Advanced cognitive Flashcards
How much does a brain weigh?
1.5 kg
Dorsal, caudal, ventral and rostral when referring to the cerebrum and the spinal cord
Cerebrum:
Dorsal is superior
Ventral is inferior
Rostral is anterior
Caudal is posterior
Spinal cord:
Dorsal is posterior
Ventral is anterior
What sections are saggital, coronal and axial (horizontal)?
Saggital - like an arrow in the middle, medial to lateral
Coronal is moving from anterior to posterior
Axial is horizontal so moving superior to inferior
What is the neocortex?
80% of brain volume, the outermost 3mm layer of the brain, 4-6 layers of cells.
What are cytoarchitectonic areas?
Brodmann areas
What are projection areas in neuroanatomy?
The areas of the body that map onto specific areas of the cortex.
What are the association cortices largely responsible for?
‘cognition’ they receive input from primary behaviours and they produce behaviour, they are the ‘higher’ cognitive areas.
Role of the thalamus?
‘relay’ station for sensory processing
Role of the hypothalamus?
Motivated behaviour i.e. eating drinking aggression, sexual behaviour
Role of the limbic system?
Memory, learning and emotional processing
Left hemispheric dominance?
Sequential analysis
Problem solving
language
Right hemispheric dominance?
Visuospatial skills
Emotion functioning - recognising and expressing
Music
Main lateral pathways, in the cerebrum?
Arcuate Fasciculus
Superior longitudinal
Inferior longitudinal
Uncinate fasciculus
Main medial pathways in the cerebrum?
Cingulum
Function of the arcuate fasciculus?
Connects the two language pathways together.
function of the superior longitudinal fasciculus?
Connects the superior frontal lobe to posterior parietal
Function of the inferior longitudinal fasciculus?
Connects inferior temporal to occipital
Function of the uncinate fasciculus?
connects inferior orbital frontal lobe to anterior temporal lobe
Function of the cingulum?
Medial frontal lobe and medial temporal lobe/parahippocampal gyrus
Function of the ventricular system?
- protection, it keeps the brain suspended inside the skull
Layers of the meninges?
Outermost: dura
Arachnoid
Innermost: Pia
main arteries supplying the regions of the brain?
Anterior is supplied by internal carotids
Posterior is Basilar (formed from the vertebral)
Laterally is Middle cerebral
Medially is Anterior cerebral
Occipital and inferior temporal supplied by the posterior cerebral.
What is laterality in neuroscience?
It is the relative theory that the left or right hemisphere is dominant for a certain task.
Findings of John-hughlings Jackson in the 1860s in terms of lateralisation?
Cortical convolutions matured quicker in the left side of the brain.
What are the eight major anatomical differences in right and left hemispheres?
- Right is heavier, left has more grey matter
- structural asymmetry between temporal lobes
- asymmetry (between L and R) in cortex of temporal lobes is correlated with midbrain asymmetry in the thalamus.
- Slope of lateral fissure gentler in LH
- Broca’s area (Frontal Operculum) is organised differently in LH and RH, area visible on the surface is larger in RH, but area in sulci is bigger in left.
- RH extends farther anteriorly, LH farther posteriorly, occipital horns of lateral ventricles 5x more likely to be longer in the RH
- Distribution of neurotransmitters is asymmetrical
- Details affected by sex and handedness.
What is a double dissociation
Two areas of the neocortex are functionally dissociated by two behavioural tests, each test being affected by a lesion in one hemisphere but not the other, e.g.
LH lesions (but not RH) result in deficits in language function (speech, writing, reading)
RH lesions (but not LH) result in deficits in spatial tasks
What is the Wada test (Carotid sodium amobarbital injection)? What would we use now?
Test used to demonstrate which hemisphere is dominant for certain activities. The injection causes anaesthesia in the ipsilateral side.
Nowadays we would use an fMRI
What percentages of R handers and L handers are language dominant in what hemisphere?
98% of RHanded are LHemisphere dominant for language
70% of LH are LH dominant for language
2% of RH are RH dominant for language
15% of LH are RH dominate for language
15% of LH are bilaterally dominant
The results of commissurotomy (split brain) studies?
The role of the corpus callosum is to transfer information to the other hemisphere.
Remember R visual field (in both eyes) processed on left and vice versa.
- Language studies:
In split brain patient does not cross-over (optic chiasm cut)
Cannot say the word banana presented to the Left visual field (right hemisphere), as language is normally processed in the left hemisphere.
Can say the word if presented to the RVF (left hemisphere)
Language is processed in left.
- Spatial studies
An object flashed to a right handed patient can be drawn if presented to the left visual field (right hemisphere) by the non-dominant left hand (I assume also in the right hand - but not sure)
Cannot be drawn if presented to RVF (LH)
RH is responsible for spatial orientation
- Perception studies
Illusory contours (fat/thin squares in circles) when outlines are added, can only be told apart by the right hemisphere (left visual field)
RH is dominant for visuospatial information
- Synthesis studies
Show one word in one hemisphere and one word in another and asked to draw both together.
e.g. arrow shown to right, and bow shown to left.
can do for bow and arrow (insubstantial as it is really common) cannot do for sky scraper.
NO synthesis across hemispheres
Can synthesise in the SAME hemisphere (including right- which is not dominant for language) however they drew different things for example in fire and arm, right drew arm on fire and left drew rifle (language).
Evidence for asymmetry in the auditory system in the brain?
left ear goes to RH, and vice versa
Right ear shows advantage to language sounds
Left ear shows advantage for melodies or musical chords (if a melody id played to both ears you will report the one heard in the left)
Two types of models in terms of theoretical explanations of lateralisation?
Specialisation theories and interaction theories.
Main points of specialisation theories for lateralisation?
Unique functions for each hemisphere
Left is more logical, more analytical, analysing sequentially and then attaches verbal labels.
Right is a synthesiser - it likes to put things together and processes information as a whole
Main points of interaction models for lateralisation?
Propose both hemispheres are able to do all the functions, but they do not (one leads). Three explanations:
- Both function simultaneously, but work on different aspects
- They compete and then inhibit each others activities (would be a drain on resources)
- The two hemispheres receive information preferentially and perform analysis simultaneously but pay attention to different aspects.
What is ‘preferred cognitive mode’?
The preferred use of one thought process over another.
What does cognition mean?
To know or conceptualise - faculty that allows the processing and application of knowledge from the environment. It is a construct of human thought, in forms such as memory attention or language perception. This can also be synthetic. It can be conscious or unconscious.
What is cognitive neuroscience, in a sentence?
Translation of mental processes into behaviour.
What is localisation in cognitive neuroscience?
The idea that certain parts of cognition are specific to certain areas of the brain that serve particular functions.
What are lesion studies?
Studies where a region is deactivated either by electrical stimulation, cooling or chemical. (or I assume in humans on people who have lesions through other reasons)
Advantages are that it can infer causality, however it has disadvantages:
- in animals, it is difficult to apply this
- in humans, lesions are often not one specific area
- in humans it relies on observations from individuals, not lots of data - not very powerful.
What is are PET and fMRI?
PET: positron emission tomography
fMRI you know
They look more holistically at the brain, and are used to localise where something happens (not when).
They rely on two main assumptions
- blood flow will increase when neurones are firing more.
- regional differences in blood flow reflect the level of mental activity
What is the concept of subtraction in fMRI?
I.e. you are doing a study on eye-movement:
Need to measure only eye movements not fixation or noise
Do one with only eye movements, and one with only fixation
Minus fixation and noise from eye-movement
What is EEG?
Electroencephalogram
Measures electrical activity of the brain by measuring it on the scalp.
- Fairly cheap.
- a bit noisy (measuring though scalp and hair)
- 64/128/254 electrodes - more electrodes more accuracy
- Can measure brain waves (alpha, beta, theta, delta and gamma). It is generally very clear disruption in waves, as they are pretty stereotypical for different activities i.e. emotions, sleeping, psychosis, epilepsy.
- Can also measure ERP (event-related-potentials)
- Good for temporal data.
Needs lots of repetitions
What is MEG?
Measures electrical impulses emitted from the brain but through magnetic forces.
More accurate that EEG (for localisation) same for temporal
Has to be done in a shielded room (from earths magnetic field)
Requires expertise to get the analysis
What is TMS?
Transcranial magnetic stimulation
Disrupt a few neurones for milliseconds, by sending in electrical pulse.
Can create virtual lesions
Creates a causal relationship between brain area and function (some others are correlational)
Looking to see if people perform worse
Have to have a control a ‘sham TMS’
Sternberg’s 1999 definition of attention?
Attention acts as a mean to focus limited mental resources, on the most salient information and cognitive processes at a given moment
4 different types of attention and their definitions?
Focused attention: Your ability to single out and respond to stimuli without interference from the environment (noise)
Sustained attention: your ability to maintain focus on a task or behaviour during a continuous or repeated stimulus.
Selective attention: your ability to filter out distracting stimuli while maintaining attention on one source of information
Divided attention: Your ability to split your attention between tasks (usually two)
Two ways in which you shift your attention to visual stimuli? (attentional shift)
Overtly - obviously, move head and eyes to another space
Covertly - when you shift your attention without moving your head or eyes.
Two different types of attention?
Exogenous - something grabs your attention (big flash)
Endogenous - voluntary shift to another area
Three types of theories of attention?
Broadbent (1957) - Early selection
Deutsch and Deutsch (1963) - Late selection
Treisman (1964) - Early selection
What was Broadbent’s early selection model?
Sensory info comes in
Stored in short storage (sensory)
Put into a working memory
The stimulus is either (i) put into long term storage or (ii) responded to.
What is Deutsch and Deutsch’s model?
Discovered that we can also remember things we are not asked to focus on - either things slip through or attention isn’t as focused as Broadbent thought.
Late selection:
- Info comes through into sensory info
- It is then put through an analysing mechanism
- it is then put into memory
- this is then either (i) attended to or (ii) left according to pertinence (which is made up of expectations and language)
What is Treisman’s (1964) model?
Attenuation model:
Can happen early, there is a system that attenuates info:
- info comes through to sensory buffer
- then goes through an attenuated process, some info if given more attention than others
- more likely to be put into short term if it has been attenuated to.
What terminology does (i) vision and (ii) audition use to describe attention?
Vision: spotlight or zoom-lens
Audition: Filter or bottleneck
EEG evidence for early selection theories?
Do dichotic listening task - there is a N1 peak in activity in the hemisphere for the attended to ear 20-50ms, which is very early on. also seen at 60ms in P1
An example for object based attention (and late selection I think)
Visual illusions - you must use higher cortical areas, if it was early you wouldn’t expect our perception to be affected.
fMRI evidence for late selectionist theories?
O’Craven et al 1999, presented an image of a face and a house merged on top of each other, found that the fusiform face area is activated when attending to the face and parahippocampal place area.
Both are quite far downstream, evidence for late selection.
What is ‘the binding problem’ in attention?
So different features of the visual scene are coded for by different systems i.e. direction of motion, colour and orientation. We know this through anatomical, neuroimaging and neurophysiological studies
It’s not completely understood how we experience a coherent world
The feature integration model may help to explain this
What is feature integration theory? (full explanation)
The idea that sensory features (orientation, colour etc) are all coded for in parallel by specialised modules.
These modules form two types of ‘maps’:
- Feature maps i.e a colour map, an orientation map
- A master map of locations - all the possible locations in the environment (the feature map is placed within this)
Visual attention is used for:
- locating features
- binding features together
The maps contain two kinds of info:
- presence of a feature anywhere in the visual field
- implicit spatial info about the feature
Two stages:
Preattentive: not using attention, just identifying features of that object in parallel
Attentive: the binding stage, where attention is focused to one area of the field - local features are combined to form a whole
An exogenous, type of attention is top down or bottom up?
Bottom up - using sensory info to bring about attention
An endogenous, type of attention is top down or bottom up?
Top down - using cognitive circuitry to drive the attention
Attention evidence from pts with hemispatial neglect? and those with hemianopia?
Hemispatial neglect:
Damage to right posterior parietal cortex.
Cannot attend to left visual field, however they can see them when they are pointed out.
Hemianopia:
Are aware of objects - but cannot SEE them
Parietal lobes important in attention
Attention evidence form pts with blaints syndrome
bilateral parietal lesions
Simultanagnosia: cannot see the scene as a whole, but only individual areas
Occulomotor apraxia: inability to voluntarily move the eyes, or refixate to a new point of interest
The reflexive system is still intact, however endogenous is not functioning - parietal lobes are important in endogenous attention
Dorsal and ventral stream evidence regarding attention?
Dorsal stream involved in ‘where’ - parietal lesions cannot indicate where an object is
Ventral involved in ‘what’ - temporal lesions cannot indicate what an object is
Frontal lobe involvement in attention?
May be involved in the integration of memory in the attention system. Hopfinger et al.
What is ‘inhibition of return’? What does this tell us about attention?
It is the fact that we have a delay in our ability to return to an object that has just been attended to. At first attention is fast (100-300ms), (facilitation) but at return it is low (500ms-3000ms) (IOR).
Part of the exogenous system of attention, I guess to enhance the presentation of new stimuli.
what areas do the exogenous and endogenous systems occur (dorsal or ventral)?
Exogenous is more ventral
Endogenous is more dorsal
Change blindness and it’s relation to attention?
We are very bad at noticing changes that occur in our field, shows we do not focus on all areas, but have focus attention or divided attention.
Function of ‘sensory memory’? Capacity, duration?
Hold sensation for long enough for you to put it in a ‘buffer’ Large capacity, small duration
Function of short term memory? Capacity, duration?
Hold the perceptions for long enough for you to be able to process them further, 30 second duration 5-9 unit capacity
Function of long term memory? Capacity, duration?
Permanent storage of info, permanent duration and unlimited capacity.
What is working memory?
A type of memory that requires ‘active’ processes in remembering - manipulating info i.e. remember this number and then repeat it back to me backwards.
fMRI findings regarding verbal semantic STM in remembering and forgetting
Left 45/47 area active (ventrolateral prefrontal) involved in semantic processing, specifically activated when remembering vs forgetting.
Areas responsible for semantic processing vs phonological processing?
Phonological - broca’s area (44)
Semantic word processing is again 45/47
TMS Findings regarding visual working memory areas in the brain?
Double dissociation suggesting that the parietal lobe is responsible for visual memory of objects, and that the temporal is for visual memory of faces.
Different types of visual memory tasks?
Maintenance only tasks - short term memory tasks:
- Digit span forward, asked to recite
- Delayed match-to-sample (was it the same)
- Delayed response (click on screen)
Maintenance and manipulation tasks - working memory
- Digit span backward
- N-back (ie 1 back, 2 back or 3)
- Mental arithmetic
What did Gnat and Anderson (1988) show?
How did Oyachi and Otsuka (1994) develop this?
Measured PPC activity during delay of memory guided saccade task - decrease in activity as they make their response.
Compared 1000ms delay and 200ms delay. There is sustained activity in the 1000ms - suggests the PPC is responsible for spatial memory
Oyach and Otsuka showed that it was the right PPC specifically through the use of TMS stimulation
Specialist brain areas involved in visual memory for faces and places?
Parahippocampal place area - places
Fusiform face area - faces