Hippocampal deafferentation: transplantderived reinnervation and functional recovery

A brief review is provided of the capacity of neural tissue transplants to reinnervate the deafferented hippocampus and repair functional deficits induced by the lesion. The techniques for transplantation of solid pieces of embryonic septum, locus coeruleus or raphe nuclei, or tissue suspensions of embryonic septum, to the adult rat hippocampus are described. Such grafts manifest good long-term survival, provide a good reinnervation of the hippocampus that is histochemically and biochemically appropriate and specific, can establish ultrastructural synaptic contacts with the host, and are electrophysiologically active. Rats with septal grafts manifest recovery of the capacity to learn certain aspects of radial 8-arm maze, T-maze alternation and Morris water-maze tasks. Rats with locus coeruleus grafts manifest an amelioration of lesion-induced hyperactivity. It is concluded that neural tissue transplantation provides a powerful new tool in the study of the functional organization of the hippocampus and its various neurotransmitter-specific afferent systems.     

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.     

The use of latent class models for assessing prerequisite relations and transference among traits

This paper presents a strategy for pairwise assessment which may be used to evaluate the nature of both prerequisite and transference relations existing among a set of traits. This strategy is appropriate for use both within a confirmatory context, in which an attempt is made to establish the validity of some specified set of relations among traits, as well as within an exploratory context, in which a search is made for unconjectured prerequisite and transference relations existing between pairs of traits. Both uses of this strategy are based on a variety of latent class models which are representative of various possible relational states existing between pairs of traits. Thus, the nature of trait relations may be investigated through the use of statistical assessments of both absolute and relative fit attained by these models. An application is presented to exemplify how this strategy may be used within the exploratory context.The author is obliged to Clifford Clogg, C. Mitchell, Dayton, and William Schafer for helpful comments made regarding a previous draft of this paper as well as to Mary Papageorgiou who provided access to the data which was considered in this study.     

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.     

Violence in children's animated television

Pairs of cartoon episodes which did and did not meet the National Association of Broadcaster's Code for Violence were rated by college students and children on a series of scales to evaluate level of violence and of enjoyment. The results indicated that the Code has been ineffective in reducing levels of rated violence; however, entertainment value has decreased.     

Consistency and error in motor performance

Two response measures that described the consistency and accuracy of motor performance were investigated. A pursuit tracking task was used as the vehicle whereby changes in perceptual motor performance could be monitored over several learning trials. The intra-individual variability of a subject's tracking response was compared to the root mean squared error that was accumulated during each block of trials. Whereas both response measures were sensitive to the changes in performance that occured as a result of practice, neither could be considered sufficiently informative as to be used as a sole indicator of skill acquisition. It appears that both consistency and error measures are needed to describe the subjects' performance as they acquire a perceptual motor skill.