The Neural Code Flashcards
What is the neural code?
How neurones get signal where information is encoded for communication
What are local brain networks?
Small generic processing units
What are global brain networks?
Relating in processes in unit dedicated to specific brain regions
How is encoding in the brain important?
For extraction of categories and finding the identity of objects and our environment
How do we identify objects?
With filtering to identify properties
How do we classify an object?
Measuring the amount with intensity and frequency
How do we adjust the precision of object classification?
Fine tunnign
What is a managing capacity?
Compression of information into small compartments for high effectiveness
How can a neural response be measured?
As a graded change in electrical potential and a change in membrane voltage which can determine excitation or inhibition
What is a neural response?
Encoding in the number of action potentials
What is the rate code?
The quantity of seconds information is encoded in the firing rate of action potentials
How can neurones compute?
Through summation, direct representation of each sampling point or lateral inhibition
What is direct representation of each sampling point?
One to one, where the size is not coded and there is low sensitivity but a high resolution
What is summation?
The neural computation that results in adding together the responses of neurons (many to one)
How do neurones interact in summation?
Through convergence
What is convergence?
A graded response where the information from other sensors are combined
What is lateral inhibition?
A neural computation in which responses from neighbouring regions are subtracted
What does the graded response in lateral inhibition cause?
An optimum size for maximum activation
What is a receptive field?
The location in space where the presence of a stimulus can produce a change in the response of a neurone
What is a visual receptive field?
The location in space where the presence of a visual stimulus can produce a change in the response of a neurone
What is a two dimensional receptive field?
When there is neural computation in two dimensions, in a receptive field light is collected from a restricted region of the visual field
What is the response in 2D receptive fields?
The balancing of excitation from the centre and inhibition from the surrond receptive field
What is spatial integration?
The adding of excitation and inhibition
Why is there opponency in spatial integration?
There are photons from neighbouring regions which are balanced against each other
What does contrast mean?
A relative difference in stimulus intensity between a bright and dark region of a visual stimulus
What happens in regions of equal luminance?
Excitation and inhibition will cancel each other out
What occurs at a luminance boundary?
Excitation and inhibition is not balanced so there is an increased difference of the perceived brightness where opponency will enhance the perceived contrast
What is filtering?
The process in which signals are transmitted from regions around boundaries, but not from uniform areasW
What do the filters do in neural networks?
Transform and compress information
What are receptive fields functions?
Contrast enhancement, redundancy reduction and spatial filtering
Small excitations and small inhibition?
Small response
Large excitation and small inhibition?
Large response
Large excitation and large inhibition?
Small response
What does the size of the receptive field determine?
Spatial detail
What is spatial frequency?
The number of cycles of a periodic pattern per degree of visual angle
What are spatial frequency channels?
Parallel sets of receptive fields with different sizes
How is feature specificity generated?
Parallel and hierarchial computations
