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Biomedical subjects

D W Harrison

Publications and source records attributed to D W Harrison.

46 records · Page 3Linked to original sources
PubMed1985

Age differences in retention of fixed-interval responding: memory or habitation effects?

Long-term retention of fixed-interval curvature as an index of recall memory which is relatively free of retrieval cues was examined in younger and older rats. Previous research on free-operant behavior in younger and older rats showing within-session decrements in behavior of older rats and within-session increments in younger rats suggested that the results of recall memory tests would depend upon the duration of the test session and the point within the session where data were collected. Consistent with such expectations, recall of fixed-interval curvature was poorer in older rats when data from late in the test session or data averaged over the entire 45-min session were used, but the opposite finding, numerically better retention in the older rats, occurred when data from the earliest part of the test session were used. The results suggest that age-related performance differences from which age-related memory differences are inferred may be confounded by other age-related effects upon performance which have nothing to do with memory.

Age Factors↗
PubMed1984

Disruption and habituation of stable fixed-interval behavior in younger and older monkeys.

Reactivity to novel and irrelevant stimuli has been shown to vary as a function of age. Since differential responsivity to irrelevant events may account for purported age differences on other tasks, the present experiment studied the extent to which these age differences may be reduced with repeated exposure, i.e., habituation. Young (2 to 3 years) and old (15+ years) squirrel monkeys were trained and their performance stabilized over months on a fixed-interval operant task. This behavior was then disrupted by periodic presentations of an auditory stimulus of moderate intensity. Disruption of stable behavior and habituation to the tone stimulus were evaluated across several measures including overall response rates between and within the daily sessions; recovery of baseline response rates during the tone stimulus; and the curvature of the fixed interval "scallop." Old monkeys responded for sweet fruit juice more frequently, but less efficiently, than young monkeys. Their responding was more severely disrupted by intermittent novel auditory stimuli, to which they were slower to habituate.

Acoustic Stimulation↗
PubMed1983

The effects of age, exposure, preexposure, and noise conditions on variable interval performance.

The present study was designed to investigate the differential effects of environmental factors on performance in young and aged rats. Specifically, within- and between-session habituation, environmental preexposure, and noise conditions were examined. Consistent age differences were found in response to environmental change and sensory condition. Variable-interval response rates of the well-habituated old animal were well below those of the young. Stimulus change and increments in noise elevated these behaviors in the aged to levels well above those seen in the young. Aged animals appeared incapable of maintaining higher response rates without corresponding conditions of novelty, contextual change, or increments in ambient sensory conditions. Preexposure to sensory conditions similar to those used in the operant chamber reduced response rates in the old, as did habituation with repeated exposure to the chamber.

Aging↗
PubMedDate not supplied

"Cotton fever": a benign febrile syndrome in intravenous drug abusers.

Cotton fever is a benign, self-limited syndrome that may mimic sepsis in intravenous drug addicts. We present an illustrative case and a review of the literature. Serious illness such as pneumonia and infectious endocarditis must always be considered in febrile addicts. However, trivial illness accounts for 16% to 26% of such fevers. Recent evidence suggests that emergency physicians are able to diagnose trivial illness with 93% specificity in febrile adult drug addicts. Short-term observation units may be an alternative to hospital admission for febrile drug users with a presumptive diagnosis of trivial illness and in those in whom the diagnosis of cotton fever is entertained.

Adult↗
PubMedDate not supplied

Blindness following minor head trauma in children: a report of two cases with a review of the literature.

The spectrum of closed head injury ranging from asymptomatic to lethal is well described in the literature. In a small number of cases, dramatic neurologic symptoms normally associated with cerebrovascular accident or vascular headache may arise following apparently insignificant head trauma. We report two cases of young males who developed transient blindness accompanied by significant neurologic abnormality following trivial head injuries. These phenomena are previously well documented, and it is believed that in certain individuals, minor head trauma can induce a type of migraine equivalent known as "footballer's migraine" or "posttraumatic cortical blindness." Current knowledge of these two conditions is reviewed.

Accidental Falls↗
PubMedDate not supplied

Grip strength asymmetry in depressed boys.

OBJECTIVE: The purpose of this experiment was to investigate the influence of depressed mood on functional motor asymmetry among school-aged boys. Thus, left- and right-hand grip strength as well as fatigue across successive trials was examined among 38 right-handed school-aged boys, half of whom had been classified as depressed (n = 19) and the other half as nondepressed (n = 19). BACKGROUND: There is support in the literature that depressed individuals experience relative right anterior activation, and previous reports of functional motor asymmetries among depressed adults are generally supportive of this notion. To date, however, little is known regarding the neuropsychology of depression as it may pertain to children; in particular, the possibility of functional motor asymmetry within this population has yet to be explored. METHOD: Participants were asked to squeeze a hand dynamometer four times successively with each hand. The order of hand presentation was counterbalanced, and the dependent measure was in kilograms. RESULTS: As hypothesized, depressed boys failed to demonstrate asymmetry for grip strength, although nondepressed boys exhibited right-hand grip strength. In addition, based on trend, right-hand grip strength for depressed boys fatigued more rapidly across successive trials than did right-hand grip strength for nondepressed boys. In contrast, depressed boys maintained left-hand grip strength longer across successive trials than did nondepressed boys. CONCLUSIONS: The data are interpreted as consistent with current neuropsychological theories of emotion, particularly depression, and suggest that the functional motor asymmetries (i.e., failure to demonstrate asymmetric grip strength) observed in depressed adults are also present among depressed children. Implications for increased right hemisphere activation, decreased left hemisphere activation, or a combination of both are discussed.

Brain↗
PubMedDate not supplied

The Takeda Model UA-751 blood pressure and pulse rate monitor.

The performance of the Takeda Model UA-751 oscillometric blood pressure and pulse rate monitor was compared with readings taken using auscultatory technique and the mercury manometer. Significant correlations (p less than 0.0001) were found between the clinical standard and the UA-751 on measurements of systolic (r = 0.85) and diastolic (r = 0.77) blood pressure. Comparison of the pulse rate measurements obtained using the Grass Polygraph with those of the UA-751 resulted in a reliable correlation (r = 0.98; p less than 0.0001), as well. The results provide empirical support for the validity of the UA-751 under controlled laboratory conditions. However, the results suggest heightened error in the measurement of systolic pressure when the UA-751 is used by individuals who have high blood pressures.

Adult↗
PubMedDate not supplied

An evaluation of the DS-175, DS-145, and DS-115, digital blood pressure/pulse meter devices.

The performances of three electronic digital blood pressure/pulse meter models, Nissei DS-175, DS-145, and DS-115, were compared with measurements obtained using the mercury sphygmomanometer and auscultatory technique. Significant correlations (p less than 0.01) were found between the accepted medical criterion and the three models evaluated for both systolic (r = 0.64 to 0.74) and diastolic (r = 0.58 to 0.61) pressure measurements; however, the accuracies of the devices were deemed inadequate. The DS-175 was found to significantly overestimate both systolic (p less than 0.025) and diastolic (p less than 0.05) pressures. Furthermore, all models tended to overestimate low blood pressures, whereas high blood pressures were underestimated. Variables associated with home use by the lay person are also discussed.

Adult↗
PubMedDate not supplied

Home blood pressure monitoring: a survey of potential users.

Fifty respondents were surveyed using a recently developed questionnaire designed to evaluate the educational needs of the users of self-monitoring blood pressure apparatus. The categories evaluated included each subject's background and family health history, general knowledge about blood pressure, lifestyle factors affecting blood pressure, and factors affecting the measurement of blood pressure, as well as questions about owning a home monitor and recalibration and maintenance factors. The results indicate considerable disparity between the subjects' levels of knowledge about lifestyle factors affecting blood pressure and the subjects' knowledge of factors essential to accurate self-monitoring of blood pressure. The implications of and need for the design of educational training protocols are discussed.

Adolescent↗