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Dissertation Information for Paul Munro

NAME:
- Paul Munro
- (Alias) Paul Wesley Munro

DEGREE:
- Ph.D.

DISCIPLINE:
- Physics

SCHOOL:
- Brown University (USA) (1983)

ADVISORS:
- None

COMMITTEE MEMBERS:
- None

MPACT Status: Incomplete - Inspected

Title: NEURAL PLASTICITY: SINGLE NEURON MODELS FOR DISCRIMINATION AND GENERALIZATION AND AN EXPERIMENTAL ENSEMBLE APPROACH

Abstract: "A special form for modification of neuronal response properties is described in which the change in the synaptic state vector is parallel to the vector of afferent activity. This process is termed ""parallel modification"" and its theoretical and experimental implications are examined.

A theoretical framework has been devised to describe the complementary functions of generalization and discrimination by single neurons. This constitutes a basis for three models each describing processes for the development of maximum selectivity (discrimination) and minimum selectivity (generalization) by neurons. Strengthening and weakening of synapses is expressed as a product of the presynaptic activity and a nonlinear modulatory function of two postsynaptic variables--namely a measure of the spatially integrated activity of the cell and a temporal integration (time-average) of that activity. Some theorems are given for low-dimensional systems and computer simulation results from more complex systems are discussed.

Model neurons that achieve high selectivity mimic the development of cat visual cortex neurons in a wide variety of rearing conditions. A role for low-selectivity neurons is proposed in which they provide inhibitory input to neurons of the opposite type, thereby suppressing the common component of a pattern class and enhancing their selective properties. Such contrast-enhancing circuits are analyzed and supported by computer simulation. To enable maximum selectivity, the net inhibition to a cell must become strong enough to offset whatever excitation is produced by the non-preferred patterns.

Ramifications of parallel models for certain experimental paradigms are analyzed. A methodology is outlined for testing synaptic modification hypotheses in the laboratory. A plastic projection from one neuronal population to another will attain stable equilibrium under periodic electrical stimulation of constant intensity. The perturbative effect of shifting this intensity level can yield important information regarding the form of the modification equation. The pathway from entorhinal cortex to dentate gyrus in the rat is an ideal candidate for such experiments."

MPACT Scores for Paul Munro

A = 3
C = 9
A+C = 12
T = 3
G = 1
W = 3
TD = 3
TA = 0
calculated 2012-07-31 14:54:28

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