Term
What is lateral inhibition what phenomenon are associated with it?
|
|
Definition
Lateral inhibition is the capacity of an excited neuron to reduce the activity of its neighbors
The Hermann Grid: Seeing spots at an intersection
Mach Bands: Seeing borders more sharply
Simultaneous Contrast: Seeing areas of different brightness due to adjacent areas
|
|
|
Term
What is white’s illusion and how is it explained? |
|
Definition
White’s Illusion
People see light and dark rectangles even though lateral inhibition would result in the opposite effect
explained by Allen Gilchrest’s theory of Belongingness
An area’s appearance is affected by where we perceive it belongs
[image] |
|
|
Term
What type of organization do receptive field is generally and how does it work?
|
|
Definition
center surround organization is generally used for perception
Uses center surround antagonism
Output of center surround antagonism dependent on area stimulated
Signals from the retina travel through the optic nerve to the
Lateral Geniculate nucleus (LGN) first synapse for ganglion cell axons occur here
LGN cells also have a center-surrounded receptive fields
Major function of LGN is to regulate neural information from retina to visual cortex
|
|
|
Term
What cells are employed in receptive fields and what is their importance? |
|
Definition
Simple cortical cells. Complex cortical cells and end-stopped cortical cells
Simple cortical cell
Elongated (vertical) with side by side excitatory region
Responds to light (bars) in particular orientation
Complex cortical cell
Respond to bars of light in particular orientation
Responds to movement of bars of light in specific direction (perpendicular)
End-stopped cortical cell
Responds to particular orientation and motion as well as
Moving lines of specific length
Moving corners or angles
No response to stimuli that are too long
Found through Hubel and Wiesel studied properties of neurons in area (V1 striate cortex) of cats
|
|
|
Term
When a patient sensitivity to a range of one stimulus characteristic is measured and then theiy’re adapted to the stimulus and re-measured it what is being tested |
|
Definition
Selective Adaptation Neurons tuned to specific stimuli fatigue when exposure is long
causes Neural firing rate to decrease Neuron to fire less when stimulus immediately present again
Selective adaption to an orientation decreases detection of that orientation
|
|
|
Term
What experiment was used to show the effects of selective rearing? (or the absence of certain stimuli in environment)
|
|
Definition
Blakemore and Cooper rearing kittens in tubes with either horizontal or vertical lines
Discovered the phenomenon of neural plasticity or experience dependent plasticity where neurons that respond to present stimulus become more prevalent
Elimination of orientation detectors decreases ability to see those orientations
Led to identification of sensitive periods in development
Sensitive period is a window of time during which neurons that code an ability/function can be altered
|
|
|
Term
What is used to describe the representation of perceived objects through neural firing and what three theories are based on this process?
|
|
Definition
Sensory code is the representation of perceived objects through neural firing
Specificity coding- specific neurons responding to specific stimuli
hippocampus respond to concepts
Problems with specificity code
Too many different stimuli to assign to specific neurons
Most neurons respond to a number of different stimuli
Distributed coding
Pattern of firing across many neurons, codes specific objects
Large number of stimuli can be coded by a few neurons
Sparse coding
Only a relatively small number of neurons are necessary
|
|
|
Term
Where is the primary reciving area for vision located? |
|
Definition
Primary visual receiving area in the occipital lobe (striate cortex or area V1)
|
|
|
