Biological Psychology - Semester 1 Flashcards
1
Q
What is biological psychology?
A
‘The relationship between brain and though/behaviour’
2
Q
What does brain function underlie?
A
Thought and behaviour
3
Q
What is the brain the crucial centre for?
A
Skilled movement, sensory, communication, language, emotion and thought itself
4
Q
What did Descartes believe?
A
He believed that there was a role for the physical body bit he thought that the soul was in charge of flexibility and thought. However, nowadays we believe the brain to be in charge of this not the soul.
5
Q
How is information sent?
A
Information is sent via electrical signals (movement of charged particles) and chemical signals.
6
Q
What do changes in wiring or brain chemicals lead to?
A
Changes in how we think and behave
7
Q
What does our thinking and behaviour rely on?
A
Our brain, brain chemicals and how they work
8
Q
What is Parkinson’s caused by?
A
Lack of dopamine
9
Q
How does drug abuse affect dopamine levels?
A
Too much dopamine
10
Q
Do all brain areas carry out the same function?
A
No. If they were all the same, then damage to one part of the brain would have the same effect as damage to any other part of the brain but this is not true. Each part of the brain is good at one function.
11
Q
What is Brodmann’s areas?
A
He made maps of brain function and found that the function of each bit of the cortex have different functions and different connections with other brain areas. At the time he did not know the role of these areas of the brain however nowadays we are understanding the functions of these areas.
12
Q
What happened to Patient HM?
A
Patient HM, had brain surgery to remove part of his brain to stop his epilepsy. However, this caused his memory to be reduced, and he did not have ability to make new memories.
13
Q
How do parallel systems within the drain function?
A
Most of them function without consciousness
14
Q
What are double dissociations?
A
Double dissociations – different parts of the brain are used when looking at an item than interacting with an item. It doesn’t feel like this, but it does use different areas.
15
Q
What does common sense tell us about the world?
A
Common sense tells us that: we perceive the world exactly as it is and we act according to our ‘will’.
16
Q
What does biological psychology tell us about the world?
A
However, biological psychology shows us that: we perceive what is useful to us, there are multiple parallel brain processes governing our cognition and action, most of these processes are unconscious.
17
Q
What is psychology?
A
Psychology is the study of how our minds actually work. Studying the brain is crucial to a full understanding of psychology.
18
Q
What is grey matter?
A
Grey matter is smooth and soft and contains cell bodies
19
Q
What is white matter?
A
White matter is bundles of fibres that come off the cell bodies. Signals from cell bodies are taken to talk to other cell bodies potentially in the brain or elsewhere.
20
Q
What is the role of grey matter?
What is the role of white matter?
A
Grey matter does the processing of information. Transmitting is the role of the white matter.
21
Q
What is Structural magnetic resonance imaging (MRI)?
A
A way of getting a picture of someone’s brain/ other parts of the body when people are still alive without need of dissection. Uses water, it can be detected from the outside. MRI can tell which part of the brain has more or less water.
22
Q
What is histology?
A
Using an electron microscope you can get a clearer picture of the structure of the cortex
23
Q
Tracing neuronal pathways?
A
If part of the brain is in charge of hand movements, then there need to be a connection from the brain to the spine. Certain chemicals are taken up by cells and transported forwards or backwards, even between cells – this reveals the pathways between brain area. Only possible to do in animals
23
Q
What did Brodmann do?
A
Looked at different parts of the brain under a microscope and drew sketches. He discovered that different structures had different roles within the brain. The structure is different when the connections are different.
24
How do we trace neuronal pathways using diffusion tensor imaging (DTI)?
Uses the differential diffusion of water molecules in different types of tissue to show routes of axons.
25
What is a Positron Emission Tomography (PET)?
Uses radioactivity (via water, glucose, neurotransmitter) injected into blood & detected by a PET scanner. There tends to be more blood in areas of high activity. Detects healthy cells through blood flow, glucose levels and neurotransmitters. If you are making a difficult decision the blood will rush to the decision-making part of the brain. You can detect these things from a distance without having to physically go into their brain.
We can see in a PET scan if someone has Alzheimer due to glucose levels.
26
What is a functional magnetic resonance imaging (fMRI)?
Looks at brain function and brain activity, to a large extent it does the same as PET. Avoids use of radioactivity making it safer. Detects increased blood flow (via magnetic haemoglobin) in active brain tissue. Active brain tissue has more oxygen filled blood flowing to it.
27
What are the pros and cons of fMRI?
Precise spatial information, imprecise temporal information (same is true for PET). It is not very time accurate as it takes a couple of seconds for the blood to flow. You cannot get the timings of brain activities with a fMRI due to the fact that it is just based on blood flow.
28
What is an electroencephalography (EEG)?
Records electrical signals at scalp, signals produced by electrical brain activity.
29
What are the pros and cons of an EEG?
Price temporal information, imprecise spatial information. The timings are very accurate, but it is difficult to know what part of the brain does each activity.
30
What is a magnetoencephalography (MEG)?
Records magnetic field at scalp. Note: these fields are produced by electrical brain activity
31
What are the pros and cons of Magnetoencephalography (MEG)?
Precise spatial and temporal information). They give precise timings and specific locations of brain activity. (very expensive).
32
What are the pros and cons of single-cell (single unit) recording?
Very precise spatial and temporal information
Only one cell at a time
Impractical in humans
Not a standard technique
33
What does prosopagnosia due to brain lesion cause?
These people may have struggles recognising faces due to damage to inferior temporal cortex damage.
34
What is meant by lesion?
damage, due to e.g. stroke, surgery, tumour
35
What does amnesia due to Alzheimer's cause?
poor new learning following damage to medial temporal lobe.
36
What does dysfunction due to Parkinsons cause?
Lack of dopamine impairs function of frontal lobes, including, ‘executive functions’
37
What is Transcranial magnetic stimulation (TMS)?
Focused magnetic field disables briefly (for a few milliseconds) a small area of cortex; a “reversible lesion”; precise temporal and spatial information. Let’s us see what parts of the brain need to be disrupted in order to prevent a task being done. Let’s us see what types of the brain are involved in which activities.
38
What is a neuron?
- The body is composed of cells
- Cells are specialised to perform specific functions (e.g. red blood cells, muscle cells)
- Neurons (nerve cells) are specialised for communication
39
What are the two main roles of a neuron?
Information transmission
Information processing
40
What does the neuron do in terms of information transmission?
- E.g. from eye to brain, or brain to muscle
- Action potential
- The part of the neuron that is important for this is the Axon
- Maintains a clear signal
41
What does the neuron do in terms of information processing?
- E.g. to interpret a pattern of visual information as being a human face
- Integration of signals
- The parts of neurons that are involved are the synapse/dendrites and cell body
- Modify signals according to context
42
What is the axon hillock?
The very beginning of the axon, this is where the signal begins.
43
What is the action potential?
- The action potential is the ‘output’ signal of a cell, triggered by a particular combination of ‘inputs’
44
Where does the action potential begin?
Axon hillock
45
What are the three steps for the action potential?
Begins at the axon hillock
Travels along the axon to the terminal
Triggers activity at the synapse
46
What are the steps of neuronal 'firing'?
- First, an electrical potential is set up: the resting potential
- This is allowed to suddenly discharge: the action potential
- This triggers further action potentials further along the axon
47
What does the row of matches/dominos show in terms of neuronal firing?
IF you set up a row of matches close enough together and then light the first one it will light the second one and so on so close. Same with dominos. You put a lot of work into setting up these things but not much energy to set it off.
48
What are cells enclosed by?
Lipid (fatty) membranes. Semi-permeable membrane
49
Where do different ions live?
- Different ions (electrically charged molecules) are concentrated in the fluid inside and outside the cell.
50
What needs to take place in order for the action potential to be reached?
- In order for the action potential to be reached certain ions need to be inside a cell and some need to stay outside.
51
What is the role of proteins?
- Protein pumps actively transport ions across the membrane. - requires energy
52
What allows ions to cross the membrane?
- Protein ion channels allow ions to cross the membrane
53
What do 'voltage-gated' ions do?
- ‘Voltage-gated’ ion channels open at a particular membrane voltage.
- What makes the gates open or closed? The voltage across the cell - the voltage of the fluid inside and the voltage of the fluid outside – affects whether the gate is open or closed.
54
What is the resting potential?
- At rest, the membrane is polarised
- -70mV (inside of cell more negative than outside)
- This acts like a store of energy, work had to be done to make it like that.
- The energy is used to create the action potential
55
How is the resting potential set up and maintained?
- The sodium-potassium pump exchanges three sodium ions for two potassium ions
- Sodium and potassium are both positive but as the push out 3 sodium this means that the outside is more positively charged that the inside.
- This makes the inside of the cell relatively negative.
- This uses energy
56
Where is there more negative charges when resting potential occurs?
More negative charges inside than outside
57
What is depolarization?
When the membrane becomes more depolarized it goes more towards 0
58
What causes the membrane to become partially depolarized?
- An ‘excitatory’ input is received from another neuron (next lecture)
- Neighbouring membrane is depolarised (passive conduction – this lecture)
59
What happens when the depolarization reaches the excitation threshold?
If depolarisation reaches the excitation threshold (around -60 mV), an action potential is triggered.
60
When do voltage-gated sodium channels open?
- Voltage-gated sodium channels open when depolarisation reaches a threshold level
61
What happens when voltage-gated sodium channels open?
- Sodium ions (positively charged) flood in.
- The membrane potential changes from -70mV to +40mV
62
What is the refractory period?
- Sodium ion channels close and briefly lock – they become ‘refractory’
63
What are the functions of the refractory period?
- Signal never goes backwards
- Keeps signals separate
- E.g. candle example, can’t unburn candles
64
What is repolarization?
- Voltage-gated potassium channels open, letting positive charge out of the cell, to re-establish the negative resting potential
- The sodium-potassium pump continues to work, maintaining the resting potential
65
What are some key features of the action potential?
- The action potential is ‘all or none’
- It is always the same size
66
Why is the action potential important?
- Important for preserving the message – signal is regenerated every time
67
What happens with a 'bigger' message?
A ‘bigger’ message is sent by more rapid firing, or by involving more neurons; the size of each action potential is identical.
68
What is diffusion?
- Within any fluid, the particles are constantly moving in random directions
- They will eventually become evenly distributed within the fluid, e.g. drop of ink in the water.
69
What is the conduction of the action potential?
- Passive conduction (diffusion of ions within the intracellular fluid) will ensure that adjacent membrane depolarizes; sufficient deporlization triggers a new action potential
70
What does setting up the membrane for an action potential use?
Valuable energy
71
What does myelination provide?
- Myelination provides saltatory conduction for some types of axons
72
What does the myelin do?
Provides insulation
73
In the brain what is the myelin sheath provided by?
Oligodenfrocytes
74
What are the pros of insulated axons?
- Ions cannot leak out of an insulated axon
- So, it takes less energy to maintain the resting potential
75
Where does the action potential only occur?
occurs in the unmyelinated regions (it ‘jumps’ from one to the next)
76
What do unmyelinated regions need to do?
The unmyelinated regions need to maintain the resting potential, saving energy
77
What is multiple sclerosis?
Immune system mistakenly breaks down myelin scarring
78
What is the synapse?
Many axon terminals synapsing with a single post-synaptic cell
79
What is synaptic transmisson?
- Information transmission between neurons
- Allows integration and processing of information
- The synapse allows information to be changed according to other information
- (roundabout analogy)
80
Synpatic transmission?
- Chemical neurotransmitters cross the synapse
- From the presynaptic to postsynaptic cell
- The synapse is very narrow, so transmission is fast
81
What are the fourstages of synaptic transmisson?
1. Release
2. Diffusion
3. Binding
4. Termination
82
What is release (synaptic transmission)?
- An action potential causes neurotransmitter release from the presynaptic membrane
- The action potential causes voltage-gated calcium channels to open; calcium ions flood in.
- Calcium ions affect synaptic vesicles containing neurotransmitter
- Calcium ions cause vesicle membrane to fuse with presynaptic membrane and empty contents
83
What is diffusion (synaptic transmisson)?
- Neurotransmitters diffuse across the synapse
- Transmission of the chemical signal is passive (takes no energy) but because the gap is small, it is nevertheless fast.
84
What is binding (synaptic transmisson)?
- Neurotransmitters bind to receptors within the postsynaptic membrane, altering the membrane potential
- Neurotransmitters binding changes the receptor’s shape
- It will open a channel for ions to pass through
- These receptors are ligand-gated ion channels
Post synaptic cell, neurotransmitter has been released from the presynaptic cell
- Some receptors allow positive ions to enter, others let in negative ions
- A neurotransmitter binds to a particular receptor (key lock), and it’s the receptor that determines which ions can enter
85
What are the postsynaptic potentials?
- The effect of the ion channel opening is to either depolarise or hyperpolarise the postsynaptic membrane
- This will make the postsynaptic cell either more or less likely to fire
86
What are excitatory postsynaptic potentials (EPSPs)?
- If the inside of the cell becomes less negative, the neuron is more likely to fire (remember the action potential: partial depolarization)
- Channels allowing in positively charged ions (e.g. sodium and calcium) will do this
- They produce ‘excitatory PSPs’: EPSPs
87
What is termination?
4. Termination
- Fast, clear signalling requires a rapid ‘off’ mechanism
- This can occur by reuptake or deactivation
88
What is reuptake?
- Transporter molecules in the presynaptic membrane take neurotransmitter back into the terminal
89
What is deactivation?
- An enzyme can deactivate the transmitter
- E.g. acetyl cholinesterase splits acetylcholine into two different chemicals, disabling it
90
How do drugs make use of synaptic processes?
Binding- e.g. diazepam
Preventing binding, e.g. curare
Preventing reuptake e.g. fluoxetine (less reuptake = longer action of neurotransmitter)
Preventing deactivation e.g. some chemical weapons work by inhibiting acetylcholinesterase
91
What are the ways that the synaptic mechanism allows information processing?
Combining PSPs
Integration of information
92
What is the combining of PSPs?
- PSPs are small
- An individual EPSP will not produce enough depolarization to trigger an action potential
- If there are enough coincident EPSPs, the cell will fire
- E.g. dropping a hot plate
- A warm plate will trigger a small number of ‘pain’ inputs; no action.
- A hot plate will trigger a large number of ‘pain; inputs drop the plate
- IPSPs (inhibitory ….) will counteract the effect of EPSPs at the same neuron
- E.g. cat is standing beneath the plate do not drop it yet
93
What is the integration of infromation?
- Axon hillock is critical: this is where the inputs are ‘summed’ and an AP triggered or not
- EPSPs and IPSPs are integrated within the postsynaptic cell
- This allows for flexibility: the meaning of a signal is changed according to other signals
94
What is executive function?
Inhibition of automatic responses
95
What about vision?
Centre-surrounded receptive fields – detection of contrast, e.g. edges
96
What is the dorsal/superior part of the brain?
the fin of the back of a shark faces the ceiling. Top of the brain facing the ceiling is the dorsal
97
What is the ventral/inferior part of the brain?
the underneath of a pig, the bottom facing the floor. Bottom of the brain is the ventral
98
What is the rostral/anterior part of the brain?
the beak is facing forward, the part of our brain facing forward is the rostral
99
What is the caudal/posterior part of the brain?
– the tail of the horse is facing backwards. The back of the brain is called the caudal.
100
What is the lateral part of the brain?
Towards the side
101
What is the medial part of the brain?
Towards the middle (midline)
102
What is the ipsilateral part of the brain?
On the same side
103
What is the contralateral part of the brain?
On the opposite side
104
What is the unilateral part of the brain?
On one side
105
What is the bilateral part of the brain?
On both sides
106
What are neurons for?
Communciation
107
What does grey matter contain?
Neurons and glia (glial cells)
108
What do glia (glial cells) do?
Support e.g. astrocytes; oligodendrocytes
109
What is the corpus callosum?
- Commissures of white matter connect the hemispheres
- The largest commissure is the corpus callosum
- In ‘split brain’ patients the corpus callosum is cut leading to neuropsychological deficits.
110
What is the role of cerebro-spinal fluid (CSF)?
The fluid cushions the brain and cleanses
111
What is the cerebral cortex?
Main part of the brain, surface is folded to increase area
112
What is a sulcus?
Groove
113
What is a gyrus?
Bulge between sulci (plural of sulcus = groove)
114
What are primary cortial areas most directly linked to?
The sensory and motor systems in the body
115
What is the association cortex?
- Association cortex is where sophisticated, higher-level processing takes place: E.g.
- Planning of a sequence of movements
- Perceiving a visual object
- Making decisions
116
What is the basal ganglia?
- Control of movement and cognition
- Close connections with cortex, esp. frontal cortex
117
What are 2 basal ganglia disorders?
Parkinsons
Huntingtions
118
What is Parkinson's disease?
- Reduced dopamine input to basal ganglia
- Poor initiation of movement
- Executive dysfunction
119
What is Huntington's disease?
- Cell loss in basal ganglia
- Writhing movements
- Executive dysfunction
120
What explains the executive dysfunction?
Connections between basal ganglia and frontal lobes, explain the executive dysfunction
121
What is the hippocampus for?
Memory
122
What is the amygdala for?
Emotion
123
What does amygdala damage cause?
- Patient S.M. has bilateral amygdala damage (Feinstein et al., 2011)
- She shows little/no fear in response to scary film clips
124
What is the thalamus for?
Closely connected to the cortex. Separate nuclei with distinct functions. E.g. LGN, visual pathway
125
What is the hypothalamus for?
- Hypothalamus (below thalamus). Controls autonomic nervous system and hormones.
126
What is the midbrain?
- Various structures, including substantia nigra
- Provides dopamine input to basal ganglia
127
What is the cerebellum?
- The cerebellum comprises two hemispheres, its own cortex and deep nuclei
- Motot and cognitive roles, including control and learning of precise movements
128
What do sensory receptors do?
- Sensory receptors project to specific nuclei within the thalamus (usually, but not smell) and these projects to cortex
129
Where do top down signals come from?
From the cortex to thalamus to suppress sensory info
130
How does the brain decode sensory input if all neurons work in the same way?
- The pathway indicates the sense. So, activity in LGN / calcarine sulcus means visual information.
131
What are phantom limbs?
- After amputation, patients can sometimes still ‘feel’ their missing limb: inputs to the cortex remain.
132
What is synaesthesia?
- Perception of sensations in an additional modality, e/g/ colours for names: extra connections between brain regions.
133
What are hallucinations?
- Charles Bonnet syndrome: activity in the inferotemporal cortex (object perception).
134
What is the auditory cortex for?
Hearing
135
Where is the visual cortex?
Calcarine sulcus
136
Where is the auditory cortex?
Superior temporal lobe
137
What is the somatosensory cortex?
Touch, proprioception
138
Where is the somatosensory cortex?
Postcentral gyrus
139
What is the gustatory cortex for?
Taste
140
Where is the gustatory cortex?
Insula
141
What is the olfactory cortex?
Smell
142
Where is the olfactory cortex?
Pyriform cortex
143
What does a scotoma look like?
- You all have a scotoma … the blind spot
- By definition, they don’t ‘look like’ anything
144
What is the homunculus?
– ‘little man’ – a representation of the body surface in a region of the brain
145
What is the receptive field?
the area (of the world/body) from which stimuli can influence the firing rate of a neuron.
146
What will neuronal damage do to the receptive field?
Neuronal damage will affect sensation in its receptive field
147
For vision and touch where is the receptive field?
- For vision and touch, the receptive field is always contralateral to the neuron (i.e. on the other side of space left-right, right-left)
148
What are the sizes of receptive fields
- A single neuron in cortex may respond to touch over a small area of skin (fingers) or a large area (forearm)
- A large receptive field corresponds to low ability to localise stimuli
- Larger cortical area for neurons with small receptive fields (see homunculus)
149
Who was John Hughlings Jackson (1835-1911)?
- A single neuron in cortex may respond to touch over a small area of skin (fingers) or a large area (forearm)
- A large receptive field corresponds to low ability to localise stimuli
- Larger cortical area for neurons with small receptive fields (see homunculus)
150
What cells does the primary motor cortex contain?
- The primary motor cortex contains giant ‘Betz cells’ projecting to spinal cord
- They are very large as they need to fire a very long way, the cell body needs to keep it alive and healthy, so they need to be large.
- Spinal cord cells project to specific muscles
151
What does stimulation of the primary motor cortex cause?
Movement of specific contralateral muscles/muscle groups
152
What is the ratio of spinal cord motoneurons?
- Ratio of spinal cord motoneurons: muscle fibres determine precision of movement
- 1:3 = very precise
- 1:300 = very imprecise
- With a 1:3 ration, you need 100 neurons for every 300 fibres
- With a 1:300 ration, you only need 1 neuron for every 300 fibres
- Hence, bigger area of cortex maps to areas of body with more precise motor control (homunculus)
153
What does damage of primary motor cortex lead to?
- Muscle weakness on the side of the body contralateral to the damage
- E.g. left-sided weakness following right primary motor cortex damage
- Paralysis on the side of the body contralateral to the damage
- E.g. right-sided paralysis following left primary motor cortex damage
154
What is the secondary motor cortex?
- Anterior to the primary motor cortex. Includes both:
Premotor cortex
Supplementary motor area
- Project to primary motor cortex
- Motor control
Movement patterns – e.g. reach to grasp, sequences of movements
Stimulation produces complex movement
155
What is the prefrontal cortex?
- Executive function – flexible, controlled cognition and behaviour, esp. for novel or unusual situations
Decision making
Working memory & planning - holding and manipulating information “on-line”
Inhibition & flexible cognition - inhibiting unwanted (automatic) actions, switching between rules
156
What is working memory?
- Holding information ‘on-line’ which is not currently present in the environment.
- E.g. a recent stimulus; a behavioural goal or plan
157
What is PFC?
PFC especially required for manipulation of this information
- E.g reorder these digits by value (lowest to highest)
158
What is utilization behaviour?
- E.g. neurologist leave matches on their desk, the patient sees them and starts striking matches on neurologists’ desk
159
What are action slips?
Action slips
- E.g. walking to work on your day off; putting milk in a ‘black’ coffee
160
Where are perception of objects and space carried out?
- Carried out by association cortex in occipital, parietal and temporal lobes
- Note: Primary sensory cortex is the cortical region which first receives sensory input (via thalamus or brainstem nuclei). Association cortex receives input from primary sensory cortex and processes it to a higher level of meaning
161
What is the role of ventral steam?
perceiving and recognising objects using vision (what)
162
What is the dorsal stream function?
locating, and interacting with, objects in space using vision (where/how)
163
What does knowing what you see involve?
- Involves retrieving name and meaning
164
In vision where does cortical processing begin?
- In vision, cortical processing begins in medial occipital cortex (calcarine sulcus) – sensation (e.g. brightness)
165
What does knowledge of what we see involve?
- Knowledge of what we see involves first perception of form, then recognition of objects and individuals (e.g. faces)
166
What does the effects of ventral steam damage depend upon?
- The effects of ventral stream damage depend on how far along the stream the damage occurs
167
What is agnosia?
- A+ gnosia = ‘lack of knowing’
- Agnosia can be visual, auditory, somatosensory …
- But each is modality specific. Therefore, for example, visual agnosia patients would be able to name an object through touch
168
What is apperceptive agnosia?
- Intact low-level perception
Acuity
Brightness discrimination
Colour vision
- Inability tp extract global structure
- Evidenced by imapirments in copying and visual recognition, even of common objetcs
- Patients are unable to recognise or copy certain things
169
What is associative agnosia?
- No problem copying figures
- However, inability to draw from verbal instruction or to recognise objects using vision
- Action-based knowledge is retained (e.g. the example of farmer milking a cow)
170
What is prosopagnosia?
- Prosopagnosia = inability to recognise faces visually
- Patients can tell that a picture shows a face, and can describe the features of the face but they cannot tell who it belongs to, even family
- Can still identify individuals through voice, hairstyles, characterise clothing etc (this confirms that it’s not a ‘knowledge’ problem
171
What does prosopagnosia tend to involve damage to?
- Prosopagnosia tends to involve damage to the fusiform gyrus in the inferior part of the temporal lobe
172
What is optic atazia?
- Problems using vision to reach & grasp objects
- Intact* ability to identify objects (note: dissociation)
- Results from lesions of posterior partial cortex, i.e. dorsal pathway
173
What is hemispatial neglect?
- A failure to attend to the contralateral side of the world
- Cannot be explained by hemianopia or other sensory deficits
- Not definitely part of either ventral or dorsal stream
- Can affect daily activities – e.g. dressing, eating
- Note: patients are often unaware of their deficit
- Neglect can occur after damage to a variety of regions, usually right-sided; especially the temporo-parietal junction
174
What is communication?
- Communication: behaviours used by one member of a species which convey information to another
175
What is language?
- Language: a communication system which has symbols (e.g. words) and rules for ways to put the symbols together (e.g. grammar)
176
What is aphasia?
- We have learned much about the brain basis of language by studying patients with aphasia.
- Distributed language function = aphasia
- Note: In aphasia, deficits must not be due simply to sensory or motor dysfunction (deafness paralysis etc.) but must be language-based
177
Where is the brain basis of aphasia?
- Aphasia tends to be produced by left-sided damage – language is lateralised in the brain
- Note: In a few people, language is right lateralised
- Damage to different areas produces different types of aphasia, because of specialised roles of distinct brain regions
178
What is Broca's area/Broca's aphasis?
- First widely recognised example of cortical localisation
179
Where is broca's area?
- Left inferior frontal lobe
180
What happens to those with broca's aphasia?
- Anterior to primary motor cortex for face & lips
- Difficulty in speech production: speech is slow and non-fluent; difficulty finding world
- Comprehension & automatic speech (relatively) intact (e.g. they could answer how are you = fine, but would struggle with I heard you are ill tell me all about it = ???)
- Broca’s aphasia; ‘non-fluent’ aphasia
181
Where is Wenicke's area?
- Left superior temporal gyrus: Wernicke’s area
182
What happens to those with Wernicke's aphasia?
- Patients fail to recognise spoken language
- Speech is fluent but meaningless (cannot monitor what is being said)
- Wernicke’s aphasia; ‘fluent’ aphasia
183
What are neologism and which patients often do it?
- Patients with Wernicke's aphasia
Neologism – ‘new word’ – errors in pronunciation or complete creation of words which are not part of the recognised language
- ‘It was my job as a convince, a confoser, not confoler but almost the same as a man who was commersed’
184
What is memory?
- Memory is not a single function
- Types of memory can be dissociated from each other i.e. disrupted independently by lesions to different brain areas
185
What are the 4 types of memory?
Episodic
Semantic
Working
Procedural
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What is episodic memory?
Events
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What is sematic memory?
Facts
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What is working memory?
Held in mind
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What is procedural memory?
Doing
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Where does episodic memory take place?
(Medial temporal lobe esp. hippocampus)
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Where does semantic memory take place?
(Lateral temporal cortex)
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Where does working memory work?
Lateral prefrontal cortex
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Where does procedural memory happen?
(Basal ganglia)
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What does Semantic dementia cause?
- Semantic dementia damages lateral temporal lobe : impaired on semantic memory
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What is cerebral lateralisation?
Cerebral lateralisation - the tendency for one of the two hemispheres to excel at a particular skill or function
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What are methods for determining lateralisation of cognitive function?
1. Neuropsychology & neuroimaging studies
2. Lateralised input in healthy participants
3. Split brain patients
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What are 4 examples of Neuropsychology & neuroimaging studies?
- Lesion studies
- Wada test
- TMS
- fMRI
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What is aphasia normally a consequence of?
- Usually a consequence of LEFT hemisphere damage
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What is hemispatial neglect and prosopagnosia normally a consequence of?
- Usually follow RIGHT hemisphere damage
- Hemispatial neglect is when you don’t acknowledge half of your world
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What is the WADA test?
- Used before brain surgery to determine patient’s language-lateralisation.
- Sodium amytal (delivered via carotid artery) anaesthetises one hemisphere temporarily.
- Most people (left- and right-handers) are left- lateralised for language; a small number (higher proportion of left-handers than of right-handers) are right-lateralised.
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What is TMS?
- Knecht et al., 2002
- Determined lateralisation via blood-flow during language task.
- TMS slowed picture-word verification only for appropriate hemisphere
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What are tachistoscopic studies?
- Stimuli are presented very briefly so that the subjects do not have the time to move their eyes towards the stimulus.
- Depending on the stimuli/task, performance may be better in the left or right visual field
- E.g. Lateralisation of word-processing.
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What are Z-lens studies?
- The Z-lens is a special type of contact lens that only allows input from one half of the visual field (left or right).
- Participants can move their eyes freely whilst only the contralateral visual cortex is directly stimulated by incoming visual information.
- Eliminates need for brief stimuli.
- Auditory input is also lateralised.
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What are dichotic listening studies?
- Present two different sounds to each ear simultaneously
- Right-ear advantage for dichotic presentation
- Right ear advantages in dichotic tasks
Numbers
Words
Nonsense syllables, e.g. “ba”, “ga”
- ... showing that the left hemisphere is specialised for these stimuli
- Left ear advantages in dichotic tasks:
Musical sounds (e.g. chords or melodies)
- ... showing that the right hemisphere is specialised for these tasks/stimuli
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What are the problems with these studies?
Info gets rapidly transferred between hemispheres – effects are subtle.
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What is the solution to these studies problems?
Test “split-brain” patients.
- “Split-brain” patients have their corpus callosum cut surgically (to relieve intractable epilepsy).
- Language, visuospatial skills & IQ are largely unaffected.
- Impairments can be demonstrated with careful testing.
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