Neonatal ablations of the gustatory neocortex in the rat: taste aversion learning and taste reactivity.

Abstract

Rats sustaining ablations of gustatory neocortex (GN) at 2, 10, 20, or 60 days of age were compared with control rats in the acquisition and extinction of a learned taste aversion; in addition, these rats were tested for taste preference across five concentrations of sodium chloride solution. Results indicated that GN ablation disrupted aversion acquisition and extinction regardless of age at surgery. Taste response functions for the sodium chloride solutions shown by all GN groups of rats mirrored those of control rats: preference (relative to water baseline) for middle concentrations and rejection of the strongest salt concentration. There was a suggestion that the 20- and 60-day-old GN rats were hyperresponsive to the suprathreshold concentrations of NaCl (except the strongest concentration). The increased response to salt solutions in the 20- and 60-day GN rats may have been related to the significant decreases in water consumption relative to that of normal rats. Water consumption of control rats and GN rats in the 2-day and 10-day groups was essentially equal. It is concluded that infant ablation of the GN does not spare normal taste aversion learning and that rats with GN ablations, regardless of age at surgery, respond in a normal manner to the hedonic aspects of sodium chloride solutions.