Hypothalamo-Pituitary-Adrenocortical Regulation Following Lesions of the Central Nucleus of the Amygdala

Previous reports indicate that the central nucleus of the amygdala (CeA) stimulates adrenocorticotropin and corticosterone secretion, suggesting a role for this region in central hypothalamo-pituitary-adrenocortical (HPA) stress regulation. To evaluate this hypothesis, this study assessed the impact of CeA lesion on the response of hypophysiotrophic paraventricular nucleus (PVN) neurons to acute restraint and chronic unpredictable stress exposure. In contrast to previous reports, CeA lesions did not affect corticosterone or ACTH secretion induced by acute stress. Acute restraint increased PVN corticotropin releasing hormone (CRH) mRNA expression, increased the number of parvocellular PVN neurons expressing the co-secretagogue arginine vasopressin (AVP), and induced cFOS mRNA expression in the parvocellular PVN. However, there was no additional effect of CeA lesion on any measure of PVN activation. Chronic unpredictable stress exposure induced long-term activation of the HPA axis, noted by thymic involution, adrenal hypertrophy and increased PVN CRH mRNA expression. Stress-induced changes in thymus and adrenal weights were not affected by CeA lesion. Further, CeA lesion rats did not differ from controls in post-stress CRH mRNA expression. However, basal CRH mRNA expression was increased in the PVN of CeA rats, suggesting that the CeA plays a role in long-term inhibition of the PVN. The results of these studies are not consistent with the hypothesis that the CeA is necessary for stress-induced pituitary-adrenocortical activation. Rather, this region may play a stressor-specific modulatory role in regulation of HPA function.     

Interactionism and Physicality

Substance-dualist interactionism faces two sorts of challenge. One is empirical, involving the alleged incompatibility between interactionism and the supposed closure of the physical world. Although widely considered successful, this challenge gives no reason for preferring materialism to dualism. The other sort of challenge holds that interactionism is conceptually impossible. The historically influential version of the conceptual challenge is now discredited, but recent discussions by Chomsky and by Crane and Mellor suggest a new version. In brief, the argument is that anything that interacts causally with physical things would have to be sanctioned by physics,and anything sanctioned by physics is ipso facto (as a matter of conceptual necessity) physical. I focus on the second premise. I show that plausible arguments for it are in fact fallacious and that counterexamples undermine it. Thus the argument fails: substance-dualist interactionism cannot be ruled out on conceptual grounds alone.     

Effect upon Desire for Social Interaction with a Physically Disabled Person of Mentioning the Disability in Different Contexts

An experiment investigated the effectiveness of strategies that could be used by a physically disabled person to reduce the social handicap of being avoided in first encounters. Female college students indicated their preference for social interaction before and after learning the other person was a male in a wheelchair or nondisabled. When the disabled person made a general comment mentioning his disability after a request for help or after a miscue, change in preference for social interaction was more positive than when he did not mention his disability, providing evidence for the effectiveness of mentioning the disability following an incident involving the disability. Mention of the disability in the absence of an incident involving the disability was not found to be effective. The different ways of mentioning the disability did not affect the favorability of impressions of the disabled person, as measured by ratings of his characteristics. Impressions were generally more favorable for the disabled person than the person not in a wheelchair.     

Speech samples in analysis of language attitudes

Samples of speech obtained under naturalistic conditions were combined with subjective reaction tests to measure attitudes toward dialect interaction and language change. A specific sound change, the merger of American English vowels in words like caught and cot, was investigated. Early results of the experiments indicated that this change was socially motivated, but later, more sophisticated experiments indicated that arguments for a social motivation for this particular change are too simplistic and rest upon too slender an empirical base. Experiments in the interaction of phonology and perception show that for this sound change various psycholinguistic factors, especially difficulties in discriminating among speech sounds, have to be taken into account.Support for the research reported on in this paper was provided by the Danforth Foundation, the University of Oregon, the University of Tromsø, and the University of Cincinnati. Earlier, partial versions were presented at the Fifth Western Conference on Linguistics, the Fourth Annual Colloquium on New Ways of Analyzing Variation in English, the Second Annual Kentucky Interdisciplinary Conference on Linguistics, and the 1976 Midwest Meeting of the American Dialect Society. The paper has benefited from the many constructive remarks it has drawn at these meetings. Those inaccuracies and examples of plain wrong-headedness that remain are, of course, entirely my own.     

Effects of pattern, spatial frequency, number, and rate of stimulus presentation on the accuracy of detection.

Brief trains of pulsed stimuli were used to assess whether magnocellular or parvocellular visual pathways could be differentiated perceptually. Trains of either one to four sine-wave, square-wave, or checkerboard gratings were presented at three temporal and two spatial frequencies to six observers. The task of the observer was to report the perceived number of stimuli (gratings) in a train. The difference between actual number and perceived number of gratings was recorded as an error score. It was found that neither the pattern nor the spatial frequency of the gratings significantly affected perceptual accuracy. On the other hand, the number of gratings in a train and the interstimulus interval between gratings produced significant differences. Perceptual accuracy was greater when lower numbers of gratings in a train were presented with longer interstimulus intervals. The observers typically reported fewer stimuli than were presented. The source of the discrepancy is discussed in terms of a light adaptive process initiated in the retina.     

Thomas Brown on the philosophy and psychology of perception

Thomas Brown's theory of perception is set in its philosophical context, and the influence of George Berkeley, David Hume, and Thomas Reid on Brown is discussed. Destutt de Tracy, who appears to have been an unacknowledged source for Brown's ideas, is also discussed. Brown's theory of perception is elaborated, and he is categorized both as a sense-datum theorist and as a phenomenalist.