Biological Flashcards
(276 cards)
1
Q
View of the mind - Aristotle (348 BC)
A
Cardiocentric hypothesis - heart controlled thoughts, sensations and body movements, brain function was to cool the heat/passions of the heart
(Heart as centre of the mind, brain as not essential)
2
Q
View of the mind - Descartes (1596-1650)
A
Mind and body = completely seperate
Dualism = philosophical position that behaviour is controlled by two entities
Only point of interaction = pineal body (mind controls body through pineal body)
3
Q
View of the mind & brain - Gall (1758 - 1828)
A
Mind is composed of multiple distinct, innate faculties, each must have a separate seat or ‘organ’ in the brain
Size of an organ = measure of its power
Shape of brain is determined by development of the organs
Surface of skull shows psychological aptitudes and tendencies - phrenology e.g. Larvey’s Electric Phrenometer 1907 - measures shape of skull and determined psychological tendencies from this
4
Q
View of the brain - Camillo Golgi (1843-1926)
A
Holistic - brain is large network of interconnected tubes (neurons) so functions cannot be localised
5
Q
Brain research - Santiago Ramon y Cajal (1852 - 1934)
A
Correctly showed that nerve cells are discrete entities
6
Q
Brain research - Brodmann (1908)
A
Map of the brain (motor and visual areas)
7
Q
Brain research - Karl Kleist (1879-1960)
A
Comprehensive functional mapping of the cerebral cortex from case notes of WW1 head wound casualties
8
Q
Brain research - Bailey and von Bonin (1951)
A
Found cortico-cortical connections (connections of neurons) in chimpanzees - some connections stretch further than others and all regions are connected in some way
9
Q
What is cytoarchitecture and what is synaptic pruning?
A
Cellular composition of CNS tissues under a microscope (the way neurons connect in the brain)
Looks at:
- Anatomical and functional connections
- Synaptic pruning (neurons not frequently activated together will lose their connectivity)
- Two neurons firing together often - connection is strengthened
10
Q
What is neuropsychology? Phineas Gage and issues of brain damage research?
A
Behavioural expression of brain function - looks at brain damage and related behavioural changes
Phineas Gage - frontal lobe damage led to personality change
However, brain damage not always perfectly localised - other regions affected/ multiple behavioural problems - one-to-one correspondence is difficult to establish
11
Q
What are brain imaging techniques?
A
MRI - brain anatomy
- Magnetic field aligns water molecules in one direction, when radio wave is applied water molecules move differently and this can create images/map of the brain
fMRI - brain function (specific behaviour)
- Tracks blood flow
- Subtraction method = stimulation - control = brain area for specific function
12
Q
What are brain listening techniques?
A
Single cell recordings - Hubel and Wiesel (1959) - electrode inserted right down to neuron, certain stimuli gives a cell response
EEG (electroencephalography) - electrical activity in the brain in wave form
ERP (event-related potentials) - task repeated 100 times, wave form associated with certain task
13
Q
What are brain stimulating techniques?
A
Direct brain stimulation - electrodes directly on brain regions - observe behaviour
TMS (transcranial magnetic stimulation) - coil creates magnetic field over certain brain region (stimulate and depress) - creates electrical activity inside the tissue in a non-invasive way
- Can be used in conjunction with MRI for more accurate targeting of brain regions
14
Q
What are the temporal and spatial resolutions of brain imaging, listening and stimulating techniques?
A
High temporal resolution = EEG, ERP
Medium temporal resolution = TMS
Low temporal resolution = fMRI, MRI, CT
High spatial resolution = fMRI, MRI, single cell recordings and microstimulation
Medium spatial resolution = TMS
Low spatial resolution = EEG, ERP
15
Q
What are causal issues with brain imaging, listening and stimulating techniques?
A
Area lighting up when certain task is performed does not imply the area is directly involved - could be passing information to another area
Complex behaviours often require coordinated activity of many brain areas
Functions are both localised and distributed
16
Q
What is electrical and electrochemical communication?
A
Electrical = communication down axon
Communication between neurons (synapse) = electrochemical
17
Q
What are structures of the neuron and how do these carry information?
A
Cell body - containing organelles
Dendrites - gather information from nearby neurons and send to cell body
- If there is enough info the cell body sends this to the axon (electrical) and signal travels to the pre-synaptic terminal and synapse (chemical)
18
Q
What is the structure and direction of a sensory neuron?
A
PNS to CNS
Cell body in the middle - dendrites, cell body, axon, pre-synaptic terminal
19
Q
What is the structure and direction of a motor neuron?
A
CNS to PNS
Cell body at the end - dendrites, cell body, axon, pre-synaptic terminal
20
Q
What is the role of the neuronal membrane?
A
To separate intracellular and extracellular fluid
Contains ion pumps and ion channels that control movement of ions in and out of the cell, this movement causes electrical signals
21
Q
Ion channels are _ gated?
A
Voltage gated, ligand gated (chemical), mechanical gated (e.g. stretching of the skin)
22
Q
What ions move in and out of neurons?
A
Na+, K+, Cl-, A- (large negative ions)
Ion channels only allow specific ions to move through neuronal membrane
23
Q
Which two forces determine ion movement in a neuron?
A
1) Concentration (high to low density - diffusion)
2) Electrical (negative or positive - always seeking to balance electrical charge)
24
Q
What happens in a neuron during resting potential?
A
Na+ channels are closed
Some K+ channels are open
K+ moves in as it is more negative inside than outside (electrochemical gradient), and moves out of the cell as there is now less K+ there (concentration gradient)
Sodium potassium pump = 3 Na+ out, 2 K+ in
Inside of cell more negative than outside
High K+ conc inside, high Na+ conc outside
25
What is the equilibrium potential of K+ during resting potential?
-90mv
26
What happens in a neuron during action potential?
Stimulus causes -65mv charge to increase to -50mv and threshold potential is met
Voltage-gated Na+ channels open, Na+ goes inside due to concentration and electrical gradients
Inside of cell becomes more positive (depolarisation) and has higher concentration of Na+
Peak of AP = +40mv, at this point voltage-gated K+ channels open
Positive K+ ions are attracted to the now negative low concentration of K+ outside of the cell so they move out
Loss of K+ = neuron more negative (hyperpolarisation) prevents AP from moving backwards as it is too negative to reach threshold potential
27
What is the charge during resting potential?
-65mv
28
What is the charge during threshold potential?
-50mv (this causes action potential)
29
What happens during saltatory conduction?
AP is propagated quickly down the axon to pre-synaptic terminals due to myelination
Myelin sheath contains myelin - fatty substance that wraps tightly around the axon - produced by Schwann cells
Exchange of ions (excitation) occurs at the Nodes of Ranvier - only part of myelinated axon that can generate an action potential
Occurs from CNS (oligodendrocytes) to PNS
30
Why is there a refractory period after an action potential?
AP = all or nothing event
Another action potential cannot be created before the preceding one is finished (hyperpolarisation)
If there is a stronger stimulus, refractory period still occurs but there is an increased firing rate of more AP's per second
31
What broadly happens during synaptic transmission?
At the presynaptic terminal a chemical neurotransmitter is released out of vesicles into the synaptic cleft
Neurotransmitters bind to ligand-gated ion channels in the post synaptic membrane
The postsynaptic potential - neurotransmitter can have an excitatory or inhibitory effect
Cell body of next neuron collects all excitatory and inhibitory potentials to determine if threshold is reached to trigger AP in next neuron
32
Why do seizures occur in conditions like epilepsy?
Balance between excitation and inhibition breaks down causing uncontrollable patterns of electrical activity (seizures)
33
What is a synapse?
Gap between two neurons, where electrical is converted to chemical to transfer AP to the next neuron
34
What happens during synaptic transmission?
1) Presynaptic terminal - voltage gated Ca channels open
2) Synaptic cleft rich in Ca, so when channels open Ca moves into pre-synaptic terminal and binds to vesicles
3) Vesicles fuse with presynaptic membrane and neurotransmitters are released into synapse
More calcium released = more neurotransmitters released = AP will continue into next neuron
35
What are neuromuscular junctions?
Synapses that cause movement that form between neurons and muscles
Axons of neurons that activate muscles are in the spinal cord
36
What is ALS? (amyotrophic lateral sclerosis)
Disease that affects neuromuscular junctions - gradually restricts movement and eventually results in death
37
What are ionotropic neurotransmitter receptors?
These receptors are proteins found on dendrites
Neurotransmitter binds to receptors and an ion channel opens (selective to certain types of neurotransmitters)
(Like a competitive inhibitor)
38
What are metabotropic neurotransmitter receptors?
Indirect - neurotransmitter binds to binding site, the alpha subunit detaches and causes ion channel to open
Influence function more slowly and their effect is longer lasting compared to ionotropic
(Like a non-competitive inhibitor)
39
What synapses are excitatory and inhibitory neurotransmitters released at?
Type 1 synapses = excitatory
Type 2 synapses = inhibitory
40
What do excitatory and inhibitory neurotransmitters cause an influx of?
Bind to receptors that cause Na+ influx = excitatory
Bind to receptors that cause Cl- influx = inhibitory
41
What is synaptic integration? (Summation)
An AP loses some of its electrical charge as it travels down axon, so neuron (axon hillock) collects charge from multiple APs through summation - results in an excitatory post synaptic potential
42
What happens if neurotransmitters are not removed from the synapse? (Examples of glutamate and mustard gas)
If not removed - prolonged activation
E.g. If there is reduced blood flow to the brain then glutamate is not removed from synapse - results in damage to postsynaptic neurons causing excitotoxicity and resulting in stroke
E.g. Mustard gas prevents deactivation of acetylcholine
43
What is glutamate?
Brain's major excitatory neurotransmitter (vital for learning and memory)
44
What is GABA?
Brain's main inhibitory neurotransmitter
45
What is dopamine?
Neurotransmitter for movement control and reward circuits
46
What is serotonin?
Feel good chemical neurotransmitter - affects mood and anxiety
47
What is acetylcholine?
Excitatory neurotransmitter at the neuro-muscular junction
48
What is Parkinson's disease caused from?
A loss of dopaminergic neurons in the brain stem (substantia nigra) causing rigidity and trembling movements
49
How does the drug 'levo-dopa' treat Parkinson's disease and what side effect does it give?
It mimics the actions of dopamine (agonist) and can relieve symptoms temporarily
Can cause schizophrenic symptoms - schizophrenia thought to be caused by overactivity of dopaminergic pathways
50
What neurotoxin was discovered in heroin and what did this lead heroin addicts to develop?
'Frozen addict'
Neurotoxin MPTP
They suddenly developed Parkinson's disease
51
What does tetrodotoxin do? (Pufferfish)
Inactivates Na+ channels
52
What do a mixture of toxins in scorpions do?
Activate Na+ channels by lowering threshold at which they open, scrambling the information flow
53
What to toxins in wasps and bees do?
Inactivate K+ channels
54
What does alpha-latrotoxin do? (Black widow spider)
Causes a huge release of acetylcholine at the neuro-muscular junction leading to paralysis
55
What does botulinum toxin do? (Bacteria)
Stops acetylcholine release, preventing contraction in affected muscles
56
What does the Tetanus toxin do? (Bacteria)
Prevents inhibitory neurotransmitters in spinal cord causing hyperactivity of muscles
57
What does alpha-bungarotoxin do? (Branded krait snake)
Blocks neurotransmitter receptors on the neuro-muscular junction
58
How do psychoactive drugs work?
They mimic the effect of neurotransmitters by binding directly to neurotransmitter receptors
59
How do LSD and mushrooms work?
Agonists - mimic serotonin effects
60
How does alcohol work?
Agonist - stimulates GABA receptors and increases effects of GABA creating a sedative effect
Also blocks glutamate receptors which are involved in memory formation
61
How does cocaine work?
Prevents reuptake of dopamine, prolonging effects of dopamine causing arousal
62
How is the dopamine system involved in drug addiction?
- Association between drug taking and reward circuits in the brain - pleasurable feelings when we do something that keeps us alive (e.g. eating)
- Dopamine important in reward circuits
- Many addictive drugs activate this system in the brain
63
What is the CNS comprised of?
Brain and spinal cord
64
What is the PNS comprised of?
Somatic and autonomic nervous systems
Within autonomic is sympathetic and parasympathetic
65
What does the somatic nervous system control?
Voluntary movements
66
What does the autonomic nervous system control?
Involuntary actions - sympathetic and parasympathetic
67
What is the sympathetic nervous system involved in?
Fight or flight
68
What is the parasympathetic nervous system involved in?
Rest and digest
69
What are gyri? (Brain surface features)
Hill tops
70
What are sulci? (Brain surface features)
Valleys
71
How are different lobes distinguished between in the brain?
Main wrinkles are common to all and are used as landmarks
72
What is the cerebrospinal fluid? (CSF)
Acts as a cushion between brain and skull
73
What is the cerebrovascular system?
Vessels that transport blood to and from the brain
- Blood separate from brain tissue as blood is toxic to brain tissue (haemorrhagic stroke)
74
What is the frontal lobe involved in?
Movement, thinking and planning
75
What is the parietal lobe involved in?
Touch, balance, movement
76
What is the temporal lobe involved in?
Hearing, speech comprehension, memory and visual recognition
77
What is the occipital lobe involved in?
Visual processing
78
What does the thalamus do?
Processes sensory information and sends it to the rest of brain (sensory relay)
79
What does the hypothalamus do?
Regulates hormonal levels
80
What does the brain stem do?
Deals with alertness and regulating repetitive behaviours like circadian rhythms, breathing, heartbeat and blood
81
What does the cerebellum do?
Deals with fine tune movements and eye movements
82
What is the cerebral cortex?
Layer of nerve cells that cover outer surface of the brain
Grey matter on the outside, white matter underneath
83
What are the functions of the 6 layers of the cerebral cortex?
They have varying thickness, cell density and complexity depending on brain region
1- 3 = Integrative function
4 = Input of sensory information
5 - 6 = Output to other parts of the brain
84
What part of the brain is evolutionarily the oldest?
Brainstem - whole reptilian brain
Nerves that run up from body into the brain
85
What are the three parts of the brainstem?
Hindbrain (including the cerebellum)
Midbrain
Diencephalon (including thalamus, hypothalamus and pituitary)
86
What does the basal ganglia do?
Controls voluntary movement (caudate nucleus)
87
What does the limbic system do? (Amygdala and cingulate cortex)
Navigation in space and memory
Amygdala - emotional function and threat detection
Cingulate cortex - give context to emotional stimulus
88
What part of the nervous system are cranial nerves in?
Part of somatic system
89
What do cranial nerves do?
Allow brain to communicate with muscles and sense organs of the head and neck
90
What part of the nervous system are spinal cord nerves in?
Part of somatic system
91
What information does the spine relay to brain?
Sensory information about touch and pain
92
What information does the brain relay to the spine?
Motor commands to produce muscle movement
93
What is the function of spinal vertebrae and how do spinal nerves leave vertebrae?
Protect the spinal cord
Spinal nerves leave the spinal cord through gaps between vertebrae
94
What do caudal and posterior mean?
Located near or toward the tail
95
What does anterior or frontal mean?
Located near or toward the front
96
What does dorsal or superior mean?
Above
97
What does ventral or inferior mean?
Below
98
What does medial mean?
Middle
99
What does lateral mean?
Side
100
What are the pre-ganglionic or post-ganglionic pathways in the autonomic nervous system?
S and PS work in opposition
Pre-ganglionic = spinal cord to ganglia (CNS)
Post-ganglionic = ganglia to target organ (PNS)
101
What are ganglia?
Clusters of nerve cell bodies that carry signals between the PNS and CNS
102
What are the pre and post ganglionic regions and neurotransmitters in the sympathetic NS?
Thoracic and lumbar regions to ganglion
Pre - Ach
Post - Noradrenaline
103
What are the pre and post ganglionic regions and neurotransmitters in the parasympathetic NS?
Brainstem and sacral regions of spinal cord
Ganglia closer to target organs
Pre and post = Ach
104
What is sensation?
Registration of physical stimuli from the environment by the sensory organs
105
What is perception?
The interpretation of sensations by the brain
- Our version of reality is our perception of the sensory world
106
Which lobe deals with touch/somatosensation?
Parietal lobe
107
Which lobe deals with audition?
Temporal lobe
108
Which lobe deals with vision?
Occipital lobe
109
Which lobe deals with taste?
Frontal lobe
110
Which lobe deals with smell/ olfaction?
Frontal lobe
111
What is hapsis and how is this detected? (Somatosensation in parietal lobe)
Hapsis = touch
Skin has rapid corpuscles and slow receptors
112
What is nocioception and how is this detected?
Nocioception = pain and temperature
Skin has slow free nerve endings
113
What is proprioception and how is this detected? (Somatosensation in parietal lobe)
Muscles - rapid muscle spindles, golgi tendon organs and joint receptors
114
How is a physical stimulus converted to an electrical signal? (Somatosensation)
Sensory receptors have specialised dendrites that will open ion channels when stimulated
* E.g hair moves the dendrite is stretched - opens stretch sensitive Na channels - depolarisation
* E.g. photoreceptors absorb light causing a change in the shape of light-sensitive pigments that result in ion channels opening
115
How do somatosensation signals reach the brain? (Pain and temp, touch and pressure)
Pain and temperature - different pathways to the brain compared to touch and pressure
1) Dorsal root ganglion
2) Ventral spinothalamic tract - pain and temp (spinal cord side)
3) Dorsal-column nuclei - touch and pressure (spinal cord side)
Cross over in the brain stem - processed by opposite side of brain
4) Medial lemniscus
5) Ventrolateral thalamus
Primary somatosensory cortex
116
What is the difference between pain neurons and other somatosensory neurons?
Pain - unmyelinated axons
Other neurons are myelinated
117
How does rubbing a pained area better actually work?
Gate control theory of pain - stimulation of non-pain receptors blocks pain
118
What is a receptive field? What does size of receptive field mean?
Small area of the body where receptors respond to stimuli
E.g. portion of skin that stimulates all dendrites of that receptor neuron
- Size of receptive field is an important factor in determining sensitivity of a sensory system: smaller fields allow greater sensitivity
- Glabrous (non-hairy) skin is much more sensitive to touch
E.g. fingers more sensitive than wrists due to smaller receptor fields
119
What is frequency coding?
- Sensory receptors indicate how strong a stimulus is by the number of action potentials they fire
- Stronger stimuli produce more action potentials per unit time than weaker stimuli - number of APs is frequency coding
120
What can excessive use of a single sense result in?
A relevant cortical area to expand (each sense is dealt with in a particular brain region)
121
What are brain maps?
Maps of the body with different parts proportionate to how much cortical space is dedicated to them
- Sensory pathways are organised to preserve the spatial relations of adjacent receptors in the body (e.g. leg region next to foot region)
- Hands and face have more cortical space than others - as there are more receptors here
- Similarly distorted brain maps are found in vision and hearing
- Stripes of somatosensory cortex produce different types of sensation (muscles, skin slow, skin fast and joints pressure)
122
What is phantom limb and what mediates this?
- Affects 60% of people who undergo amputation
- Patients feel the presence of their lost limb despite the fact it is not there
- Brain cells in the somatosensory cortex, which once received signals from the sensory receptors in the amputated limb, now receive input from the neighbouring regions of the body and this may give rise to the feeling that the limb is still there
- Phantom pain may be mediated by a mismatch in expected feeling and visual reality
123
What are tastants?
Chemicals detected by taste receptors on the tongue
124
What four basic tastes do taste receptor neurons detect? Any others?
Salty, sour, sweet, bitter
Scientists have recently discovered unami (meat or savoury) receptors, as well as receptors specific to fat
125
What is Gourmand syndrome?
Damage to right frontal lobe can turn previously normal people into fanatical seekers of fine food
126
What does the surface of the tongue contain?
Papillae - containing 10,000 taste buds
- Each taste bud contains multiple taste cells with microvilli that detect tastants
- Opening of ion channels on the microvilli leading to membrane potential changes
127
Is taste preference genetic?
Yes
128
What is the main gustatory nerve comprise of? (Taste pathway)
Cranial nerves 7 (facial), 9 (glossopharangeal) and 10 (vagus)
129
What is the taste pathway?
- The nerve first travels to the nucleus of the solitary tract in the brainstem, then to the thalamus
- It divides into two pathways, one for sensation, one for an emotional and hormonal response
130
What is mastication?
Chewing - unlocks odours from food and mixes them with air
- The brain can distinguish between orthonasal and retronasal olfaction
130
What is flavour?
Taste and olfaction combine to give us flavour
131
What is synesthesia
About 1 in 25,000 people consistently experience two or more senses together
- One explanation = signals from receptors in one sensory system have diverted to the wrong part of the brain
132
How do we detect smells? (Neurons)
- Scent (odorants) interacts with chemical receptors
- Chemicals dissolve in the mucosa and interact with the cilia
- Changes in the membrane potential are mediated by metabotropic ion channels
133
How do we discriminate between different scents?
- Neurons respond to a range of odours, and summed activity over a range of neurons allow perception of a particular smell
- 350 strong gene family that allows discrimination of 10,000 different smells
134
How do we detect smells? (Brain)
- Odours entering one nostril are processed by same side of brain
- Smell signals bypass the thalamus and go directly to amygdala and pyriform areas - one projection goes to limbic system - activates emotional value of smell, one projection goes to the thalamus to the orbitofrontal region (conscious perception of odours)
135
How does human receptor area for smell compare to cats and dogs
It is smaller
136
How are pheremones detected and what do they do?
Olfactory receptor cells detect pheremones - influence behaviour in respect to attraction
137
How is audition detected by the ears?
Vibrations caused by moving air molecules are converted into electrical signals by the cochlea in the inner ear.
Different regions of the cochlea contain receptor neurons that respond to different frequencies of sound
138
How is audition processed by the brain?(Lateralisation)
- Information from the left ear is passed mainly to the right hemisphere and vice versa
- Both hemispheres have a distinct role in sound processing:
- The left hemisphere is more sensitive to the identification and naming of sounds.
- The right hemisphere is more sensitive to musical sounds.
- So, rhythm and melody may be blunted, if a person becomes deaf in the left ear
139
How is vision processed by the eye?
Light from a visual stimulus is inverted as it passes through the lens. It then hits the retina at the back of the eye, where light-sensitive cells (photoreceptors) turn it into electrical signals.
140
How is vision processed by the brain?
- Electrical signals are relayed to visual thalamus and then onto primary visual cortex.
- The left side of each retina projects to the right hemisphere and the right to the left hemisphere.
- Visual cortex is composed of many areas that process different aspects of the same visual scene.
- There are areas involved in processing form, colour, motion and there are even areas that specialise in processing faces and other complex objects.
141
What is the function of the ears?
Sensory organ for hearing
(also involved in balance - telling brain the motion of our head - fluid in vestibular system)
142
What is sound and how is it perceived?
- Sound waves - (physical stimulus) changes in air pressure caused by vibrating air molecules
- Energy of sound waves decreases with the distance from the source
- No sound is perceived unless the auditory cortex processes it and converts sound waves into electrical signals
143
What is frequency?(Sound)
Pitch
The rate at which air molecules vibrate
(high frequency= fast vibrations= high pitch)
144
What is amplitude?
Loudness
Number of air molecules that are vibrating in a sound wave
(more molecules= more energy= louder sound)
145
Why is the auditory system better at processing language and music?
It conveys meaning
146
What is the function of the outer ear? (pinna)
Collects and amplifies sound waves. Sound waves that occur at about ~ 3,000 Hz (i.e. human speech) are selectively amplified by pinna.
147
What is the function of the middle ear? (ear drum)
Transmits sound energy mechanically (ossicles vibrate) to the fluid filled inner ear (cochlea)
148
What is the oval window?
Start of the inner ear
149
Wat is the function of the inner ear? (cochlea)
Endolymph vibrating, auditory receptors convert mechanical vibrations to electrical energy
150
Where are auditory receptor neurons found in the cochlea and what is their function?
Found next to the basilar membrane
They convert sound into electrical signals
151
What causes vibrations in different parts of the basilar membrane?
Different parts vibrate at different frequencies of sound - high frequencies at cochlear base of basilar membrane (narrow, thick base), low frequencies at the end (wide, thin apex)
Sound waves at medium frequencies cause peak bending of the basilar membrane
152
What is a tonotopic map?
Receptor neurons on different parts of the basilar membrane respond to different frequencies (tones) of sound and form a tonotopic map.
153
How are sound waves converted to electrical signals by the basilar membrane?
- Basilar membrane bends in response to soundwaves, bending the cilia of the hair cells
- Only inner hair cells create electrical signals
- Outer hair cells - selectively hear certain frequencies and types of sound - pulling tectorial and basilar membrane together
154
What is the function of auditory receptor cells? (Hair cells)
Have hairs that are attached to the basilar membrane of the cochlea and vibrate if the appropriate frequency is heard
Vibrations of these hairs result in the physical opening and closing of ion channels
155
How can hearing loss occur?
Damage to hair cells:
- Essentially, they are pulled off the receptor neuron
- This process is usually caused by repeated exposure to loud sounds
Ruptured eardrum:
- Extremely loud noises (e.g. gunfire or explosives) can lead to the rupturing of the eardrum
- In this case, the loss of hearing is severe and abrupt
156
Why do different people hear Laurel and Yanny?
Yanny - high frequencies - detected by the base of the basilar membrane
Laurel - low frequencies - detected by apex of the basilar membrane
157
What are pathways of auditory processing in the brain?
- Receptor neurons (hair cells) in the cochlea send their axons to regions of the brainstem
(Ventral and dorsal cochlear nucleus, olivary complex, trapezoid body) - crosses to opposite side of brain
These signals are then relayed to the midbrain in same hemisphere (inferior colliculus), and thalamus (MGN) and primary auditory cortex in the temporal lobe of both hemispheres
Although signals from one ear are processed in both hemispheres, the opposite hemisphere receives preferential input (in the midbrain)
158
What is the audible spectrum for humans?
20 - 20,000 Hz
159
Why can smaller animals detect higher frequencies and larger animals detect lower frequencies?
The cochleas of smaller animals are smaller and therefore resonate better at higher frequencies.
Also explains the differences in sound that come from different musical instruments e.g. violin and cello.
160
How do we detect where a sound is coming from?
- Sound localization results from integrating information from the two ears.
- Sounds that originate on the left side of the body reach the left ear before the right ear (delay). The sound will be louder in the left ear than the right ear (difference in volume).
- These differences are not interpreted as being two different sounds, but are perceived as a single sound coming from one specific location.
- These differences are detected by neurons in the brainstem and midbrain.
- Detecting the location of sound is very important for animals that hunt at night such as owls.
161
What does it mean that neurons in the primary auditory cortex are arranged in a tonotopic map?
Neurons that respond to high frequency tones are grouped together and neurons that respond to low frequency tones are grouped together
(Similar to the arrangement of hair cells in the cochlea)
- Complex sounds like music require more sophisticated processing
162
How is a thought converted to speech?
Thought
Wernicke's area for language comprehension
Broca's area - stores motor programs for speaking words
Facial area of motor cortex
Cranial nerves
Speech
163
What is Broca's aphasia?
Inability to speak fluently despite normal comprehension and intact vocal mechanisms
164
What is Wernicke's aphasia?
Inability to understand or produce meaningful language even though the production of words is intact
165
How does language develop hemispherically?
Language initially develops in both hemispheres, but in 95% of people it shifts by the age of 5 to the left hemisphere, and the abandoned speech areas in the right hemisphere are given over to other things
166
What may cause stuttering?
- Disturbance to lateralisation may cause stuttering - people with a stutter show different patterns of activity from non-stutters
- May be due to competition for dominance between left and right hemispheres
166
What is the role of the right and left hemisphere in language and music?
- Understanding the emotional content in language (prosody)
- Role in processing music
E.g. Maurice Ravel suffered a left hemisphere stroke and developed aphasia while at the peak of his career. Yet his ability to recognize melodies remained intact. Unfortunately, his lesion meant that he was no longer able to transpose the music onto paper.
167
Which brain areas mediate reading and writing and what could be a cause for dyslexia?
- Visual cortex takes info from the page and the motor cortex activates muscles for writing
- Children are taught to read and write after they learn to speak - ability to read and write is a recent development in evolutionary terms and we have probably not developed a specific brain system for these behaviours
- If information does not flow freely between these areas - if it is blocked or disrupted - could result in dyslexia
168
What are circannual rhythms?
Yearly rhythms (hibernation/migration)
169
What are circadian rhythms?
Daily rhythms - 24 hours
170
What are ultradian rhythms?
Within 24 hours, multiple times
(Heart rate, body temp)
171
What type of rhythm is the sleep-wake cycle?
A circadian rhythm - matches the day-night cycle
172
What are zeitgebers?
Environmental events that entrain biological rhythms (e.g. light)
173
What is our biological clock in relation to the sleep-wake cycle?
We have a daily rhythm of waking and sleeping without cues about the day and night
174
What did the Bunker experiment show about the sleep-wake cycle?
Humans have a biological clock that governs sleep-wake cycle
- Biological clocks can be reset each day so that they accurately correspond to the season
- In the absence of external cues, the daily sleep-wake cycle lasts for about 26 hours
175
At what times are our deepest sleep and melatonin secretion?
Melatonin secretion starts - 21:00
Deepest sleep - 2:00
Melatonin secretion stops - 7:30
176
When is our highest and lowest body temperature?
Lowest = 4:30
Highest = 19:00
177
When is our fastest reaction time and best co-ordination?
Best co-ordination = 14:30
Fastest reaction time = 15:30
178
When is there a sharp rise in blood pressure and high blood pressure?
Highest = 18:30
Sharp rise = 6:45
179
When are bowel movements suppressed and likely?
Suppressed = 22:30
Likely = 8:30
180
When is our greatest cardiovascular efficiency and muscular strength?
17:00
181
What does a dropping body temperature promote?
Sleep
(Also a link between body temp and cognitive abilities)
182
What is the neural basis of our biological clock?
SCN - suprachiasmatic nucleus of the hypothalamus (bio clock)
- SCN is disconnected from rest of brain
- SCN receives direct input from the retina - light directs rhythmic activity of SCN via the retinohypothalamic pathway
- SCN acts as a pacemaker for other rhythms
183
What happens to animals with a damaged SCN?
Animals with damaged SCN - continue to eat, drink, sleep, but at haphazard times because
SCN acts as a pacemaker for other rhythms
184
How do hamster transplants prove that SCN controls circadian rhythms? (2)
(1)
Male hamster with 22 hour (short) circadian rhythm due to gene mutation
- Offspring bred - 20 hour rhythm
- If 20 hour SCN is transplanted into previously 24 hour hamster, this hamster also has 20 hour rhythm
(2)
- Circadian rhythms of hamsters with lesioned SCN were observed - displayed chaotic rhythmic behaviours
- SCN from another animal was transplanted - normal circadian rhythm was observed
185
How is melatonin formed?
Melatonin is converted from serotonin in the pineal gland - levels of both of these fluctuate together
186
How does melatonin work in relation to night/day? What role does the SCN have?
Dark phase - pineal gland secretes melatonin
Light phase - inhibits this secretion
- Melatonin acts on receptors on SCN
- SCN may act on adrenal glands to release mood and alertness altering hormones like cortisol at different points throughout the day
187
How is melatonin release different in adolescence?
Adolescence causes melatonin release to be delayed by about an hour
188
How does jet lag occur and what treats it?
Body's internal rhythm being out of sync with light/dark cycle
- Disruption likely to be more pronounced when travelling from west-to-east rather than east-to-west
- Melatonin - treatment for jet lag when taken close to target sleep time
- Its effects are more pronounced as more time zones are crossed
- More effective for easterly flights (against the sun)
189
What is seasonal affective disorder (SAD)? How can it be prevented?
- Lack of light in winter months
- Winter months in northern hemisphere - 60% of people report depression, anxiety and drowsiness
- Explanation - lack of light signals hibernation
- Disruption of circadian rhythm can be prevented by sitting in front of a bright light for 20 mins a day
190
How do EEG brain waves differ during sleeping, waking and REM?
Awake - low amplitude, high frequency
Deeper sleep - high amplitude, low frequency
REM (rapid eye movement) - low amplitude, high frequency (like waking pattern)
191
What happens in the 4/5 stages of sleep?
Stage 1 & 2 - will report having not slept at all
Stage 3 & 4 - delta wave activity - groggy and confused, most nightmares in stage 4
REM - people feel awake and reports of dreams happen here
192
What happens biologically during Non-REM sleep?
Body temp declines, HR decreases, levels of growth hormone increase
193
What disorders can take place during NREM sleep?
Restless leg syndrome - unpleasant tingling and pricking sensations occur in legs and feet causing a disruption to sleep
Insomnia (inability to sleep) and sleep apnea (can't sleep and breathe at the same time) are disorders of NREM sleep
194
What activities can take place during NREM sleep?
Sleepwalking (somnambulism) - complex behaviour while sleeping
Sleep eating
195
What is the biological explanation of sleep walking and eating?
- Occurs when people are roused incompletely and at the wrong point, in the delta wave stages
- Sleepwalker has no conscious awareness
- Cerebellum - controls automatic movement and coordination, is active
- Frontal and parietal lobes - correspond to reasoning and conscious control of movement, are dormant
196
What activities happen during REM sleep?
- Become paralysed during REM sleep
- If we wake up during REM sleep, we are more likely to report that we have been dreaming
197
What are disorders of REM sleep?
- Sleep paralysis - a person enters REM sleep but has partly awakened, frightening as the body is fully paralysed. Can be snapped out of it by being touched or someone calling their name. REM intrusion - 40% of people suffer from it
- Narcolepsy - falling asleep at inappropriate moments - also a form of REM intrusion
- Cataplexy - an wake person suddenly loses all muscle tone in response to anger, surprise or laughter and falls to the floor entering into a hallucinogenic (hypnogogic) form of REM sleep. Person lies there, fully conscious, for a few mins. Only happens in narcolepsy sufferers.
198
How do dreams occur? (biological explanation)
- REM - high brain activity in occipital areas but lower in inferior frontal areas - high visual imagery but chaotic organisation of events
- Cerebral cortex is bombarded by signals from the brainstem that generate a random collection of images from memory stores
- Not all dreams occur during REM sleep - nightmares occur during NREM sleep
199
What are the biological (evolutionary) functions of sleep? (Energy conservation and predator avoidance)
Energy conservation - cope with scarcity of food
- Polar bears - sleep-wake cycle is designed optimally so they will only be awake when they can gather food
- Humans - because our night vision is so poor, it makes sense for us to sleep at night
Predator avoidance
- If an animal is a predator, it can sleep at ease. If it is prey, its sleep is reduced because it must remain alert
- Sleep time is affected by amount of time needed to obtain food and risk of predation
200
How does sleep aid memory consolidation?
Sleep usually increases after a session of learning and sleep deprivation has been shown to impair memory function
- Areas of brain active prior to sleep are also active during REM sleep
- REM - learning and consolidation of non-declarative or implicit memories
- NREM - learning and consolidation of declarative or explicit memories
201
What does sleep deprivation cause and what prompts recovery sleep?
Rat studies - immune response similar to stress
Increased levels of the enzyme Nitric Oxide Synthase (NOS) - strong predictor of heart disease
Nitric oxide prompts recovery sleep
202
What part of the brain puts us to sleep?
- Preoptic area in hypothalamus promotes sleep via the action of melatonin
- Hypothalamus slows down the firing rate of the thalamus via the brainstem
- Thalamus is the sensory relay station - slow firing means sensory information flow to the cortex is slowed down
- Neurotransmitter that mediates the overall slowing down of brain activity is GABA
203
How does the posterior hypothalamus promote wakefulness through the Reticular Activating System?
Neurotransmitters:
- Noradrenaline from locus coeruleus
- Serotonin from raphe nucleus
- Acetylcholine from brainstem and forebrain
With hypothalamus and brainstem waking up, thalamus sends more sensory information to the cortex
204
What does damage to Reticular Activating System (RAS) result in?
Coma
205
How is sleep controlled neuronally?
NE, serotonin and Ach neurons fire during waking and enhance the awake state
Ach also enhances critical REM events
Metabolic activity during awake times - increase adenosine which promotes sleep by inhibiting excitatory neurotransmitters
Regulatory systems control the rhythmic behaviour of the thalamus which controls EEG rhythms of the cortex
Slow rhythms block the flow of sensory information to the cortex
Descending activity is required to inhibit motor neurons during dreaming
206
How do regulatory hormones possibly initiate sleep?
Regulatory hormones possibly initiate sleep resulting in a decrease in firing rate of most brain stem neurons, NE, serotonin, Ach
207
How is REM sleep controlled?
Control of REM sleep comes from regulation in the brain stem, at the pons
Firing rates of the locus corerulus and raphae nuclei decrease to nothing
Ach neurons in the pons increase firing
208
What are binary and inclusive views of sex differences in behaviour?
Binary view - male behaviour and female behaviour
Inclusive view - we are all ruled by our hormones
209
What is a genotype and what are the sex chromosomes?
Genotype - full set of genes an organism has
Each somatic cell - 46 chromosomes (23 pairs)
23rd pair = sex chromosomes - produce physical and behavioural sexual characteristics
210
What are male and female genomes?
Female genome = two X
Male genome = X and Y
211
What gonadal hormones are released and what are these converted from?
All released by both males and females
- Androgens (testosterone)
- Estrogens (estradiol)
- Progesterone
- Come from cholesterol
212
Which hormones and in what order is cholesterol broken down into?
Cholesterol
Progesterone
Testosterone
Estrogens and dihydrotestosterone
213
What is our biological sex a product of?
1) Genotype (XX or XY)
2) Action of sex hormones pre-natal
3) Proportion of sex hormones post-natal
214
What are the Mullerian and Wolffian systems?
Mullerian system = female pre-cursor
Wolffian system = male pre-cursor
To create a female, the Mullerian system simply continues development
To create a male, the Anti-Mullerian system has to release androgens
'Nature's impulse of create a female'
215
What does the pre-optic nucleus do and how is this different in males and females?
Sexually dimorphic - same size at birth in both sexes but larger in the adult male
Controls:
- Action of estradiol
- Testosterone levels and sexual activity in males
- Lesions here impair sexual behaviour in males
216
What is the ventromedial nucleus of the hypothalamus involved in?
Female sexual behaviour
217
What are sexual differences of the INAH3?
Twice as large in males (some evidence shows differences in homosexual and heterosexual males)
218
What are sexual differences in the suprachiasmatic nucleus?
Twice the number of neurons in the male brain than the corresponding female region
219
Where are LH and FSH released from?
Gonadal hormones released from the hypothalamus have different actions in men and women
220
What is Turner's syndrome (XO)?
Lack of second X chromosome in women - short stature and lack of sexual development
221
What is congenital adrenal hyperplasia (CAH)?
Abnormally high levels of androgens (testosterone) that result in a masculine phenotype of XX individuals
222
What is Androgen insensitivity syndrome (AIS)?
Feminisation of XY individuals as they are not responsive to androgens
223
What is female sexual behaviour in rats mediated by? (Neural area and hormones)
Mediated by ventromedial area of hypothalamus
Dependent on estrodial and progesterone
224
What is proceptive behaviour and lordosis in female rats?
Proceptive behaviour - hopping, darting and ear wigging
Lordosis - back arched exposing the genitals
225
What is sexual behaviour in male rats mediated by? (Neural area and hormone)
Mediated by preoptic area of hypothalamus
Dependent on testosterone
226
What is involved in male rat sexual behaviour?
Nuzzling, sniffing genitals, mounting
Shows interest in females in 'estrus' (heat)
227
What des oxytocin play a role in?
Pair bonding
- Feelings of calmness and wellbeing
- Relaxation and anxiety reduction
- Increased trust
Oxytocin may be involved in mother-infant bonds - increase in activity of brain regions rich in oxytocin receptors when mothers looked at pictures of their infants
228
How does women's facial attractiveness change during the fertile period?
- Estradiol levels higher in fertile window and luteal phase
- Faces in fertile window and luteal phase more consistently ranked as first compared to faces in the follicular phase
- Estradiol produces changes in face attractiveness
229
What have rat experiments shown about the roles of the hypothalamus and amygdala in the motivation and action of sex?
- Male rats need to press a lever for receptive female rat to be dropped into the cage
- Lesions to hypothalamus - male rat will press bar but not engage in sex
- Lesions to amygdala - male rat will not press bar but will have sex
- Hypothalamus is involved in initiating the action of sex while amygdala regulates the animal's interest and motivation to have sex
230
What is the amygdala's involvement in human sexual motivation?
Viewing erotic movies caused activity in:
- Amygdala for men and women
- Hypothalamus for men only - increased sexual arousal and potentially linked to penile tumescence
Amygdala volume correlated with sexual interest in epilepsy patients who underwent temporal resection
Stimulation of amygdala in an epilepsy patient elicited sexual experience related sensations
Potentially relating to amygdala's processing of emotional arousal
231
What is the role of the frontal lobe in sexual behaviour?
Lesions to frontal lobe:
- Loss of inhibition about sexual behaviour vs loss of libido
- Erotomania - a condition in which people believe that another person is in love with them
232
In what ways is human sexual behaviour complex?
- Sexual fantasies
- Voluntary inhibition of sexual urges
- Cultural and moral norms around sexual behaviour
233
What is the role of the dorsolateral prefrontal cortex in sexual behaviour?
Stimulation, aggression and moral judgement
- Lesions to left DLPFC - aggressive sexual behaviour
- Stimulation of DLPFC = ppts reported a lesser intention to commit either physical or sexual assault and an increase in immorality of the act
234
What neurochemical rewards are involved in sexual activity?
Orgasm is accompanied by a reward
- Dopamine release
- Relaxation due to oxytocin release
235
Women perform better than men in verbal fluency - what are evolutionary and neural explanations?
- Evolutionarily left behind in social group leading to development of communication skill
- Larger Broca's and Wernicke's areas
Larger posterior corpus callosum suggesting increased connectivity
236
Men perform better than women on tests of spatial reasoning - what are evolutionary and neural explanations?
- Evolutionarily needed to cover large areas for hunting, developing spatial abilities
- Large inferior parietal lobe involved in spatial and mathematical abilities
237
Are differences within sexes greater than differences between sexes?
Yes
238
What are pheremones? How are they detected and processed?
- Carry messages from one animal to another and affect reproductive behaviour
- Detected by olfactory receptors but not perceived consciously as odours
- Pheromones are processed by the vomeronasal organ which activate the amygdala and hypothalamus
239
What does exposure to pheromones lead to in rats?
- Acceleration of puberty when housed with a male
- Restarting the estrus cycle of female rats when exposed to odour of a male
- Termination of early pregnancy when exposed to a new male who is not the father
240
What does exposure to pheromones lead to in humans?
- Synchronisation of menstrual cycles
- Higher pleasantness rating of odour of fertile females by males
241
How is brain symmetry different depending on sexual orientation?
- Homosexual women and heterosexual men show asymmetrical brains
- Heterosexual women and homosexual men show more symmetry
242
How does amygdala connectivity differ depending on sexuality?
- Similar in het men and homo women - sensorimotor systems and striatum regulating an action-related response
- Similar in homo men and het women - regions of limbic system regulating stress, mood and anxiety related response
243
Do homosexual male's brains resemble female brains?
Not necessarily - this is culture-bound and inadequate
244
What are differences in the SCN, INAH3 and the hypothalamus in homosexual and heterosexual men?
- The SCN is twice as large in gay men as heterosexual men
- INAH3 is twice as large in a heterosexual male compared to the homosexual male brain
- Differences in structure of the hypothalamus
245
Do differences in brain structures explain differences in sexual behaviour between gay and straight men?
No
246
How are genetics linked to homosexuality?
- Gene Xq28 linked to homosexuality via its effect of circulating androgens
- Higher likelihood of both identical twins being homosexual vs fraternal (dizygotic) twins, both male and female
Evidence to suggest sexual orientation is polygenic and genes play a minor role in homosexuality
247
What does exposure to prenatal stress lead to in male rats? Is this the same in humans?
- Exposure to prenatal stress leads to suppressed androgen release and smaller preoptic area in males
No such reliable evidence in humans
248
What is the purpose of emotions?
Emotions - survival mechanisms - accompanied by physiological responses and species specific behaviours
e.g. fear response to spiders, disgusted response to rotten food, caring response to someone crying
249
What brain system are emotions mediated by?
The limbic system
250
What is the network of brain areas involved in emotional response?
- Emotional stimuli are relayed by our sensory systems to the amygdala
- Amygdala - direct and indirect signals from amygdala to frontal cortex
- Indirect - hypothalamus sends messages to ANS, creating changes in physical state (e.g. increased HR), these changes are then fed back to the frontal cortex which interprets the emotion
251
What is the amygdala?
Bilateral structure, part of limbic system and within the temporal lobes
252
What is Kluver-Bucy syndrome?
Results from damage to medial temporal lobe
Monkey's with KB syndrome:
- Loss of normal anger and fear responses - e.g. no longer a strong aversion to snakes
- Hypersexuality
- Visual agnosia (impairment in recognising objects) and excessive oral exploration
253
How does the amygdala improve chances of survival?
Improving chances of survival by minimising contact with dangerous animals, objects and places
The amygdala links sensory stimuli with other stimuli that are directly associated with threat
254
What are innate and learned components of awareness of danger? (Rat studies)
Innate component - rat is exposed to odour of the ferret and produces a fear response, despite never having seen a ferret before
Learned component - Skinner's rat box - fears are learned through association
255
What is the amygdala's role in acquiring fear through observation?
Skin conductance and amygdala activity increased when participants:
- Watched someone receive electric shocks from a stimulus
- Were made to believe they will receive electric shocks for the same stimulus they observed
256
How is the amygdala involved in emotional memory in humans?
- Increased amygdala activity when recalling emotional videos compared to neutral ones
- Increased amygdala activity when seeing threat related words vs neutral
257
How is fear related to the human amygdala? (Patient SM)
Patient SM with bilateral damage to the amygdala
- SM was impaired in rating the intensity of a variety of emotions but particularly bad for fear and anger
- Avoided looking at the eye region - impaired attention to salient facial features
- Unable to sketch a face depicting fear
- Lack of fear response to live snakes, scary videos and taking a tour of haunted house
258
What is the modern biopsychology view of whether fear or physiological response comes first?
Cyclical feedback loop - fear and physiology affect each other
259
What neural areas and hormones mediate our stress response?
- Hypothalamus releases corticotropin-releasing hormone (CRH)
- CRH then acts on anterior pituitary gland to release adrenocoricotropin hormone (ACTH)
- ACTH acts on adrenal glands to release cortisol into the blood stream
260
What body functions does the hypothalamus control?
Body temp, HR, eating and drinking
These neurons receive connections to the amygdala
261
What is the importance of an intact cerebral cortex to interpret emotional states?
Studying animals with lesions to the cerebral cortex but an intact hypothalamus - these animals were very aggressive to any external stimulus
262
How does spinal cord injury affect emotion?
The idea that changes in body state are necessary to perceive emotion comes from spinal cord injury patients
- Because ANS is disconnected from the brain, people suffer a decrease in perceived emotion, severity depending on location of legion
263
How is the prefrontal cortex important for emotional rationality and understanding our emotions? (Lobotomies)
- 1930s - lesions to frontal lobes of monkeys resulted in change to neuroticism to more relaxed behaviour
Lobotomies - behavioural treatment in humans
- Changes a person's personality completely removing the capacity to understand their emotions
- Thought this would produce a more rational person - however emotional responses are a necessary function of rational decision making
- Emotions necessary for moral judgement
264
How are phobias and tantrums caused by lack of connections between frontal lobe and limbic system?
- Emotional responses are initiated by the amygdala and hypothalamus before information has reached frontal lobes.
- However, frontal lobes can act to inhibit an emotional response
- Tantrums in children probably occur because connections between frontal lobe and limbic system are yet to develop
- If these connections fail to develop in adults, phobias often arise
265
What brain areas are associated with increased and decreased phobic responses?
Exposure therapy for phobias reduced the activity of the amygdala
Frontal lobe activity regulates phobic responses
266
267
What is happiness caused by?
Happiness - rush of dopamine
Absence of negative emotion is essential for happiness
Amygdala is responsible for generating negative emotions
268
What is affective (mood) disorder?
A psychiatric condition involving an abnormal regulation of sadness and happiness
269
What is depression caused by?
Depression - involves connections between the amygdala and prefrontal cortex
Most commonly linked to decreased levels of serotonin
270
What is the cortical lateralisation of emotional function?
Right hemisphere - negative emotions, important in the expression and comprehension of emotional aspects of speech (intonation)
Left hemisphere - positive emotions
271
What evidence supports the cortical lateralisation of emotional function?
Incidence of depression is significantly higher in patients with lesions to the left hemisphere
Patients with lesions to right hemisphere appear unduly cheerful
272
How do facial expressions express our emotions? (Brain areas involved)
Darwin - emotional expression is inherited
Neurons that control muscles in the face receive input from cerebral cortex and limbic system
Asked to smile for the camera - activate motor cortex, produces an unnatural asymmetric smile
Actually feel happy - more symmetric and natural smile
273
How does Tibetan monk meditation reduce negativity?
When meditating, they can triple the gamma wave activity in areas of the frontal and parietal-temporal regions
274
What are synchronised gamma rhythms (bursts of 30-80hz) in areas across the cortex associated with?
Binding various neural components into a single perceptual construct
