Miscellaneous Flashcards
1
Q
What are the 3 fluid filled compartments we can consider the brain to consist of
what are they separated by
A
Extracellular space
blood vessels
ventricles
selectively permeable barriers
2
Q
What is the Monro-Kelly Doctrine
A
If any of the brain fluids changes in volume, one or both of the other two must also change, otherwise intracranial pressure will rise and brain tissue will become compressed
3
Q
How much blood does the brain require per min
A
800ml/min
4
Q
Why is cerebral blood flow so regulated
A
too much blood flow can lead to raised intra-cranial
pressure (normal range, 5-15 mmHg),
too little blood flow (ischaemia and resulting hypoxia) can lead to loss of neuronal function.
If blood flow is interrupted for a few seconds, unconsciousness results; after a few minutes infarction may occur
5
Q
What is a ‘stroke’
A
a rapid onset of neurological dysfunction due to impaired blood supply to brain tissue
6
Q
What are the causes of interrupted blood flow to the brain?
What % of strokes does each count for
A
- Thrombotic strokes (~50% of strokes)
- Embolic strokes (~30%)
- Haemorrhagic strokes (~20%)
7
Q
What is a haemorrhagic stroke
A
Leaking or ruptured blood vessels, eg due to high blood pressure, aneurysm, trauma
8
Q
What is a TIA
A
‘transient ischaemic attack’ - a stroke that lasts for < 24 hours.
Although blood supply is restored, a TIA can indicate the risk of a major stroke
9
Q
What do the arteries from the ICA in the circle of Willis supply
A
anterior cerebral
arteries (ACA) supply medial aspects of the cortical hemispheres forward of the parietal-occipital border,
middle cerebral arteries (MCA) supply lateral parts of the hemispheres, the basal ganglia and the internal capsule (sensory and motor axonal tracts conveying information to and from the cerebral cortex).
A choroidal artery branch supplies part of the choroid plexus
10
Q
What do the most common strokes in the Circle of Willis arise from
A
occlusion of MCA branches, notably ‘striate‘ branches
11
Q
What does the Post. cerebral artery supply
A
occipital lobe,
posterior-inferior surface of the temporal lobe,
diencephalon and midbrain,
the choroid plexus.
12
Q
What do branches of the basilar and vertebral arteries supply
A
midbrain, pons, medulla, cerebellum and spinal cord.
13
Q
2 ways of doing a cerebral angiograph
what does this allow
A
X-ray/CT or MRI angiography
allows visualisation of cerebral blood flow following introduction of a radio-opaque substance (‘contrast medium’) into the anterior or posterior systems. This allows obstructions or leaks to be located.
Magnetic Resonance Angiography can be used (rather than x-rays) to image the vessels, although this depends on MRI availability and cost.
14
Q
True or false
cerebral blood vessels have some independence from systemic blood pressure
A
true
Cerebral blood vessels can alter their diameter, autoregulating blood flow to a given brain region despite changes in systemic blood pressure. For example, increased pCO2 or decreased pH or pO2 cause vasodilatation, increasing blood flow
15
Q
What makes fMRI possible
A
autoregulation of cerebral blood vessels
Increased neuronal activity demands an increase in regional blood flow
16
Q
What is the BBB formed from
A
formed in the walls of the blood vessels that penetrate into brain tissue, whose endothelial cells have specialised tight junctions between them and this is covered by astroglial foot processes
17
Q
what are the 3 functions of the BBB
A
(i) Prevent harmful substances in the body reaching the brain.
(ii) Prevent exogenous toxins from the external environment reaching the brain.
(iii) Allow essential substances, such as glucose and amino acids, to reach neurones and glia.
18
Q
How do substances required by the brain cross the BBB (3)
A
passive diffusion, either across the tight junctions (small hydrophilic substances), or across the endothelial cells membranes (small lipophillic substances);
carrier-mediated facilitated diffusion (eg glucose, amino acids)
vesicular movement (eg adsorptive endo/transcytosis of plasma proteins, receptor-mediated endo/transcytosis of insulin).
19
Q
Give an example of a drug that can cross the BBB
A
L-DOPA, used to treat Parkinson’s disease, is carried across endothelial cells by a facilitated diffusion system normally used to transport essential amino acids
20
Q
Where is the BBB absent in the brain
A
(i) In circumventricular organs - secretory/receptive structures at the interface of the brain and endocrine system eg the pineal gland.
(ii) In choroid plexus
(iii) In certain neurological disorders. For example brain tumours often contain ‘leaky’ blood vessels. A leaky BBB may allow toxins into the brain and can lead to vasogenic oedema (increased ECF volume).
21
Q
Where is CSF found (4)
A
(i) The ventricles of the brain.
(ii) The central canal of the spinal cord.
(iii) The subarachnoid space (between the arachnoid & pia membranes in brain and spinal cord).
(iv) The cisterns (expansions of the subarachnoid space- eg cisterna magna and lumbar cistern).
22
Q
What is the purpose of the CSF
A
acts as a cushion against physical trauma and displacement of the brain, and removes
harmful metabolites from ECF.
23
Q
How much CSF is secreted each day, what secretes it, and what is it secreted into
A
Around 500ml per day is secreted by choroid plexus in the lateral, third and fourth ventricles
24
Q
What does the choroid plexus consist of
A
branches of the choroidal arteries surrounded by a specialised epithelium called choroid epithelium
25
Give a function of choroid epithelium
another mechanism for limiting the entry of toxins - choroid endothelium allows free movement like a normal blood vessel so the epithelium's tight junctions stop movement out of the choroid plexus
26
Describe choroid endothelium
Inside the choroid plexus the blood vessel walls have normal (fenestrated) spaces between endothelial cells, allowing free movement of substances out of the blood vessel.
27
What does the choroid epithelium consist of
it is a fusion of pia materand ependyma (the epithelium lining the ventricles).
28
Why is the choroid epithelium considered a blood-CSF barrier
Essential substances cross the choroid epithelium (into the ventricles, forming CSF) by specialised transport mechanisms similar to those in the BBB (facilitated diffusion/ ion exchange and active transport/ ion exchange)
29
Give 4 key differences between CSF and blood composition
why can this difference happen
(i) CSF has much lower protein content
(ii) CSF contains no red blood cells
(iii) CSF contains <5 lymphocytes per ml under normal conditions
(iv) CSF contains about 50% of the [glucose] found in blood.
the choroid epithelium acting as a barrier
30
Name a disease that requires a lumbar puncture
In bacterial meningitis, CSF becomes cloudy, and contains more protein and blood cells.
CSF can be sampled by lumbar puncture
31
How is CSF removed to the systemic circulation per day
how much?
why is CSF removed?
via arachnoid villi, one-way valves formed from arachnoid mater in the walls of dural sinuses
400ml
to maintain constant CSF volume
32
What happens in hydrocephalus
excess of CSF in the brain:
either too much production or too little removal or a blockage in the flow of CSF (eg in the cerebral aqueduct).
The outcome (after the cerebral sutures are fused) may be an increase in intracranial pressure, and tissue damage
33
How does blood drain from different parts of the brain
Superficial cerebral veins from cortex and white matter drain into the superior and inferior sagital sinuses and then into the transverse or straight sinuses, while deep veins e.g. from basal ganglia and diencephalon, drain into the great cerebral vein and then into the straight sinus. The sinuses meet at the confluens.
From the straight sinus, venous blood drains into the sigmoid sinus and then into the internal jugular vein, which removes exhausted blood and CSF from the brain
34
What are the 3 types of psychological research
the first concerns identification and description of psychological phenomena by means such as classifying types of mental illness, measuring distributions of behavioural phenomena and observing reliable behavioural phenomena.
The second looks for relationships between between data sets and attempts to distill statistical regularities that might then inform further research to explain these relationships.
The third is experimental research which attempts to characterize the causal, explanatory mechanisms underlying psychological phenomena
35
What is the purpose of classifying complex issues like stigma
that further research can be conducted asking questions such as whether different types of stigma have different consequences, for example on whether people will seek help for addiction, social isolation of those with addictions, reluctance by health providers to treat addictions, decisions regarding public spending on addiction services and so on.
36
What does mentalise mean
when does this ability appear
infer the mental states of others
sudden onset around the age of 4
37
Give an example of how mentalisation is useful socially
involves an appreciation that the other person’s mental states could be the same as one’s own but could also be different. If they are different, mentalizing allows you to adjust your communication to accommodate to the other person’s perspective, allowing smooth and more efficient interaction.
38
Give an example of a task to assess a person's ability to mentalise
2 characters: A and B
A puts a ball in a box and leaves the room with B still in the room
B puts ball into the basket
Examiner asks where A thinks the ball is
From the child’s perspective, the true location of the ball is in the new location. If the child is able to represent the mental states of the first character, they can infer that the character does not have access to this new information and now has a false belief based on where she originally placed the ball.
39
how does value placed on social responsibility change through development
steadily declines through childhood and adolescence
40
Are developmental changes always linear?
no some are quadratic
shift in who influences adolescents, where unlike children and adults, adolescents are more influenced by their same age peers.
41
Why are observations of U shaped curves when looking at psychological developmental changes useful
there could be a fundamental restructure of a process during adolescence or the change may reflect the influence of two processes, one which operates in childhood and then declines in adolescence and a second but different one which begins in adolescence and matures in adulthood.
42
How did empathy vary with stress and social support in the Park et al. study (2015)
Empathy correlated negatively with perceived stress levels (more empathy, less stress) and positively with perceived levels of social support (more empathy, more support).
43
Park et al advocated that medical programmes should include training on resilience towards stress and means to enhance social support networks in order to optimize levels of empathy. Why may this be misleading?
assumes a causal direction where stress lowers empathy and social support enhances it. But it is equally possible that having higher levels of empathy produces resilience to stress and fosters good social networks. So in order to establish whether medical programmes should invest in training resilience to stress and means of increasing social support, we would need further research
44
How could we to establish whether medical programmes should invest in training resilience to stress and means of increasing social support
we could run an experiment where we have four groups of participants matched for levels of empathy and then give each group different types of experience as they go through their training. One group gets some resilience training, another help in strengthening social support networks, a third gets both types of training and the control group gets nothing. If there are effects of either resilience or social support, we might see changes in empathy scores over time in group 1 or group 2 compared to the control group 4, or perhaps resilience and social support are themselves related in which case we might see the greatest difference in empathy scores between group 3 and group 4.
45
What is factor analysis
identifies superordinate correlations among subordinate correlations.
46
What is a 'general factor' in factor analysis
a factor that is involved in all subtests even though they are all quite different from one another in IQ research has earned the name ‘general factor’
47
What does a good hypothesis need to be
falsifiable
one which enables observation of the null hypothesis rather than one that limits observations to examples of the experimental hypothesis
48
What did Pavlov note in 1927?
what did he hypothesise about thia
neutral stimulus (CS) that is paired repeatedly with a motivationally significant stimulus (US) that provokes certain natural responses (UR) comes to elicit those responses (CR) even in the absence of the US
that this was due to the formation of an association between the CS and the CR
49
What were the variables in Pavlov's experiment's
independent variables would manipulate whether different CSs are followed by a US and the dependent variable would be a change in the CR after repeated pairings of CS and US.
50
Despite Pavlov not being a behaviorist, how did his hypothesis fit with this ideology
Pavlov’s theory makes no reference to any internal mental states – it explains learning entirely by reference to observable stimulus conditions and observable responses.
51
What was the central scientific paradigm in behaviorism
only directly observable states can be the subject of science – all else is speculation.
Scientific psychology should strictly adhere to reference to stimulus events and related responses if it was to be able to identify the laws underpinning behaviour.
52
Name something in psychology which cannot be explained in behavioural terms alone
‘sensory pre-conditioning’.
Two potential CSs are presented together simultaneously. One (A) is then paired with a US until it elicits the CR. If the other CS (B) is presented, it will also show some elicitation of the CR indicating that it has acquired some associative strength despite never having been paired with the US.
53
Explain sensory pre conditioning in cognitive terms
Instead of CS-CR associations, cognitive associative learning theory states that associations are formed between mental representations of the CS and the US. Hence, sensory pre-conditioning can be understood as the formation of an association between CS A and CS B when they co-occur. When CS A is subsequently paired with the US, its associative strength (power to elicit a CR) is shared with the associated CS B. Hence CS B will also elicit the CR.
54
How do we think consciousness and implicit learning are related
cognitive awareness may occur alongside the implicit learning process but is not required for human learning.
55
How can you assess someone's racial biases implicitly
IAT - implicit association test
Both the design of the task and the requirement to respond quickly prevents participants from pondering over their responses and therefore in principle allows the opportunity to measure biases to which they have little conscious access.
56
IAT about racial bias show people who claim not to be biased really are. What does brain imaging suggest
responses on the IAT positively correlate with amygdala activity but explicit questionnaire responses do not.
57
What is overt attention
where you physically move in order to process one object or region preferentially– e.g., moving your eyes toward a particular object
58
Who initially proved covert attention exists
Hermann von Helmholtz -
showed we can covertly select some objects and ignore others with our attention independently of eye movements.
59
Why was covert attention mostly ignored in the early 20th Century
how was research on covert attention restarted
due to the dominance of behaviourism in psychology, which focused on directly-observable relations between stimuli and elicited external behaviour
Cherry’s (1953) observations concerning selective listening in shadowing experiments
60
What were Cherry's (1953) experiments on selective listening
Two messages were presented simultaneously (e.g., by earphones to the two ears: dichotic listening) and subjects were instructed to continuously repeat back one of the messages heard. When one message was presented to one ear and one to the other, subjects had no difficulty in performing this task as they could attend to one of the ears’ inputs. They also remembered little of the ignored message in dichotic listening.
61
What model did Broadbent propose about attention (this was the first cognitive model i think)
proposed a filter model of selective attention, assuming that incoming sensory information has to pass a bottleneck in order to reach limited-capacity stages where full processing takes place.
The filter selects the incoming information in an all-or-none fashion on the basis of elementary physical attributes, operates prior to the contact of sensory information with memory, and thus prior to the identification of this information
62
Give 2 examples which contradict Broadbent's model where there is an all or nothing filter for selective attention
what do both show
when a participant’s own name was presented in the ignored stream, it would often be noticed
words previously associated with electrical shock would rise to
galvanic skin responses even when presented to the irrelevant side
suppression of ignored stimuli is not absolute
63
True or false
| suppression of ignored stimuli is absolute
false
| Particularly salient stimuli can sometimes overwhelm the attenuation imposed on them by attention.
64
How did Posner come up with the idea of the moving "spotlight" of attention
describe this spotlight idea
Cueing Paradigm
The movement of attention from its initial central
location to the location of the cue was characterized as the movement of a “spotlight” of attention across the visual field.
Stimuli falling within the spotlight were assumed to have been processed more efficiently and hence responded to more quickly
65
Explain the cueing experiment used to test movement of covert attention
```
cues (e.g., central arrows) are presented prior to the appearance of a target that could appear to the left or right of a central fixation point. The cue summons the subject’s attention to either the left or right location.
When, the target appeared at the location to which attention had been cued (validly-cued trials) participants detected the target and responded to it more quickly than when neither position was
preferentially cued (neutral trials).
```
Conversely, on trials where the target appeared on
the opposite side to the location that had been cued (invalidly-cued trials) subjects detected the target and responded to it more slowly than when neutral trials.
66
What were the 2 types of spatial cueing studied by Posner
endogenous
exogenous
67
What is endogenous cueing
elicited by centrally- presented symbolic cues (e.g. ►). These cues reliably cue attention when they are spatially informative – that is, when they predict the likely position that the target will appear in.
They probably typically reflect voluntary shifts of attention
68
What is exogenous cueing
cue attention even when they hold no information about the likely position of the target.
associated in particular with peripheral onsets,
elicits exogenous
orienting that is fast and reflexive (involuntary).
69
What does attention select?
object (not a circular region of space)
70
Give 2 examples of studies which show attention does not operate as a simple spot light
1) measured responses to targets
following a cue located at one end of an object, comparing responses to targets
presented at the other end of the same object as the cue versus to targets appearing
equally far away from the cue but on a different object
2)Tracking Studies of Attention
71
Give an example of a tracking study of attention
objects moving in periphery and a word appears the in centre
electrode attached to the visual neurons which track movement
person asked hard or easy questions about words
during easy questions, they were still aware of movement, but not for harder questions
this is incompatible with attention operating as a simple spotlight
72
Name 3 disorders of attention
what part of the brain is affected in each
Unilateral Neglect Syndrome,
Balint’s Syndrome
Unilateral Extinction
all associated with damage in the right parietal (however, neglect can be associated with damage to other frontal and subcortical areas)
73
What is Neglect Syndrome
what can cause it
a patient fails to pay attention to stimuli on their left side
unilateral damage to the right parietal
74
What is Unilateral extinction
arises when the patient does notice stimuli presented in isolation on either their left or right sides, but when a left-side and right-side stimulus are presented together, will fail to notice the left-side stimulus
75
Which attention disorder courses Balint's syndrome
what is this
bilateral parietal damage
‘simultanagnosia’ (an inability to see two objects simultaneously) and fixity of gaze, reflecting a difficulty in switching attention between objects
76
What is an aphasia
Disorders of language, very often in the absence of additional cognitive impairment or the inability to move the muscles used in speech
77
What did Broca suggest originally
based on patient 'Tan'
language appeared dependent upon the left but not the right hemisphere in a region of the frontal lobe - one of the first suggestions of hemispheric specialisation
78
Describe the speech of patients with Broca's aphasia in general
laboured and slow,
articulation impaired
impaired at repeating complex
sentences spoken to them, BUT, these patients appear to comprehend the words and sentences they hear
79
Can Broca's aphasics communicate?
yes as their selection of words, especially nouns, is often correct even though they are difficult to understand
80
Which words do Broca's aphasics struggle with
Verbs, as well as grammatical conjunctions are less well selected and may be missing altogether
81
Give a severe case of Broca's aphasia
. Broca’s original subject could only say the word ‘tan’
82
in Broca's original patient, Tan, what was damaged in his brain (4)
is this typical for Broca's aphasics
- Broca’s area (Brodmann’s areas 44/45)
- surrounding frontal fields,
- underlying white matter
- insula and basal ganglia.
Damage restricted to Broca’s
area produces a far less severe
and transient aphasia.
83
Where did Wernicke report his original patient had lesions
in the left hemisphere, on the superior surface of the temporal lob
84
Describe the speech of Wernicke's aphasics
effortless, melodic and produced at a normal rate.
The content however is unintelligible because of frequent ‘wrong’ words and phonemes (individual or
combined letter sounds, ‘a’, ‘ch’
etc).
85
Do Wernicke's aphasics have difficulties in comprehension
```
have
difficulty comprehending sentences
and this aphasia was originally
thought to be a deficit in auditory
comprehension
```
86
Why was it thought that Wernicke's aphasia was a deficit in auditory comprehension
Wernicke's aphasics have difficulty comprehending sentences
It is important to monitor and understand one’s own speech as well as to understand that of others, hence spontaneous speech is full of
errors.
87
Damage to which structures leads to Wernicke's aphasia
- posterior sector of the left auditory association cortex (brodmann’s area 22)
- in severe, persistent cases there is also damage to middle temporal gyrus and underlying white matter.
88
is there a deficit in comprehension in Broca's aphasia
Can understand a sentence when the meaning can be pieced together by knowledge of individual content words and of knowledge of how the world works but when dependent upon complex grammar, they are impaired.
89
Why do Broca's aphasics have a deficit understanding sentences with complex grammar
it is not simply a deficit in ‘grammar’ as some grammatical error types can be detected by Broca’s aphasic’s.
Particular problem in using grammar when elements to be linked are in different parts of the sentence thereby requiring short term memory
90
What did Wernicke's original model of language processing propose
that the two different aspects of language
processing were associated by fibre tracts – arcuate fasciculus.
While damage to one or other centres produced the characteristic Broca’s motor or Wernicke’s sensory aphasia, damage to the fibre tracts would produce an impairment in the repetition of the spoken word, in the absence of spontaneous speech deficits or word comprehension
91
What aphasia fits the description of damage to the arcuate fasciculus as proposed by Wernicke
conduction aphasia -
impairment in the repetition of the spoken word, in the absence of spontaneous speech deficits or word comprehension
92
Which 2 studies have suggested that t language deficits were associated primarily with damage to the left hemisphere, not the right?
i) . study of split brain subjects
| ii) . use of the WADA procedure.
93
What are split brain patients
Patients whose corpus callosum and anterior commissure had been severed for the treatment of medically intractable epileptic seizures.
94
How was the laterality of language processing in the brain tested in split brain patients
Designed a task that took advantage of the fact that somatosensory information from right hand was processed by left somatosensory cortex and vice-versa for the left hand. Split brain subjects asked to describe an object that they were allowed to examine with either their left or right hand (but not ‘see’).
Object in right hand was named appropriately.
Object in left hand could not be named - only indirect description relying on rudimentary words (eg round thing)
95
What kinds of language/ communication can the left and right hemispheres respond to
left hemisphere can respond to written commands while the right hemisphere responds primarily to non-verbal stimuli (pictorial, rudimentary written commands).
96
How was it shown that the left hemisphere can respond to written commands while the right hemisphere responds primarily to non-verbal stimuli (pictorial, rudimentary written commands).
with use of tachistoscopic presentation
97
What part of language is the right hemisphere important for
prosody (the emotional and tonal colouring of language)
98
What can be a language difficulty of patients with damage to anterior right hemisphere
produce inappropriate intonation in their speech
99
What language difficulties of patients with damage to posterior right hemisphere (5)
have difficulty interpreting emotion in others speech.
may have difficulty incorporating sentences into a coherent narrative and using appropriate language in social setting.
Not very good at understanding jokes!
May find it difficult functioning in social settings
100
What is the WADA procedure?
A short acting anaesthetic, e.g. sodium amytal, is injected into either the left or right carotid artery, thereby anaesthetising the ipsilateral hemisphere.
The patient is then asked questions to assess their ability to speak
101
What was found using the WADA technique
Of 140 right handers, 96% showed speech representation on the left, 4% on the right, 0 bilateral.
Of 122 left handers, 70% showed speech representation on the left, 15% on the right and 15% bilateral.
102
Which 2 aphasias were described by Lichtheim in 1885
transcortical motor aphasia
transcortical sensory aphasia.
103
What are the language deficits of transcortical motor aphasia and transcortical sensory aphasia.
Patients with transcortical motor aphasia (TMA) speak non fluently but can repeat even very long sentences.
Likewise, patients with transcortical sensory aphasia (TSA) show poor comprehension but can repeat sentences and even make grammatical corrections to a sentence they don’t understand
104
Which aphasias are considered the complement of conduction aphasia?
transcortical motor aphasia and transcortical sensory aphasia
105
What did Lichtheim suggest TSA and TMA were due to
a disconnection of language centres from so called ‘concept’ centres
106
Describe the Wernicke-Geschwind model
suggested distinct routes, for the spoken and written word
spoken word came through auditory cortex and the words were only recognized after being processed in Wernicke’s area.
written word came through visual cortex and was processed within the angular gyrus and then Wernicke’s area and ultimately converted to an auditory format
107
Give the results of testing the following using neuroimaging
(i) passively viewing words,
(ii) listening to words
- Passively viewing words (- at rest) caused activation in striate and extra-striate cortex
- Listening to words (- at rest) activated primary and secondary auditory cortex including Wernicke’s area
These specific visual and auditory regions were not activated by non- word stimuli
108
Activity following repeating written (or spoken) words minus (–) activity following passively viewing (or listening to) words. What was seen after this subtraction?
What was seen following subtraction of the following results: Generating new words – repeating words.
After subtraction, there was activity remaining in primary motor and supplementary motor cortex and Broca’s area
Activity remaining after subtraction occurring in frontal and temporal cortex thought to be related to word association task.
109
Give 2 problems with the Wernicke-Gerschwind model
Information coming in through visual cortex (when reading) does not go via the angular gyrus or Wernicke’s area
It is clear that there is considerable overlap between speech production and word comprehension such that these abilities are not completely independent
110
What is anomia
category specific
naming deficits
e.g. naming animal and living things inferior to naming man-made objects, e.g. tools
111
What are modality specific language deficits
ability to define the names of animals inferior to comprehension of pictures
112
What does the existence of anomias and modality specific deficits suggest about the language system
argues against a single semantic or comprehension system
| Backed up by recent functional neuro-imaging studies
113
Give 2 neuroimaging findings arguing against a single semantic or comprehension system
No inclusion of subcortical structures, regions that play a significant role in language including the basal ganglia.
- Cortico-cortical connections from visual and auditory regions to speech zones, and the arcuate fasciculus joining the speech zones together can apparently be removed without incurring aphasia.
