Chapter 4 Flashcards
spatial organization
the way stimuli at specific locations in environment are represented at specific locations in the nervous system
electronic maps
translation of image on retina into electrical signals higher up
retinotopic map
electronic map of retina on cortex where location on visual cortex correspond to locations on the retina (2 pts cloase together on an object and on retina are close on visual cortex) - distorted, not equivalent to size of receptor area
fovea
accounts for 0.01% of retinal area but 8-10 % of retinotopic map on cortex - studied with brain imaging, a dot presented on fovea and in periphery, more excitation in cortex when spot is on fovea
PET
brain imaging, low does tracer injected that indicates volume of blood flow which indicates increased activity
fMRI
magnetic field presented, iron in blood is magnetically charged, more iron = more blood = more activity as blood loses oxygen; very precise
Localization columns
organization of occipital cortex - perpendicular to surface - all neurons in a localization solumn have their receptive fields at the same location on the retina
orientation columns
all neurons along perpendicular fire more to specific locations; when electrode is moved obliquely across columns, preferred orientation of neurons changes in an orderly fashion (all represented within 1mm, called a hyper column)
ocular dominance
most neurons respond better to one eye than the other
ocular dominance column
neurons with same dominance organized into columns in cortex (1L and 1R in each hypercolumn)
tiling
columns working together to cover whole visual field
streams and pathways
studied by Ungerlieder and Mishkin, used ablation to measure- monkeys taught to carry out particular tasks, area ablated and retaught, if they could no longer do task researchers could extrapolate that the area removed was in charge of that task
object discrimination problem
shown one object then presented with 2 choice task, if correct object was pushed over they received a food reward
landmard discrimination problem
push over/remove cover of shape closest to a tall cylinder
ventral pathway
“what” pathway; after ablation of temporal lobe, object discrimination was very difficult; indicates that this is the pathway responsible for determining an objects identity
dorsal pathway
“where, how/action” pathway; ablation of parietal lobe made landmark discrimination difficult; indicates that this is the pathway responsible for determining location
double dissociations
helps in understanding effects of brain damage - study of 2 people; in one funciton A absent and B is present, and opposite in the other
pathway study in “normal” functioning patients
Ganel; illusion of two lines - length estimation task (spread thumb and index to indicate how long), grasping task (reach toward line and grasp by ends, sensors on fingers measure length); illusion worked for perception but not action
module
structure that is specialized to process information about a particular type of stimuli
Fusiform face area (FFA)
in fusiform gyrus on underside of brain below IT cortex (roughly equiv. to face area in monkeys)
Parahippocampal face area (PFA)
activated by images depicting indoor and outdoor scenes, spatial layout (same response to furnished and unfurnished rooms)
Estrastriate body area (EBA)
activated by pictures of bodies/parts of bodies (not faces)
spatial organization of visual system
spatial map is retinotopic (pts on LGN and cortex correspond to particular points on retina), weaker as messages reach higer areas
functional organization of visual system
what, where, how? cortical areas rich in neurone that respond to specific stimulation
experience dependent plasticity
supports that experience perceiving plays a role in perceptual development
expertise hypothesis
proficiency in perceiving certain things can be explained by changes in the brain caused by long exposure, practice or training i.e. Greebles, FFA response to faces may be because we are “face experts”
