BUTTER, C. M. Perseveration in extinction and in discrimination reversal tasks /bllowing selective frontal ablations in Macaca mulatta. PHYSIOL. BEHAV. 4 (2) 163-171, 1969.-In order to determine whether the perseverative syndrome exhibited by monkeys with frontal lobe lesions can be fractionated by partial frontal lesions, monkeys with dorsolateral frontal lesions, those with orbital frontal lesions, and those with partial orbital lesions were tested in three tasks: extinction of a food rewarded bar pressing response, spatial discrimination reversals and object discrimination reversals. Perseveration of barpressing in extinction was selectively related to the posteromedial or "limbic" portion of orbital frontal cortex. Deficits in object discrimination reversal, on the other hand, were specifically associated with the lateral sector of orbital cortex and possibly to the adjoining ventral portion of dorsolateral frontal cortex as well. Impairment in spatial discrimination reversal was most severe in monkeys with dorsolateral frontal removal. These findings suggest that the perseverative effects of orbital frontal ablation cart be fractionated into at least two components and further support the view that dorsolateral frontal cortex is associated with spatial factors.
Simple reaction times to lateralized visual (Experiment 1) or auditory (Experiment 2) targets were studied in normal subjects. The targets were preceded by a visual or auditory cue located on the same (valid cue), or opposite (invalid cue) side as the subsequent target, or on both sides (neutral cue), with one of four cue target intervals. The validity of visual and auditory cues influenced the speed of response to the visual target but not to the auditory target. It is hypothesized that cross-modal cueing of spatial position works only with modalities for which a movement (e.g. saccade) leads to improved sensory analysis.
Rhesus monkeys were tested for emotional reactions to human observers and to animal-like objects (doll and snake) before and after removal of orbital frontal (OF) or portions of temporal neocortex (T). The OF lesions, but not T lesions, initially produced hyporeactivity and anorexia, followed by hyperreactivity to environmental stimulation and heightened oral tendencies. The OF monkeys, unlike those with T lesions, showed increased frequencies of certain aversive reactions to the doll initially following surgery and reduced frequencies of aggressive reactions in all test situations as late as 10 mo. following surgery. The critical focus for producing deficits in aggression appears to be the posteromedial sector of OF cortex. This decrease in aggression is situationally dependent and may reflect an impairment in the modulation of arousal mechanisms.In the course of testing monkeys with orbital frontal (OF) ablations in an instrumental learning situation (Butter, Mishkin, & Rosvold, 1963), the present authors observed abnormalities in emotional behavior, abnormalities not seen following resections of other neocortical areas. These emotional alterations appeared, at least to casual observation, to be striking and long lasting. For this reason, and because the particular role of frontal cortex in the control of emotionality is unclear (Brutkowski, 1965), a systematic investigation of these alterations was undertaken. In an initial experiment, monkeys with OF lesions, along with operated and unoperated controls, were tested for aversive and aggressive responses to human observers, whose presence tends to elicit strong emotional reactions from rhesus monkeys. Compared to their controls, the OF monkeys showed more frequent aversive reactions and, to a smaller extent, less frequent aggressive reauthors express their thanks to Kirsten McEnaney for her assistance in testing the animals and data analysis and to Raymond Jaeger for histological analyses.
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