Dissociation of consummatory and vocal components of feeding in squirrel monkeys treated with benzodiazepines and alcohol

Abstract

The primary aim of the current experiments was to develop methods that engender vocalizations associated with positive social situations comprising affiliative behavior and feeding that could be quantified under controlled laboratory conditions and were sensitive to anxiolytic drugs. Classical conditioning procedures were used to elicit vocalizations during presentation of stimulus lights (i.e., CS condition) previously paired with either preferred foods (e.g., grapes, peanuts, bananas) or standard foods (e.g., monkey chow) as well as during presentation of both food types (i.e., UCS condition). When compared to the period before stimulus light presentation (i.e., Pre-CS condition), the rate, duration and number of elemental units of food-related “twitter” vocalizations were increased during the CS conditions regardless of food type. Monkeys spent significantly more time oriented toward the food box during the light stimulus that preceded preferred food than for the light stimulus that preceded standard food. However, twitter vocalizations were higher for standard food regardless of the stimulus conditions (i.e., Pre-CS, CS and UCS). Administration of the benzodiazepine full agonist chlordiazepoxide (CDP, 1–10 mg/kg), the partial agonist bretazenil (BRZ, 1–10 mg/kg), the antagonist flumazenil (FLZ, 1–10 mg/kg) and ethyl alcohol (EtOH, 0.1–1.0 g/kg) differentially altered vocalizations. Although CDP and BRZ increased feeding of standard food, twitters were reduced across stimulus conditions. CDP and BRZ did not alter other social contact calls (i.e., “peeps”). FLZ also reduced twitters without altering peeps, but did not increase feeding. In contrast, EtOH did not increase feeding or peeps, but did increase food-related twitters. These results indicate that there is a dissociation between food-related behaviors, such as food consumption and orientation towards the food source, and vocal behaviors associated with group communication during feeding.