Biological psychology Flashcards
1
Q
what do sensory receptors do?
A
Sensory receptors project to specific nuclei within the thalamus (usually, but not smell) and these projects to cortex
2
Q
what happens at each stage in sensory receptors?
A
Processing occurs at each stage.
E.g. “top-down” signals from cortex to thalamus to suppress sensory info
3
Q
do all neurons work the same way?
A
yes
4
Q
how to decode sensory inputs?
A
The pathway indicates the sense. So activity in LGN / calcarine sulcus means visual information.
5
Q
what are phantom limbs?
A
After amputation, patients can sometimes still “feel” their missing limb: inputs to the cortex remain
6
Q
what is synaesthsia?
A
Perception of sensations in an additional modality, e.g. colours for names: extra connections between brain regions
7
Q
what are the primary sensory areas of the cortex?
A
- visual cortex - calcarine
- auditory cortex (hearing) - superior temporal lobe
- somatosensory cortex (touch, proprioception) - postcentral gyrus
- gustatory cortex (taste) - insula
- olfactory cortex (smell) - pyriform cortex
8
Q
what are the primary sensory areas of the cortex?
A
- visual cortex - calcarine
- auditory cortex (hearing) - superior temporal lobe
- somatosensory cortex (touch, proprioception) - postcentral gyrus
- gustatory cortex (taste) - insula
- olfactory cortex (smell) - pyriform cortex
9
Q
who is Gordon Holmes (1876 - 1966)?
A
- Neurologist in WWI.
- Mapped the visual field - the region in which visual targets can be detected.
- Orderly mapping in contralateral occipital lobe
10
Q
who is Wilder Penfield?
A
- Canadian neurosurgeon
- Surgical removal of parts of the cortex for treating intractable epilepsy
- Electrical stimulation of the cortex in awake patients
Penfield stimulated numbered regions of the cortex and noted the reaction of the patient
11
Q
what is a homunculus?
A
“little man” - a representation of the body surface in a region of the brain
12
Q
what do biggers areas of the cortex signify?
A
Bigger areas of cortex (= more neurones) devoted to more sensitive regions of the body
13
Q
what is a receptive field?
A
the area (body) from which stimuli can influence the firing rate of a neurone
14
Q
what does neuronal damage affect?
A
Neuronal damage will affect sensation in its receptive field
15
Q
where is the receptive field for vision and touch located?
A
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).
16
Q
how does a single neurone in the cortex respond to touch?
A
A single neuron in cortex may respond to touch over a small area of skin (fingers) or a large area (forearm)
17
Q
what does a large receptive field correspond to?
A
A large receptive field corresponds to low ability to localise stimuli
18
Q
what size of neurone are larger cortical areas linked to?
A
Larger cortical area for neurones with small receptive fields (see homunculus)
19
Q
what are the size of the receptive fields on your fingers and why are they important?
A
- Neurons in the sensory cortex for the finger have small receptive fields* I.e., They receive input from a small area of skin.
- So neighbouring patches of skin from the finger will probably project to different cells in the cortex
.* But from the forearm… they may project to the same cell, so impossible to differentiate
20
Q
what are “centre surround” receptive fields in the eyes used for?
A
“Centre-surround” receptive fields in retinal (eye) cells are useful for edge detection
21
Q
what does the secondary motor cortex consist of?
A
supplementary motor area
premotor cortex
22
Q
what does the supplementary motor area do?
A
folds onto medial surface
23
Q
what does the frontal lobe consist of?
A
- primary motor cortex
- prefrontal cortex
- secondary motor cortex (supplementary motor cortex and premotor cortex)
24
Q
what does the frontal lobe consist of?
A
- primary motor cortex
- prefrontal cortex
- secondary motor cortex (supplementary motor cortex and premotor cortex)
25
what is the function of the Primary motor cortex: Precentral gyrus
it is the motor homunculus
26
who is John Hugh Jackson?
* British neurologist
* First to map human motor cortex by observing a type of epileptic seizure.
* The “Jacksonian March”: seizures spread along the primary motor cortex (“motor strip”) in both directions
27
what does the primary motor cortex contain?
Primary motor cortex contains giant “Betz cells”. projecting to spinal cord
28
what do spinal cord cells project to?
Spinal cord cells project to specific muscles
29
what does the stimulation of the primary motor cortex lead to?
Stimulation of primary motor cortex → movement of specific contralateral muscles/muscle groups.
30
what does the Ratio of spinal cord motoneurons determine?
Ratio of spinal cord motoneurons : muscle fibres determines precision of movement
Hence, bigger area of cortex maps to areas of body with more precise motor control(~homunculus)
31
what can damage of the 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.
32
what is located anterior to the primary motor cortex?
* premotor cortex
* supplementary motor area
33
what does motor control include?
* movement patterns, e.g. reach-to-grasp, sequences of movements
* stimulation produces complex movement
34
what is the executive function of the prefrontal cortex?
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
35
Who is phineas gage?
* Poor control, including impulsivity & disinhibition (e.g.breaking social rules)
* Social problems & inability to work well
* N.B. preserved intellect, memory, sensation and perception
36
what are good and bad decks in the Iowa Gambling Task?
Bad decks - high immediate gains but overall loss
Good decks - low immediate gains but over overall gain
37
what happened to the healthy patients in tge IGT?
Healthy participants gradually learn to avoid the“bad” (high risk) card
Skin-conductance response (SCR) differed in anticipation of a choice from the “good” and “bad”decks, probably guiding decision-making: “somatic markee"
38
what happened to ventromedial PFC lesion patients and the IGT?
* Patients with VM-PFC damage continue to make bad choices.
* This is despite being able to say which cards are“good” and “bad”.
* They lack the SCR response: not guided away fromthe bad choices.
39
what is working memort?
* Holding information “on-line” which is not currently present in the environment;
- E.g. a recent stimulus; a behavioural goal or plan.
The PFC is especially required for manipulation of this information
40
what is the multiple errands task?
Carry out a number of tasks (e.g. “buy bread”,“find out the coldest place in Britain yesterday”), within certain restrictions (e.g.“spend as little money as possible”, “be at a certain place in 15 minutes”)
.Frontal lobe damage patients made more errors,including being inefficient and breaking the rules.
41
what is the wisconsin card sorting test?
* Rule changes require flexibility.
* PFC damage leads to perseveration – continued use of aprevious rule
42
what is the motor system hierarchy?
Multimodal association cortex:prefrontal cortex --> Secondary motor cortex:premotor cortex, supplementary motor area --> Primary motor cortex: precentral gyrus ---> Spinal cord --> Skeletal muscles
43
what is the perception of objects and space carried out by?
* Carried out by association cortex in occipital,parietal and temporal lobes.
44
what is the primary sensory cortex
Primary sensory cortex is the cortical region which first receives sensory input (via thalamus or brainstem nuclei)
45
what is the association cortex?
Association cortex receives input from primary sensory cortex and processes it to a higher level of meaning.
46
what are the two visual streams?
the ventral stream and the dorsal stream
* Attention to visual objects in space
47
what does the ventral stream do?
Ventral stream function: perceiving and recognising objects using vision.
48
what is the dorsal stream?
Dorsal stream function: locating, and interacting with, objects in space using vision
49
what is the ventral stream made of?
occipital cortex (association cortex) ---> inferior temporal cortex (association cortex)
50
how do humans know what they are seeing?
* Recognition of objects is not trivial. (Thinkline-drawings, unusual views, lighting conditions etc.)
* Involves retrieving name & meaning.
51
where does cortical processing begin? (vision)
* In vision, cortical processing begins in medial occipital cortex (calcarine sulcus) – sensation(e.g. brightness).
* Knowledge of what we see involves first perception of form, then recognition of objects and individuals (e.g. faces).
* The effects of ventral stream damage depend on how far along the stream the damage occurs.
52
what increases along the ventral pathway?
Specificity of function increases along the ventral pathway
53
what is the ventral pathway?
brightness/ accuracy --> from perception -->object recognition
54
what are agnosias?
* a + gnosia = “lack of knowing”* Agnosias 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.
* (Assume “visual” unless otherwise stated.)
55
what are the qualities of apperceptive agnosia?
* Intact low-level perception
– acuity
– brightness discrimination
– color vision
* Inability to extract global structure.
* Evidenced by impairments incopying and visual recognition,even of common objects
56
how does apperceptive agnosia affect the ventrak pathway?
brightness and accuracy --> xform perceptionx
57
who was patient DF? (apperceptive agnosia)
* DF: carbon monoxide poisoning.
* Damage to ventrolateral occipital cortex.
* Apperceptive agnosia – inability to perceive structure of visual objects.
* Preserved reach/grasp ability (...compare this to patients with dorsal stream damage).
* Dissociation of functions (impaired vs. preserved).
58
what is associative agnosia?
* No problem copying figures.
* However, inability to draw from verbal instruction or to recognize objects using vision.
* Action-based knowledge is retained (e.g. the example of farmer milking a cow).
59
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, hairstyle,characteristic clothing etc. (This confirms that it’s not a “knowledge” problem.)
60
what is an example of prosopagnosia?
“When Bodamer discovered the patient’s problem he was able to establish that S. could tell that certain objects were faces, but not to whom they belonged-indeed he was unable to read facial expressions or even distinguish women from men,except by using hair or hat cues. When confronted with his own face in a mirror, S. could not recognise it-nor even be sure of its gender.”
61
where does prosopagnosia affect?
* Prosopagnosia tends to involve damage to the fusiform gyrus in the inferior part of the temporal lobe.
* ‘Fusiform face area’ (FFA)
* “Greebles” activate the FF
* usually follows right hemisphere damage
62
what does the dorsal stream consist of?
occipital cortex (association cortex) --> posterior parietal cortex
63
what is optic ataxia?
* Problems using vision to reach & grasp objects.
* Intact* ability to identify objects (note:dissociation).
* Results from lesions of posterior parietal cortex; i.e., dorsal pathway.
64
what is the posting task?
* Post item (or hand) through the slot (requires dorsal stream)
* there is impaired posting ability in optic ataxia patients
* Test visuomotor function:Post item (or hand) through the slot (requires dorsal stream
* test perceptual function:Match orientation of item with slot (at a distance) –requires ventral stream
65
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 definitively part of either ventral or dorsal stream.
* Can affect daily activities, e.g. dressing, eating.
* N.B. Patients are often unaware of their deficit.
66
how does neglect occur?
Neglect can occur after damage to a variety of regions, usually right-sided; especially the temporo-parietal junction
(usually a consequence of right hemisphere damage)
67
what is the definition of communication?
behaviours used by one member of a species which convey information to another
68
what is the definition of language?
a communication system which has symbols (e.g. words) and rules for ways to put the symbols together(e.g. grammar)
69
what is aphasia?
* Disturbed language function = aphasia.
* In aphasia, deficits must not be due simply to sensory or motor dysfunction (deafness,paralysis etc.), but be language-based.
70
how does aphasia occur?
* Aphasia tends to be produced by left-sided damage - language is lateralised in the brain.
* N.B. In a few people, language is right-lateralised (see also Lecture 10).* Damage to different areas produces different types of aphasia, because of specialised roles of distinct brain regions.
71
what are the two language areas in the brain?
Broca's area and Wernickle's area
72
what is Broca's area responsible for?
Langauge production
First widely recognised example of cortical localisation
73
what is wernickles area responisble for?
language recognition
74
where is Broca's area located?
* Left inferior frontal lobe: Broca’s Area.
* Anterior to primary motor cortex for face & lips.
75
what is Broca's aphasia?
non-fluent aphasia
* Difficulty in speech production: speech is slow and non-fluent; difficulty finding words.
* Comprehension & automatic speech (relatively) intact.
76
where is wernickle's aphasia located?
Left superior temporal gyrus: Wernicke’s area.
77
what is wenickle's aphasia?
fluent aphasia
* Patients fail to recognise spoken language.
* Speech is fluent but meaningless (cannot monitor what is being said).
78
what does neologism mean?
“new word” - errors in pronunciation or complete creation of words which are not part of the recognized language
79
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
80
what are the types of memory?
episodic memory - events
semantic memory - facts
working memory - held in mind
procedural memory - "doing"
81
what part of the brain does episodic memory affect?
Medial temporal lobe,esp. hippocampus
82
what part of the brain does semantic memory effect?
lateral temporal cortex (probably other cortical areas too)
83
what area of the brain does working memory affect?
the lateral prefrontal cortex
84
where does procedural memory happen?
basal ganglia
85
who was patient HM?
Surgical removal of bilateral medial temporal lobes (including hippocampus), in 1953 to control epilepsy.
86
what happened to patient HM's episodic memory?
* Complete absence of new episodic memories
– Could not remember events occurring since operation.
– Memories acquired before operation relatively intact.
87
how was patient HM's working memory affected?
* Normal digit span (e.g. repeat thesequence: 5 3 8 2 9 1 6)
* Unless interrupted (constant rehearsal).
* Can hold a conversation, even though later that day he will not remember having held it.
88
how did the operation affect patient HM's procedural memory?
* Could learn new skills
– Normal improvement on mirror tracing task
– There is also evidence that amnesic patients canlearn new piano pieces
89
who was Patient KC
* Road traffic accident; brain damage to bilat. MTL.
* Severely amnesic; no new episodic memories.
* Learned new semantic information
* Learning was slow, required many repetitions, but very long-lasting.
90
what evidence is there for double dissociation?
Testing two groups of patients with distinct damage gives evidence of separated functions: double dissociation.
91
what does alzheimers disease affect?
Alzheimer’s disease damages medial temporal lobe, especially hippocampus: impaired on episodic memory
92
what does semantic dementia impact?
Semantic dementia damages lateral temporal lobe: impaired on semantic memory.
93
what is cerebral lateralisation?
the tendency for one of the two hemispheres to excel at a particular skill or function
94
what are the methods used to determine lateralization of cognitive function?
1. Neuropsychology & neuroimagingstudies
2. Lateralised input in healthy participants
3. Split brain patients
95
what are examples of neuropsychology + neuroimaging studies?
Lesion studies
Wada test
TMS
fMRI
96
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
97
what is TMS?
* Determined lateralisation via blood-flow during language task.
* TMS slowed picture-word verification only for appropriate hemisphere.
98
what are the two types of studies used for determining lateralised input in healthy patients?
Tachistoscopic / z-lens studies (vision)
Dichotic listening studies (audition)
99
how does visual stimuli travel for lateralised visual input?
* Visual stimuli reach the contralateral hemisphere before the ipsilateral hemisphere.
* So performance is improved by presenting stimuli to the visual field contralateral to the specialised hemisphere.
* Compare performance for left and right presentation to indicate specialised hemisphere(contralateral to input).
* In healthy people, information passes between hemispheres so this is just a relative advantage
100
what problem do tachistiscopic and z-lens studies eliminate?
The results are often weak because we can move our eyes, so input was not restricted to one hemisphere.
101
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 maybe better in the left or right visual field.
102
what did hunter and brysbaert find?
Tachistoscopic word-reading predicts dominant hemisphere for language (validated against fMRI activation for word-generation)
103
is auditory input lateralised?
yes
104
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
* Left ear advantages in dichotic tasks:
- Musical sounds (e.g. chords or melodies)
105
what gap in research do split-brain patients fill?
they are helpful as info gets rapidly transferred between hemispheres – effects are subtle.
106
what are 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
107
how do you test split brain patients?
* Procedures are similar to tachistoscopic studies in healthy volunteers – e.g. still need to control for eye movements.
* But results are much more striking – e.g.,complete lack of ability rather than subtle differences in performance.
