Cognitive Neuroscience Test 2 Flashcards
Abstract
words, objects (left hemisphere)
Specific
faces, object (right hemisphere
Accidental view
a view where you can’t see the non-accidental properties. It is very hard to recognize. This is rare and it usually as simple as moving your head a bit to shift your view.
Achromatopsia
not having any color perception. This is a brain damage related color blindness rather than an eye related color blindness
Akinetopsia
(no motion perception resulting from damage to V5)
Associative agnosias types
There are 3 types: word agnosia, object agnosia, posopagnosia
Word agnosia (alexia)-
difficulty recognizing words (reading)
Object agnosia -
difficulty recognizing objects
Prosopagnosia -
difficulty recognizing faces
Ames room
Fancy room thats not parallel
Blindsight
Damage to primary visual cortex (V1)
No awareness of visual stimuli
Some visual abilities nonetheless, for example:
* Line orientation
* Navigation of environments without running into things
* Also, Emotional stimuli( Can judge if someone is happy or fearful from view, even though they can’t see.)
Contralateral organization
Right and left sides of body are controlled by opposite-side hemisphere
Divided-visual field paradigm
Takes advantage of contralateral organization of visual system
* Information presented in left visual field is processed by right hemisphere first; Information presented in right visual field is processed by left hemisphere first
Dorsal pathway
V3 –> parietal lobe
This is the “where” and “how” pathway
* Object interaction
Face-inversion effect
Recognition of faces is impaired by inversion to a greater extent than recognition of other (non-face) objects
Functional properties of V1
Primary
If V1 is active, you think it is real
V2
illusory contours (lines that aren’t actually there, but they are illusions
V3
Receiving info from V2 and there is a split where Ventral projects to V4 and Dorsal projects to parietal lobe
V4
color perception
V5
Tuned to properties of motion
Fusiform cortex
a key structure for functionally-specialized computations of high-level vision such as face perception, object recognition, and reading
Greebles
Used non-face stimuli called ‘Greebles’
* Each one had a unique look and had unique names too.
Participants were trained to recognize upright Greebles
* There were Novices and experts
* Experts trained to recognize the greebles for 10 hours
* Novices were only about 1 hourish
Question asked: do participants exhibit a ‘greeble-inversion’ effect?
* Novices didn’t, but experts did
* So many faces aren’t as special as we thought, we are just ‘experts’ in recognizing them
Handedness
- 96% of right-handed individuals are left dominant for language
- 60% of left handed individuals are also left dominant for language
- 93% of population is left dominant for language
Hemisphere asymmetries- why do they happen?
- Maybe there are advantages to having non-identical forms of representation(Unique tuned for particular task)
- OR- crossing to other hemisphere take time, maybe asymmetries make it more efficient to keep processes associated with complicated tasks in the same language
Illusory contours
lines that aren’t actually there, but they are illusions(think of the triangle)
Lateral geniculate nucleus
a multilayered structure that receives input from both eyes to build a representation. 90% visual signal goes here and then to V1
Non-accidental properties and views
Vertices, parallel lines, etc.
i.e. we see parallel lines of something, and no matter what orientation the object is, there are still parallel lines
Object agnosia example
- Caused by damage in ventral pathway
- Could not recognize objects
- Could draw from memory (visual imagery)
- He drew two objects (celery + an owl) 4 years after damage to the brain. They were somewhat accurate. Then 10 years later he was asked to draw the same thing and they were not very accurate at all.
- With no object recognition and real representations of these objects, the idea of these objects drifted away as time went on.
Optic ataxia
damage to parietal lobe
Dorsal Pathway Damage
Issues with interacting with objects in space
The lady who couldn’t grab something in front of her.
Parahippocampus
The area where places are processed. Ranked best for places rather than objects, faces, etc.
Parts-based
Words, objects
Left hemisphere
Details by detail to recognize
whole-based (holistic) processing
Right hemisphere
Whole processing
Faces, objects
Priming
Priming is a phenomenon in which previous stimuli influence how people react to subsequent stimuli
Prosopagnosia
difficulty recognizing faces
Planum temporale
larger planum temporale in the left hemisphere(Planum temporale is part of Wernicke’s area). This is an idea as to why language is in the left hemisphere
Retinotopic organization
in V1. Cells to retina organization. a complete map in the brain of the visual field
Split-brain patients
- Patients that have a severed corpus callosum
- Dramatically reduces inter-hemispheric communication
- Studying split brain can isolate hemisphere functions by presenting information to one or other hemisphere
Patient W.J.- split brain movement
- He is supposed to form a pattern with blocks
- Using either right or left hand
- Did well with right hand (left hemisphere), but not with left hand (right hemisphere)
- When both hands did it, it was as if they were fighting over it, not working together
- What does this tell us? That the right hemisphere has great spatial techniques
*
Patient J.W - split brain words
- Words were presented to left or right hemisphere
- Can read words presented to left hemisphere (right side)
- Cannot read words presented to right hemisphere (left side)
- Can draw pictures of words presented to right hemisphere using left hand
Superior colliculus
- the route of the 10% of vision stimulus that doesn’t go to V1.
- cells in the superior colliculus are not tuned to orientation,
- This route is very fast and connects to the amygdala, where fear is processed.
Thatcher illusion
Face-inversion effect with margaret thatcher nose, eyes, and mouth right side up. But we don’t realize it. This provides support for holistic approach to face viewing
Ventral pathway
- V3 –> V4 –> inferior temporal lobe
- Often referred to as the “what” pathway
- Object identification
*
Viewpoint dependence
- Uses viewpoint info- Only in a specific view you can recognize it. This is based on angle. It is DEPENDENT on angle.
- Based on wholes.
- Right hemisphere
Viewpoint Invariance
- Regardless of angle, your brain will be able to recognize an object with non-accidental properties (unless its an accidental view)
- This is what we use when looking at an inverted face
- Based on parts
- Left hemisphere
*
Visual expertise
We recognize things because we’ve have seen them so often are have expertise in them
Visual imagery
- imagery(imagining the picture)
- Not using V1, so you know its not real. (but with hallucinations, you ARE using V1)
*
Wada test
They anesthetize one side of the brain, and if you can’t speak then you must have language processing in that side
normal vs inverted face
When looking faces, you’re looking at with a whole in the fusiform cortex (face area) in the right hemisphere. When a face is inverted, your brain has to quickly switch to left hemisphere to parts because you’re like huh what?
