spindle, causing AP to travel down sensory neurone 2) It synapses in the spinal chord with the motor neurone required causing the quadriceps to contract 2) It also synapses with an interneurone that causes the antagonist to relax.

Answer 155

The flexion withdrawal reflex. It is elicited by noxious stimulation, consisting in flexion on the same side, and extension on the other leg (prevent falling over). The inter-neurones convey information to multiple motor neurones, causing multiple motor units to contract, resulting in effects.

Answer 156

Higher centers of the CNS exert inhibitory and excitatory regulation upon the stretch reflex - USUALLY INHIBITORY.

Answer 157

If you clench your teeth or make a fist while having the patellar tendon tapped, the reflex is increased!

Answer 158

Pitch and loudness respectively

Answer 159

20-20000 Hz

Answer 160

Pinna (auricle), and the auditory CANAL (external acoustic meatus)

Answer 161

The portion between the tympanic membrane and the oval and round windows: the ossicles (malleus, incus and stapes)

Answer 162

The cochlea and vestibular apparatus

Answer 163

Through the auditory canal --> malleus --> incus --> stapes --> oval window vibrates causing a pressure wave inside the fluid of the cochlea

Answer 164

Amplify the sounds by 30db

Answer 165

a) lever system of articulated ossicles | b) a larger area of the tympanic membrane compared to the membrane of the oval window (17:1 ratio)

Answer 166

1) Reflex contraction of the tensor tympani and strapedius muscle to reduce leverage through the ossicle bridge. Only protects against natural sounds that tend to get gradually louder as contraction of the muscle takes unto 100ms 2) Equilibration of air pressure on either side of the tympanic membrane by the esutachain tube (auditory tube). Eustachian tube connects the middle ear with the back of the nasopharynx behind the nasal cavity.

Answer 167

Scala vestibuli (contains perilymph), Scala media (endolymph) and Scala tympani (perilymph) [from top to bottom]

Answer 168

On the tips of cochlear hair cells, on the basilar membrane

Answer 169

Sound waves hit the oval window, causing a pressure wave to travel through the scala vestibuli and then the scala tympani. The vibrations travel up and down on the vestibular membrane, causing a pressure wave in the scala media. The pressure wave goes across the basilar membrane (moving stereocilia in the process) and joins the pressure waves in the scalar tympani.

Answer 170

The organ of the inner ear that has sensory hair cells. The hair cells are covered by the TECTORIAL membrane with the stereocilia touching it. The tectorial membrane is a gelatinous structure and does NOT vibrate with sound.

Answer 171

It is lined by the stria vascularis, which maintains a high K+ concentration by secreting endolymph.

Answer 172

Spiral ganglia from CN VIII (embedded in the modiolus) produces axons that innervates the hair cells. Impulses from the hair cells pass laterally through the modiolus --> vestibulocochlear nerve --> brainstem

Answer 173

Support cells

Answer 174

The basal membrane of the cell synapses with nerve endings. Movement or deflection of the stereocilia causes depolarisation of the nerve endings.

Answer 175

Hair cells

Answer 176

There are inner hair cells and outer hair cells. Arrangement of a single row of inner hair cells followed by 3 rows of outer hair cells.

Answer 177

Inner hair cells provide auditory information. Info from outer hair cells goes to the brainstem and forms a refinement mechanism (adjusting sensitivity)

Answer 178

Movement can be divided into an upwards or downwards phase. Upwards: movement causes shear forces AWAY form modiolus, moving cilia away. This causes opening of K+ channels and depolarisation of the hair cell. Downwards: movement causes shear forces directed towards the modiolus causing closure of K+ channels, so no AP is generated.

Answer 179

Adjacent stereocilia are connected together by tiplinks. Stereocilia are arranged in order of increasing length (away from modiolus)

Answer 180

During the upwards phase of vibration, there is movement towards the tallest stereocilia, therefore there is greater tension between the tiplinks. The greater distance between the tips causes opening of K+ channels.

Answer 181

They only need to be deflected 0.3nm (/500nm stereocilia) in order to be detected by the auditory system as a sound.

Answer 182

The basilar membrane is a heterogenous structure. Sound will only make part of the membrane that corresponds to the particular frequency to resonate. Lower frequencies cause vibration near the apex, higher frequencies near the base. As the apex membrane is wider and more flexible and base fibres are stiff with narrow membrane.

Answer 183

Tonotopic organisation

Answer 184

Two CN VIII nerves carry impulses to the cochlear nucleus in the medullary-pons junction. Information is then projected to the superior olive, but also the contralateral superior olive, giving a bilateral projection. The superior olives then send the impulse to the inferior colliculus before the information is passed to the medial geniculate body in the thalamus. Here the information is processed before it passes into the auditory cortex in the temporal lobe.

Answer 185

Lateral inhibition of neurones in the central auditory pathway.

Answer 186

Primary auditory cortex receives auditory input first. It is divided into zones which analyse different frequency ranges. Broadmann areas 41 and 42. Located on the temporal lobe. The Secondary auditory cortex surrounds the primary auditory cortex and is where neurones respond to more complex sound patterns. Involved in more subtle processes such as quality and tone of sound and musical sound.

Answer 187

Conductive hearing loss is when sound is prevented from reaching the cochlea due to outer or middle ear dysfunction.

Answer 188

- Wax build up - Otitis media (middle ear infection --> inflammation --> fluid build up impairing amplification) - Otosclerosis of ossicles - bony extensions grow from the ossicles affecting leverage system. - Perforated eardrum - Congential malformation

Answer 189

- Conductive hearing loss | - Sensorineural deficiencies

Answer 190

These occur when the root cause lies in the vestibulochochlear nerve, inner ear or central processing centers

Answer 191

- Presbyacusis - loss of hair cells with ageing - Loud noise can cause death to some hair cells - Meziere's disease - drainage problem leading to buildup of pressure affecting hair cells in inner ear. - Toxicity (gentomycin can damage hair cells) - Acoustic neuroma - benign tumour of CN VIII - Viral infections can cause damage to nerves - Demyelination in MS - Injury to central auditory pathways

Answer 192

Change in head position and linear acceleration detected by otolith organs. Angular acceleration is sensed by the semicircular canals

Answer 193

In the utricle and saccule (in the vestibule)

Answer 194

Each otolith organ contains a sensory epithelium called the macula. This is vertical in the sauce, and horizontal in the utricle. Note, the hair cells project at a normal to the plane.

Answer 195

Hair cells lie on the macula (epithelium), among a bed of supporting cells with their cilia projecting onto a gelatinous cap.

Answer 196

Those in the sacule are sensitive to vertical (and antero-postero directions), while those in the utricle are sensitive to horizontal (and antero-postero directions)

Answer 197

The vector sum of the urticular and saccule stimulation patters.

Answer 198

They are calcium crystals that sit on the gelatinous cap on top of cilia. When the head accelerates, a force is exerted on the otoliths, which exerts a force in the same direction into the gelatinous cap causing stereocilia to deflect.

Answer 199

Towards the kinocilium

Answer 200

They respond to the static head, its lift and acceleration. When upright, the vestibular ganglion that innervates the saccule has tonic discharge do to constant displacement by gravity.

Answer 201

There are three of them, oriented perpendicular to each other, positioned in three dimensions.

Answer 202

They are located within sheets of cells called the crista, which are located within a bulge along the canal called the ampulla.

Answer 203

They are covered by a jelly-like layer called the capula. The semicircular cabals are filled with endolymph (same as cochlea)

Answer 204

Bending of the cilia (towards kinocilium --> depolarisation) is facilitated when rotational acceleration causes the endolymph of the canal to spin, exerting a force to the capula. Like wind on a sail.

Answer 205

Each canal has a tonic firing rate - the bonuses from both ears balance out. When acceleration cites hair cells on one canal, it inhibits the hair cells on the contralateral canal. This is a 'push-pull' arrangement that optimises the brain to detect rotational movements.

Answer 206

- Control balance reactions - Provide compensatory reflexes (such as vestibulo-occular reflex) - Tune cardio-vascular functions - Serve perception of motion in space - Provide a spatial reference for other sensory motor co-ordinations

Answer 207

There are four vestibular nuclei (superior, inferior, lateral and medial) for each side. Otoliths send information to the lateral and inferior nuclei . Semicircular canals send information to the superior and medial nuclei.

Answer 208

- Spinal chord for maintenance of balance (neck and limb motor neurones) - Nuclei of the extraoccular muscles - Cerebellum - Cortex via the thalamus - Centres for cardiovascular and respiratory control

Answer 209

Otolith organs --> lateral and inferior vestibular nuclei --> lateral vestibulospinal tract (which descends ipsilaterally in the VENTRAL FUNICULUS of the spinal chord --> axons terminate to influence motor neurones controlling muscles in the legs that help maintain posture.

Answer 210

Semicircular canals --> medial and superior vestibular nuclei --> medial vestibulospinal tract descends down in the medial longitudinal fascilicus also connects to extraoccular motor neurones of CN III and VI to keep retinal image stationary.

Answer 211

The vestibulocollic pathway maintains the position of the head on the trunk. The vestibule-spinal reflex maintains the rest of the body in posture.

Answer 212

Vestibular afferents from the vestibular ganglion and nuclei project to the cerebellar cortex - the flocculonodular lobe. Cerebellar efferents from the fastigal nucleus project to all vestibular nuclei.

Answer 213

Ventral Posterior and Ventral Lateral nuclei

Answer 214

This would require the eyes to move clockwise. Axons from the left horizontal canal innervates the left vestibular nucleus. This sends excitatory axons to the CONTRALATERAL abducens nucleus, which in turn excites the lateral rectus muscle of the right eye. Another excitatory projection from the abducens crosses the midline and ascends via the medial longitudinal fascilicus to excite the left oculomotor nucleus, which excites the left medial rectus muscle of the left eye. To ensure speedy operation, the left oculomotor nucleus is also directly excited from the left vestibular nucleus. Speed is also maximised by inhibiting opposing movement.

Answer 215

Vertigo is the false perception that the world is spinning

Answer 216

Vestibular ataxia - instability of gait and posture

Answer 217

Inability to stabilise eyes: vestibular nystagmus in unilateral lesions; oscillopsia during head movement in bilateral lesions

Answer 218

- If acute and uni-lateral, cases are associated with prominent vertigo, nausea and vomiting - If slow-onset and chronic bilateral, they may not have these characteristics, disequilibrium may be the side-resentation

Answer 219

The tonus of the intact canal gives a signal as if the head is rotating to the intact side - so patients experience symptoms of intense spinning.

Answer 220

- Benign paroxysmal positional vertigo (BPPV) due to debris in canal causes intense vertigo and nausea for a few seconds. Most common. - Vestibular Neuritis caused by inflammation of ear. Lasts minutes to hours. Second most common cause. Continuous vertigo with obvious nystagmus. - Migrainous Vertigo - Meniere's diseases can cause intense vertigo and nausea, hearing distrubance for hours. Rare. Less common: - Infarction of labyrinth - Uncompressed vestibular lesion or stroke - Acoustic neuroma, tinnitus, hearing loss

Answer 221

- Bilateral vestibular disorder causes mild gait ataxia - Unilateral vestibular disorder causes the body to lean/ 'fall' on the lesioned side as the bonus of the intact one tells brain you're falling on that side.

Answer 222

- Vestibular nystagmus if unilateral: unopposed bonus of intact canal causes eyes to be driven to the lesioned side though VOR. Drifting movement detected by brainstem which resets eye positioning with fast saccades. - Oscillopsia (bilateral loss): impaired eye stabilisation so world is seen to bounce.

Answer 223

Outer layer is the sclera, and forms the wall. Inside the sclera is the choroid, which is dark and has a red pigment. The inner layer is the retina, which has neurotissue.

Answer 224

Anterior segment can be described as the ocular structure anterior to the lens, with the posterior segment posterior to the lens.

Answer 225

The anterior chamber is between the cornea and the lens and is filled with Aqueous humour which supplies nutrients to surrounding cells. The posterior chamber is filled with a jelly like substance called the vitreous humour which provides mechanical support.

Answer 226

The collagen and GAG chains of the vitreous humour can break down, presenting as floaters.

Answer 227

An ageing vitreous humour.

Answer 228

The ciliary body is a ring of tissue between the anterior and posterior segment of the eye, which bends the iris.

Answer 229

The ciliary body is the main engine for accommodation, and also secretes aqueous fluid.

Answer 230

12-21 mmHg

Answer 231

The ciliary body supports the zonular fibres (suspensory ligaments) which attaches to the lens. On contraction, the ciliary body moves up and in and the zones are relaxed, allowing the lens to become more spherical --> increase in power.

Answer 232

To regulate how much light enters into the eye. (Also gives eye 'colour')

Answer 233

Pupil contraction is Miosis; Pupil dilation is Mydriasis.

Answer 234

Miosis is achieved by contraction of the sphincter papillae which are circular muscles in the eye. Mydriasis is achieved by the contraction of dilator papillae which are radial muscles of the iris.

Answer 235

A group of diseases that presents with sustained intraocular pressure.

Answer 236

Retinal ganglion cell death and can lead to optic disk cupping.

Answer 237

- Primary open angle glaucoma (most common) is caused by a dysfunctional trabecular network (drainage system into the Canal of Schlemm). In this type there is normal-high IOP, but shows signs of glaucoma - Closed angle glaucoma is when increased pressure pushes iris/lens complex forwards, blocking the trabecular network leading to a cycle of increased pressure.

Answer 238

- Can be acute or chronic - Very rapid and painful + drop in vision + red eye - Risk factors include hypermetropia (small eye) and narrow angle at trabecular pressure - Can be treated with peripheral laser iridotomy to create drainage hole for iris.

Answer 239

- Made of water (65%) and protein (35%) - Biconcave, elliptical and avascular - The outer acellular capsule envelopes the lens as a basement membrane. - The zones attach to the lens epithelium - The bulk of helens consists of regular inner elongated fibres, which only maintain transparency due to their regularity. With age, they lose their transparency, causing cataracts.

Answer 240

The cornea (2/3 of refractory power)

Answer 241

Distant - gets thinner | Near - gets fatter

Answer 242

- It is continuous with the sclera. - It has a convex structure. - It has 5 layers, absorbing UV - It has a tear film that supplies the cornea with oxygen.

Answer 243

Has a superficial lipid layer to reduce evaporation. Below that is an aqueous layer, and below that a mucin layer.

Answer 244

Basal (keep the cornea with a supply of oxygen) Reflex (in response to irritation) Crying

Answer 245

They are produced by the lacrimal gland. They drain through the superior and inferior canaliculi, gathering into the tear sacs before emptying into the tear duct.

Answer 246

The uvea (pigmented layer consisting of retina + chorioid + sclera)

Answer 247

They have emmetropic eyes. Here parallel rays converge exactly on the retinal surface of the fovea, forming a clear image on the retina.

Answer 248

- Hypermetropia (long sighted): Parallel rays focus behind the retinal surface, caused by a short globe or flat corneal surface - Myopia (short sighted): Distant objects focus in front of retinal surface. Glove too long, or high conner curvature.

Answer 249

- Hypermetropia with a convex lens | - Myopia with a concave lens

Answer 250

- Sphincter pupillary contraction --> pupillary mitosis - Convergence of eyes by medi recti - Accommodation by circular ciliary muscle to increase refractive power. (Constriction to increase size of lens)

Answer 251

Naturally occurring loss of accommodation (less ability to see near objects).

Answer 252

The optic disk, where the ganglion cells exit into the optic nerve.

Answer 253

The macula

Answer 254

- Superior-Temporal retinal artery (and vein) - Superior-Nasal retinal artery (and vein) - Inferio-temporal retinal artery (and vein)

Answer 255

A pit at the centre of the macula, which contains only cones (not ganglia as these are pushed aside).

Answer 256

Central vision if used for reading, facts recognition etc. | Peripheral vision is used to recognise shapes and movement, as well as night vision.

Answer 257

Visual acuity assessment measures central vision | Visual field assessment measures peripheral vision

Answer 258

A pigmented region at the centre of the retina, about 6mm in diameter. It contains the fovea at the centre. The macula is also blood-vessel free as it absorbs blood from the choroid.

Answer 259

- retinal blood vessels supply blood to the inner 2/3 of the retina. - the choroid supplies blood to the outer 1/3 of the retina (photoreceptors)

Answer 260

Light ~~> Ganglion cells > Bipolar cells > Horizontal cells > Rods and Cones > Retinal epithelium > Choroid

Answer 261

- Rods: 100x more photosensitive; responsible for night vision; slow response to the light - Cones: less sensitive, but faster response; responsible for day light fine vision and colour vision.

Answer 262

Rods contain the photo receptor rhodopsin. It is a transmembrane protein opsin with cofactor 11-cis-retinal. The cofactor reacts with a photon causing a conformational change --> action potential. Reacts to blue-green light

Answer 263

Cones contain 3 subtypes of photopsin that react to 3 light frequencies: S-cone reacts to blue M-cone detects green L-cone detects red

Answer 264

When two of the frequencies detected by rod cells combine. Most common form is M and L peak frequencies because they are already close to each other (leading to red-green confusion)

Answer 265

8% of males and 0.5% of females

Answer 266

The ishihara test

Answer 267

The ganglia of the outermost layer of the retina conduct action potentials to the brain via the Optic Nerve (CNIII). 53% of the nerve fibres cross at the optic chiasm. Approximately 90% of the axons in the optic nerve go to the lateral geniculate nucleus in the thalamus via the retinogeniculostriate, where they synapse. Optic radiation cells transmit the impulses to the primary visual cortices.

Answer 268

1st order - rods and cones 2nd order - bipolar cells 3rd order - retinal ganglion cells 4th order - optic radiation cells

Answer 269

Only fibres from the nasal retina decussate, at the optic chiasma. This is responsible for the temporal visual field. The uncrossed fibres originate from temporal retina and are responsible for the nasal field. The criss-cross is due to the way light is reflected onto the retina.

Answer 270

The superior visual field projects to areas above the CALCARINE FISSURE, while the inferior visual fields below it. The right hemifield projects to the left primary visual cortex, and visa versa.

Answer 271

homonymous (same-side visual field) hemianopia (partial blind-ness) - so inability to see left or right visual field. Macula sparing as the area representing the macula in the cortex is disproportionally large, and has dual blood supply.

Answer 272

Bitemporal hemianopia as the tumour presses against the optic chiasm.

Answer 273

Constriction: - decrease glare and spherical aberrations - increases depth of field (near response triad) - reduces bleaching of photopigments Dilation: - increases light sensitivity to the dark - aqueous humour drainage?

Answer 274

Bipolar cells -> Pupil-specific ganglion cells exit at the posterior third of the optic tract before entering the lateral geniculate nuclei -> pretectal nucleus of the brainstem then the Eidinger-Westphal Nuclei on both sides

Answer 275

Eidinger-Westphal nucleus --> Oculomotor nerve (CN III) --> Synapses at ciliary ganglion --> Short Posterior Ciliary Nerve --> Pupillary Sphincter

Answer 276

The direct light reflex is the contraction of the pupil of the light-stimulated eye. The consensual light reflex is the contraction of the pupil of the other eye.

Answer 277

Shining a light on the affected eye will not result in direct light reflex nor consensual light reflex but shining light on unaffected eye will result on both pupils constricting.

Answer 278

The affected eye will not constrict whether any eye is stimulated. However, the normal eye will construct whether any eye is stimulated.

Answer 279

This is when a partial pupillary response is still present when the damaged eye is stimulated. Can be tested by winging the torch from eye to eye. You will be able to tell which eye elicits the weaker response as the pupils will paradoxically relatively dilate

Answer 280

Occuolomotor Nerve: Superior, Inferior and Medial rectus + Inferior oblique muscle Trochlear Nerve: Superior oblique Abducens: Lateral rectus

Answer 281

Convergence is simultaneous adduction movement in both eyes when viewing a near object Abduction is movement of the eye away from the midline Adduction is movement of the eye towards the midline

Answer 282

Supraduction is elevation/movement upwards | Infraduction is depression/movement downwards

Answer 283

Intorsion is rotation towards the midline Extortion is rotation away from the midline Dextro (right) for Levo (left) can be used to describe the direction both eyes are looking at. For example, dextroversion is looking right.

Answer 284

The affected eye will look down and out It will also have a droopy eye lid (as lid elevator is controlled by CN III) This is because of unopposed superior oblique and lateral rectus muscles

Answer 285

Affected eye unable to abduct and deviated inwards. Double vision worsens gazing to the side of the affected eye.

Answer 286

This is due to damage to the medial longitudinal fascilicus. Right eye auction nor accompanied by left eye adduction. Also accompanied by nystagmus on right gaze.

Answer 287

The sensation of movement of self or environment. It is a non-specific term which can mean vertigo, light-headedness, weakness, unsteadiness etc.

Answer 288

Plasticity to suppress dizziness by reducing the size of the vestibulocerebellum. This is why ballerinas don't get dizzy.

Answer 289

- Check postural blood pressure - Atrial saturation - ECG This is to make sure vertigo is not due to pulmonary embolism nor cardiac dysrhythmia.

Answer 290

- Eyes: cover, gaze testing, pursuit, saccades, VOR, fundoscopy - Ears: otoscope - Legs: gait

Answer 291

Peripheral nystagmus, it may combine a rotational component with vertical and horizontal eye movements. NOT central nystagmus which is not due to a problem in the vestibular organ - it can result in up and down-beat nystagmus.

Answer 292

Dolls Eyes

Answer 293

A visual disturbance in which objects in the visual field appear to oscillate.

Answer 294

The neocortex

Answer 295

- Layer 1: molecular layer - Layer 2: external granular layer - Layer 3: external pyramidal layer Layers 1-3 mainly cortico-cortical connections. Layer 3 also connects to corpus callosum - Layer 4: internal granular layer Layer 4 receives input from the thalamus - Layer 5: internal pyramidal layer - Layer 6: multiform/fussiform layer Layers 5-6 have connections with subcortical, brain stem and spinal chord. Layer 6 also outputs to the thalamus.

Answer 296

The reticular activating system and the brainstem monoaminergic nuclei

Answer 297

The primary cortical area receives the retinal input before information is passed on to the visual association area in the occipital lobe for higher level analysis. This analysis includes: - a ventral stream (what pathway) to the temporal lobe, which interprets form and colour - a dorsal stream (where pathway) to the parietal lobe which interprets spacial awareness.

Answer 298

Prosopagnosia

Answer 299

Prosopagnosia

Answer 300

The posterior part of the frontal lobe is involved in planning motor functions (premotor and primary motor cortex). The prefrontal association cortex is important in decision making, judgement, planning and foresight, basis for personality and appreciation of the self in relation to the world. Evidence also shows it is involved in restraining emotional functions.

Answer 301

The anterior part of the parietal lobe is the primary somatosensory cortex. The posterior parietal association cortex is involved in creating a spacial map of the body in its surroundings.

Answer 302

Disorientation, inability to understand spacial relationships, apraxia and hemispatial neglect (ignoring one side of the body/picture etc)

Answer 303

Important in language (vernickle's area), object recognition and more medially for the reconsolidating of memory and emotion (limbic system).

Answer 304

Agnosia (disruption in object recognition), receptive aphasia (inability to understand language) and amnesia

Answer 305

The left hemisphere is more involved in writing, calculation etc. The right hemisphere is more involved in drawing, music etc

Answer 306

- study people with lesions - electron stimulation (lol) - measure brain activity with fMRI etc while being asked to perform a task

Answer 307

- Association fibres: Intracortical they connect cells in one area of the cortex within the same hemisphere. Long fibres include the superior longitudinal fasciculus and inferior longitudinal fascilicus. - Commissural fibres: Intracortical they connect corresponds cells in both hemispheres. Corpus callous interconnects frontal, parietal, occipital and some temporal, The rest of the temporal lobe is connected by the anterior commissure. - Internal capsule is extracortilal; passes through the base of the hemisphere connecting cerebral cortex with structures outside cerebral cortex.

Answer 308

On the roof of the nasal cavity - the cribriform plate

Answer 309

- olfactory receptor neurones - substenacular/supporting cells (similar to glia and produce mucus - basal cells (the source of new neurones)

Answer 310

Axons from the olfactory receptor cells pass through perforations in the cribriform plate to enter the olfactory bulb. Here they synapse with mitral cells forming a glomerulus-like structure. The axons of the mitral cells form the olfactory tract.

Answer 311

Olfactory tract divides into two olfactory striae: - medial striae to the spatial nuclei - lateral striae to the piriform cortex The anterior commissure connects the two halves of the olfactory system instead of the corpus callosum.

Answer 312

It is the piriform cortex and orbitofrontal cortex that processes olfactory information. They have connections to the brainstem and can promote autonomic responses

Answer 313

The clinical deficit in olfaction leading to the loss of sense of smell.

Answer 314

Trauma to the crirform plate. Neurodegenerative disorders like Alzheimer's or Parkinson's may show early pathology in the olfactory bulb.

Answer 315

Prodromal aura

Answer 316

Structurally and functionally interrelated areas considered as a single functional cortex

Answer 317

- maintenance of the homeostatic response via activation of visceral effector mechanisms, modulation of pituitary hormone please and imitation of feeding and drinking - agonistic behaviour (defence and attacking) - sexual and reproductive behaviour - memory and learning

Answer 318

- Frontal lobe - Hippocampus (vital in memory) - Amygdala (responsible for fear and aggression) - Thalamus and various parts of the hypothalamus - Olfactory system feeds into the limbic system extensively - Septal nuclei

Answer 319

1. Hippocampus efferent is the fornix, which runs underneath the corpus callosum and comes down to terminate in the mamillary bodies at the base of the hypothalamus. 2. From the mamillary bodies is the mamillothalamic tract which projects to the anterior nucleus of the thalamus. This causes emotional expression via the parasympathetic system (e.g sweating, changing pupil size) 3. From the anterior nucleus of the thalamus there is a projection to the cortex lying immediately above the corpus callosum - the cingulate cortex (allows reactions to emotions to be coloured by previous experiences) 4. From cingulate cortex there is a bundle of fibres that reinervates the hippocampus The neocortex feeds into the cingulate cortex.

Answer 320

Main afferent is the perforant pathway to the enterorhinal cortex. Main efferent is the fornix/fimbria

Answer 321

On the floor of the inferior horn of the lateral ventricle

Answer 322

Vital in laying down new memories and learning. | It is also responsible for the prodromal aura of epilepsy

Answer 323

Next to the hypothalamus, buried in the white matter of the temporal lobe.

Answer 324

Responsible for initiating fear and aggressive response, as well as flight and fight.

Answer 325

Afferent: Olfactory cortex, septum, temporal neocortex, hippocampus and brainstem. Main efferent: stria terminalis

Answer 326

Kluver-Bucy Syndrome: - hyperorality - loss of fear - visual agnosia (inability to recognise objects) - hypersexuality

Answer 327

Early: - hippocampus and entorhinal cortex is where pathology starts --> short term memory loss Mid: - Parietal love affected --> affects procedural memories - Dressing apraxia --> inability to get dressed Late: - Frontal lobe affected - Loss of executive skills

Answer 328

Dopaminergic pathway running from the substantia nigra to the basal ganglia. Another small group of neurones in the tegmental area (midbrain) project to the cortex, nucleus accumbent and amygdala via the medial forebrain bundle. This pathway seems to be most important in drug dependence.

Answer 329

A cognitive process that enables us to experience the world around us.

Answer 330

The reticular activating system

Answer 331

It is a polysynaptic network in the core of the midbrain, pons and upper medulla. It projects to the thalamus and cortex so it can control whether or not sensory signals reach cortical sites of conscious awareness like the frontoparietal cortex.

Answer 332

It regulates many vital functions (such as cardiovascular, respiratory, bladder and motor patterns) and moderates the levels of consciousness.

Answer 333

There is always activity in the RAS. Specific sleep promoting pathways correlate with reduced reticular activating system (RAS) activity.

Answer 334

- Cholinergic neurones excite individual thalamic relay nuclei leading to activation of the cortex - Cholinergic projections to intralaminar nuclei, which in turn project to all areas of the cortex - Chlonergic projections to the reticular nucleus, which regulates flow of information through other thalamic nuclei to the cortex

Answer 335

Tuberomammillary nucleus (histaminergic) projects widely to cortex and is involved in maintaining wake state.

Answer 336

Using an electroencephalogram (EEG)

Answer 337

1) Delta (0.5-4 Hz) present during sleep 2) Theta (4-8 Hz) associated with drowsiness 3) Alpha (8-13 Hz) subject relaxed with eyes closed 4) Beta (12-30 Hz) indicates mental activity 5) Gamma (~40Hz) associated with creation of conscious content in the minds eye.

Answer 338

Confusion is a sustained disturbance of consciousness where mental processes are slow.

Answer 339

A state of stupor is a more profound state of confusion, which can only be roused by strong sensory stimuli. A comma cannot be roused by even strong sensory stimuli. Different from sleep as metabolic activity in the brain is depressed and there is total amnesia for the period in coma.

Answer 340

The Glasgow Coma Scale

Answer 341

- metabolic alteration e.g hypoglycaemia, hypoxia, intoxication - lesions in cerebral hemispheres - only if massive and bilateral - lesions in thalamus or brainstem

Answer 342

- Irreversible coma due to brainstem death, but body can be kept alive artificially. Decision to cease treatment depends on demonstration of absence of brainstem reflexes and response to hypercapnia. Spinal reflexes and some postural movements may still be present.

Answer 343

Irreversible coma due to disconnection of cortex from brainstem or widespread disease in cerebral hemisphere. Brainstem still functioning therefore reflexes, postural movements and sleep-wake cycle may still be present.

Answer 344

- species specific posture - reduced responsiveness to external stimulation - minimal movement - reversible

Answer 345

Using an electroencephalogram (EEG) electrooculogram (EOG) and an electromyogram (EMG)

Answer 346

Sleep stages 1-4 are non-REM sleep/slow wave sleep: - state changes gradually from drowsiness, through light sleep to deep sleep - the EEG shows gradual slowing from theta waves to delta - general muscle tone decreases gradually - relatively few eye movements Sleep stage 5 is REM sleep: - EEG rhythm speeds up to Beta - General muscle tone becomes very low - Rapid eye movements occur

Answer 347

At any stage of sleep, but most prominent in REM sleep

Answer 348

The limbic system is more active and the frontal cortex is less active.

Answer 349

The Raphe nuclei, nucleus coerules and cholinergic nuclei

Answer 350

In a cyclical manner: - Lateral hypothalamus promotes arousal - Ventrolateral prophetic nucleus promotes sleep through inhibitory effects to RAS. The two antagonistic nuclei alternate activity to regulate sleep-wake cycle as well as NREM/REM cycle.

Answer 351

The caudal pontine reticular formation is activated during REM sleep, to stress muscle tone and sensory input into the RAS, and activate eye movements (through superior colliculi) at the same time.

Answer 352

Special retinal cells detect a decrease in light level and ACTIVATE the suprachiasmatic nucleus of the hypothalamus. This nucleus modules sleep-wake circuits, allowing you to get drowsy and sleepy. The SCN also has an endogenous biological clock and stimulates the pineal gland to secrete malting, which affects a range of physiological processes with day length.

Answer 353

- highly conserved through evolution - sleep deprivation is detrimental. performance decrements > concentration difficulty > energy management issues > hallucinations > death - sleep is regulated very accurately

Answer 354

- Restoration and recovery - Energy conservation - Predator avoidance - Memory consolidation - Other effects on brain function e.g dream are through to be important for dispersal of unwanted memories and a steam valve for antisocial emotions.

Answer 355

Insomnia (too little sleep) is highly prevalent: - in most cases causes transient effect on stress and emotional disturbance - some cases have physiological cause (sleep apnoea) - some causes due to psychological causes (depression) - treatment is to administer hypnotics - enhance GABAergic circuits Narcolepsy (too much sleep) is when people enter REM sleep directly and repeatedly throughout the day. Often accompanied by cataplexy (sudden loss of muscle tone). - Genetic deficiency in orexin - Treatment is sleep management or stimulants

Neuroscience & Mental Health Flashcards

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