Electrophysiological studies on the effects on single cells of silver electrodes implanted in the visual cortex of cats.

We have studied whether the presence of an artificial metal conductor in the visual cortex has an effect on the responsiveness pattern of the cells there. The physiological properties of single cells have been characterized in the mammalian primary visual cortex, following the acute and chronic implantation of silver wire electrodes. The Experimental group was Chronic and Acute operated and implanted adult cats. The Control group consisted of operated, but not implanted, adult cats and intact (Normal) adult cats. A sagittal incision was unilaterally made in the primary visual cortex (area 17) and a silver wire was implanted. Single cells were extracellularly recorded in the pre- and postincision regions following anesthesia and paralysis, 4-8 weeks following the implantation in the Chronic and immediately in the Acute group. The responsiveness, ocular dominance, receptive field properties, orientation, and direction selectively of the cells were examined. The responsiveness level was different in the preincision (afferented) regions of all operated groups. I was consistently affected compared with their deafferented region. The main effect was found on the binocularity of cells in all operated groups. The following are the differences found between the preincision and postincision regions. Our findings show that although a metal wire conductor implanted in the mammalian visual cortex has an effect on the efficiency of the cells there, chemically inert metals may serve in the future as artificial conductors in the brain.