Frontal Cortical Lesions Research Articles

Impaired tolerance to the effects of oral amphetamine intake in rats with frontal cortex ablations.

When offered a solution of d-amphetamine sulphate (0.025 mg/ml) in place of water, normal rats initially drank more drug solution per day than previously consumed water. The drug solution quickly became aversive to normal rats as daily intake decreased. Tolerance to the anorexic effect of d-amphetamine paralleled the decrease in daily drug intake. Rats with bilateral lesions of frontal cortex initially consumed as much drug solution and as much food as normal rats. Although frontal rats' daily intake of drug solution also decreased, an aversion never developed. Tolerance to d-amphetamine's anorexic effect took much longer to occur in frontal rats. The results indicated possible roles for both cumulative drug effects and conditioning factors in the response to chronic d-amphetamine use. A possible mechanism by which frontal cortical lesions interfered with chronic changes was suggested.

Changes in amphetamine sensitivity following frontal cortical damage in rats and mice

Frontal cortical lesions potentiated amphetamine-induced hyperactivity in both rats and mice tested one month after surgery. This lesion effect in rats was found to interact with the duration of habituation to the testing apparatus (photocell cage) prior to drug administration. The potencies of d- and l-amphetamine were compared in mice tested in either photocell cages or running wheels. The two drugs had similar dose-response curves in the running wheel but very different dose-response curves in the photocell cage. Frontal lesions altered responsiveness to 1- as well as to d-amphetamine in both apparatus. It was suggested that prior discrepancies among studies involving time-dependent changes in amphetamine sensitivity following frontal cortical damage could be attributed to the interaction of two recovering neurochemical systems differentially affecting noradrenergic and dopaminergic neurons.

Differential rates of recovery following frontal cortical lesions in rats.

Abstract Recovery from frontal neocortical lesions in rats was assessed with two measures: (1) amphetamine-induced stabilimeter activity and (2) spontaneously occurring daily wheel running activity. Frontal ablation potentiated the stimulant-like properties of amphetamine in rats tested 10 days after surgery but had little or no affect on animals tested 30 days after surgery. These results held true across a wide range of dosages. The increased wheel running produced by frontal lesions was, on the other hand, still prominent in animals given 40 days of postoperative recovery.

Frontal cortex lesions and fixed-interval acquisition in the rat.

This research was designed to study the behavioral effects of frontal cortex lesions upon the performance of rats in a fixed-interval reinforcement situation. Prior to testing, 10 Ss were prepared with posterior frontal cortical lesions in areas 10 and 6. 10 control Ss received sham operations. Following post-operative recovery, the animals were placed on a 23-hr. food deprivation schedule and trained to press a bar for a pellet of food which would be delivered only if 1 min. had elapsed since the previous reward. Analysis of variance showed no significant difference between the 2 groups in the ability to learn the temporal discrimination. However, lesioned Ss yielded a significantly divergent distribution of responses within the interval and a much lower terminal rate of response than the controls.

Hippocampal control of behavioral arousal: Duration of lesion effects and possible interactions with recovery after frontal cortical damage

The effects of gross hippocampal aspiration were compared with those of frontal cortical lesions on wheel running and generalized activity of rats during control and arousal conditions. The rate of recovery of these functions was then measured in animals with hippocampal lesions or with combined hippocampal and frontal lesions. From these studies, it appears that the hippocampus shares arousal control functions with frontal cortex, that it is partially responsible for the recovery that has been reported to occur after frontal lesions, but does not itself recover after damage.

Effects of bilateral frontal lesions on habituation of the head-shake response in the rat

This experiment investigated the effects of bilateral frontal cortical lesions on the frequency and shape of the habituation curve of the head-shake response, elicited by stimulating the ear with a stream of air, in the rat. The results from an initial procedural-control group indicated that the damage done to the ear by mounting the rats in a stereotaxic was sufficient to increase responding. The results from the basic experiment, using a before-after design, indicated that bilateral frontal cortical lesions led to an overall increase in responding but had no effect on the shape of the habituation curve over trials. The responding of control animals given bilateral cortical lesions in the occipito-parietal area had no effect on responding. The results suggest that the frontal cortex, at least in the rat, is not involved in habituation of all responses.

Contour discrimination in rats after frontal and striate cortical ablations

Summary Thirteen hooded rats were trained to discriminate between either a pattern of stationary or moving vertical black and white stripes and a uniform grey stimulus matched for total luminous flux. The striate cortex was then removed in 7 animals, and the dorsolateral frontal cortex in the remaining 6. Animals with frontal cortical lesions relearned the task with substantial positive savings. All animals with striate cortex removed succeeded in relearning the discrimination, although with negative savings. Control tests showed that the animals were not discriminating on the basis of any uncontrolled differences in luminosity.

I. Introduction

Rats were given frontal cortical lesions at day 1 or 10 of life. Later, as adults, they were either: (1) processed with Golgi-Cox in order to analyze cortical dendritic arborization; (2) given injections of True Blue into the parietal or visual cortex, or (3) given injections of [3H]leucine into the substantia nigra. An additional group of normal rats were given injections of fluorescent dyes into the cortex on day 4 or 10 of life. The main findings were that (1) adult hemispheres with day 10 lesions had greater dendritic arbor than normal hemispheres, (2) adult hemispheres with day 1 lesions had reduced dentritic branching relative to normal hemispheres, (3) adult rats with day 10 lesions had no obvious abnormalities in cortical connections, (4) adult rats with day 1 lesions had abnormal thalamo-cortical, amygdalo-cortical, and nigro-cortical connections, and (5) many of these abnormal connections were present in the brains of 4-day-old normal rats. Since the ‘abnormal’ connections in the very early frontal operates were present in day 4 animals, it appears that they result from the failure of exuberant connections to retract after the lesions. The increased dendritic growth in day 10 operates does not appear related to qualitative changes in cortical afferents or efferents and may related to increased intrinsic cortical connectivity. Since rats with day 10 lesions have previously been shown to exhibit significant recovery of function, it is possible that the increased dendritic arborization is supporting the functional restitution.

Effects of frontal, median cortical and caudate lesions on two-way avoidance learning by rats☆

Abstract Spontaneous activity and visual shuttle-box avoidance conditioning were studied in rats with either caudate lesions or cortical lesions (dorsal frontal, anterior median or posterior cingulate). Frontal operates had higher avoidance scores than rats with anterior median lesions or controls which had received the same amount of damage to the skull. Median cortical lesions produced an avoidance deficit only in those animals with anterior damage. Rats with caudate lesions were unaffected. Intertrial activity was above normal in the groups with frontal and anterior median cortical lesions. These data, and those obtained by studying correlations within groups and across groups, indicated that changes in spontaneous and intertrial activity were not a major factor in determining the direction of the effects on avoidance conditioning. The same animals were also given additional training with a reversed cue (light off as CS). The performances during reversal were positively correlated to those during original learning.

Functions of prefrontal cortex in animals.

Functions of prefrontal cortex in animals.

Evidence for dissociation of impairment on auditory discrimination and delayed response following lateral frontal lesions in monkeys

Impairments on both delayed-response and auditory-discrimination tasks have been reported to follow lateral frontal cortical lesions in monkeys. The present study is primarily concerned with the relationship of these two deficits. Three monkeys received ablations of sulcus principalis; three received ablations of lateral frontal cortex excluding sulcus principalis. Acquisition and retention of auditory-discrimination, delayed-response, and visual-discrimination tasks by the two groups were compared. Sulcus principalis lesions produced greater impairment on the delayed-response tasks. The lesions sparing sulcus principalis produced greater impairment on the auditory-discrimination tasks. The performance of the groups did not differ on the visual-discrimination tasks. These results suggest that the delayed-response deficit and the deficit in auditory discrimination that follow large frontal lesions may be dissociated by smaller frontal lesions. The results confirm that the focus for impairment on tests of the delayed-response type is in the region of sulcus principalis. The experimental data do not indicate the focus (if any) for the auditory-discrimination deficit, nor do they permit the definition of the nature of this deficit including its modality specificity.

Effects of temporal and frontal cortical lesions on auditory discrimination in monkeys.

Effects of temporal and frontal cortical lesions on auditory discrimination in monkeys.

The effect of frontal cortical lesions on activity wheel and open-field behavior.

The effect of frontal cortical lesions on activity wheel and open-field behavior.