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48 Cards in this Set

  • Front
  • Back
What is the general organization of sensory systems like?
A hierarchical system of plates - cells that process information as it moves thrugh the nervous system.
What is the definition of a receptive field?
A region within which an individual neuron's activity may be influenced.
3 examples of receptive fields:
-area of the retina
-area of skin
-area of the basilar membrane
What type of influences can be stimulated by the receptive field?
Excitory, inhibitory, or both.
Topography means:
Configuration of a surface in a way that it maps the organ from which it receives input.
3 types of topography:
What is retinotopy?
A map of the retina
What is somatotopy?
The map of the homunculis
What is tonotopy?
The map of the basilar membrane.
Why do topographical maps look distorted compared to the actual map of a sensory organ?
Because of areas that have high receptor densities, but little spatial summation. They require more cortex for integration.
Why is it hard to pinpoint where someone touches you on the back compared to your hands?
-Lots of spatial summation in back; touch receptors converge to go to brain in one fiber
-Less in hands - individual fibers for each receptor.
So in general the sensory system layout is:
Predictable - by Topographical maps.
How is it possible that Topographical maps can be made?
Because axons in the cortex tend to remain adjacent as they pass through the nervous system to innervate adjacent receptors.
How does development affect topographical organization in sensory systems?
There are active mechanisms that refine it during development.
What happens to sensory information as it progresses through hierarchical plates?
It is processed.
What type of connections are found in the sensory systems?
-Straight through
-Lateral inhibitory
What type of connection are straight through connections?
Almost Always Excitatory
What is the function of lateral inhibition?
To sift out unimportant information and extract important information.
2 types of sensory neuron responses:
What is predominant?
1. Graded potentials (most)
2. Action potentials
Function of graded potentials:
To process info in an analog way.
Function of Action potentials:
To send info over long distances.
How many neural types in the retina?
How many produce action potentials?
1 type
What is the deal with the thalamus?
All sensory information passes through them on their way to the cortex except some olfactory info.
How are the thalamic nuclei arranged?
Each sensory system has its OWN set of relay nuclei.
What do Labeled Line codes in neurons give information about?
QUALITY of a stimulus - modality
What is modality?
The quality of stimulus
What increases the specificity of information encoded in a labeled line?
The degree of TUNING
What information do Frequency codes give?
2 other types of codes:
What are population codes?
Pattern codes that disambiguate the modality and intensity of broadly tuned receptors.
What are temporal codes?
Like Morse code?
What are sensory signals designed to signal?
What is receptor adaptation?
A decrease in the initial vigorous response to a stimulus if the stimulus stays on for a long time.
2 ways that sensory systems are designed to signal change:
1. Receptor adaptation
2. Lateral inhibition
What is lateral inhibition?
Silencing of neural activity via interneurons between adjacent cells.
What is the purpose of lateral inhibition?
To enhance the difference between two adjacent objects. (ie vision of light/speck)
What is the prominent exception to sensory systems being designed to signal change?
Pain - it can be constant as we all know.
What are Psychophysical methods for?
Measuring our sensory INABILITIES.
What is the definition of psychophysical?
A psychological reaction to a physical stimulus. (you get touched and then tell about your feelings)
What is "Threshold"?
The point of intensity at which a stimulus can just be detected.
What is Absolute Threshold?
How MUCH intensity must be impinged to just be detected.
What is Difference Threshold?
The magnitude of difference between the intensities of two stimuli that can be differentiated by the person.
What does Weber's law tell us?
How sensitive a sensory system is in relation to the Stimulus Intensity
What is the equation for Weber's Law?
deltaI/I = k
What is delta I?
The intensity of a stimulus increment that can just be barely detected when added to an already present stimulus.
What is I?
The intensity of background stimulus
what is k?
A constant