Alexander Dimitrov

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It is not known with certainty at which level of face processing by the cortex the distinction between a familiar and an unfamiliar face is made. Subdural electrodes were implanted under the fusiform gyrus of the right temporal lobe in a patient who developed an unusual inability to distinguish differences between faces as part of the epileptic aura ("all(More)
A powerful approach to studying how information is transmitted in basic neural systems is based on finding stimulus-response classes that optimize the mutual information shared between the classes [2,6]. The problem can be formally described in terms of finding a optimal quantization´µ of a large discrete joint´µ distribution and various algorithms have(More)
A simple mathematical model for the large{scale circuitry of primary visual cortex is introduced. It is shown that a basic cor-tical architecture of recurrent local excitation and lateral inhibition can account quantitatively for such properties as orientation tuning. The model can also account for such local effects as cross{orientation suppression. It is(More)
We propose a model for the lateral connectivity of orientation-selective cells in the visual cortex. We study the properties of the input signal to the visual cortex and find new statistical structures that have not been processed in the retino-geniculate pathway. Using the idea that the system performs redundancy reduction of the incoming signals, we(More)
In this paper we introduce methodology to determine the bifurcation structure of optima for a class of similar cost functions from Rate Distortion Theory, Determin-istic Annealing, Information Distortion and the Information Bottleneck Method. We also introduce a numerical algorithm which uses the explicit form of the bifur-cating branches to find optima at(More)
The nature and information content of neural signals have been discussed extensively in the neuroscience community. They are important ingredients in many theories on neural function, yet there is still no agreement on the details of neural coding. There have been various suggestions about how information is encoded in neural spike trains: by the number of(More)
A formal approach for deciphering the information contained within nerve cell ensemble activity patterns is presented. Approximations of each nerve cell's coding scheme is derived by quantizing its neural responses into a small reproduction set, and minimizing an information-based distortion function. During an experiment, the sensory stimulus world(More)