Biomedical subjects

J R Jennings

Publications and source records attributed to J R Jennings.

At least 19 recordsLinked to original sources

PubMed2001

Attention influences sensory integration for postural control in older adults.

This study investigated the influence of attention on the sensory integration component of postural control in young and older adults. Eighteen young and 18 older healthy subjects performed information-processing tasks during different postural challenge conditions. Postural conditions included seated, standing on a firm surface, standing on a sway-referenced floor, and standing on a sway-referenced floor while viewing a sway-referenced scene. During each condition, reaction time (RT) was measured during two simple and one inhibitory RT tasks. For the inhibitory task, the time required to inhibit an action was derived, termed the inhibitory time (IT). Performing a RT task was associated with increased postural sway in older subjects, but not in young subjects. The greatest influence of RT task on sway of older subjects was found during the sway-referenced floor/sway-referenced scene condition. Conversely, postural condition had an influence on RT task performance in both young and older subjects. The IT was increased in both young and older subjects only during the sway-referenced floor/scene condition. These results suggest that the sensory integration component of postural control in particular seems to require attention. Further, our data suggest that attentional processes related to inhibitory control are engaged when sensory integration requirements are high.

Age Factors↗

PubMed2000

Anticipatory blood pressure responses to exercise are associated with left ventricular mass in Finnish men: Kuopio Ischemic Heart Disease Risk Factor Study.

BACKGROUND: Exaggerated cardiovascular reactivity to psychological demands may contribute to the development of left ventricular (LV) hypertrophy. We examined the cross-sectional association between anticipatory blood pressure (BP) responses to bicycle exercise and LV mass in the Kuopio Ischemic Heart Disease Risk Factor Study, a population-based epidemiological sample. METHODS AND RESULTS: Among 876 men from 4 age cohorts (ages 42, 48, 58, and 64 years), we collected echocardiographic assessments of LV mass along with measures of BP response taken before bicycle ergometry testing. Anticipatory BP responses were positively associated with LV mass, with significant associations only among younger (age <50 years) subjects with elevated resting pressures (3-way interactions for anticipatory BP x age x resting pressure for systolic and diastolic BP, all P:<0.05; for younger subjects with elevated systolic BP, P:<0. 01; and for younger subjects with elevated diastolic BP, P:<0.001). Among these subgroups, exaggerated anticipatory BP responses (top quartile) were associated with an incremental increase in LV mass of 10% or greater, corrected for body surface area. Results remained significant after adjusting for age, education, salt consumption, and resting BP, and the pattern of findings was maintained among men with no previous history of cardiovascular disease. CONCLUSIONS: The tendency to show exaggerated pressor responses to psychological demands may be a significant independent correlate of LV mass, especially among young men with high resting pressures. This is the first study to examine such associations in a middle-aged population sample.

Adult↗

PubMed2000

Dissociation of response conflict, attentional selection, and expectancy with functional magnetic resonance imaging.

Two different attentional networks have been associated with visuospatial attention and conflict resolution. In most situations either one of the two networks is active or both are increased in activity together. By using functional magnetic resonance imaging and a flanker task, we show conditions in which one network (anterior attention system) is increased in activity whereas the other (visuospatial attention system) is reduced, showing that attentional conflict and selection are separate aspects of attention. Further, we distinguish between neural systems involved in different forms of conflict. Specifically, we dissociate patterns of activity in the basal ganglia and insula cortex during simple violations in expectancies (i.e., sudden changes in the frequency of an event) from patterns of activity in the anterior attention system specifically correlated with response conflict as evidenced by longer response latencies and more errors. These data provide a systems-level approach in understanding integrated attentional networks.

Adult↗

PubMed2000

Wisconsin Card Sorting in adolescents: analysis of performance, response times and heart rate.

Forty-nine adolescents performed the Wisconsin Card Sorting Test (WCST). A main PCA component of WCST performance was identified as 'efficiency of reasoning'. This factor was related to feedback processing. From the WCST, a perseveration score can be derived. Perseveration is the continued application of a rule, after it has been disconfirmed. We compared more and less perseverating subjects in relation to stimulus-response (SR) time, feedback inspection time and cardiac acceleration and deceleration. Less perseverating subjects responded faster, and had longer and more adaptive inspection times of error feedback. We examined the switch from rule application to rule search, and the difference between correct and error responses. A transient cardiac deceleration at the initiation of rule search was interpreted as a change in supervisory attention. An error-related deceleration to negative feedback was interpreted as a disturbance of higher control processing. Previous trial feedback influenced current processing time, feedback inspection time, and the cardiac acceleration and deceleration responses.

Adolescent↗

PubMed2000

Behaviorally-evoked plasma catecholamine response and 24-hour excretion of urinary catecholamines among cardiac and vascular reactors.

Individuals differ in the cardiac and vascular processes that underlie blood pressure elevations evoked by environmental stimuli; such differences may reflect variability in sympathoadrenal response. We separated 108 healthy, young-adult males into those with predominant elevations in either cardiac output or peripheral resistance when exposed to psychological challenges. We then asked if they differed on other measures of cardiovascular response, concomitant plasma catecholamine reactions or 24-h urinary excretion of catecholamines. Cardiac reactors, relative to vascular reactors, showed reduced cardiac pre-ejection period, a smaller reduction in stroke volume, and elevated plasma epinephrine response and 24-h urinary epinephrine excretion. Vascular reactors, relative to cardiac reactors, responded to mental stress with more elevated diastolic blood pressure, a rise in peripheral resistance and pulse wave velocity, and a greater reduction in stroke volume. Vascular reactors, however, did not show plasma norepinephrine response or 24-h urinary norepinephrine excretion that was greater than cardiac reactors. The results provide partial support for the hypothesis that variability in sympathoadrenal activity contributes to individual differences in cardiac and vascular reactivity, and extend prior observations by demonstrating covariation of behaviorally-elicited cardiac reactivity with the 24-h excretion of epinephrine.

Adolescent↗

PubMed2000

Developmental change in auditory selective attention as reflected by phasic heart rate changes.

Heart rate was recorded from five different groups of children (ages 7, 10, 12, 14, and 20 years) while they were performing an auditory selective attention task. The participants were instructed to count rare tone pips embedded in a series of standard tone pips presented at one (attended) ear while ignoring rare and standard stimuli presented at the other (unattended) ear. A pattern of anticipatory heart rate deceleration followed by acceleration was associated with rare tone pips at the attended ear but not with rare tone pips that should be ignored. The absence of differential sensitivity of heart rate responses to rare tone pips presented at the unattended ear was observed for all age groups. These findings were interpreted to suggest that the ability to ignore irrelevant target stimuli has reached mature levels during middle childhood. The depth of anticipatory deceleration increased until age 14, suggesting that the ability to maintain attentional set continues to develop beyond childhood.

Acoustic Stimulation↗

PubMed2000

Selective inhibition is indexed by heart rate slowing.

This study examined the hypothesis that global and selective inhibition are mediated by distinct mechanisms: respectively, a peripheral mechanism, indexed by heart rate slowing, and a central mechanism, indexed by cortical but not autonomic measures. Three varieties of a Go-NoGo task were presented in which the Go signal required an index finger response rapidly followed by a middle finger response. The NoGo signal required the inhibition of (a) both responses (global inhibition), (b) the middle finger response (simple selective inhibition), or (c) the index finger response of one hand and the middle finger response of the other hand (complex selective inhibition). As anticipated, global inhibition was indexed by heart rate slowing. Most importantly, heart rate slowing was also elicited by selective inhibition and was more pronounced for complex than simple selective inhibition. These findings suggest that global and selective inhibition are mediated by one rather than two mechanisms and that heart rate is sensitive to the demands placed on this inhibition mechanism.

Adolescent↗

PubMed2000

Evaluation of treatment efficacy of Raynaud phenomenon by digital blood pressure response to cooling. Raynaud's Treatment Study Investigators.

Our previous studies have suggested that digital blood pressure response to cooling could provide a measure of the efficacy of treatments that are administered to patients with Raynaud phenomenon (RP). This method was used on 158 primary RP patients participating in a multicenter, randomized clinical trial that compared the efficacy of sustained-release nifedipine with temperature biofeedback in the treatment of RP. A pill placebo and electromyography served as controls. The response to local finger cooling was measured at 30 degrees, 20 degrees, 15 degrees and 10 degrees C in a temperature-controlled room under standardized conditions. The results showed that, at the 15 degrees C and 10 degrees C local cooling temperatures, the patients in the nifedipine group had a higher mean digital systolic blood pressure, a higher relative digital systolic blood pressure (RDSP), a smaller proportion of subjects with RDSP < 70% and a smaller proportion of subjects with a zero reopening pressure than the patients in the three other treatment groups. These results were statistically significant at 10 degrees C, the nifedipine group being significantly different from all others (p < 0.05); no significant difference was found between the three other treatment groups.

Blood Pressure↗

PubMed1999

A thermal vascular test for distinguishing between patients with Raynaud's phenomenon and healthy controls. Raynaud's Treatment Study Investigators.

This study tested the reliability and validity of a diagnostic thermal vascular test (TVT) for patients with Raynaud's Phenomenon (RP). The TVT examined digital blood pressure responses to combined cooling and occlusion and was developed as part of the Raynaud's Treatment Study, a multicenter clinical trial comparing the efficacy of biofeedback and pharmacological treatment. A computerized system permitted efficient, accurate, and uniform testing at different geographical sites. A comparison of 199 patients with RP and 52 healthy controls is reported. The TVT showed a sensitivity of 79% and a specificity of 88%. Test-retest reliability was acceptable (r = .80). Addition of a psychological challenge failed to improve the discrimination between patients with RP and controls. The TVT separated patients with RP and controls as well as or better than existing tests and did so with enhanced ease of operation.

Diagnosis, Differential↗

PubMed1998

Postural control, attention and sleep deprivation.

We investigated the effect of sleep deprivation on postural control during a simple reaction time task (SRT), during a task requiring the intermittent inhibition of a reaction (IRT), and in the absence of a concurrent information processing task. Postural sway, i.e. changes in center of pressure on a force platform, was recorded in three increasingly difficult standing conditions (fixed platform, sway-referenced platform and sway-referenced platform with sway-referenced visual scene) during the three information-processing task conditions. Five healthy subjects performed the tasks either after normal sleep or following 24 h of sustained wakefulness. As hypothesized, sleep deprivation significantly increased postural sway only in the IRT condition. Within the IRT condition, sleep deprivation significantly increased sway across all postural conditions.

Adult↗

PubMed1998

Changes in heart beat timing: reactivity, resetting, or perturbation?

A widely held hypothesis within behavioral medicine is that cardiovascular reactivity is a risk factor for cardiovascular disease. The measurement model for this cardiovascular reactivity is rather simple. A basal level of function is seen to increase while the organism is stressed and then return to basal function. We argue that this model is incomplete and that other forms of 'reactivity' may be relevant to pathophysiology. A pathophysiological hypothesis is discussed which assumes a cyclic heart beat generation mechanism that is sensitive to stimulation only at certain phases of its cycle. Implications of this hypothesis for measurement are developed to illustrate the point that models of normal function can determine the measures most relevant to pathophysiology.

Arousal↗

PubMed1998

Cerebral blood flow in hypertensive patients: an initial report of reduced and compensatory blood flow responses during performance of two cognitive tasks.

We asked whether the altered cerebral vasculature associated with essential hypertension might dampen or redirect the regional cerebral blood flow (rCBF) response to cognitive work. Relative rCBF was assessed with [(15)O]water positron emission tomography during a working memory task, a memory span task, and two perceptual control tasks. Unmedicated hypertensive patients and control subjects differed in rCBF response during both memory tasks. Hypertensives showed relatively diminished rCBF responses in right hemisphere areas combined with compensatory activation of homologous areas in the left cerebral cortex. Essential hypertension appears to selectively influence the circulatory reserve of portions of cerebral cortex and secondarily induce recruitment of other cortical areas to process certain tasks.

Aged↗

PubMed1998

Preparing the heart, eye, and brain: foreperiod length effects in a nonaging paradigm.

Psychophysiological "preparatory" responses may or may not depend on a focused expectation of when a stimulus will occur. Changes in heart rate, pupillary diameter, and brain potentials were examined during trials in which foreperiod of a simple reaction time (RT) task was fixed or unpredictable. Trials were also included in which stimuli for the speeded motor reaction were triggered by psychophysiological changes occurring spontaneously in the foreperiod. Thirty-two college-aged volunteers equally divided by gender participated in the experiment. Reducing expectancy, by using nonaging foreperiods, eliminated transient prestimulus psychophysiological responses but failed to eliminate slow changes over the foreperiod--slowing of heart rate, dilation of the pupil, and cortical surface negativity. Triggering the reaction stimulus by physiological changes did not influence RT. Correlations between psychophysiological changes in the foreperiod and between these changes and RT were generally low. The results were consistent with a multiprocess view of preparation.

Adult↗

PubMed1997

Exaggerated blood pressure responses during mental stress are associated with enhanced carotid atherosclerosis in middle-aged Finnish men: findings from the Kuopio Ischemic Heart Disease Study.

BACKGROUND: Exaggerated cardiovascular reactivity to mental stress is hypothesized to increase atherosclerotic risk. We examined this hypothesis using cross-sectional data from the Kuopio Ischemic Heart Disease study, a population-based epidemiological sample. METHODS AND RESULTS: 901 Eastern Finnish men from four age cohorts (age, 42 to 60 years) were administered a standardized testing battery to assess cardiovascular reactivity to mental stress. Ultrasound measures of intima-medial thickness (IMT) and plaque height from the common carotid arteries were used as noninvasive markers of atherosclerosis. Diastolic blood pressure (DBP) responses to mental stress were significantly associated with mean IMT (b=.021, P=.006), maximum IMT (b=.026, P=.013), and mean plaque height (b=.017, P=.041). Significant associations were also shown between stress-related systolic blood pressure (SBP) reactivity and mean IMT (b=.0151, P=.042). When examined separately by age, associations with IMT were significant only in the youngest half of the sample (age, 46 and 52 years, n=433; for mean IMT, DBP b=.033, P=.0002, SBP b=.0266, P=.003; for maximum IMT, DBP b=.039, P=.002, SBP b=.032, P=.011). Results remained significant in the younger subjects after adjustment for smoking, lipid profiles, fasting glucose, and resting blood pressure (b=.024, P=.011); results also remained significant in a subgroup of unmedicated younger subjects without symptomatic cardiovascular disease (n=135; for SBP reactivity, b=.031, P=.036; for DBP, b=.037, P=.007). CONCLUSIONS: The tendency to show exaggerated pressor responses to mental stress is a significant independent correlate of atherosclerosis in this population sample of Finnish men. The effect does not appear to be accounted for by the confounding influence of other risk factors or preexisting clinical disease.

Adult↗

PubMed1997

Mnemonic search, but not arithmetic transformation, is associated with psychophysiological inhibition.

The possibility that mnemonic search and arithmetic transformation induce transient heart rate (HR) slowing was studied. Transient HR slowing was assumed to result from the inhibition of premature responding during information processing. Twenty young men performed a 2-step reaction time task. Two precues were followed by a choice cue: 2 additional precues and 1 final choice cue. Choice cues were varied to compare spatial and perceptual-motor processing with mnemonic or arithmetic processing. Cardiac interbeat interval and impedance cardiograph measures were taken beat by beat. The preparation for the respond cue was associated with HR slowing followed by HR speeding associated with response initiation. Mnemonic search induced a transient HR slowing before the speeding initiated by the motor response. Arithmetic transformation did not, but processing of the arithmetic series decreased cue-induced transient HR slowing. Mnemonic search may be associated with a psychophysiological inhibition analagous to that observed in perceptual-motor tasks during response selection.

Adolescent↗

PubMed1997

Aging or disease? Cardiovascular reactivity in Finnish men over the middle years.

Cardiovascular responses to psychological events may mediate the influence of stress on cardiovascular disease. In this study the authors asked whether cardiovascular responses to psychological challenge changed with age and whether such changes were intrinsic to aging or could be attributed to the influence of disease and medications. Cardiovascular reactivity to mental challenge was examined in 902 men ranging in age from 46 to 64 years who participated in the Kuopio Ischemic Heart Disease Risk Factor Study. A battery of 4 tasks was used to induce cardiovascular responses. Current disease status, age, and medication use were entered into hierarchical regression analyses to assess their relation with measures of cardiovascular reactivity. Age and hypertension contributed independent, approximately equal, but small amounts of variance in the cardiac and vascular reactivity indexes. Medications also influenced reactivity independently of age and disease. Performance on the tasks was more consistently altered by age than by disease or medication. Cardiac and vascular reactivity increased with increasing age and the presence of hypertension. The authors conclude that both age and disease state must be considered when examining cardiovascular reactivity as a risk factor for disease.

Aging↗

PubMed1997

Psychological stress and the progression of carotid artery disease.

BACKGROUND: We examined the relation between cardiovascular reactivity (the response of the cardiovascular system to psychological stress) and the severity and progression of carotid atherosclerosis. METHODS: Using duplex ultrasonography, we measured the change in the area of all detectable plaques in the extracranial carotid arteries during 2 years. Cardiovascular reactivity was assessed by measuring changes in hemodynamics during a frustrating cognitive task (the Stroop Color Word Interference Task). Established risk factors for atherosclerosis were measured by interviewing patients, a physical examination, and blood assays for 351 subjects with a wide range of types of atherosclerotic disease. RESULTS: Atherosclerotic plaques were present in the carotid arteries of 273 (78%) subjects. In a forward stepwise multiple regression analysis, it was found that greater age (beta = 0.46), a history of hypertension (beta = 0.20), use of lipid level-lowering agents (beta = 0.18), a longer history of smoking (beta = 0.13), a larger cholesterol:high-density lipoprotein ratio (beta = 0.13), a smaller change in heart rate during the task (beta = -0.12), and a higher resting systolic blood pressure (SBP; beta = 0.11) were associated significantly with a greater plaque area (R2 = 0.35). In 136 untreated subjects who were followed up for 2 years, a greater change in SBP during the task (beta = 0.28), a higher total cholesterol: high-density lipoprotein ratio (beta = 0.23), a shorter resting preejection period (beta = -0.19), and a lower body mass index (beta = -0.17) were significant predictors of the change in atherosclerosis, after controlling for age and initial plaque area in a stepwise multiple regression analysis (R2 = 0.24). CONCLUSIONS: These results support the hypothesis that hemodynamic responses under conditions of mental stress may influence the progression of atherosclerosis.

Adult↗

PubMed1996

Hypertension and neuropsychological performance in men: interactive effects of age.

Potentially interactive effects of hypertension and age on the performance of neuropsychological and information processing tests were examined in 123 untreated hypertensive and 50 normotensive men. After covarying education, average alcohol consumption, trait anxiety, and depression scores, results indicated an interaction of age and hypertension. Young hypertensive men (23-40 years) scored significantly worse than young normotensive men on tests of attention/executive function and working memory; middle-aged hypertensive (41-56 years) and normotensive participants were not distinguished by any measures. Hypertensive men performed significantly more poorly than normotensive men on tests of manual dexterity. Results suggest that neuropsychological sequelae of hypertension are more pronounced in young than in middle-aged hypertensive individuals and are independent of various demographic, psychosocial, and alcohol-related factors.

Adult↗