Design of Cortical Neuron Circuits With VLSI Design Approach

A.d.tete A.D.Tete,Deshmukh Deshmukh

doi:10.5121/ijsc.2011.2405

Abstract

A simple CMOS circuitry using very less number of MOSFETs reproduce most of the electrophysiological cortical neuron types and is capable of producing a variety of different behaviors with diversity similar to that of real biological neuron cell. The firing pattern of basic cell classes like regular spiking (RS), chattering (CH), intrinsic bursting (IB) and fast spiking(FS) are obtained with a simple adjustment of only one biasing voltage makes circuit suitable for applications in reconfigurable neuromorphic devices that implement biologically resemble circuit of cortex. This paper discusses spice simulation of the various spiking pattern ability with required and firing frequency of a given cell type. The circuit operation is verified for both conditions-constant input and pulsating input .

Highlights

The neocortex is that part of the brain which makes up the outer 2 to 4 mm of the cerebral hemispheres
This paper focuses on the different spiking and firing patterns of the cortical neuron
Threshold voltage at the comparator stage of the cortical neuron is set to 1.4V and the bias voltage Vc is set to 0.6V which is kept constant for all firing patterns

Summary

INTRODUCTION

The neocortex is that part of the brain which makes up the outer 2 to 4 mm of the cerebral hemispheres. Neurons in the cortex are found with great variety of dendritic morphology, ion channel distribution and composition These neurons exhibit different electrical behavior transforming the same input signal into different firing patterns. Effort has been made for implementing simple neuron circuits that are capable of providing different types of cortical spiking behavior by utilizing as few transistors as possible to enable integration of large number of cell in a single chip. The IB neurons respond to a step current injection with a cluster of three to five initial spikes followed by an AHP, and by either single spikes or burst at more or less regular intervals These types are observed in sub-population of bitufted cells, bipolar cells and martinotti cells in the neocortex

VLSI MODEL OF CORTICAL NEURON

SIMULATION RESULTS

CONCLUSION