Biomedical subjects

J H Hollis

Publications and source records attributed to J H Hollis.

At least 19 recordsLinked to original sources

PubMed2000

Abnormal adaptations to stress and impaired cardiovascular function in mice lacking corticotropin-releasing hormone receptor-2.

The actions of corticotropin-releasing hormone (Crh), a mediator of endocrine and behavioural responses to stress, and the related hormone urocortin (Ucn) are coordinated by two receptors, Crhr1 (encoded by Crhr) and Crhr2. These receptors may exhibit distinct functions due to unique tissue distribution and pharmacology. Crhr-null mice have defined central functions for Crhr1 in anxiety and neuroendocrine stress responses. Here we generate Crhr2-/- mice and show that Crhr2 supplies regulatory features to the hypothalamic-pituitary-adrenal axis (HPA) stress response. Although initiation of the stress response appears to be normal, Crhr2-/- mice show early termination of adrenocorticotropic hormone (Acth) release, suggesting that Crhr2 is involved in maintaining HPA drive. Crhr2 also appears to modify the recovery phase of the HPA response, as corticosterone levels remain elevated 90 minutes after stress in Crhr2-/- mice. In addition, stress-coping behaviours associated with dearousal are reduced in Crhr2-/- mice. We also demonstrate that Crhr2 is essential for sustained feeding suppression (hypophagia) induced by Ucn. Feeding is initially suppressed in Crhr2-/- mice following Ucn, but Crhr2-/- mice recover more rapidly and completely than do wild-type mice. In addition to central nervous system effects, we found that, in contrast to wild-type mice, Crhr2-/- mice fail to show the enhanced cardiac performance or reduced blood pressure associated with systemic Ucn, suggesting that Crhr2 mediates these peripheral haemodynamic effects. Moreover, Crhr2-/- mice have elevated basal blood pressure, demonstrating that Crhr2 participates in cardiovascular homeostasis. Our results identify specific responses in the brain and periphery that involve Crhr2.

Adaptation, Physiological↗

PubMed1983

Haptic attention and visual transfer by mentally retarded and nonretarded individuals.

Four mentally retarded and four nonretarded adolescents learned compound discriminations in the haptic (touch) modality using Ray's (1969) conflict-compound procedure. Reinforcement history was controlled so that prior reinforcement contingencies were unchanged for one element and reversed for the other element of a compound (two-element) stimulus during discrimination training. Consistent with Huguenin and Touchette's (1980) results in the visual modality, our retarded subjects evinced selective attention effects in posttraining tests conducted in the haptic modality. Results with nonretarded subjects similarly indicated that they had selectively attended to only one element of a conflict-compound stimulus during compound discrimination training. Visual transfer tests revealed that for most individuals the effects of conflict-compound discrimination training transferred from the haptic to visual sensory modalities. Results were discussed in terms of selectivity of attention to nonredundant stimulus elements as an effective strategy for discrimination learning rather than a perceptual deficit.

Adolescent↗

PubMed1983

An inverse relationship between serum immunoglobulin-G and intellectual functioning.

Serum immunoglobulin levels for IgA, IgE, IgG, and IgM were measured in 13 institutionalized, profoundly mentally retarded individuals and for 20 retarded and 29 intellectually average noninstitutionalized individuals. A significant elevation in IgG was observed for the retarded groups as compared with the intellectually average group. There was a significant inverse relationship between IgG and level of intellectual functioning. The elevated IgG is suggestive of the findings with auto-immune diseases and warrants further investigation.

Adolescent↗

PubMed1982

Life threatening behavior: analysis and intervention. Summary and discussion of special issues.

This chapter summarizes issues relevant to analyzing and treating LTB. This is a difficult area in which to conduct research and develop functional interventions; however, it is important to the welfare and dignity of those afflicted with LTB. This chapter has suggested the development of a unified approach to the study and treatment of LTB. We should view LTB as a system or class of systems (composed of multiple behavioral components) rather than isolated incidences of maladaptive behavior. It has been shown that the various classes of LTB have common ground, including 1) theoretical orientation; 2) intervention techniques; and 3) future research strategies. Finally, because many of the factors controlling the occurrence of LTB are unknown, research should be directed toward those factors. Once these factors are understood and effective treatment methods and procedures are established, it will be necessary to conduct direct and systematic replications to establish empirical validity and generality (Sidman, 1960).

Behavior Therapy↗

PubMed1978

Analysis of rocking behavior.

Operant conditioning techniques were applied to the study of stereotyped body-rocking movements. Six mentally retarded children were tested individually in a fully automated situation under the following conditions: (a) free operant baseline; (b) intense auditory stimulation; (c) variable-interval (VI) and fixed-ratio (FR) reinforcement schedules; (d) differential reinforcement of low rate (DRL); (e) differential reinforcement of other behaviors (DRO); and (f) noncontingent reinforcement. The results indicated: (a) intense auditory stimulation increased the rate of rocking movements in four of six subjects; (b) VI and FR schedules generated curves that are representative of these schedules; (c) DRL schedules decelerated high-rate rocking; (d) DRO schedules eliminated high-rate rocking; (e) noncontigent reinforcement increased variability and resulted in decreased rate of responding. In conclusion, the data support the hypothesis that body-rocking movements in the mentally retarded are an operant and reflect the established characteristics of reinforcement schedules and operant controls.

Acoustic Stimulation↗

PubMed1978

A nonvocal system for teaching retarded children to read and write.

This study investigated the development of nonvocal teaching of reading and writing in severely retarded children. Fourteen subjects were selected who demonstrated limited communication skills, and were randomly placed into two groups. Group A received training procedures utilizing abstract plastic symbols which were arbitrarily assigned to represent specific words. The training program was divided into three phases. Phase I consisted of training left to right sequencing of four color--coded forms; Phase II consisted of training of matching symbols to stimulus pictures; and Phase III consisted of training of fading from symbols to printed words. The subjects completing this training program demonstrated the ability to learn selected reading and writing skills, i.e., they learned to sequence an article, subject noun, auxiliary verb, and verb. They also demonstrated functional semantic comprehension of five nouns and five verbs. Thirteen subjects finished the communication training program in less than four months with a mean training of 7 hours and 55 minutes. This is approximately 2 hours of training a month per subject to learn these skills. The data showed that Group B (rebuses) required fewer trials than Group A (abstract symbols) to meet criterion for Phase II, matching symbols to stimulus pictures. This suggests that Group B subjects may have had a meaningful association for the rebus signs which generalized to stimulus pictures. Group A (abstract symbols) required fewer trials than Group B (rebuse) to meet criterion for Phase 111, matching printed words to stimulus pictures. This indicates that perhaps Group A's training with abstract symbols positively affected learning to read printed words. The success of the visual nonvocal treatment program with the severely retarded is encouraging. Indeed, this is a different and viable approach in teaching communication skills (reading and writing) to the retarded.

Adolescent↗

PubMed1976