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

Sprague-Dawley rats sustaining ablations of gustatory neocortex (GN) at 2, 10, 20, or 60 days of age were compared with control-lesion and anesthetized controls ( N = 151) in the acquisition and extinction of a learned taste aversion. Ss were also tested for taste preference across 5 concentrations of NaCl solution (.04, .08, .15, .3, and .6 M). Results indicate that GN ablation disrupted aversion acquisition and extinction regardless of age at surgery. Taste-response functions for solutions shown by all GN Ss mirrored those of controls: preference (relative to water baseline) for middle concentrations and rejection of the strongest concentration. It is suggested that the 20- and 60-day-old GN Ss were hyperresponsive to the suprathreshold concentrations of NaCl (excepting the .6-M concentration). The increased response to NaCl in 20- and 60-day-old GN Ss may have been related to the significant decreases in water consumption relative to that of controls. Water consumption of controls and GN Ss in 2- and 10-day-olds 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 NaCl solutions. (22 ref)