The nature of information processing in complex dendritic trees has remained an open question since the origin of the neuron doctrine 100 years ago. With respect to learning, for example, it is not known whether a neuron is best modeled as 35 36 Mel a pseudo-linear unit, equivalent in power to a simple Perceptron, or as a general nonlinear learning device, equivalent in power to a multi-layered network. In an attempt tocharacterize the input-output behavior of a whole dendritic tree containing voltage-dependent membrane mechanisms, a recent compartmental modeling study in an anatomically reconstructed neocortical pyramidal cell (anatomical data from Douglas et al., 1991; "NEURON" simulation package provided by Michael Hines and John Moore) showed that a dendritic tree rich in NMDA-type synaptic channels isselectively responsive to spatially clustered, as opposed to diffuse, pattens of synaptic activation (Mel, 1992). For example, 100 synapses which were simultaneously activatedat 100 randomly chosen locations about the dendritic arbor were less effective at firing the cell than 100 synapses activated in groups of 5, at each of 20 randomly chosen dendritic locations. The cooperativity among the synapses in each group is due to the voltage dependence of the NMDA channel: Each activated NMDA synapse becomes up to three times more effective at injecting synaptic current whenthe post-synaptic membrane is locally depolarized by 30-40 m V from the resting potential.

We develop a model-independent method for characterizing the reliability of neural responses to brief stimuli. This approach allows us to measure the discriminability of similar stimuli, based on the real-time response of a single neuron. Neurophysiological data were obtained from a movementsensitive neuron(HI) in the visual system of the blowfly Calliphom erythrocephala. Furthermore,recordings were made from blowfly photoreceptor cells to quantify the signal to noise ratios in the peripheral visual system. As photoreceptors form the input to the visual system, the reliability oftheir signals ultimately determines the reliability of any visual discrimination task. For the case of movement detection, this limit can be computed, and compared to the HI neuron's reliability. Under favorable conditions,the performance of the HI neuron closely approaches the theoretical limit, which means that under these conditions the nervous system adds little noise in the process of computing movement from the correlations of signals in the photoreceptor array.

Feedforward networks composed of units which compute a sigmoidal function ofa weighted sum of their inputs have been much investigated. We tested the approximation and estimation capabilities of networks using functions more complex than sigmoids. Three classes of functions were tested: polynomials, rational functions, and flexible Fourier series. Unlike sigmoids,these classes can fit nonmonotonic functions. They were compared on three problems: prediction of Boston housing prices, the sunspot count, and robot arm inverse dynamics. The complex units attained clearlysuperior performance on the robot arm problem, which is a highly nonmonotonic, pure approximation problem. On the noisy and only mildly nonlinear Boston housing and sunspot problems, differences among the complex units were revealed; polynomials did poorly, whereas rationals and flexible Fourier series were comparable to sigmoids. 1 Introduction

During waking and sleep, the brain and mind undergo a tightly linked and precisely specified set of changes in state. At the level of neurons, this process has been modeled by variations of Volterra-Lotka equations for cyclic fluctuations of brainstem cell populations. However, neural network models based upon rapidly developing knowledge ofthe specific population connectivities and their differential responses to drugs have not yet been developed. Furthermore, only the most preliminary attempts have been made to model across states. Some of our own attempts to link rapid eye movement (REM) sleep neurophysiology and dream cognition using neural network approaches are summarized in this paper.

Indeed, this is true, if for no attraction reaches almost all of us. Fairy stories let us enter an enchanted world. We do Magic abounds, though always in special ways. Villainy is there, certainly danger. We need the hidden guidance of The spell is broken, and the Princess smiles and fairy stories to tell us of the trials we must marries the youth who made her laugh.

I met Allen for the first time when I came for a two semester long visit to Carnegie Mellon University in 1968. This encounter was a distinct factor in my later decision to join the faculty at Carnegie Mellon University.

This technology was developed with funding from the National Sony, the Japanese consumer electronics Science Foundation. Working with experts from Armco Steel (Middletown, company, has developed OH), Carnegie Group developed a prototype system to diagnose an intelligent system to improve chatter in a coldrolling mill. In the and consulting company, has developed a PCbased virtual reality system company's semiconductor group, to provide financial planners a visual metaphor for viewing large The system allows the user to "fly" over the The expert system is installed in Meiji's Tokyo service two-thirds. With Domain Dynamics Ltd. (Windsor, England) has developed a PCbased the system, technical support neural network application to automate the recognition of data from the Currently available in days to solve with a text retrieval the form of two circuit boards, TESPAR (which stands for Time Encoded system now take just afew minutes. Signal Processing and Recognition) is capable of being converted to a single piece of silicon.

AAAI Workshop on Cooperation Among Carifio, Mike see Rewari, Anil. Language, A, 13(1): Spring 1992, 9-Chalupsky, Hans see Shapiro, Stuart 13(2): Summer 1992, 39-42. Fourth International Symposium on Chen, Tony see Hadavi, Khosrow. Christopher J. Knowledge Discovery Adler, Mark see Rewari, Anil. Functional Categorization of Knowledge: Downes, Stephen see Dietrich, Eric.

Books in the Innovative Applications of Artificial for the documents they want.

Another issue concerned The survey of 80 KBS developers in Knowledge-Based Systems, Marc Ayel structural validation of KBS, given financial domains by Daniel O'Leary and Jean-Pierre Laurent, eds., John that the architecture of these systems opens the collection and raises some Wiley and Sons, Chichester, England, (having separate knowledge base and interesting points. VVT is revealed to 1991, 219 pp., $49.95, ISBN 0-471- inference engine components) was be a significant concern, with developers 93018-0 (paper). Testing his volume contains a selection First European Workshop on studies were launched to determine with real and contrived test cases was Verification, Validation, and Test of the applicability of software engineering found to account for about half the Knowledge-Based Systems, held evaluation techniques to overall VVT effort on average, with during the 1990 European Conference KBSs and to develop new techniques direct inspection of the knowledge on Artificial Intelligence (ECAI specific to KBSs. Several such studies base accounting for another 30 percent 90) in Stockholm, Sweden. In reviewing were initiated by organizations that in the survey.