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Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Stereotypical behavior or response perseveration dominating early mammalian responding, especially under conditions of aversive motivation, may be radically modified through damage in the prefrontal and hippocampal systems. These observations contribute evidence to the notion that changes in neural circuitry may be supporting behavioral recovery of function after selective brain damage. The extent of behavioral deficits as well as the prognosis for recovery are governed by task-specific variables, usually related to a discriminative element in stimulus control. Conversely, reversion to earlier, stereotypical behavior may be produced in adult rats exposed to damage at points within the same sites. Specific experiments tested weanling and adult rats within tasks that differed in the (1) extent and site of damage, (2) variety of signalling stimuli, (3) complexity of the task requirements, and (4) time since surgery for initiation of training. Experiments on 1-way active avoidance, alternation and reversal learning indicated that performance deficits are attributed to developmental immaturity early in ontogeny, and enhanced neurophysiological growth with age provides a reliable predictor of recovery. However with increasing age, variables related to the subtleties of damage site and task also emerge as salient factors in behavioral deficiencies. Interestingly, the cue properties or information value contained in the conditioned stimulus (CS) and the environmental context provide differential compensation for selected types of injury-induced deficits, and there was some evidence that the utility of environmental signals can be improved over long-term recovery periods. The results support the view that relationships between age at the time of injury and extent of recovery are perhaps best explained within developmentally determined constraints.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Ontogenic factors in short- and long-term recovery of discriminative behavior in rats after selective brain damage. 213 Jun 36

Schacter, Moscovitch, Tulving, McLachlan, and Freedman propose that infants may make the AB error because of immaturity of the memory system damaged in amnesia (e.g., the hippocampus). They contrast this with the proposal that infants may make the AB error because of immaturity of the frontal lobe system (Diamond; Diamond & Goldman-Rakic). Schacter et al.'s choice of subjects, however, did not permit a test of these 2 proposals, and characteristics of their task, such as length of delay, make comparison with infants difficult. Schacter et al. discuss sensitivity to proactive interference as a possible explanation for the AB error, but sensitivity to PI is more closely associated with frontal lobe damage than with amnesia. Schacter et al. associate perseveration with immaturity or damage to the frontal lobe; it is suggested here that this is better characterized as lack of inhibitory control. Tasks that are most likely to require frontal cortex function are those that demand both short-term memory and inhibitory control. AB is an excellent example of such a task.
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PMID:Abilities and neural mechanisms underlying AB performance. 335 70