NeuroPhysiology Terms Flashcards
Trigger Feature
pattern of stimuli that will maximally activate a particular neuron
eg. centre-surround receptive field (on centre/off suround) maximally activated by a light just on centre
M-Pathway
photoreceptors (rods/cones) -> diffuse bipolar cells -> parasol ganglion cells (M-Cells).
P-Pathway
photoreceptors (cones) -> midget bipolar cells -> midget ganglion cells (P-Cells)
M-Cells
large cell body,
very few (10%),
sparse/long branching,
input from periphery,
rapid conduction speed, transient response type,
large receptive field,
high sensitivity to contrast,
black and white wavelengths
P-Cells
small cell body,
many (80%),
dense/short branching,
input from fovea,
low conduction speed,
sustained response type,
small receptive field,
low sensitivity,
wavelength sensitive (color)
Bistratified Type Cells
(10%) carry signals from short wavelength cones
project to koniocellular layer
Lateral Geniculate Nucleus
where most ganglion cells project too,
has two major subdivisions: magnocellular, parvocellular, also koniocellular
in thalamus
Magnocellular Layer
2 ventral (bottom) large cell layers,
input comes from large M-cells, found in all Mammals,
good for motion detection, temporal analysis, depth perception
more primitive
Parvocellular Layer
4 dorsal (upper) small cell layers,
input comes from small P-Cells,
found in Primates,
form analysis, spatial analysis, colour vision,
recently evolved
Koniocellular
smallest LGN cells located between (and ventral to) parvo and magno layers, input from bistratified RGCs, only in primates
Equiluminant Stimuli
same intensity of light (amount of light), different wavelengths, can impair motion perception
Blobs
pillar-like cortical sections,
found in V1 layers 2/3,
revealed by cytochrome oxidase staining of mitochondria,
input from parvo and konio,
no orientation selectivity, monocular sensitivity, wavelength/brightness selective,
most doubly colour opponent
Interblobs
areas between blobs in V1 layers 2 and 3,
input from parvo,
cells are orientation selective, small receptive field, binocular sensitivity, not wavelength selective, not sensitive to direction of movement
Simple Cell
(V1, layer 4) responds best to bar/line/edge of light, in particular location on retina, having specific orientation, constructed by converging centre-surround cells
Complex Cell
(V1; layers 2, 3, 4, 6, V2) responds best to: bar/line/edge of light, in particular location on retina, having specific orientation and moving in certain direction
Hypercomplex/End-stopped Cell
(V2, V3) responds best to: bar/corner/angle having certain lenght/width, in particular location on retina, having specific orientation, moving in certain direction
Location Column
cells respond to stimuli from same retinal location
Occular Dominance Column
cells respond to stimuli presented to one eye only
Orientation Column
Cells respond to stimuli of same orientation; adjacent orientation columns differ in orientation selectivity by 10 degrees
Packing Problem
how are three parameters of information (3D), mapped onto a 2-D representational space, solving this problem produces singularities
Cerebral Achromatopsia
deficit in colour vision without loss of object perception
eg. implicated with V4
Ventral Path
Prospagnosia
loss of ability to recognize faces with otherwise normal vision
implicated with IT
Ventral Path
Akinetopsia
inability to perceive motion of objects
implicated with MST
Dorsal / Parietal Path
Balient’s Syndrome
has optic ataxia (cant reach/grasp objects),
optic apraxia (inability to guide eye movements and change visual fixation),
simultagnosia (inability to perceive more than aspect of a visual stimulus and integrate into a whole.
Intact what system but damaged where
Visual Form Agnosia
inability to extract global structure, despite intact low-level sensory processing (acuity, colour, brightness discrimination intact), can’t recognize/discriminate like shapes,
intact where system but damaged what system
Double Dissociation
When function in 1 aspect is impaired but another aspect is intact and vice versa. shows two functions are independent of each other
eg. Dorsal / Ventral stream through visual form agnosia and Balient’s Syndrome
