Involvement of gustatory neocortex in the learning of taste aversions

The gustatory neocortex of the rat

“…It was hypothesized further that GN ablation selectively disrupts associative salience thresholds for taste stimuli without necessarily disrupting detection thresholds (Braun & Rosenthal, 1976); that is, the systems underlying associability and detectability of the same stimuli could be viewed as being dissociated by the GN lesion. Braun and Rosenthal (1976) found that a procedure known to reduce the associative potential of normal rats for tastes, the imposition of a very long CS-US interval (e.g., Revusky & Garcia, 1970; J. C. Smith & Roll, 1967), produced results for normal rats that were essentially identical to those reported by Braun et al (1972) for rats lacking GN (see Table 3). It was therefore concluded that the Braun et al (1972) finding of a salience difference between .1-mM-quinine and 4.8-mM-saccharin stimuli was probably due to the unmasking, by ON ablation, of a normal salience difference between these stimuli.…”

“…We speculated that the change in the "salience" (Kalat & Rozin, 1970), or conditionability, of the saccharin cue, without concomitant changes in detectability relative to water, might be a common effect of GN lesions across taste qualities, an effect which may not have been observed for the quinine stimulus in this first study because of a floor effect (Braun et al, 1972). As a basis for follow-up studies, it was hypothesized that there were two kinds of relatively independent thresholds to consider for taste stimuli: a preference-aversion, or reactive, threshold, and a conditionability, or associative salience, threshold.…”

“…However, the saccharin cue was readily conditionable for normal rats and for rats with control lesions (Braun et al, 1972). Subsequent work by Divac, Gade, and Wikmark (1975) indirectly suggested the specificity of involvement of the GN area in taste aversion learning by showing no effect of orbital frontal lesions on such learning.…”

“…Other studies examined the effects of area postrema lesions (Berger, Wise, & Stein, 1973), electroconvulsive shock (Kral, 1970), and cortical spreading depression (Best & Zuckerman, 1971). The first study of GN involvement in taste aversion learning appeared also at this time (Braun, Slick, & Lorden, 1972).…”

Differential Brain Activity in Alcoholics and Social Drinkers to Alcohol Cues: Relationship to Craving

“…The insula receives input from the basolateral amygdala (Krettek and Price, 1977;Shinonaga et al, 1994) and projects to the striatum (Wright and Groenewegan, 1996) and is thus is considered an integral part of the corticomesolimbic system. The insula is hypothesized to mediate higher cognitive processes such as memory and learning related to taste (Balleine and Dickinson, 2000;Braun et al, 1972;Kiefer and Braun, 1977). Lesion studies support the hypothesis that insular cortex is crucial to encoding the incentive value of taste during instrumental conditioning (Balleine and Dickinson, 2000).…”