lecture five; Vision Flashcards
cutaneous sense
touch
nocicepsis
pain/temperature
propriocepsis
Position own bodyparts
interocepsis
organs
olfaction
smell
gustation
taste
balance
vestibular sense
which part of which cortex is used. vision vs. hearing
Thalamus-LGN and Thalamus MGN
which cranial nerve is used by the eye?
- cranial nerve
What is the receptive fiel?
Region of space where a stimulus induces a change in firing frequentie (the region a ganglion cel/neuron sees)
What are the properties of cones?
- Most prevalent in the central retina; found in the fovea
- Sensitive to moderate to high levels of light
- Provide information about hue
- Provide excellent acuity
properties of rods
- Most prevalent in the peripheral retina; not found in the fovea
- Sensitive to low levels of light
- Provide only monochromatic information
- Provide poor acuity
What are the bipolar cells doing and where is there location?
1.connection between photoreceptors and ganglion-cells
horizontal and amacrine cells
combine information in a direction diagonal to the retina
transduction
Transduction is the name of the process by which energy
from the environment (for example, light) is converted to a
change in membrane potential in a neuron.
When are ganglion cells inhibited and when excited?
- On cells:
active when light hits center of receptive field
Inhibited when light falls outside center - Off cells:
Inhibited when light in center
Active when light outside center
how can we perceive yellow without having apropriate cones
red and green cones are excited equally
on which cells is the oponent color theory represented in the cells
on the ganglion cells
what ganglion cells exist, regarding the colors
red/green ganglion cells (excited=red, inhibited=green)
yellow/blue ganglion cells ( yelow: red and green cones are exciting and inhibiting ->canceling each other out)
Thalamus-LGN layers one and two
Thalamus lateral geniculate reticulus : Layers 1 and 2: large cells magnocellular (M) system
shape, movement, depth
layers 3-6
what is between (below) each layer
Layers 3-6: small cells parvocellular (P) system
color and fine details
And below each layes koniocellular (K) system for perception of blue
striate cortex
first cortex to combine visual information of different sources
P, M, K systems enter in different layers
binocular disparity
: difference in image location of an object seen by the left and right eyes
dorsal stream
parietal lobe (where)
95% magnocellular)
Spatial awareness
Movement perception
Visuomotor coordination (tracking)
ventral stream
temporal lobe (what)
50% magno, 50% parvo+konio
Colors
Shape
Patterns (faces)
damage in v4 results in :
impaired color constancy:
(corrects for different background lighting conditions
damage in v8 resultsin :
in impaired color vision and color imagination and color memory (cerebral achromatopsia)
Apperceptive agnosia
(“not knowing”): problem with recognizing objects
Basal visual functions like visual acuity, color vision, movement perception, etc. are intact
Difficulty in combining individual elements to 1 “whole” object
Prosopagnosia
(face-blindness)problem with recognizing faces
akinetopsia
Lesions in an area of the medial temporal lobe (MT in V5) result in problems with perception of movement
MST
Neighbouring area MST (neighbouring V5) important for Optic Flow
(perception of heading)
