Functional recovery following brain damage: conceptual frameworks and biological mechanisms

Mammals are well known to manifest recovery over time of many functional impairments induced by brain lesions. A brief reveiw is provided of the different conceptual frameworks within which functional recovery has been examined in the literature, and of different neurobiological mechanisms that have been proposed to account for the phenomenon. We observe that these two levels of analysis have frequently been only loosely related. Finally, a newly identified biological mechanism—compensatory collateral sprouting—is described which appears to be closely related to functional recovery in animals with hippocampal lesions, and this is proposed as a powerful new model within which to investigate further the relationship between the phenomenon of functional recovery and its underlying mechanisms.     

Effect of telencephalon ablation on the reinforcing and eliciting properties of species-specific events in Betta splendens

In male Betta splendens, aggressive behavior is drastically attenuated following telencephalon ablation. Because instrumental training and Pavlovian conditioning experiments with intact fish have suggested that associative factors may play an important role in the performance of agonistic behaviors, the effect of ablation on instrumental learning and Pavlovian conditioning was studied. In Experiment 1, ablation had no effect on the learning of the instrumental tunnel-swimming response reinforced by mirror presentation (i.e., viewing a conspecific), although the mirror presentations in yoked-control groups elicited fewer responses in ablates than in normal and sham-operated control fish. Yoked controls further established that instrumental responding was maintained by the reinforcement contingency and was not merely the result of increased motor activity. Experiment 2 studied Pavlovian conditioning of the components of the agonistic display. Unconditioned fin erection, gill erection, and tail beating (i.e., unconditioned responses, URs) to the mirror US all were less frequent in ablates than in normals or shams. Of these, only gill cover erection showed evidence of true conditioning (i.e., conditioned responses; CRs) in which responses to the conditioned stimulus (CS) are due to the pairings of CS and US (unconditioned stimulus). However, ablates suffered no impairment of conditioned gill erections. Ablates performed fewer fin erections to the CS; however, fin erection responses were not due to CS-US pairings but were attributable to pseudoconditioning. These results are related to hypotheses postulating the involvement of learning mechanisms in ablation-produced deficits and normal aggressive behavior.     

Do learning-disabled children exhibit peripheral deficits in selective attention? An analysis of eye movements during reading

It has been suggested that deficits in selective attention play a functional role in the learning and behavior problems of children diagnosed as learning- disabled. In the present study, peripheral and central aspects of selective attention were distinguished and peripheral aspects were examined. The attending eye movements during reading of 12 fifth-grade learning-disabled children who read at the third-grade level were compared with 12 fifth-grade children who read at the fifth-grade level (grade placement controls) and 12 third-grade children who read at the third-grade level (reading level controls). The learning-disabled children did not differ from their reading level controls on any of W measures but showed a pattern of eye movements that was generally slower and less smooth than their grade placement controls. While these patterns might be considered to be immature relative to normal readers of the same age, they are not indicative of peripheral deficits in selective attention. Males, however, did exhibit more variability in duration of fixations and made more regressive eye movements than did females.     

Interpreting idioms

Immediate comprehension processes involved in the interpretation of idiomatic expressions were investigate. Idioms like bury the hatchet were used in sentential contexts that (1) biased the listener toward a literal interpretation, (2) biased the listener toward a figurative interpretation, or (3) left the interpretation ambiguous between the literal and figurative readings. In control sentences, the final words of the idioms were used in nonidiomatic expressions. Listeners monitored the sentences for specified targets. In all cases, the target words were the final words of the idiomatic phrases. The listeners were instructed to detect words that were identical to cue words, that rhymed with the cue words, or that were members of semantic categories specified by cue words. Thus, hatchet was cued with either hatchet, ratchet, or a tool. Reaction-time latencies from the onset of the targets to the listeners' responses were obtained. Identity, Rhyme, and Category matches were detected more rapidly in all three idiomatic contexts than in the nonidiomatic controls. These results suggest that idioms are automatically processed as discrete lexical entries, and that previously observed reaction time advantages for figurative expressions may reflect integrative processes rather than retrieval of meaning.This research was supported by PHS Training Grant T32 MH 15134-02 from the National Institute of Mental Health. A preliminary version of this paper was presented at the Annual Meeting of the American Psychological Association, Los Angeles, August 1981.     

Sex differences,sex-role orientation,and reward allocations

In study 1, 52 male and 52 female undergraduates allocated rewards to pairs of children for their performances in team and competitive situations. Males allocated rewards more equitably, especially when allocating to boys in competition, while females allocated rewards more equally. Boys, but not girls, who did more work received more rewards than their partner; and children with greater work inputs under competitive conditions received more rewards than children in team conditions. In study 2, the sex-role orientation of 60 college students was found to be related to their reward allocations. Males and females with a masculine sex-role orientation allocated rewards equitably, while individuals with a feminine sex-role orientation allocated rewards equally. Results indicated that sex and situational differences in reward allocations are affected by sex-role orientation and differential socialization practices by adults.Portions of study 1 were presented at the Midwestern Psychological Association Meeting, Chicago, May 1978.