MICROELECTRODE ARRAYS FOR STIMULATION OF NEURAL SLICE PREPARATIONS

A planar 6 x 6 array of iridium electrodes with four reference electro des has been developed for use with neural tissue preparations. Precis e knowledge of the relative locations of the array elements allows for spatial neurophysiological analyses. The 10 mu m diameter platinized iridium electrodes on a 100 mu m pitch have been used to stimulate acu tely prepared slices of spinal cord from free-ranging rodents. An intr acellular recording from a single neuron in the substantia gelatinosa (SG) using the whole-cell, tight-seal technique allowed low noise, hig h resolution studies of excitatory or inhibitory electrical responses of a given neuron to inputs from the primary afferent fibers or from s timulation by individual electrodes of the array. The resulting maps o f responses provide an indication of the interconnectivity of neural p rocesses. The pattern emerging is that of limited interconnectivity in the SG from areas surrounding a recorded neuron but with strong excit atory or inhibitory effects from those oriented in a longitudinal (ros tral-caudal) direction relative to the neuron. The observations to dat e suggest the neurons of the SG are arranged in sets of independent ne tworks, possibly related to sensory modality and input from particular body regions. (C) 1997 Elsevier Science B.V.