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Block 6: Neuro > B06W06 > Flashcards

Flashcards in B06W06 Deck (375):
1

List the 4 important centres in the motor cortex that are important for motor control

1. Primary motor cortex (M1) 2. Posterior parietal cortex (PPC) and primary somatosensory cortex (S1) 3. Premotor cortex (PMC) 4. Supplementary motor area (SMA)

2

List the 5 descending motor pathways

1. Corticospinal tract (pyramidal system) 2. Rubrospinal tract 3. Vestibulospinal tract 4. Reticulospinal tract 5. Tectospinal tract (2-5 = extra pyramidal system)

3

List the descending pathways that make up the extra-pyramidal system

Rubrospinal, vestibulospinal, reticulospinal and tectospinal tracts

4

Motor cortex = M1 + ___ + ____ + S1

MC = M1 + PMA + SMA + S1

5

Which structures make up the regulatory systems 1 and 2 in the motor system?

System 1 = basal ganglia and thalamus. System 2 = Cerebellum.

6

Which part of the brain makes the cognitive decision to perform a motor task? Give an example

Prefrontal cortex. Example = I'm thirsy, I will go and get a drink

7

List the 5 things that are required for voluntary movement (in terms of the motor system), and comment on which part of the system is responsible for each step

1. Intent to move (prefrontal cortex) 2. Knowledge of where things are in space (posterior parietal cortex) 3. Sequence of actions (premotor/SMA) 4. Requires motor program to be executes (M1) 5. Continual updates during task (S1 and PPC)

8

What is the function of the supplementary motor area (medial)?

Sequences and coordinates direct control of distal muscles

9

The primary somatosensory cortex (S1) corresponds to which Broadmann area?

3a: muscle proprioceptor region (also corresponds to areas 1-3)

10

What sort of information is integrated in the posterior parietal cortex?

Sensory integration from other brain regions (body image and environmental map)

11

What is the function of the pre-motor area (lateral)?

Intent and preparation of movement (reticulospinal; proximal muscles)

12

Which motor area is the main output to the spinal cord?

M1 - primary motor area

13

What is the name given to the rostal/ventral region of the lateral premotor area? What is this area responsible for and what Broadmann areas does it correspond to?

Broca's area - speech (Brodmann's areas 44 and 45)

14

The primary motor area (M1) corresponds to which Broadmann area?

4

15

The posterior parietal cortex corresponds to which Broadmann areas?

5 and 7

16

Which components of the motor system correspond to Broadmann area 6?

Pre-motor area and supplemetary motor area

17

Broadly speaking, what does the M1 area control?

Complex motor behaviours (rather than individual muscles)

18

Each cell in the M1 motor area 'votes' for a particular movement by coding for which 2 factors? What is the net result of this?

Force and direction. Net result is a vector sum of the population which will govern the final outcomes of movement force and direction

19

The posterior parietal cortex is the location of convergence of which sensory inputs?

Visual, auditory, somatosensory

20

It is believed that the PPC informs the premotor cortex of what information?

Positioning and movement status

21

Give one example of a disorder which may result from a lesion in the PPC

Affects sensory awareness and may lead to body integrity indentity disorder

22

Give at least 2 examples of sensory awareness integrated via the PPC

Awareness of the body, personal space (near space/within reach) and far space (out of reach)

23

The neural activity of the PPC is dependent on what factor?

The goal: highly active when reaching/searching/manipulating an object, but otherwise silent for similar 'goal-less' hand guestures'

24

Which motor area is thought to prime the M1 motor sequence for action?

Lateral premotor cortex

25

Give an example of what may happen if a lesion effects the lateral premotor cortex

This area is crucial for coordination on both sides of the body. Therefore, a lesion in this area on one side of the brain would cause deficits in fine motor tasks requiring both hands (for example)

26

What is the lateral premotor cortex thought to code for?

Intention to execute the appropriate motor behaviours in response to an external event

27

Describe what happens to the neurons in the lateral premotor cortex when an external cue is sensed and an appropriate motor behaviour is warranted

Neurons begin to fire at external cue (precedes motor commant o execute movement). Neurons fire until movement is triggered and are also active during the imagination of the motor task

28

The premotor cortex contains which specialised neurons?

Mirror motor neurons (respond to the goal of motor acts/intention of others)

29

Which neurons of the lateral premotor cortex are thought to be important for imitation learning of new motor tasks?

Mirror motor neurons

30

Which Broadmann areas are active when performing a motor task? How does this differ when the task is imagined only?

Both areas 4 and 6 involved in performing task, but only area 6 when imagining the task

31

Describe what might be the result of a lesion in the lateral premotor cortex

Lesions result in impairment of visually/verbally cued motor tasks, despite being able to perform the movement in another context

32

Which area of the motor system includes frontal eye fields and areas of the cingulate sulcus? What are each of these areas responsible for?

Supplementary motor area (SMA) - medial. Directs visual gaze towards a location of interest, and expression of emotional behaviour

33

Which motor area may be activated by memory (internal cues) rather than external cues?

Medial SMA

34

It is believed that the mirror motor neurons in the SMA may facilitate what?

Empathy

35

Which motor tracts connect the motor cortex directly with the spinal cord?

Lateral and ventral corticospinal tracts

36

Which motor tracts connect the brainstem with the spinal cord?

Bulbo-spinal tracts (reticulo-, rubro-, vestibulo- and tecto-)

37

Which fibres connect the motor cortex with the brainstem?

Corticobulbar fibres

38

Corticospinal fibres originate from which 2 cortexes?

Frontal and parietal

39

What are the cells of origin of the corticospinal fibres, and in which layer do they originate?

Triangular pyramidal cells in layer V of the cortex

40

What is the lateral corticospinal tract responsible for, and from where does it receive input?

Conscious control of movement. 80% from contralateral cortex and 10% from ipsilateral cortex

41

The ventral cortico-spinal tract receives 10% input from the ____ cortex

Ipsilateral

42

The cortico-spinal tracts originate from cells in M1, SMA, PMA, S1 and descend through the ____ ____, then the _____ ____. From here, they enter the _____ _____, pass through the ______ and enter the ____ on the ventral aspect of the medulla

Corona radiata and then the internal capsule. Enter cerebral peduncles. Pass through pons, enter pyramids

43

Which fibres cross over the corticospinal tracts as they pass through the pons?

Pontocerebellar fibres

44

The pyramids are located on the ____ surface of the medulla

Ventral

45

Discuss the fate of the fibres of the corticospinal tracts after entering the pyramids

80% of axons cross in the pyramidal decussation to form the lateral corticospinal tract. 10% do not cross and remain in the lateral CSP, and another 10% also remain on the ipsilateral side to form the anterior corticospinal tract (most of these them cross before entering the ventral horn)

46

Input from the corticospinal tracts travels to motor neuros that innervate skeletal muscles, especially _____

Flexors

47

Where do the corticobulbar fibres originate?

From cells in the head and face regions of the motor areas (lateral regions)

48

Describe the course of the corticobulbar fibres from their origin

Originate from cells in the had and face regions of the motor areas (lateral regions) and descend through the corona radiata, then the middle (around the genu) part of the internal capsule. Enter the cerebral peduncles medial to the corticospinals and sympase bilaterally on the motor nuclei of cranial nerves and in cells of the brainstem that make up the reticular formation

49

What is the principle neurotransmitter of the corticobulbar tract?

Glutamate (excitatory)

50

The corticobulbar tract provides no ipsilateral innervation of which neurons?

Lower facial motor neurons

51

Which of the extra-pyramidal motor tracts mainly terminate at the cervical levels?

Rubro-spinal, tecto-spinal and medial vestibulospinal

52

Which 3 extra-pyramidal motor tracts are crucial for life (posture, balance, gaze)?

Reticulo-spinal, texto-spinal and vestibulospinal

53

What is the rubro-spinal tract responsible for?

Auxillary control of flexors

54

What is the reticulo-spinal tract responsible for?

Antigravity extensors (modifies reflex control of extensors)

55

What is the Tecto-spinal tract responsible for?

Head orientation to external stimuli

56

What is the vestibulo-spinal tract responsible for?

Posture and balance

57

Where do the cells in the rubro-spinal tract originate?

In the red nucleus in the upper midbrain (level of the superior colliculus)

58

Where do the subro-spinal tract fibres cross?

In the midline in the midbrain or upper medulla

59

Where does the red nucleus receive input from?

Motor areas that are somatotopically organised

60

The rubro-spinal tract consist of discrete bundles of fibres in the lateral ____ and in the lateral spinal cord adjacent to the ______ tract

Medulla and lateral to the corticospinal tract

61

Where does the rubro-spinal tract terminate?

Mainly in cervical levels of spinal cord, intermediate region (Rexed V-VII)

62

What muscles do fibres from the rubro-spinal tract mainly innervate?

Flexor groups

63

What is the principle neurotransmitter of the rubro-spinal tract?

Glutamate (excitatory)

64

What is the reticular formation?

A complex network of cells and processes located just outside the periaqueductal grey matter that surrounds the cerebral aquedyct and fourth ventricle - runs entire length of the brainstem

65

The reticular formation gives rise to which 3 functionally distinct fibre systems?

1. Mediating motor functions 2. Mediating autonomic functions 3. Modulating pain signals

66

What is the purpose of the pontine/medial RS tract?

Activates spinal reflexes of antigravity muscles, helping to maintain posture (enhances spinal reflexes that hold the body upright) and stabilises in anticipation of other movements

67

Which 2 substances are contained within the pontine/medial RS tract?

Enkephalin (-) and substance P (+) and glutamate

68

Where does the pontine/medial RS tract originate?

From large cells in the pontine RF (nucleus reticularis pontis oralis and caudalis)

69

Where does the pointine/medial RS tract terminate?

In all levels of the spinal cord (VII and VIII) on ipsilateral alpha and gamma neurons

70

Where does the medullary/lateral RS tract originate?

From large cells in the medial medulla

71

Where do fibres from the medullary/lateral RS tract terminate?

At all levels of the spinal cord (VII and IX) on alpha and gamma motor neurons

72

What does the medullary/lateral RS tract do?

Inhibits antigravity (axial) muscles from reflex control (i.e., inhibits spinal reflexes that hold the body upright)

73

Describe the opposing effects of the lateral (medullary) and meidal (pontine) reticulo-spinal tracts

Lateral (medullary) = inhibits locomotion and postural control. Medial (pontine) = stimulates locomotion and postural control

74

Where do cells from the tecto-spinal tract originate?

Deep layers of the superior colliculus

75

The superior colliculus gets direct input from which systems?

Retina, visual cortex, somatosensory and auditory systems.

76

Describe the course of the tecto-spinal tract

Originate from superior colliculus and fibres cross midline in the midbrain and descend in contralateral medulla close to medial lemniscus.

77

Where do fibres from the tecto-spinal tract terminate?

In contralateral intermediate grey mater (Laminae VI and VII) in the cervical levels of the spinal cord

78

What is the primary role of the tecto-spinal tract?

Orientation reflexes of the head, especially towards auditory, visual and somatosensory stimuli

79

Where does the vestibulo-spinal tract originate from?

Cells in the lateral and medial vestibular nuclei of CN VII

80

Cells from the vestibular nuclei are relay cells that get input from cells in which 2 locations?

Vestibular ganglion (located in the internal acoustic meatus) and cerebellum

81

Discuss the course of fibres from the medial vestibular nucleus of CN VIII in the formation of the vestibulo-spinal tract

Fibres descend bilateraly in the medial longitudinal fasisculus to the lower medulla (spinal accessory nucleus) and upper cervical spinal cord to innervate muscles controlling head position and orientation reflexes

82

Discuss the course of fibres from the lateral vestibular nucleus of CN VIII in the formation of the vestibulo-spinal tract

Fibres project to all levels of the ipsilateral spinal cord

83

What is the purpose of the vestibulo-spinal tract?

Mainly innervate extensor groups, and help maintain posutre and balance

84

What is an upper motor neuron syndrome?

Refers to disruption of central motor pathways resulting from damage to the cortex or to fibres originating in the cortex

85

List at least 3 anatomical locations where disruption of central motor pathways can cause an upper motor neuron syndrome

Cortex, internal capsule (most common site), cerebral peduncles, lower medulla and lateral funiliculus of the spinal cord

86

What is the most common anatomical site of pathology for upper motor neuron syndrome, and in what condition does this occur?

Internal capsule - as a result of stroke

87

Describe why hypertonia and spasticity occur as a result of upper motor neuron disease

Loss of descending input into inhibitory neurons in the spinal cord, or loss of descending input to reticular formation, resulting in disinhibition of extensor muscle groups and/or gamma motor neurons

88

Describe and explain the posture seen in a patient with a lesion above the red nucleus

Decorticate posture: disinhibition of the red nucleus causes rubrospinal tract to dominate with flexion of the upper limbs. Disruption of the CST causes flexion from CST to be overridden by pontine reticulospinal and vestibulospinal tracts, resulting in lower body extension

89

Describe and explain the posture seen in a patient with a lesion below the red nucleus

Decerebate posture: extended neck and elbows with internally rotated feet and hands. Abnormal extensor posturing may result from innappropriate gamma motor neuron activity from loss of RST control

90

What are lower motor neuron lesions?

Damage t omotor neurons that make up peripheral nerves and innervate muscles

91

Lower motor neuron lesions may lead to what appearance in the affected muscles?

Fasciculations/fibrillations

92

What are the 5 steps of classical transmission (of a neuronal signal)

1. Synthesis (presynaptic - requiring specific enzymes) 2. Storage (presynaptic - requiring vesicular transport proteins) 3. Release into synaptic cleft via exocytosis or a constituative pathway 4. Binding to receptors 5. Termination

93

Termination of a classical neuronal signal is dependent on which 2 factors?

Transmitter type and extracellular space (tortuosity)

94

Describe the 5 main steps involved in a metabotropic neuron signalling pathway, and how this signal becomes amplified

1. NT activates multiple G proteins 2. Subunits of G proteins then activate many AC molecules 3. AC molecules create many molecules of cAMP 4. cAMP activate many PKA molecules 5. Each PKA can phosphorylate and open many K+ channels

95

What kind of receptor is involved in ionotropic neural signalling?

Ligand-gated ion channel

96

What kind of receptor is involved in metabotropic neural signalling?

7TM-receptor coupled to a G protein

97

Compare the speed of signal transmission in an ionotropic and metabotropic neural signal

Ionotropic = fast (less than 50ms). Metabotropic = slow (100ms to minutes)

98

The action of ionotropic pathways in neural signalling is dependent on which factor?

Concentration of neurotransmitter

99

Describe the principle of increased excitability in neurophysics

Excitability is increased if the same input current is able to generate more action potentials

100

In neurophysics, if the same current causes a larger voltage change, ____ is increased. Comment on how this is possible in the body.

Excitability - intrinsic properties of ion channels and membranes

101

Input current is _____ if it results in an increase in the rate of action potentials. This always causes ______

Excitatory. Depolarisation

102

Decrease in the rate of action potentials often causes _____polarisation

Hyperpolarisation

103

Glutamate receptor deactivation is via what mechanism?

Diffusion and re-uptake

104

Describe the glutamate cycle

EAATS remove glutamate from synaptic cleft and carry it into neurons and glial cells. Once in the glial cells, glutamate is converted to amino acid glutamine by the enyme glutamine synthetase. Glutamine is then transported back into neurons where it is converted back to glutamate

105

What is glutamate/aspartate?

Amino acid that acts as the most abundant neurotransmitter in the body and is used by every major excitatory pathway

106

What is the glutamate-glutamine cycle?

glutamate/glutamine cycle is a metabolic pathway that describes the release of glutamate or GABA from neurons which are then taken up into astrocytes (star shaped glial cells). In return, astrocytes release glutamine to be taken up into neurons for use as a precursor to the synthesis of glutamate or GABA

107

Glutamate present in the synaptic cleft after release from pre-synaptic neurons can be removed by which 3 mechanisms?

1. Uptake into the postsynaptic compartment 2. Re-uptake into the presynaptic compartment 3. Uptake into a third, nonneuronal compartment

108

What are EAATS and what is their function?

Transporter protein - excitatory amino acid transporters - remove glutamate from synaptic cleft. EAATS carry glutamate into neurons and glial cells.

109

List at least 3 ionotropic glutamate receptors

Kainate-type, AMPA-type and NMDA-type

110

Describe the structure of an NMDA receptor

4 subunits: NR1-2 with 2 glutamate binding sites

111

NMDA receptors are permeable to which 3 ions?

Na+, K+, and Ca2+

112

List the agonists and antagonists of NMDA receptors

Agonists = NMDA/experimental. Antagonists = APV, MK801, ketamine, memantine, phencyclidine

113

Describe the speed of activation/deactivation of an NMDA receptor

Slow - 20ms to over 100ms

114

What is the action/function of NMDA receptors?

Coincidence detector, important for synaptic plasticity, memory and learning

115

NMDA receptors can be voltage-dependently blocked by which substance?

Magnesium (at -40mV)

116

Most signalling pathways in the nervous sytem modulate which glutamate receptor?

NMDA

117

Name an antagonist of NMDA receptors that can be used as anaesthetic in children

Ketamine

118

Describe the structure of an AMPA receptor

4 subunits (iGluR1-4) with 2 binding sites occupied with glutamate.

119

AMPA receptors are permeable to which ions?

Na+, K+, and only some to Ca2+ (GluR2-deficient)

120

AMPA receptors are often co-localised with which other ionotropic glutamate receptor?

NMDA

121

Describe the speed of activation/deactivation of an AMPA receptor

Fast (less that 100 microseconds to about 1-10ms)

122

List the agonists and antagonists of AMPA receptors

Agonists = AMPA. Antagonists = NBQX, CNQX, DNQX, GYKI53655 > none clinically relevant

123

What is the action/function of AMPA receptors?

Fast CNS signalling; workhorse - most transmission in CNS is via AMPA receptor

124

What glutamate receptor is responsible for the most signal transmission in the CNS?

AMPA

125

Regarding the molecular biology of AMPA receptors: at synapses onto excitatory cells, heteromultimers contain ____, while at synapses onto inhibitory cells, heteromultimers lack this.

GluR2

126

What is the significance of the lack of GluR2 at AMPA inhibitory synapses? What is this property used to test for?

Inward rectification (polyamine block) and significanct calcium permeability > used to test for AMPA receptor recycling

127

Describe the different roles of AMPA receptor subunits (GluR1 and GluR2) at synapses

GluR1 = inerted during synapse formation in an activity-dependent way (CaMKII and NMDA-R dependent from dendrite). GluR2 = responsible for constituitive recycling

128

How often are GluR2 AMPA subunits recycled? Comment on what factors influence recycling rate.

Every 40 mins. Changes in recycling rates very in activity-dependent way (synaptic plasticity)

129

What are TARPs?

Transmembrane AMPA-R regulatory proteins - ancillary subunits

130

How do TARPs modulate AMPA-R activity?

By direct interavtion with the channel and by regulating trafficking of AMPA-Rs

131

Describe the waysin which TARPs can regulate trafficking of AMPA receptors

1. Can bring extra-synaptic receptors to sub-synapse 2. TARP phosphorylation stabilises AMPA receptors in PSD-95 3. Stabilises receptors in postsynaptic density to a raft size of about 100

132

Which transmembrane regulatory proteins are implicated in neurodegeneration and epilepsy?

TARPs

133

Describe the struture of a Kainate receptor

4 subunits: 2 binding sites for gluatamate

134

Kainate receptors are permeable to which ions?

Na+, K+, and some to Ca2+

135

Describe the speed of activation/deactivation of an kainate receptor

Fast = 100micro seconds/1-10ms

136

List the agonists and antagonists of kainate receptors

Agonists = kainic acid. Antagonists = LY 382884 (GluR5)

137

What is the action/function of kainate receptors?

Control of presynaptic release/inhibition: anaesthesia. Kainic acid also causes epilepsy

138

Kainic acid causes which neuro disorder?

Epilepsy

139

mGluR1-8 are found at which location?

Perisynaptically

140

Group II/III mGlu receptos (G-coupled) have what action? What is their role?

Inhibit AC, modulates K+ and Ca2+ channels and has inhibitory action on release > role is autoreceptor (decrease transmitter release)

141

Group I mGlu receptos (G-coupled) have what action? What is their role?

Activates PLC and can be excitatory in nature. Role is mainly postsynaptic.

142

G-couples mGluR1-8 have been implicated in which clinical pharmacology?

Experimental only (tumours, hypoxic insults, Parkinsons, fragile X syndrome)

143

What characteristic of glumatate makes it a contributor to disease?

Essential for normal transmission but can also potentially cause neuronal death

144

Discuss the sources of glutamate

1. Ingestion: MSG, plant alkaloids 2. Excitotoxicity where there is increased glutamate release (positive feedback)

145

Synthesis of GABA depends on synthesis of which other factor?

Glutamate

146

What is GABA responsible for?

GABA is Responsible for Relaxation of Brain and Muscle. GABA (gamma-aminobutyric acid) is an amino acid that is a major inhibitory neurotransmitter found throughout the nervous system and is important for down regulating excitatory inputs

147

How is GABA deactivated?

Via diffusion, uptake into glia and re-uptake as glutamine

148

The specific transporter for GAMA is located at which site?

Nerve terminal

149

Describe the structure of the GABA-A receptor

5 subunits with 2 binding sites for GABA on alpha subunits (2 alpha, 2 beta and 1 gamma subunit)

150

The GABA-A receptor is permeable to which ions?

Cl- and HCO3-

151

Describe the speed of activation/deactivation of the GABA-A receptor

Fast - 250micro seconds to 5-10ms

152

List the agonists and antagonists of the GABA-A receptor

Agonists = muscimol. Antagonists = picrotoxin, bicuculline and gabazine (potent convulsants)

153

What is the action of the GABA-A receptor?

Fast inhibition in the CNS

154

How are GABA-A receptors related to clinical pharmacology?

Involved in sleep (barbituates and benzodiazapines), anaesthesia and can be modulated by steroids

155

What effect do benzodiazapines have on GABA-A receptors?

Benzo's are positive allosteric modulators, so they increase the opening time of the receptor and the conductance. Bind to distinct benzodiazepine binding sites situated at the interface between the _- and _-subunits of _- and _-subunit containing GABAA receptors

156

What is Angelman syndrome and which neuro receptor is involved?

Neurodevelopmental disorder characterized by severe intellectual and developmental disability, sleep disturbance, seizures, jerky movements (especially hand-flapping), frequent laughter or smiling, and usually a happy demeanor. Loss of beta 3 unit in GABA subunit as part of deletion of chromosome 15

157

Which substance in high doeses increases GABA-A currents via direct interaction (i.e., falling asleep)?

Alcohol

158

What is the metabotropic GABA-B receptor permeable to?

Nothing

159

GABA-B receptors work by coupling to which other channels?

GIRK

160

Describe the speed of activation/deactivation of an GABA-B receptor

Slow - 50ms-250ms

161

What is the action of the GABA-B receptor?

Pre- and postsynaptic inhibition in the CNS (at the spinal and cortical levels)

162

List the agonists and antagonists of GABA-B receptors

Agonists = baclofen. Antagonists = salcophen, phaclophen

163

What are some of the slinical roles of GABA-B receptors?

Role in absence seizures, temporal lobe epilepsy (in mice)

164

Clinical agonists of GABA-B receptors are used in the treatment of what disorders?

Spinal spasticity, dystonia, some times of neuropathic pain and GORD

165

Clinical antagonists of GABA-B receptors are used in the experimental treatment of which disorders?

Cognitive decline, drug addiction, anxiety and visceral pain

166

What is the main important difference between ionotropic and metabotropic receptors?

Ionotropic are much faster, but metabotripic allow signal amplification despite being slower

167

GluRs are continually recycled, and the rate depends on _____?

Subunit composition

168

GABA-A receptors show a large molceular and pharmacological _____

Heterogeneity

169

Dorsal column lesions cause what symptoms?

Tingling parasthesia in all limbs (can cause loss of joint position sense and ataxia)

170

A mixed lesion of the cortico-spinal tract and spinothalamic tract can cause what symptoms?

Weak spastic legs and deep unpleasant spinothalamic sensations or pain and temperature loss

171

What is a dermatome?

The area supplied by a spinal sensory nerve root

172

The biceps jerk reflex tests which nerve/s?

C5(6)

173

The brachioradialis reflex tests which nerve/s?

C6

174

What is a myotome?

A set of muscles supplied by a spinal motor nerve root

175

Dermatome for the nipples

T4

176

Dermatome for the xiphoid process

T6

177

Dermatome for the umbilicus

T10

178

The triceps jerk reflex tests which nerve/s?

C7

179

The finger jerk reflex tests which nerve/s?

C8

180

The knee jerk reflex tests which nerve/s?

L4

181

The ankle jerk reflex tests which nerve/s?

S1

182

Damage to C5 nerve root

Biceps jerk

183

What is the likley site of pathology for UMN vs LMN lesions?

UMN (brain and spinal cord). LMN (nerves, nerve roots, plexus, possible spinal cord)

184

Describe how loss of decending inhibition in a UMN lesion affects stretch reflexes

Stretch reflexes overactive

185

Describe the changes in reflexes seen in a LMN lesion

Final output pathway from spine is damanged > Reflexes are reduced

186

____ motor neuron lesions lead to spasticity, whilst ____ motor neuron lesons lead to weakness

Upper, lower

187

Give an example of a specific sign of weakness observed in the lower limb/gait of a patient with a lower motor neuron lesion

Foot drop

188

What is meant by the pyramidal pattern of weakness seen in UMN lesions?

Relative preservation of upper limb flexors and lower limb extensors

189

List 2 reflexes that are usually positive in UMN lesions (which are also negative in LMN lesions)

Babinski and finger jerk (Hoffman's)

190

Compare and contrast atrophy seen in UMN vs LMN lesions

UMN - minimal atrophy proportional to disuse. LMN - marked atrophy

191

List at least 4 causes of spinal cord lesions

Trauma, extrinsic compression from disc or tumour, intrinsic mass such as a tumour or abscess, syrinx (expansion of CSF space in centre of cord), imflammatory lesions (MS, infective), vascular lesions and B12 deficiency

192

Vitamin B12 deficiency tends to affect which part of the spinal cord?

Dorsal columns

193

What is a syrinx?

Expansion of potential CSF space in centre of spinal cord (considered a cord lesion)

194

Symptoms of a cord lesion depend on which 2 factors?

1. Level of lesion 2. Which longitudinal tracts are disrupted

195

Describe what is the result of a transverse cord lesion in the lumbar spine

Lesion covers spinal cord segment, and impinges on all tracts. Result is vibration and position sense loss (posterior columns), pain and temperature sense loss (anterolateral pathways) and motor loss below the level of the lesion on both sides of the body

196

Sacral segments of the spinal cord are located predominantly next to which vertebrae?

L1

197

Pain and temperature fibres cross in the _____ _____ soon after entering the spinal cord

Anterior/ventral

198

When is a cord compression considered to be a true neurological emergency?

If progressing over the course of hours-days

199

Describe what is seen in a hemicord lesion (Brown-Sequard syndrome) of the lower spine

Half spinal cord damaged (i.e, plaque in half of spinal cord impinging on all tracts on one side). Results is loss of vibration and position sense loss (dorsal column) plus weakness in the leg on the side of the lesion (motor loss), but there is pain and temperature sense loss in the opposite leg (due to loss of dorsal tract which does not decussate at the level of the spinal cord and spinothalamicinvolvement which crosses a the level of the lesion)

200

Describe what is seen in a central cord syndrome (small lesion) of the cervical region

Small lesion on middle of cervical cord = can affect spinothalamic pathways (which cross in the middle of the cord at the level of the lesion and can therefore interfere with a small segment of spinothalamic supply (i.e., over shoulders - 'cape' distribution)

201

Describe what is seen in a large lesion central cord lesion at the level of the cervical cord

Affects all tracts (possibly sparing periphery). All vibration/position sense, pain and temperature and motor function will be affected below the level of the lesion. Sometimes the groin in spared, as information to this area is often at the most peripheral sites in the cord

202

Describe what is seen in a posterior cord syndrome of a cervical cord lesion. What could cause this syndrome?

B12 deficiency - lose vibration and position sense below the level of the lesion (as dorsal tracts affected)

203

Describe what is seen in an anterior cord syndrome

Loss of motor pathways and spinothalamic pathways anteriorly (motor function, loss of pain and temperature sense) but preserved dorsal tract vibration and position sense

204

Prognosis of cord compression depends on what factor?

Severity of deficits at the time that compression is relieved

205

Why can cervical spondylosis cause cord compression?

Degenerative disease - may lead to disc bulges, osteophyte development, buckling of ligamentum flavum narrowing of central canal (in congential cases)

206

List at least 3 causes of cord compression

1. Degenerative disease (cervical sponylosis) 2. Thoracic disc prolapse 3. Tumours 4. Haematoma or abscess

207

Why is cord compression common in the cervical region?

Due to the high mbility of the spine in this region

208

Explain why cord compression in the cervical region can present with a mixed UMN/LMN picture

LMN signs in upper limbs but also interference in descending tracts - will reach lower limbs and present with UMN signs

209

Describe what structures are affected flexion and extension of the cervical spine in cervical spondylosis

Flexion: cord stretched over spondylotic bar. Extension: ligamentum flavum buckles

210

What is the most common cause of cauda equina syndrome?

Disc prolapse

211

Describe the presentation of cord compression due to cervical spondylosis

Created predominantly motor presentation in the legs with LMN and sensory signs in the arms

212

List at least 3 syndromes that can be caused by cord compression

1. Transverse cord lesion 2. Anterio motor dominant syndrome 3. Posterior cord syndrome 4. Pseudocerebellar syndrome (from loss of dorsal columns and spinocerebellar tracts) 5. Mixed hemicord lesion and transverse lesion syndrome

213

What is hyperaesthesia?

Excessive physical sensitivity, especially of the skin

214

Describe the evolution of cord compression

Early picture often dominated by spastic weakness, hyperaesthesia, tight girdle sensation, pain and temperature loss (similar to Brown-Sequard syndrome). Can lead to complete paraplegia if untreated

215

List at least 3 lesions of the PNS that can produce LMN weakness and/or sensory change

Cauda equina syndrome (most common), radiculopathies, plexus lesions, neuropathies

216

What does cauda equina syndrome refer to?

Dysfunction of most of the descending nerve roots within the lumbar spinal canal

217

List at least 5 causes of cauda equina syndrome

Central lumbar disc prolapse, epidural metastasis, benign tumour, trauma, abscess

218

List at least 3 typical features of cauda equina syndrome

Sensory loss in saddle area (dermatome S2-S5). Distended atonic bladder, constipation, decreased anal/rectal tone, faecal incontinence, loss of erectile function

219

Cauda equina syndrome may cause weakness in sacral myotomes, leading to flexion of which joints?

Knee flexion and ankle plantar flexion

220

A central disc prolapse may cause cauda equina syndrome, whereas a lateral disc prolapse more typically causes what?

Isolated radiculopathy

221

Radiculopathy is pathology of which strucutre?

Nerve root

222

List the 2 most common causes of radiculopathy

1. Compression at the neural exit foramen due to disc prolapse, facet joint hypertrophy and/or osteophytes 2. Compression of the descending root within the central canal (most common in lumbar and sacral region)

223

List at least 2 non-compressive causes of radiculopathy

Trauma, auto-immune inflammation, malignant infiltration and infection

224

What are the sensory symptoms of radiculopathy?

Pain in the affected dermatome and sensory loss/change in affected dermatome

225

What are the motor symptoms of radiculopathy?

LMN weakness in the affected myotome, and attenuation of the corresponding tendon reflex

226

What are the associated symptoms of radiculopathy?

Back pain, lumbar/cervical muscle spasm, postural change, intolerance of head movements or straight leg raising

227

Describe the symptoms of radiculopathy is the C5 nerve root is affected

Upper lateral arm changes (but never below elbow)

228

Describe the symptoms of radiculopathy is the C6 nerve root is affected

Lower lateral arm changes, and into thumb if pain goes into hand

229

Describe the symptoms of radiculopathy is the C7 nerve root is affected

Deep pain in triceps and front and back of forearm and into middle finger

230

Describe the symptoms of radiculopathy is the C8 nerve root is affected

Pain in medial forearm and into the 2 medial fingers

231

Describe the symptoms of radiculopathy is the T1 nerve root is affected

Deep pain in the axilla and shoulder with some radiation down inside of upper arm

232

List the symptoms and signs common in cases of cervical spondylosis with radiculopathy

Mixed upper and lower motor neuron signs, often with a dermatomal sensory disturbance from the radiculopathy. There is absence of biceps and supinator reflexes withbrisk triceps reflex

233

Absent biceps and supinator reflexes with brisk triceps reflex is nearly pathognomonic for which disease?

Cervical spondylosis with radiculopathy

234

List at least 3 factors which may cause damage to the brachial plexus

Penetrating trauma, traction injuries (childbirth), malignany infiltration, radiation injury

235

List an upper trunk lesions with proximal lesions and a lower trunk lesion with distal weakness

Erb-Duchenne Palsy, Klumpke's Palsy

236

Compare and contrast the difference between mononeuropathy, peripheral neuropathy and mononeuritis multiplex

Mononeuropathies = lesions of individual nerves. Peripheral neuropathy = generalised disease of most of the nerves, with the longer nerves most prominantly affected. Mononeuritis multiplex = multiple individual nerves affected in a patchy fasion

237

Describe motor functions of the radial nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = extension at all arm, wrist and finder joints below the shoulder, forearm supination, thumb abduction. Region of sensory loss with neuropathy = posterior cutaneous nerve of arm and forearm and dorsal digital nerves

238

Describe motor functions of the median nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = thumb flexion and opposition, flexion of digits 2 and 3, wirst flesion and abduction and forearm pronation. Region of sensory loss = median nerve (thumb plus 2 and a half fingers (half of ring finger) and back of same fingers

239

Describe motor functions of the ulnar nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = finger adduction and abduction other than thumb, thumb adduction, flexion of digits 4 and 5, wrist flexion and adduction. Sensory loss = ulnar nerve (1 and a half lateral fingers - half of ring finger and pinky)

240

Describe motor functions of the axillary nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = abduction of arm at shoulder beyond first 15 degrees. Sensory loss in upper outer arm

241

Describe motor functions of the musculocutaneous nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = Flexion of arm at elbow, supination of forearm. Sensory loss in lateral cutaneous nerve of forearm

242

What is meralgia parasthetica?

Pain from lateral cutaneous nerve of the thigh

243

How can common peroneal nerve lesions and L5 lesions be distinguished?

Peroneal nerve lesions spare tibialis posterior and the hamstrings

244

Describe motor functions of the femoral nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = leg flexion at the hip, leg extension at the knee. Sensory loss = femoral nerve and saphenous nerve distribution (anteriomedial leg, including knee and medial calf)

245

Describe motor functions of the obturator nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = Adduction of the thigh. Sensory loss = small field on inner medial thigh

246

Describe motor functions of the sciatic nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = Leg flexion at the knee. Sensory loss = Common peroneal nerve, sural nerve, posterior tibial nerve (calf, sole of foot, lateral side of top of foot and lateral melleolus

247

Describe motor functions of the tibial nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = foot plantar flexion and inversion, toe flexion. Sensory loss = sole of foot and lateral foot, including toes

248

Describe motor functions of the superficial peroneal nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = foot eversion. Sensory loss = lateral loweer leg, including top of foot and toes

249

Describe motor functions of the deep peroneal nerve and comment on what regions would be affected by sensory loss with neuropathy

Motor functions = foot dorsiflexion and toe extension. Sensory loss = medial half of big toe

250

List at least 3 common conributing causes to carpal tunnel syndrome

Arthritis, fluid retention, pregnancy and overuse

251

Which muscles show weakness in carpal tunnel syndrome?

Thenar eminence (LOAF muscles), especially the abductor pollicis brevis

252

Carpal tunnel syndrome typically causes paraesthesia in which parts of the hand?

Thumb and adjacent 2 and a half digits, sparing sensation over the thenar eminence

253

What are the LOAF muscles?

Lumbricals 1 and 2, Opponens pollicis, Abductor pollicis brevis and flexor pollicis brevis

254

Why is ulnar nerve compression at the elbow more common in women?

Due to naturally increased carrying angle

255

Describe the common presentation of ulnar compression at the elbow

Weakness of FDP on the medial side, and all intrinsic muscles of the hand APART from the medial LOAF muscles. Causes sensory loss in lateral 1.5 digits and adjacent palm

256

Describe the appearance of the ulnar claw hand and comment on what it is suggestive of

Highly suggestive of ulnar nerve lesion. Involves hyperextension at MCP and flexion and PIP and DIP joints on the ulnar side of the hand.

257

Describe the mechanism underlying a presentation of ulnar claw hand

Loss of lumbrical function with preservation of MCP extensors (radial nerve), PIP flexors (median nerve) and possibly DIP flexors (proximal ulnar nerve)

258

Why is ulnar claw hand less severe with proximal ulnar nerve lesions?

Because the long finger flexors of the DIP joints, if spared, exaggerate the clae

259

What is Froment's sign in ulnar neuropathy?

Weakness of thumb adduction (first interossus - ulnar nerve) with compensatory flexion of thumb IP joint (FPL: medial nerve via anterior interosseus nerve)

260

Describe the presentation of radial nerve entrapment neuropathy in the hand

Wrist drop and sensory loss on dorsum of hand

261

Why is radial nerve entrapment neuropathy sometimes called "Saturday night Palsy"?

Radial nerve may be compressed in spinal groove of humerus while sleeping drunk in a chair

262

Peripheral neuropathy classically affects longer fibres first, leading to what classical pattern?

Glove and stocking pattern

263

List at least 5 causes of peripheral neuropathy

Alcoholism, autoimune diseases, diabetes, exposure to poisoning/heavy metals, medications (chemo), infections, vitamin deficiencies, bone marrow disorders

264

List the deep 4 layers of the posterior segment of the eye, and state where the blood supply originates

Nerve fibre layer, ganglion cell layer, inner plexiform layer and inner nuclear layer. Blood supply from retinal vessels (branches of opthalmic artery)

265

The retinal blood vessels are braches of which main artery?

Ophthalmic

266

List the superficial 4 layers of the posterior segment of the eye, and state how these layers are oxygenated

Outer plexiform layer, outer nuclear layer, inner segments (outer segments) and retinal pigmented epithelium. This are is avascular and is oxygenated by diffusion from the choroidal blood supply that lies outside the retina

267

The retina is technically part of which organ?

Brain

268

Developmentally, what is the retina derived from?

Forebrain vesicle (i.e., neural retina + retinal pigmented epithelium)

269

The outer aspect of the retina contain what type of cell? What is this cell responsible for?

Photoreceptors: transduce light into electrical signals

270

Which structure of the posterior eye is essential to phototransduction?

Rentinal pigmented epithelium (RPE)

271

____ cells on the inner aspect of the retina send processed signals to the brain

Ganglion cells

272

Which cranial nerve can be considered as a 'tract'?

Optic nerve

273

Light passing through the cornea and central lens is brought to focus on what structure of the posterior eye?

Foeva centralis

274

The foeva of the eye exists within which other structure?

The macula

275

Cell bodies of photoreceptors are located in which layer?

Outer nuclear layer (ONL)

276

Describe how light is processed by the eye

1. Transduction of light into electrical signal in outer segments of photoreceptors 2. Signals filtered and relayed via interneurons in the inner nuclear layer (INL) 3. Ganglion cells of the ganglion cell layer (GCL) receive the signals and pass them onto the primary relay nuclei of the brain via the optic nerve (CNII)

277

Interneurons that are responsible for filtering and relaying light electrical signals in the eye exist in which layer of the posterior eye?

Inner nuclear layer (INL)

278

Most humans have ___ types of cone photoreceptors (opsins) in the eye, each with a peak sensitivity at a different wavelength in the ___, ___ and ___ ranges

3 - blue, green and red ranges

279

Perceived colour is determine by the relative activation of which 3 photoreceptor types?

S, M and L cones

280

Quote the wavelengths that correspond with S-cones, M-cones and L-cones

S (430nm), M (530nm) and L (560nm)

281

The L-opsin gene has arisen as a mutation of which other gene, making the 2 almost identical?

M-opsin

282

Genes for the M and L-opsins are on which chromosome? What does this mean, clinically?

X-chromosome: leads to higher incidence of colour vision defects in males compared with females

283

What is opsin and what is it for?

Opsins are a group of light-sensitive proteins found in photoreceptor cells of the retina which mediate the conversion of a photon of light into an electrochemical signal, the first step in the visual transduction cascade

284

What is the light-sensitive protein in rod photoreceptors?

Rhodopsin

285

The majority of photoreceptors in mammalian eyes are _____

Rods

286

What is rhodopsin most sensitive for?

Vision in low light conditions (scotopic vision)

287

Which photoreceptor type is responsible for scotopic vision?

Rods

288

Rhodopsin is _____ under daylight conditions

Bleached

289

What is scotopic vision?

The vision of the eye under low-light conditions

290

The pherule of a rod = the ___ of the cone

Pedicle

291

Which photoreceptor type has a longer/thicker axon?

Cone

292

Which photoreceptor type has more mitochondria?

Cone

293

Discuss the distribution of cones in the human eye

More numerous in central retina and at very low density in peripheral retina

294

Under what conditions are cones used in vision?

In high illumination conditions (daylight and artificial light) - photopic vision

295

Both rods and cones release ____ in the dark, which is shut off by light

Glutamate

296

Photoreceptors consume most of their energy in what situation?

In the dark (because both rods and cones release glutamate in the dark)

297

What characteristic of cones means that they are more useful in photopic conditions?

They cannot be saturated

298

In what specific structure of the eye are rods completely absent?

Foeva (and reduced in number in the macula)

299

Which specific cones are NOT present in the foeva?

S-cones (blue light, short wavelength)

300

Which two subtypes of cones reach peak density in the foeva?

M (green) and L cones (red)

301

List the 3 most abundant ganglion cell types in the eye, and comment on how they are distinguished

1. Parasol 2. Midget 3. Bistratified - distinguished based on shape and size

302

Compare and contrast the shape of parasol, midget and bistratified ganglion cells in the eye

Parasol and midget have similar branching patterns, whilst bistratified branch less frequently and in a different pattern

303

How can parasol and midget ganglion cells of the eye be distinguished?

Morphologically by size, as a function of eccentricity

304

Which ganglion cells of the eye provide information about red/green colours to the brain?

Midget ganglion cells

305

Which ganglion cells comprise 70-80% of all ganglion cells in the human retina?

Midget ganglion cells

306

What is the result of the 1:1 ratio of midget GC and cones?

Excellent visual accuity

307

What information do midget and parasol ganglion cells in the human eye code?

Code either on or off responses to light

308

Which ganglion cells of the human eye have large cell bodies and dendritic fields, and comprise 15% of the total ganglion cell population in the retina?

Parasol cells

309

Where are parasol ganglion cells mostly concentrated?

In the peripheral retina

310

Where are midget ganglion cells mostly concentrated?

In the foeval and macula region

311

Which ganglion cell of the eye is involved in pathways that resolve fine detail?

Midget ganglion cells

312

Describe how parasol cells enhance sensitivity in vision

One parasol cell may get information from up to 150 cones (converging pathway) > enhances sensitivity

313

Which ganglion cells of the eye are involved in detecting 'form' and contrast/motion?

Parasol cells

314

Bistratified ganglion cells in the eye receive input from which subset of cones?

S-cones (blue light, short wavelength)

315

What is the difference between off and on responses coded by midget cells, parasol cells and bistratified gangion cells in the eye?

Midget and parasol cells code EITHER on or off, whilst bistratified cells code BOTH on or off responses

316

Bistratified ganglion cells in the eye are involved in the detection of which colours?

Yellow/blue

317

Descibe the distribution of bistratified ganglion cells in the human eye

Approximately uniform

318

Compare the conduction velocities of parasol, midget and bistratified ganglion cells in the eye

Parasol - fast. Midget - slow. Bistratified - medium.

319

What colour response are parasol ganglion cells in the eye responsible for?

None

320

What is the funciton of bistratified ganglion cells in the eye?

Colour vision; medium contrast sensitivity

321

Which pathway do parasol ganglion cells of the eye operate in?

Magonocellular (M-pathway)

322

Which pathway do midget ganglion cells of the eye operate in?

Parvocellular (P-pathway)

323

Which pathway do bistratified ganglion cells of the eye operate in?

Koniocellular pathway

324

What is the name given to the term used to describe different lines of information converging on a retintopically mapped region in the cortex (V1)?

Parallel processing

325

Discuss the vascularity of the macular and foeva, and commen on why this is of key importance to optical quality

Reduced vascularity in macula and complete absence of retinal vessels from foeva - key importance to optical quality because it prevents shadowing of the photoreceptors by vessels and blood cells

326

Which structure in the eye is responsible for the physiological blind spot?

Optic disc

327

The optic disc is the site for which structures?

Sensory fibres (ganglion cell axons) to exit the eye on the way to the brain (these fibres constitute the optic nerve CNII)

328

Which fibres make up the optic nerve, and where does this exit the eye?

Sensory fibres (glangion cell axons) - leave via optic disc

329

25% of the ganglioncells that enter the optic nerve come from which part of the eye?

The central 2mm of the retina, including the foeva

330

What sort of vision is the macula responsible for?

Almost all 'useful' vision - reading, recognising faces, discriminating details

331

The macula contains what sort of pigments? What is this area called?

Yellow xanthophyll pigments (vitamin A derivatives) . Referred to as the macular lutea

332

What is the purpose of the yellow pigments in the macula?

Filter damaging short wave length light

333

What would be the result of a 2mm lesion centred on the foeva?

Loss of 25% ganglion cell input into the brain (90% from Midget pathways) > legal blindness

334

Visual acuity is best at what structure in the eye?

Foeva

335

Visual acuity is a function of which factors?

1. Number and type of cells present at retinal location (photoreceptors, bipolar cells and ganglion cells) 2. Amount of convergence built into the retinal circuits at that location

336

What is visual accuity?

A measure of how much detail our visual systems can resolve

337

What is the legal acuity definition of blindness?

6/60.

338

Axons arising from ____ cells enter the optic nerve at the _____ -____

Ganglion cells, optic disc

339

Axons from temporal retina project to he ____ side of the brain, while axons from the nasal retina project to the ____ side

Temporal = ipsilaterally, Nasal = contralaterally

340

Axons and blood vessels in the retina avoid crossing which line? What is the other name for this arrangement?

Avoid crossing the horizontal meridian 'the temporal raphe'

341

What is the temporal raphe of the eye?

A horizontal line of demarcation on the temporal side of the macula, separating the arcuate nerve fibres from the upper and lower retina

342

What % of optic axons cross at the optic chiasm?

50%

343

Ganglion cell axons leaving the eye project to which 4 major structures/areas?

1. Nucleus of the optic tract 2. Pretectal area 3. Superior colliculus 4. Dorsal lateral geniculate nucleus (thalamus)

344

Part of the pretectal area send projections to the medial _____ area

Vestibular

345

Nucleus of the optic tract cells are preferentially stimulated by what? In which direction does this occur?

Movement at low velocity, in temporal to nasal direction

346

Over activation of the nucleus of the optic tract cells induces what clinical sign?

Nystagmus

347

Where is the rretectal area located?

Just rostral to the midbrain

348

The pretectal area receives input from what cell types?

Melanopsin-containing ganglion cells

349

The pretectum projects bilaterally into the parasympathetic nuclei of which cranial nerve? What is this nucleus called?

CN III (Occulomotor). Edinger-Westphal

350

Which reflex is controlled by the pretectal area?

Pupillary reflex

351

Output from the Edinger-Westphal nucleus sympase in ipsilateral ciliary ganglion of the iris to mediate what response?

Mediate pupillary response to light

352

What is the superior colliculus responsible for?

Visual, auditory and somato-sensory coordination

353

Superficial layers of the superior colliculus receive mapped input from which areas?

Retina and visual cortex

354

The superior colliculus coordinates rapid _____ eye movements to orient gaze toward novel stimuli

Saccadic

355

All sensory information destines for conscious perception much pass through which brain structure before reaching the cortex?

Thalamus

356

The dorsal lateral geniculate nucleus (thalamus) received abundant mapped input from which structure? What does it do with this information?

From the retina - projects processed information onto the primary visual striate, cortex V1

357

Describe layers 1 and 2 of the dorsal lateral geniculate nucleus

Large cells (magnocellular layers)

358

Describe layers 3-6 of the dorsal lateral geniculate nucleus

Small cells (parvocellular layers)

359

Which cells exists between layers 1 and 2, and layers 3-6 of the dorsal lateral geniculate nucleus?

Clusters of very small cells (koniocullular layers)

360

Small ____ ganglion cells project into the koniocellular layers of the dorsal lateral geniculate nucleus

bistratified

361

____ ganglion cells project into the magnocellular layers of the dorsal lateral geniculate nucleus

Parasol

362

Midget ganglion cells project into the _____ layers of the dorsal lateral geniculate nucleus

Parvocellular (P-pathway)

363

The left half of the visual field projects to the ____ dorsal lateral geniculate nucleus, and vise versa

Right

364

The right hemifield is represented in the left ____ cortex, surrounding the _____ sulcus

occipital, calcarine

365

What is the name given to the region in the right visual hemifield that is seen by both eyes?

Right binocular hemifield

366

The extreme right visual field is represented anteriorly in ____, near the _____ sulcus

V1. Near the parieto-occipital sulcus

367

Explain why the macular representation at the posterior pole is greatly magnified

Due to the large number of ganglion cells present in the central retina

368

Fibres forming the optic radiation pass lateral to which structure before reaching V1?

Third ventricle

369

Describe the passage of fibres from the upper visual field to the formation of the Meyer's loop

Fibres carrying information from the upper visual field pass anteriorly then inferiorly to the inferior limb of the 3rd ventricle, to form the Meyer's loop

370

The ocular dominance column exist in which part of the brain?

Striate cortex (area 17)

371

What name is given to the disorder when visual deprivation involving one eye results in the non-deprived eye taking over the territories of the deprived eye?

Ambylopia

372

V1 receives all projection fibres from which nucleus?

Dorsal lateral geniculate nucleus

373

Into which 2 areas does V1 project?

18 and 19

374

Most information from the magnocellular pathway enters the _____ stream. And carries information about _____

Dorsal stream, motion

375

Most information from the parvocellular pathway enters the ____ stream, carrying informtaiton about ____, ____ and ____

Ventral - form, position and colour