cognitive neuroscience vision Flashcards
rods allow to see in the dark but what is their limitation?
they can’t perceive colour
cones allow to perceive what?
colour
what is receptive field?
location of photoreceptors that can change the bipolar cells membrane potential
retinotopy, what is it?
retinotopy is the way in which the visual system maintains a spatial relationship between the retina and the brain, enabling the brain to create a representation to the visual world that matches the organization to the objects in your field of view
which retianal ganglion cells are highly sensitive to wavelength (red-green)?
Parvicellular type neurons (parvo means small)
what is collumnar architecture?
structural arrangement where neurons are grouped into vertical columns, and these columns extend through multiple layers of a particular brain regions
columnar architecture is like having organized bookshelves in a library where each shelf (column) contains books (neurons) about a specific topic (visual aspect)
this organization helps the brain efficiently process and understand visual information
dorsal stream
“how” pathway, analysis of visual motion and unconscious visual perception ofr the control of action, the ‘what; pathway is asspciated with perception linked to consciuos visual experience
ventral stream
”what” pathway, concious visual perception/recognition of objects, the ‘how’ pathway is associated with perception linked to visually-guided action
what happens when MT(V5) is lesioned?
incapability of perceiving motion, cannot pour coffee without spilling, cannot see cars aproaching while crossing the street
FFA
fusiform face area
visual expertise area (greater over in the right hemisphere compered to left) RIGHT FUSIFORM GYRUS
PPA
parahippocampal place area
optic ataxia
can’t estimate how big the thing is when grabbing (grab it) but can manually estimate
visual form agnosia
can grab the things by different size but can’t manually estimate their size (how big it is?)
visual agnosia
individual is unable to interpret or recognize what they are seeing
optic ataxia
inability to conduct meaningful movements
visual mechanisms mediating the perception of objects are..
functionally and neurally distinct from those mediating the control of skilled actions directed at those objects
cells futher along the ventral stream fire to what stimuli?
they fire more to complex and specific stimuli
sparse coding
a small but specific group of cells responds to presence of a given object (grandmother cell theory)
population coding
the same cells participate in coding the same objects (all cells participate in coding for all possible objects in the world)
receptive field become larger as we move futher along..
the ventral stream
receptive field in IT (inferotemporal) cortex..
is bigger then in V1
what is visual angle?
is a measure of how much of your visual field an object occupies, based on its size and distance from your eyes
how colour affect object recognition?
color aids it, since it helps to figure-ground segrecation (separating an object fro its background)
associative agnosia
individuals with associative agnosia can see and describe the object’s physical features but can’t connect these features to a known object or concept, trouble attaching meaning to what they see
apperceptive agnosia
individuals with apperceptive agnosia have difficulty perceiving and distinguishing the basic visual features of an object, such as shape, form, or color. This impairs their ability to even describe the object’s physical characteristics accurately
what is perceptual constancy?
the ability to recognise objects seen from different angles, at different postioin sor sizes
lateral occipital complex (LOC)
response is constant regardless of the form of the cure that represents the object
lessions in left hemisphere
lessions in left hemisphere disrupt the ability to perceive local, but not global aspects of an object, whereas right hemisphere lesion shave the opposite effect
what does inversion effect lead to?
recognition becomes substantially poorer when the object is persented upside down. the inversion effect is dependent on the right more than the left hemisphere
perceptual narrowing
babies are born with capacity to recognise wide variety of faces how however with age it gets narrowed down, being more tune to the faces baby was exposed to
prosopagnosia
inability to recognise the faces (occipital and occipital-temporal regions), but can determine a face is the face (even tell the sex or age), do not have general memory deficit, rely on non-facial information
what is aperture problem?
if a moving object is viewed through aperture, the direction of motion of local feature is ambiguous
visual angle
measure of how much of your visual field an object occupies, based on its size and distance from your eyes
radiological convention
Radiological images, such as X-rays, CT scans, and MRIs, are typically displayed with a standard orientation. For example, in X-rays, the left side of the patient is on the right side of the image, and the right side of the patient is on the left side of the image. Standardization ensures consistency in interpretation.
cortical magnification
disproportionate representation of different parts of the sensory field in the cerebral cortex, particularly in the brain’s primary sensory areas
