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Biomedical subjects

B Kolb

Publications and source records attributed to B Kolb.

At least 91 records · Page 5Linked to original sources
PubMed1988

Recovery from early cortical damage in rats. IV. Effects of hemidecortication at 1, 5 or 10 days of age on cerebral anatomy and behavior.

Rats with complete removal of the neocortex of one hemisphere in adulthood (hemidecorticate) were compared behaviorally and anatomically with rats with similar removals at 1, 5, or 10 days of age. There was an unexpected relationship between cortical thickness in adulthood and age at surgery: the earlier the lesion the thicker the cortex. At the two extremes rats hemidecorticated in adulthood had a reduction of up to 10% in the contralateral hemisphere, rats with hemidecortications on the day of birth had cortex that was thicker than adult operates. Behaviorally, the animals were administered several tests including a spatial navigation task, tests of beam walking and swimming, tests of turning bias, and a measure of claw cutting. The main finding was that although the hemidecortication at all ages produced a reliable behavioral change on all measures, the neonatal hemidecorticates performed better than the adults. Further, the earlier the lesion, the better the animals performed. These results are contrasted with the effects of bilateral frontal or parietal neocortical removals in infancy where the earliest lesions have the most severe effect on cortical thickness and behavior. This comparison shows that unilaterality of brain damage is an important factor in predicting recovery or sparing of function from early lesions.

Animals↗
PubMed1988

The effects of neonatal gonadectomy and prenatal stress on cortical thickness and asymmetry in rats.

In Study I measures of cortical thickness were taken in 90-day-old male and female Sprague-Dawley, Wistar, and Long-Evans rats that were born to pregnant females shipped to the laboratory in late pregnancy and that were either gonadectomized at birth or left intact. No evidence for hemispheric differences in cortical thickness was found in any of the groups. Gonadectomy resulted in increased cortical thickness in male Sprague-Dawley and Wistar rats and in small increases in thickness of the left hemisphere in Long-Evans rats, especially males. No effects of gonadectomy were found in females of any strain. The lack of the expected right-over-left difference in cortical thickness in intact males may have been due to prenatal stress caused by housing, handling, and shipping. In Study 2 measures of cortical thickness were taken in 90-day-old male and female Sprague-Dawley rats that were bred in our laboratory, but otherwise similarly treated at birth. In this second study, the expected right-over-left hemispheric difference in cortical thickness was found in intact male rats; none was found in gonadectomized males or in either of the female groups. The lack of asymmetry in gonadectomized males appeared to be due to an increase in thickness in the left hemisphere. Taken together these studies provide support for the idea that hormones of testicular origin suppress cortical enlargement in the perinatal period, particularly in the left hemisphere.

Animals↗
PubMed1988

Frontal cortex grafts have opposite effects at different postoperative recovery times.

We studied the effect of different postoperative times on the behavioral recovery following brain implants. Adult male rats received cortical tissue grafts 2 weeks after aspiration of the medial frontal cortex. Either 2 (Immediate Group) or 28 (Delay Group) days after grafting, the performance of these rats on a behavioral battery, comprising the Morris water maze task, forepaw use, and grooming, was compared to that of rats with similar lesions and postoperative recovery times but no grafts. Rats tested immediately after receiving implants performed better on the spatial navigation task than rats with similar lesions but no grafts. This improvement, however, was less than that shown by rats with lesions but no grafts permitted to recover for 28 days before testing. In contrast, in the Delay Group, rats with grafts were more greatly impaired than were their operated controls. Neither lesions nor grafts affected grooming although the Immediate Group with grafts were significantly more impaired in using their forepaws during feeding than were any of the other groups. These results lead us to conclude that differing postoperative recovery times and task requirements may account for some of the inconsistent results of the influence of brain grafts on behavioral recovery reported in the literature. We also conclude that cortical tissue implants can have two effects with different time courses and opposite net behavioral effects.

Animals↗
PubMed1988

Contributions of cingulate cortex to two forms of spatial learning and memory.

The contribution of anterior and posterior cingulate cortical areas to spatial learning and memory was examined in 4 experiments using the place-navigation task. Rats with complete bilateral cingulate cortex aspiration or aspiration of posterior cingulate cortex (area 29) alone could not swim directly to a hidden platform located in a fixed place. When animals with these lesions were tested for 40 d in a place-alternation task in which they received 16 daily trials with the platform placed in a new location each day, they did not show reliable improvement in place navigation. The inability to swim to changing locations or to a single location was not overcome by preoperative training in these tasks. Rats with anterior cingulate cortex aspirations showed a less severe impairment in both tasks and, with more training than is necessary for control rats, they acquired near-normal place-navigation accuracy. Rats with complete cingulate cortex aspiration were almost as accurate as control rats in learning to swim to a visible platform. The results imply that posterior cingulate areas play an essential role in the use of topographical information, probably by transmitting and elaborating information passing between the hippocampal system and neocortical association areas.

Animals↗
PubMed1987

Recovery from early cortical damage in rats. II. Effects of experience on anatomy and behavior following frontal lesions at 1 or 5 days of age.

Perinatal cortical damage is often associated with significant overall shrinkage of the remaining cortex and severe behavioral impairments. Environmental experience was manipulated in order to determine if the anatomical and behavioral effects of neonatal frontal decortication might be attenuated by rearing in a complex environment. Rats received frontal decortication on the day of birth or 5 days later and were subsequently raised, along with littermate controls, in a complex environment or in standard laboratory cages. In adulthood, the animals were tested on a battery of behavioral tests which showed that enrichment markedly attenuated the effects of the early lesions, especially for the 5-day operates, even on tests such as tongue extension that would not be expected to benefit from specific practice in the complex environment. Analysis of the remaining cortex revealed that all groups raised in the complex environment developed thicker cortex, the increase being most dramatic in the rats given lesions at 5 days of age.

Animals↗
PubMed1987

Behavioural and anatomical studies of the posterior parietal cortex in the rat.

Primates have an area of posterior cortex characterized by multimodal sensory projections to and from the frontal association cortex and a clear behavioural syndrome resulting from lesions to this zone. The posterior association cortex of the rat was examined in two series of experiments, one anatomical and one behavioural, to see if an analogous region could be found. The anatomical connections of Krieg's area 7 in the rat were examined by placing the retrograde tracer, True blue, into the frontal or posterior cortex, and the behaviour of rats with this cortex removed was studied on a variety of tasks. This area appears to be a multimodal sensory association region. It receives projections from striate (area 17), extrastriate (areas 18a and 18b), and somatosensory cortex (area 3). It is also reciprocally connected with the posterior cingulate cortex and two frontal association zones in the medial frontal cortex, namely the anterior cingulate cortex and the frontal eye fields. Lesions produced deficits on tasks of tactile discrimination, and walking a narrow beam, two tasks requiring animals to navigate accurately to a point in space, and a task requiring the association of two spatially discontiguous cues. The animals were not impaired at navigating to a cue or in opening puzzle latches. Overall, the results show that the rat has a sensory association zone that may be analogous to the posterior parietal cortex of primates.

Animals↗
PubMed1987

Recovery from early cortical damage in rats. I. Differential behavioral and anatomical effects of frontal lesions at different ages of neural maturation.

Rats with complete removal of the cortex anterior to bregma in adulthood (frontal cortex) were compared behaviorally and neuroanatomically to rats with similar removals at 1, 5, or 10 days of age. The age at which animals received the cortical excision made a significant difference with respect to the development of the thalamus and the remaining cortex as well as the behavioral outcome in adulthood. There was a direct relationship between cortical thickness in adulthood and the age at surgery: the earlier the lesion the thinner the cortex. Part of this anatomical effect was acute, and could be observed within 24 h of surgery, but the major reduction in thickness was not observed until adolescence. Behaviorally, the animals were administered several tests including tongue extension, grooming, beam walking, swimming, and a spatial navigation task. Like the cortical measurements, the behavioral measurements showed a clear relationship between age at surgery and behavioral outcome: the earlier the lesion in infancy, the greater the behavioral impairments. Thus, whereas rats with lesions at 10 days of age showed behavioral sparing, relative to adult operates, on every measure, rats with lesions at 5 days of age performed at about the level of adult operates on most tests and rats with lesions at 1 day had more extensive behavioral impairments than all other groups. These results imply that the effects of cortical injury in infancy are tightly correlated with the precise level of neural maturation at the time of lesion.

Animals↗
PubMed1987

Ethological study of facial behavior in nonparanoid and paranoid schizophrenic patients.

This investigation addressed the question of affective disturbance in schizophrenia by applying quantitative measurement techniques to patients' facial behavior. The subjects were medication-free male inpatients: nine nonparanoid and six paranoid schizophrenic patients and 12 drug- or alcohol-abuse rehabilitation control patients. Two judges scored the subjects' behavior, which was recorded on videotape, according to a system that included 16 different types of facial movements. Eye blinks, eye contact, and words spoken were also scored. Compared to the control patients, the nonparanoid schizophrenic patients spoke significantly fewer words and had significantly less eye contact, while the paranoid schizophrenic patients had significantly fewer eyebrow and lower facial movements.

Adult↗
PubMed1986

Brain development in the neonatally decorticated rat.

The brain weights, cross-sectional areas of subcortical structures, gross morphology, and retrograde degeneration in the thalamus and basal ganglia were compared in rats with neonatal (1 or 5 days of age) or adult ablation of all of the neocortex. Neonatal decorticate and control rats also were given injections of fluorescent retrograde tracers. True blue or Nuclear yellow into the striatum, hippocampus, or subiculum in order to identify afferent pathways to these structures. Neonatal decortication resulted in morphological changes that included a dramatically shrunken and misshapen thalamus, a shrunken brainstem, distortion of the hippocampal structure and abnormal growth of the subiculum, none of which were observed following adult decortication. There was a complete absence of gliosis and calcification in the 1-day decorticates that was present in 5-day and adult decorticates. Although most striatal and hippocampal afferents from subcortical structures were present, label was not found in the ventral tegmental area or thalamus after True blue injections into the striatum and hippocampus, respectively. Acetylcholinesterase staining showed the normal striatal patchy organization. The absence of evidence for the development of new pathways or the reorganization of existing pathways is consistent with previous behavioral studies showing little sparing of function after neonatal decortication. The results suggest that the cortex plays little role in programming pattern formation and connections in subcortical structures and that cortical and subcortical structures provide unique contributions to the control of behavior.

Age Factors↗
PubMed1986

Effects of neonatal forebrain noradrenaline depletion on recovery from brain damage: performance on a spatial navigation task as a function of age of surgery and postsurgical housing.

The experiments examined the contributions of forebrain noradrenaline and environmental enrichment to recovery of place navigation ability in rats after hemidecortication in infancy or adulthood. Noradrenaline depletion did not affect recovery from neonatal hemidecortication, although the early hemidecortications did allow sparing of function relative to adult operates. Noradrenaline depletion also failed to attenuate the positive effects of enriched housing on otherwise normal rats. Noradrenaline depletion did retard recovery of adult hemidecorticate rats housed in standard laboratory cages, but it did not retard recovery of adult hemidecorticate rats housed in enriched environments. The results suggest that noradrenaline is importantly involved in enhancing recovery from brain damage when other sources of compensation (e.g., neonatal injury, enriched environment) are absent.

Animals↗
PubMed1985

Non-cholinergic globus pallidus cells that project to the cortex but not to the subthalamic nucleus in rat.

A substantial population of small globus pallidus neurons was demonstrated to have axonal projections to the cerebral cortex using fluorescent retrograde transport techniques. This population was separate from the more numerous population of medium size globus pallidus cells projecting to the subthalamic nucleus and was also separate from the pallidal and especially peripallidal population of large cholinergic cells projecting to the cortex. Some of the small, non-cholinergic cells projecting to the cortex also gave off axonal collaterals to the paraventricular thalamic nucleus.

Acetylcholinesterase↗
PubMed1985

Performance of complex arm movements and facial-movement sequences after cerebral commissurotomy.

Two patients with presumed complete midline section of the interhemispheric commissures and two patients with partial section were asked to copy complex arm movements and facial-movement sequences. Their performance was compared with our previously published findings on these tasks for patients with unilateral removals from the frontal, temporal or parietal region. On the arm-movement task, the commissurotomized patients were impaired equally with either the left or right arm and were as poor at performing this task as patients with excisions of left parietal cortex. On the face-movement task, commissurotomized patients performed very poorly, scoring significantly lower than all excision groups. There was no significant difference on either task between the performance of the patients with partial and those with complete sections.

Adult↗
PubMed1985

Earlier is not always better: behavioral dysfunction and abnormal cerebral morphogenesis following neonatal cortical lesions in the rat.

Rats with lesions of the medial frontal, ventral frontal or posterior parietal cortex in adulthood were compared behaviorally and neuroanatomically in adulthood with rats with similar removals at 7 days of age. The neonatal lesions altered cortical morphogenesis, especially in the ventral frontal and parietal groups, in which there was a marked thinning of remaining cortex distal to the lesion site. Behavior was assessed on an extensive battery of sensorimotor and maze-learning tests. Although there was sparing of function on some tests, the overall result was very little sparing on sensorimotor tests and only partial sparing on tests of maze learning in the frontal groups. The parietal neonates showed sparing on only one sensorimotor task and, in addition, showed unexpected deficits on sensorimotor and maze-learning tasks that were not observed in the adult operates. The results suggest that there may be more localization of function in the infant cortex than is generally believed and that early cortical damage may produce different behavioral effects than similar damage in adulthood.

Age Factors↗
PubMed1985

The mating movements of male decorticate rats: evidence for subcortically generated movements by the male but regulation of approaches by the female.

The study shows that although many features of copulation in decorticate male rats are normal, copulatory success is importantly dependent upon the control of approaches exerted by the normal female rat. Copulation by neonatally decorticated adult rats and normal adult rats was studied in cohabitation and videotaped tests. Seven of 10 decorticate rats and 6 of 6 normal rats sired pups in the cohabitation test. When initially paired with ovariectomized and primed female rats, in the videotaped tests, all normal rats, but only one decorticated rat, copulated. All decorticate rats made movements indicative of sexual interest including: treading on the female's back, passing over the female, and sniffing the female's genitals. After activating stimulation, 5 of 6 remaining decorticated males copulated. After one successful mount the remaining copulatory patterns proceeded relatively normally. Numbers of mounts, intromissions, ejaculations, postejaculatory songs, and the intromission and ejaculatory patterns were like those of control rats, although the decorticate rats had fewer mount bouts and showed abnormalities in the execution of movements. Precopulatory movements were notated, using the Eshkol-Wachmann system, and compared with copulatory movements. Non-copulatory and copulatory approaches were similar, except that clasping appeared to be the key movement involved in the transition of an approach movement into a copulatory movement. The analysis also showed that the females' movements of hopping, turning, and kicking were important for regulating the males' approaches, and were instrumental in the success achieved by the decorticated males. The study shows that although the cortex, insofar as it facilitates the appearance of certain movements and contributes to their efficiency, is involved in male sexual activity, in its absence well organized sexual activity is possible, although this is dependent, in part, upon the behaviour of the female.

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