PYSC 111 Flashcards
what part of the eye focusses the image?
cornea and lens
what are cataracts?
the clouding of the lens to the point that the person is unable to see
What does the Critical Period mean?
How long is it in humans?
the time in which the beings critical systems develop (6-9 months in humans)
Name the 3 cell layers that stimulus is carried through, in order.
(Sensation) -> ganglion -> bipolar -> photo receptors
Name the 4 lobes of the brain
parietal, frontal, occipital, temporal
Frontal lobe role:
Executive lobe of the brain
Parietal lobe role:
spacial
Temporal lobe role:
multiple roles - visual, memory
Occipital lobe role:
vision
Name the 3 steps that visual info goes through to get to the brain
eyes (ganglion cells) -> lateral geniculate nucleus (subcortex) -> V1 (cortex)
explain why it is said that the right side of your brain sees through your left eye and vise versa.
half of the neural messages come out of the ganglion fibres at the back of the eye and go t the opposite side and the other half come out and got to the same side of the brain.
What did the Miskin & Ungerleider 1982 study show?
that there are different parts of the brain that are responsible for different types of perception/vision. When one is damaged the subject can no longer percieve that type of vision, however they may be able to learn to percieve the set of things in a different way eg. differentiating objects based on their shape instead of their pattern.
What are the 2 visual pathways in the brain and what do they do?
Ventral stream - pattern perception (what)
dorsal stream - spatial location (where)
How do you test when each cell in the visual system does?
by doing a test in which the cells are shown a certain stimulus and the rate at whcih they are firing electrical impulses is measured. They have a base rate and if they increase or decrease that rate then they care about that stimulus type.
what do rods and cone ‘care’ about?
diffused light (changes in illumination) ONLY
what do retinal ganglion cells ‘care’ about?
spots of light
what do lateral geniculate nucleus cells ‘care’ about?
spots of light
what do V1 cells ‘care’ about?
lines of different orientations
What do the cells beyond V1 do and what area are they in?
what is their nickname?
area: TE/IT
they identify features (eg. facial features)
‘grandmother cells’
Give 2 examples in how grandmother cells can help an animal:
merino sheep can only recognise merini sheep faces
frogs can recognise flies etc
explain how grandmother cells are developed:
there are a base number/type of cells that we are all born with, however, we develop more cells that recongise finer details of things we are more exposed to.
what is retinotopic mapping?
point to point mapping of the external world into the retina.
where does retinetopic mapping occur?
only before V1, after V1 the cells are advanced enough to recognise the stimulus no matter where it lies on the visual feild.
what does it mean when a cell ‘likes’ something?
that its architecture is such that the stimulus type will maximumly stimulate the cell.
what is centre surround architecture?
if light falls onto the middle of the cell it responds, if the light falls beyond the centre of the cell then it inhibits the cells response.
what is the purpose of centre surround architecture?
to enhance contrast (makes the image sharper or crisper)
what happens to the cells repsonse to stimulus?
it is sent to the brain
as you go down the __ __ __, info processing becomes more ____.
ventral visual stream
complex
receiptor field is like a ___.
line
If someone knows where something is but not what it is what has gone wrong?
some signalls are getting to the pariental lobe through the alternate V5 route rather than the damaged V1 route.
what is V5s job?
to tell if something is moving.
If there is something moving it can tell where it is but not what it is unless it has been through the V1 stream.
what is achromatopsia?
absense of colour vision (damage to V4)
what is akinetopsia?
absense of motion vision (damage to V5) eg snapshot vision.
Name 4 characteristics of apperceptive agnosia:
- failure of object recognition due to failure of visual perception
- preserved elementary visual function
- poor matching/copying
- colour vision is still good
was kind of effects do different damages to the V1 have?
poison could damage V1 without destroying it completely, resulting in partial blindess or visual impairment such as agnosia.
trauma such as the V1 being removed or destroyed completely will result in full blindness.
what does scatoma mean?
blind spots (small or large eg. peppery vision making it hard to recognise objects.
what are the 4 types of visual agnosia?
- apperceptive agnsia
- dorsal simultagnosia
- ventral simultagnosia
- associative agnosia
what is dorsal simultagnosia?
- failure to recognise obects due to spatial perceptual impairment.
- can recognise objects but not more than one at a time
- cant see where the object is.
what is ventral simultagnosia?
- failure of object recognition due to a complex perceptual impauirment
- can recognise one obect at a time but can see more
what is associative agnosia?
failure of object recognition due to a higher-order complex perceptual impairment
- seemingly normal copying however perception isnt normal and copying they do is from shapes not recognition of the actual obects.
eg. Dr. P
what did Rene Descartes do?
was the first to introduce the idea that there had to be some central/connected part of the brain that each side of the vision met at.
what did Gall + spurzheim do?
introduced the idea that there were localised faculties in the brain.
thought that because a part of someone skull is big that must mean that they are particually good at the skill that the part of the brain is associated with.
what did Broca do?
(patient Tan)
introduced ‘broca aphasia’ in which he predicted and showed that speech difficulties were linked to damaged tissue in a certain part of the brain, proving localisation.
what did Wernicke do?
challenged Brocas localisation of speech impairment (speaking) by showing that another part of the brain also was responsible for speech (hearing). They were both right that those different parts were both linked to speech impairments.
what did Fritsch + Hitzig do?
discovered that the brain used electrical impulses.
found out that if you stimulate part of the brain then part of the body will move, proving that localised parts of the brain are associated with physical movement in the body.
how much of the brain is for visual?
around 1/3
what is a sulcus?
groove in brain
what is a gyrus?
the ridge between sulci in the brain.
what does damage to the occipital lobe mostly cause?
blindess/blightsight and apperceptive agnosia
what are the parts of the temporal lobe?
lateral surface - superior gyrus, middle gyrus, inferior gyrus.
medial surface - medial temporal lobe
what shape is the temporal lobe like?
a tube
what does the superior temporal gyrus do, and what happens if you damage it?
auditory. if damaged (especially in the A1) it can cause deafness, wernickes aphasia (hearing to speaking), and auditory agnosia (similar to visual)
what does the middle and inferior gyrus do?
ventral visual system
what does damage to the middle/inferior temporal gyrus do?
- achromotopsia (colour) A4
- akinetopsia (motion) A5
- ventral similultagnosia
- associative agnosia
what kind of impairment happens when the medial temporal lobe is damaged?
memory impairment
what is the main structure of the MTL?
the hipocampus
when the right of the MTL is damaged how does the impairment present itself?
visual:
they can copy fine but cannot recall an image.
verbal:
they can hear and recall a story well (no verbal impairment)
when the left of the MTL is damaged how does the impairment present itself?
visual:
they can copy and recall fine (no visual impairment)
verbal:
they can hear but cannot recall a story
what impairments are caused by the removal of the MTL
retrograde amnesia and anterograde amnesia.
what is retrograde amnesia and anterograde amnesia?
retrograde: cant recall past memeories
anterograde: cant make new memories
what does temporally graded amnesia mean?
when they can remember memories far in the past (already stored) but not recent memories.
what does temporally graded amnesia tell us?
that the MTL recieves memories b ut does not store them. they are stored in higher places of the visual and auditory streams.
what is the exception of anterograde amnesia?
people cant remember 90% of the memories but they are able to impove in simple tasks over time which shows that they must have some memory. this proves that there must be many memory systems in the brain.
what are the two types of memory?
declaritive: explicit, eg. a thing that happened to them
nondeclaritive: implicit eg. a skill