Tech Report Announcement

[Harry.Printz@IUS1.CS.CMU.EDU]

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    Foundations of a Computational Theory of Catecholamine Effects

	        Harry Printz and David Servan-Schreiber

			     CMU-CS-90-105

This report provides the mathematical foundation of a theory of
catecholamine effects upon human signal detection abilities, as developed in
a companion paper[*].  We argue that the performance-enhancing effects of
catecholamines are a consequence of improved rejection of internal noise
within the brain.  

To support this claim, we develop a neural network model of signal
detection.  In this model, the release of a catecholamine is treated as a
change in the gain of a neuron's activation function.  

We prove three theorems about this model.  The first theorem asserts that in
the case of a network that contains only one unit, changing its gain cannot
improve the network's signal detection performance.  The second shows that
if the network contains enough units connected in parallel, and if their
inputs satisfy certain conditions, then uniformly increasing the gain of all
units does improve performance.  The third says that in a network where the
output of one unit is the input to another, under suitable assumptions about
the presence of noise along this pathway, increasing the gain improves
performance.  We discuss the significance of these theorems, and the
magnitude of the effects that they predict.  

The report includes numerical examples and numerous figures, and intuitive
explanations for each of the formal results.  The proofs are presented in
separate sections, which can be omitted from reading without loss of
continuity.


[*] Servan-Schreiber D, Printz H, Cohen JD.  "A network model of
    catecholamine effects: gain, signal-to-noise ratio, and behavior,"
    Science, 249:892-895  (August 24, 1990)


You can obtain this technical report by sending email to copetas at CS.CMU.EDU,
or physical mail to

	Catherine Copetas
	School of Computer Science
	Carnegie Mellon University
	Pittsburgh, PA  15213

Ask for report number CMU-CS-90-105.  There is no charge for this report.

Please do not reply to this message.


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