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Biomedical subjects

B Kolb

Publications and source records attributed to B Kolb.

At least 127 records · Page 7Linked to original sources
PubMed1982

Cortical noradrenaline depletion eliminates sparing of spatial learning after neonatal frontal cortex damage in the rat.

The possibility that cortical noradrenaline (NA) is necessary for the sparing of function that occurs after neonatal frontal cortex damage was examined. Spatial localization by rats with frontal cortex damage sustained neonatally was better than by rats with similar damage sustained as adults. The sparing was abolished in rats depleted of cortical noradrenaline by means of neonatal 6-hydroxydopamine (6-OHDA) administration. NA depletion alone did not affect spatial localization. These data are consistent with the notion that NA has some general function in maintaining some forms of plasticity in posterior cortex.

Animals↗
PubMed1982

Neonatal decortication and adult female sexual behavior.

Neonatal lesions of the cerebral cortex in female rats did not eliminate female sexual behavior as measured by lordosis. However, lordosis in response to prolonged low levels of estradiol benzoate (1.0 micrograms/day for 6 days) was attenuated in lesioned females. Following estradiol benzoate plus progesterone (0.5 mg) treatment the probability of lordosis increased markedly in the decorticate females, but still remained below control levels. Decorticate females were mounted by the male at least as often as control females. Hopping and darting and rejection behaviors on the part of the female were virtually eliminated in the decorticate group. However, these females continued to direct sniffing behavior toward the male at levels above those of the controls.

Animals↗
PubMed1982

Dissociation of the contributions of the prefrontal cortex and dorsomedial thalamic nucleus to spatially guided behavior in the rat.

Rats with lesions of the medial frontal cortex or dorsomedial nucleus of the thalamus (MD) were studied in two spatial localization tasks: the Morris water task and the 8-arm radial arm maze. Rats with medial frontal lesions failed to learn to swim from different locations to a hidden platform located at a specific place in a large tank (Morris task) and were impaired at learning the location of reward in the radial arm maze. Rats with MD lesions were not impaired at spatial orientation in either task. The results provide the first unequivocal evidence of a spatial orientation deficit following frontal lesions and lend support to the notion that the frontal cortex forms part of a 'spatial mapping system'. The results suggest that although MD is the major afferent to the frontal cortex, it does not provide necessary spatially-relevant input.

Afferent Pathways↗
PubMed1981

Affective behavior in patients with localized cortical excisions: role of lesion site and side.

The perception of emotion in verbal and facial expression, and the spontaneous production of conversational speech were studied in patients with unilateral focal excisions of frontal, temporal, or parieto-occipital cortex. Lesions of the left hemisphere impaired the matching of verbal descriptions to appropriate verbal categories of emotional states, whereas with lesions of the right hemisphere, the matching of different faces displaying similar emotional states was impaired. The effects of lesions of both left and right hemisphere occurred regardless of the locus of the lesion. On the other hand, frontal-lobe lesions had differential effects upon unsolicited talking; lesions of the left frontal lobe virtually abolished this behavior, whereas lesions of the right frontal lobe produced excessive talking. These data suggest that the nature of the behavioral stimulus as well as the locus and side of damage must be considered in the study of the neural basis of affective behavior.

Affect↗
PubMed1981

An analysis of feeding and sensorimotor abilities of rats after decortication.

Feeding and sensorimotor abilities of decorticate rats are described. Within 24 hr after surgery, the rats ate mash, unfamiliar foods, dry chow, and tap and sugar water from a spatula. They sampled nonnutritive substances but rejected noxious substances. Although initially anorectic, given mash, they arrested weight loss as early as 2 to 4 days. With training, they drank water from a spout by Day 10 and gained weight on dry food and water. Throughout survival they had difficulties with chewing food, lapping water, and trimming toenails. They showed sensorimotor neglect to objects touched to the body; they did not orient to the place in space where touched, they did not orient when touched on the head. There may be different types of orienting, one which is lost and one spared following decortication. When lifted from a surface, they showed limb and postural abnormalities; when dropped, righting responses were impaired. They showed stereotyped reflexive responses to surface and became trapped on platforms and in alleys. The range of abnormalities, from simple acts to more complex behaviors, considered within the context of feeding behavior in its broadest sense, shows the rats simplest environment. Furthermore, cortically controlled feeding seems partly independent from hypothalamically controlled feeding.

Animals↗
PubMed1981

Decortication of rats in infancy or adulthood produced comparable functional losses on learned and species-typical behaviors.

Rats with complete ablation of the neocortex at 1--8 days of age were compared behaviorally with rats with similar excisions at 120 days of age. Decortication at both ages produced (a) chronic deficits in feeding behaviors indicated by chronic reduction in body weight, chronic deficits in pattern of food ingestion, and abolition of food-hoarding behavior; (b) increased general activity as measured in running wheels; (c) several chronic abnormalities in grooming behavior; (d) chronic abnormalities in paddling during swimming; (e) abolition of male sexual behavior; (f) elimination of defensive burying of a shock prod; and (g) severe impairments in the acquisition of a spatial reversal task. In sum, complete removal of the neocortex in infancy does not allow convincing sparing of function, a result demonstrating that subcortical structures are unable to take over functions of the neocortex. Thus, sparing of function reported following subtotal decortication requires neocortical circuitry, either alone or in combination with subcortical structures.

Aging↗
PubMed1981

Environmental constraints on motor abilities used in grooming, swimming, and eating by decorticate rats.

In a number of successive tests, grooming, swimming, and eating behaviors of decorticate rats were reexamined by evoking the behaviors in various circumstances (stimulus conditions). The rats showed normal-length grooming sequences during spontaneous home cage grooming; when grooming was elicited by removing the rats from their home cage and soaking their fur by a brief swim, grooming-sequence length was abbreviated. In cold (18 degrees C) water, they swam well and with exaggerated vigor and frequently inhibited forelimb movements; in warm (37 degrees C) water, they swam poorly and paddled with all four limbs. To eat small pieces of food, they sat up and used their forepaws as do normal rats, but they frequently dropped the food; they did not use their forepaws to eat large pieces of food. When given powdered food, they first tried to grasp it in their mouth while they scratched at the floor surface with their front limbs; thereafter, they became increasingly proficient in licking it up. Thus, in a narrow range of stimulus conditions, decorticate rats can make movements resembling those of normal rats. They also improve with practice in some (eating powdered food) but not other (forepaw immobility, eating large food pellets) tasks. The study shows that in order to elucidate the role of the cortex in control of motor behavior, it is necessary to obtain "behavior profiles" of each behavior by testing the animals repeatedly and under widely varying test conditions.

Animals↗
PubMed1981

Neonatal Frontal Lesions in the rat: sparing of learned but not species-typical behavior in the presence of reduced brain weight and cortical thickness.

Rats with complete removal of the cortex anterior to bregma in adulthood (frontal cortex) were compared behaviorally and neuroanatomically with rats with similar removals at 7 or 25 days of age. Excision of the frontal cortex in adult rats produced transient aphagia, chronic motor abnormalities in feeding, a chronic drop in body weight, increased activity in running wheels, impaired performance at a spatial reversal learning task, and chronic abnormalities in a variety of species-typical behaviors, including swimming, food hoarding, and defensive burying. In contrast, similar lesions in infant rats failed to produce aphagia, a chronic drop in body weight, increased activity, or impaired learning of a spatial reversal task. Infant lesions did not allow sparing of complex species-typical behaviors, however, such as those involved in feeding, swimming, hoarding, or defensive burying. Furthermore, when the brains of neonatally operated rats were compared with those of control rats or rats operated on in adulthood, there were striking differences. The cerebral hemispheres of the neonatal operates were smaller both in surface dimensions and weight, the thalamus was smaller, and the cerebral cortex was thinner. These data imply that there may be substantially less sparing of function following frontal cortex lesions in infancy than previously believed and that neonatal frontal lesions in rats have significant effects on brain development in regions far removed from the actual site of surgical excision.

Aging↗
PubMed1980

Effects of kainic acid lesions in the lateral hypothalamus on behavior and hippocampal and neocortical electroencephalographic (EEG) activity in the rat.

Electrolytic lesions of the lateral hypothalamus (LH) are known to produce severe and chronic behavioral and electrographic abnormalities. In order to assess the effects of damage to LH cells vs damage to fibers of passage in the LH, a comparison was made of the effects of electrolytic lesions and microinjections of the neurotoxin kainic acid (kainate) in the LH. Behavior and neocortical and hippocampal electroencephalographic (EEG) activity were studied before, immediately after, and for 25 days after the lesions were made. Electrolytic-lesioned rats were aphagic and adipsic, showed an absence of normal atropine-resistant EEG activity, and a release of atropine-sensitive EEG activity in the hippocampus and neocortex. Kainic acid-lesioned rats showed some similar behavioral impairments but the kainate lesions produced different EEG abnormalities, including chronic slow-wave and seizure activity in both the neocortex and hippocampus. Following extended recovery hippocampal EEG was normal despite extensive cellular loss in areas CA3 and CA4. Understanding of the differences in EEG between the electrolytic and kainate effects was compounded by widespread cellular damage in areas outside the hypothalamus in the rats with kainate lesions. Thus, the kainate-produced abnormalities precluded a simple analysis of the contribution that cell damage alone makes to LH lesion-induced behavioral and EEG changes.

Animals↗