EFFECTS OF CHRONIC REDUCTIONS IN BRAIN CHOLINESTERASE ACTIVITY ON ACQUISITION AND EXTINCTION OF A CONDITIONED AVOIDANCE RESPONSE

R ussell , R. W., W atson , R. H. J., and F rankenhaeuser , M. Effects of chronic reductions in brain cholinesterase activity on acquisition and extinction of a conditioned avoidance response. Scand. J. Psychol ., 1961, 2 , 21–29.—Significant effects of five different levels of reduction in brain ChE activity in the white rat were found during the extinction, but not during the acquisition, of a conditioned avoidance response. The reductions were produced and chronically maintained throughout the experiment by administration of an organo-phosphorous anticholinesterase. (1) Reduced brain ChE activity was associated with differential effects on the behavior, i.e., speed of conditioning was not altered significantly, whereas speed of extinction was so affected. (2) There appears to be a 'critical level' between 60 and 65 per cent reduction of normal ChE activity below which extinction was significantly affected.     

The method of constant stimuli is inefficient

Simpson (1988) has argued that the method of constant stimuli is as efficient as adaptive methods of threshold estimation, and has supported this claim with simulations. We show that Simpson's simulations are not a reasonable model of the experimental process, and that more plausible simulations confirm that adaptive methods are much more efficient than the method of constant stimuli.     

Identification of time-compressed sentential stimuli by good vs poor readers

Ability of eight good and eight poor readers (in Grade 1, ages ranging from 6.7 to 7.4 yr.) to discriminate phonemic contrasts presented in 50% time-compressed sentential stimuli (Subtest 13 of the Carrow-Auditory Visual Abilities Test) was measured. Good readers exhibited a significantly higher over-all mean performance than poor readers on the time-compressed task. Effects of time-compression on the perception of manner, place, voicing and frequency contrasts showed a similar pattern of errors for both groups of readers. Implications of the effects of auditory discrimination on reading abilities are discussed.     

Locus of control and adjustment to cancer

The English form of the Cancer Locus of Control Scale was administered to an heterogeneous sample of 68 cancer patients. A principal components analysis confirmed the three subscales described in the original Dutch form, however, with five items excluded. Correlations with other measures indicated that high internal control over the course of the illness was associated with a tendency to adopt an attitude toward cancer of 'fighting spirit' whereas high internal control over the cause of the illness was associated with an 'anxious preoccupation' about cancer. No specific relationship was found between scale scores and either depression and anxiety or the tendency to be emotionally controlled. It was concluded that the scale provides a valid measure of perceptions of control of cancer patients and is a useful method of assessing these important psychological responses.     

The relation between oral movement control and speech

A large series of neurological patients, selected solely on the basis that they had damage restricted to one hemisphere of the brain, was given a variety of tests of basic speech and praxic function. Within the left-damaged group, patients were further identified as aphasic or nonaphasic, based on preexisting standard tests of aphasia. Subgroups of aphasics were studied on the basis of lesion location, rather than on the basis of aphasia type. The focus of the study was the relation between the production of speech and nonspeech oral movements, particularly across anterior and posterior lesions. Reproduction of single nonverbal oral movements and of single isolated speech sounds was found to be very highly correlated, and both depended selectively on the left anterior region of the brain. This same region was critically important for rapid repeated articulation of a syllable, suggesting that it mediates control at some "unit" level of movement, in a phenomenological sense, for both speech and nonspeech movements. Other "speech" regions in the left hemisphere appeared to be dispensable for the production of single oral movements, whether these were verbal or nonverbal movements. However, for most aphasic patients, an area in the left posterior region was inferred to be essential for production of multiple oral movements, whether nonverbal or verbal, suggesting a critical role in the accurate selection of movements. Within the posterior region, there was further differentiation for multisyllabic speech into a parietal system, which appeared to mediate primarily praxic function, and a temporal system, which appeared to mediate verbal-echolalic function. Aphasias from anterior and posterior lesions resembled "Broca's" and "Wernicke's" aphasia only insofar as they differed in fluency, with anterior aphasics clearly less fluent. Tests of speech comprehension did not differentiate the groups. It is suggested that classifying aphasic patients via lesion location rather than aphasic typology might yield a view of functional subsystems different from those commonly accepted.     

Effects of flurazepam and triazolam on neuropsychological performance

A double-blind study examined the effects of a single dose of either triazolam or flurazepam on measures of concept formation, attention, concentration, and motor function, the morning following drug ingestion. Subjects were 53 healthy university students, screened for history of neurological or psychiatric illness. In comparison to placebo-treated controls, there was no difference in the effects on neuropsychological performance, although subjects who received flurazepam reported more side effects. It was concluded that although these drugs may produce side effects, single doses do not appear to impair various aspects of neuropsychological ability the morning after ingestion.