Eleven monkeys with bilateral lesions of the frontal granular cortex and 11 matched controls were observed during pairings with each of 12 stimulus monkeys. The frontal subjects were more withdrawn and distressed than the control animals. The operated animals showed less proximity and contact with the stimulus animals, directed less exploration toward the inanimate environment, and displayed more fear grimacing, screeching, and other disturbance behaviors. The stimulus animals, in turn, interacted less with the frontal monkeys than with the controls. They spent less time near the operated animals, and less frequently mounted and presented to them. Overall, the operated subjects directed more challenges toward the male stimulus animals, threatening them more than was appropriate for the circumstances, although levels of overt physical aggression were no higher, and in some cases depressed, in the monkeys with frontal lesions.

The nerves innervating the tongue were stimulated electricany and multineuron responses were recorded i n the nucleus of the solitary tract. Stimulation of the chorda tympani and the IXth nerves evoked responses in the lateral and medial ipsilateral solitary nucleus in a rostral-caudal order. Responses to lingual nerve stimulation were found only i n the lateral, larger-celled portion of the ipsilateral solitary nucleus overlapping the chorda tympani and the IXth nerve areas. Stimulation of the above three nerves also evoked somewhat longer latency responses in the ambiguus nucleus. Responses to lingual nerve stimulation were found i n the XIIth nerve motor nucleus and the solitary nucleus at the level of the obex using high voltage levels of stimulation. The results were discussed in terms of the anatomical discreteness of the relays of the gustatory and the other tongue modalities in the solitary nucleus. These results were obtained in the white rats.Three nerves innervate the receptors of the tongue. The lingual, chorda tympani and IXth nerves supply fibers to the mechanical and thermal tongue receptors. The chorda tympani and IXth nerves also innervate gustatory receptors. In this experiment the nerves innervating the tongue receptors were stimulated electrically and multi-neuron responses recorded in the nucleus of the solitary tract. The results show the relationship among the terminal regions for the tongue afferents in the solitary nucleus. METHODSTwenty-three Sprague-Dawley rats weighing 250-300 gms were anesthetized with intraperitoneal injections of nembutal (40 mg/kg). The chorda tympani, the lingual or the IXth nerve was dissected free, cut, tied and stimulated electrically. The lingual nerve was stimulated in nine rats and the chorda tympani nerve was stimulated in six rats. Both nerves were stimulated at the point where they form a common bundle and stimulation was limited to one by section of the other central to the region in which they branch and become separate nerves. The IXth nerve was stimulated in eight rats at a point just central to the hyoid cartilage. The nerve was placed on a pair of silver electrodes and stimulated with a 0.5-1.0 volt, 1.0 msec square wave presented at J. COMP. NEUR., 124: 127-130.

No abstract

Abstract. Delayed response ability, and to a lesser extent visual discrimination performance, is seriously impaired by extensive bilateral damage to the frontal lobes. Reciprocal anatomical connections between the frontal and temporal lobes suggested that massive lesions in both lobes might produce an impairment more complete than that resulting from frontal lobectomy alone. Five monkeys were given combined bilateral frontal and anterior-temporal lesions, and were found to be inferior to both frontal lobectomized monkeys and to unoperated controls on the object discrimination task. The combined lesion did not increase the deficit on delayed response over that obtained after only bilateral frontal lobectomy. Results indicate that the anterior-temporal neocortex is involved in the mediation of visual discrimination ability.

Rhesus monkeys were given a series of 720 two-trial object-discrimination problems. Each problem involved presentation of one object on Trial 1, which was either rewarded or not rewarded, an intertrial interval (ITI) of 5, 10, or 20 sec., and presentation of the Trial 1 object along with a second object on Trial 2. The ITI duration had no effect upon performance during the initial stages of training for object-discrimination learning set (ODLS), but an effect was apparent during the later stages of training, when Trial 2 performance decreased as a function of increased ITI. Better Trial 2 performance followed a nonrewarded Trial 1 response at all stages of ODLS acquisition, but the difference decreased during the later stages of training. The ITI duration and Trial 1 reward and nonreward did not interact to affect performance at any stage of ODLS acquisition. The findings were discussed in terms of Bessemer's short-term memory analysis of learning sets. Bessemer (1966) has proposed that acquisition of a learning set entails the development of a short-term memory process that relates events from trial to trial. Such a short-term memory process is termed a hypothesis and is described as "a response tendency elicited by the contents of an immediate memory for recent events [p. 87]." Development of an objectdiscrimination learning set (ODLS) depends upon the acquisition of an "object win-stay lose-shift" hypothesis, which is based upon a short-term memory mechanism that retains information about objects and outcomes from the preceding trial. With extensive ODLS training, this hypothesis becomes the principal determinant of response, overriding and masking error factors such as position and object preferences.A short-term memory process could conceivably be affected by the duration of