bluuebunny/crossref_metadata_2025_split huggingface dataset:
Individual Differences in Stages 3 and 4 Sleep
Authors: Bliwise Donald L. , Bergmann Bernard M. 
Published: February 2007

ABSTRACTIndividual differences in stages 3 and 4 sleep are usually unrecognized., although several reports have mentioned large inter‐individual variation of the stages within a restricted age range. This study investigated individual differences and nightly reliability in stages 3 and 4 sleep in a homogeneous sample of 34 young adult males. Sleep was analyzed from the final two of three consecutive lab nights. Results indicated that stage 4 steep was an exceedingly prominent individual difference. Stage 4 occupied 7.9 to 50.0 percent of the first 3 hrs after sleep onset and was highly reliable across nights (.78). Individual differences were less pronounced in the second 3 hrs after sleep onset. Stage 3 and stage 4 were reliably distinguished. Persons high in one of these stages had relatively little of the other. Combining stage 3 and stage 4 may be a reasonable strategy if visually scored delta activity per se is of interest, bat it may obscure potentially meaningful individual differences in which state is characteristically achieved.
Comparison of Discrete Cardiovascular Fitness Groups on Plasma Catecholamine and Selected Behavioral Responses to Psychological Stress
Authors: Sothmann Mark S. , Horn Thelma S. , Hart Barbara A. , Gustafson Anthony B. 
Published: February 2007

ABSTRACTDiscrete cardiovascular fitness groups consisting of high‐fit (n=10) and low‐fit (n=9) men performed a well‐learned vigilance task and their self‐report, performance, and plasma catecholamine responses were compared. No significant differences were observed between the fitness groups on self‐report or psychomotor performance responses to the vigilance task. However, the low‐fit group took significantly longer than high‐fit subjects to complete the first of three sets of anagrams administered immediately after the vigilance task. Plasma norepinephrine but not epinephrine response was greater in the low‐fit group compared to their high‐fit counterparts. The findings indicate that enhanced cardiovascular fitness may be characterized by an attenuated plasma norepinephrine response to a vigilance task with sustained cognitive performance subsequent to the task.
Heart Rate and Oxygen Consumption during Mental Arithmetic, a Video Game, and Graded Static Exercise
Authors: Carroll Douglas , Turner J. Rick , Rogers Stephen 
Published: February 2007

ABSTRACTHeart rate, oxygen consumption, and respiratory activity were recorded while 18 young male subjects performed a stressful mental arithmetic task and played a video game. Measurements were also taken while subjects undertook a graded static leg lifting exercise. Physiological activity increased as an orderly function of exercise workload. For each subject, heart rate was plotted against oxygen consumption over the various exercise loads. Knowing oxygen consumption during the psychological tasks, these regression equations allowed the prediction of heart rate, and thus the computation of “additional” heart rate as the difference between actual and predicted heart rate. Overall predicted heart rate values were significantly less than the values actually recorded during the psychological tasks. However, whereas mental arithmetic was associated with “additional” heart rates of the same order as those observed in earlier research using graded dynamic exercise, the video game elicited decidedly less “additional” heart rate in the present case. The explanation for this lay in the regression lines; static exercise was characterized by heart rate‐oxygen consumption regressions which were much steeper in terms of slope, as well as somewhat lower in terms of intercept, than those observed with graded dynamic exercise.
Baroreceptor Stimulation Alters Pain Sensation Depending on Tonic Blood Pressure
Authors: Elbert Thomas , Rockstroh Brigitte , Lutzenberger Werner , Kessler Manfred , Pietrowsky Reinhard , Birbaumer Niels 
Published: February 2007

ABSTRACTIt has been hypothesized that activation of the baroreceptor reflex arc, by its central nervous inhibitory effects, is involved in an operant learning mechanism of blood pressure elevation. The present study investigated the effects of mechanical stimulation of the baroreceptors in the carotid sinus on pain threshold and electrical brain activity in two groups of humans with different tonic blood pressure levels. In normotensives, baroreceptor stimulation lowered pain threshold as compared to a control condition, while borderline hypertensives tolerated more intense electric stimulation when baroreceptors were activated. A marked reduction of the contingent negative variation in anticipation of the aversive stimulation accompanied baroreceptor stimulation, probably a consequence of baroreceptor afferent impulses exerted via brainstem centers to cerebral cortex. The distribution of the potential change across the scalp depended on the tonic blood pressure, indicating differences in brain functioning between normotensives and borderline hypertensives.The present results suggest that the hypothesis of an operantly‐conditioned blood pressure elevation under stress may be valid only in subjects with a predisposition for essential hypertension.
The Effects of Task on the Modulation of Event‐Related Potentials by Word Repetition
Authors: Rugg Michael D. , Furda Jur , Lorist Monicque 
Published: February 2007

ABSTRACTEvent‐related potentials were recorded while subjects viewed 3 series of visually presented words. In each series some of the words were repetitions of an immediately preceding word. The subjects' task was to respond to occasional items (‘targets’), the nature of which was varied across the 3 series. Targets were either lower‐case words, non‐words, or animal names. When the targets were non‐words or animal names, event‐related potentials to repeated items were characterised by a large, Cz‐maximum, positive‐going shift with an onset latency of around 300 ms. When the targets were lower‐case items, this repetition effect was greatly attenuated, due primarily to an increase in positivity in ERPs to unrepeated items.It is concluded firstly that the modulation of event‐related potentials by word repetition is task‐dependent. Secondly, the repetition effect seems better interpreted as an attenuation of an endogenous negativity present in ERPs to unrepeated items, than as a positive‐going component elicited by repeats.
Facts and Artifacts in Cardiac Cycle Time Analysis: A Simple Model of Vagal Control
Authors: Somsen Riek J.M. , Jennings J. Richard , van der Molen Maurits W. 
Published: February 2007

ABSTRACTCardiac cycle time effects occur when stimuli or responses presented at different times within the cardiac cycle induce differential changes in the same or following interbeat interval (IBI). Two related problems regarding cardiac cycle time effects are discussed. One problem concerns how to separate anticipatory from stimulus‐induced changes in interbeat intervals that occur around the time of presentation of an expected stimulus. The other problem is an anomalous finding in reaction time tasks: prestimulus interbeat intervals are longer when they precede stimuli presented early, rather than late, in the cardiac cycle.These two problems can be understood if some simple assumptions are made about anticipatory and stimulus‐induced vagal excitation. If vagal excitation regularly increases prior to an expected event, the anomalous effect of stimulus delay in the cardiac cycle on preceding interbeat intervals can be explained. The presentation of events and IBI times on an ordinal IBI axis induces an inappropriate time shift. Furthermore, estimates of maximal anticipatory deceleration at stimulus onset in the interbeat interval of the stimulus and of subsequent stimulus‐induced vagal changes can be inferred. The relevance of this analysis to earlier experimental results is discussed.
Cardiac and Metabolic Activity in Mild Hypertensive and Normotensive Subjects
Authors: Sims Jane , Carroll Douglas , Turner J. Rick , Hewitt John K. 
Published: February 2007

ABSTRACTHeart rate, respiration, and metabolic activity were monitored at rest and during the mental challenge of a video game in 22 mild hypertensive and 53 normotensive young men. Subjects also completed the Eysenck Personality Questionnaire and the Jenkins Activity Survey. The mild hypertensive subjects displayed higher resting heart rates than the normotensives and larger magnitude heart rate increases to the video game. Although groups did not differ in resting respiratory activity, the metabolic rates tended to be higher in the mild hypertensives and they showed reliably greater increases in oxygen consumption and carbon dioxide production during mental challenge. These data were subjected to a variety of interpretations. However, in the absence of psychophysiological assessment during physical exertion, and without direct measurement of cardiao output and arteriovenous oxygen differences, the present results did not permit a choice to be made between rival explanations, and they certainly cannot discount the hypothesis that some borderline hypertensives display excessive cardiac activity and tissue overperfusion during stress. The personality measures did not differentiate groups. However, correlational analyses within each group revealed that whereas systolic blood pressure was positively and significantly related to neuroticism in the mild hypertensive group, for the normotensive subjects the direction of correlation was reversed. In addition, scores on the Jenkins Activity Survey correlated positively with heart rate reactivity to the video game for the mild hypertensives, but not for the normotensives.
Event‐Related Potentials to Time‐Deviant and Pitch‐Deviant Tones
Authors: Nordby Helge , Roth Walton T. , Pfefferbaum Adolf 
Published: February 2007

ABSTRACTTwelve subjects were run in a paradigm designed to compare event‐related brain potentials (ERPs) elicited by infrequent pitch‐deviant and time‐deviant tones under different attentional conditions. Tones with a pitch of 500 Hz or 1000 Hz were presented at regular interstimulus intervals of 800 ms. Changes in pitch or a shortening of interstimulus interval to 400 ms each occurred with 10% probability. Three different tasks (reading or reaction time to pitch or to timing deviances) were assigned on separate runs.N150 to deviant tones was not influenced by task. Its amplitude, peak latency, and frontally maximum distribution did not differ between pitch and timing deviance, but to pitch deviance it had an earlier onset. P350 amplitude to both types of deviant tones was larger than to standard tones when subjects pressed to time‐deviant tones; only P350 to pitch‐deviant tones was larger than to standards when subjects pressed to pitch‐deviant tones. P350 latency was longer to timing deviance regardless of task.Our results support the view that negativities generated by mismatches in expected timing and pitch are qualitatively the same. ERP differences between these two types of deviance were probably due to differences in stimulus salience or discriminability.
Effects of Methylphenidate on Stimulus Evaluation and Response Processes: Evidence from Performance and Event‐Related Potentials
Authors: Fitzpatrick Patricia , Klorman Rafael , Brumaghim Joan T. , Keefover Robert W. 
Published: February 2007

ABSTRACTThis study investigated the effects of methylphenidate in a memory scanning task with two levels of high cognitive load (memory set sizes 2 and 4 presented in displays of size 4) and two response requirements (simple mapping or rotation). Twenty young adults were tested under placebo and methylphenidate (0.3 mg/Kg) in a double‐blind protocol. As expected, memory load increased misses, false alarms, confusions, and failures to respond by the deadline. In turn, the rotation requirement increased confusions and nonresponses. Reaction time (RT) was slowed by both factors. P3b latency also was increased by memory load and, to some extent, by the rotation requirement. These results are consistent with the proposition that P3b latency reflects largely evaluation, rather than response processes.Misses and reaction time were decreased in response to targets presented in the center vs. the periphery of the display. Confusions, however, showed the opposite trend. The display position did not affect P3b latency. These results can be explained by assuming that the subject was focusing on the center of the display and that accuracy diminished when stimuli were presented toward the periphery of the display.The stimulant challenge speeded up reaction times overall and specifically reduced the slowing effect of rotation. However, P3b latency was not affected by methylphenidate, so that the speeding of reaction time by the stimulant can be attributed to post‐evaluation processes.
The Effect of Body Composition and Gender on Cardiac Awareness
Authors: Rouse Connie H. , Jones Gary E. , Jones Kenneth R. 
Published: February 2007

ABSTRACTThis experiment investigates the previously reported relationship between body composition and cardiac awareness. Four groups, containing 20 subjects each, were formed using estimates of percent body fat (%BF) obtained using skinfold measures. The four groups were lean males, non‐lean males, lean females, and non‐lean females. “Lean” was defined as 15%BF or below in young males, 17%BF or below in older males, 21%BF or below in young females, and 23%BF or below in older females. Subjects were tested while seated in a recliner chair using 50 Whitehead‐type discrimination trials. Subjects were asked to discriminate true from false feedback provided in 10‐s trials. True feedback was defined as a .1‐s light flash occurring 128 ms following each R‐spike, and false feedback was defined as a flash occurring 384 ms after the R‐spike. Heart period and respiration were recorded continuously. A 2(Genders) × 2(Body Composition Groups: Lean, Non‐lean) ANOVA of discrimination scores revealed a main effect for body composition (p<.0001), but no gender main or interaction effects. One‐group t‐tests revealed that the lean male and female groups both demonstrated discrimination at greater than chance level, but the non‐lean groups did not. The implications of these results are discussed in the context of the previously reported gender effect, and their possible contribution in understanding the mechanisms and mediation of cardiac awareness.
The Startle Response to Acoustic Stimuli Near Startle Threshold: Effects of Stimulus Rise and Fall Time, Duration, and Intensity
Authors: Blumenthal Terry D. 
Published: February 2007

ABSTRACTThe present study assessed the interaction of several stimulus parameters in the elicitation of the startle response in humans. Broadband noise stimuli with intensities of 80 and 85 dB(A) and durations of 30 and 50 ms were presented to four groups of 15 college undergraduates. Within subjects, stimulus rise and fall times of 2.5, 10, and 25 ms were presented in a 3 × 3 factorial design. Amplitude, probability, and latency of integrated EMG activity from orbicularis oculi (eyeblink) were assessed. As stimulus rise time increased, response amplitude and probability decreased, and response latency increased, for both durations and both intensities tested. A main effect of stimulus duration on response probability was found, with higher probability for 50‐ms than for 30‐ms stimuli. In conjunction with previous research which found no effect of stimulus rise time on startle responding with more intense stimuli, these results suggest that startle response elicitation is determined by an interaction of stimulus parameters, with manipulation of some parameters being more effective at certain levels of other parameters.
Comparing Repeated Measures Means in Factorial Designs
Authors: Keselman H.J. , Keselman Joanne C. 
Published: February 2007

ABSTRACTThe effects of violating multisample sphericity were investigated for multiple comparison procedures for pairwise contrasts in nonorthogonal split‐plot repeated measures designs. Results indicated that rates of Type I error of the multiple comparison procedures are affected not only by assumption violations but also by the type of nonorthogonal solution. Specifically, if one intends to test contrasts of unweighted means, as would be the case when the unequal group sizes are due to random loss, then all multiple comparison procedures investigated, including the previously recommended Bonferroni procedure, are prone to excessive rates of Type I errors. A satisfactory solution to this bias is to obtain additional data in order to achieve equal group sizes and hence an orthogonal design. For tests of contrasts of weighted repeated measures means, which would be of interest when the unequal group sizes are representative of population group sizes, the Bonferroni approach to Type I error control is satisfactory. In most instances, a Bonferroni critical value will provide a more powerful test than a multivariate critical value.
Modern Mind‐Brain Reading: Psychophysiology, Physiology, and Cognition
Authors: Coles Michael G. H. 
Published: February 2007

ABSTRACTThis paper reviews the actual and potential benefits of a marriage between cognitive psychology and psychophysiology. Psychophysiological measures, particularly those of the event‐related brain potential, can be used as markers for psychological events and physiological events. Thus, they can serve as “windows’ on the mind and as “windows’ on the brain. These ideas are illustrated in the context of a series of studies utilizing the lateralized readiness potential, a measure of electrical brain activity that is related to preparation for movement. This measure has been used to illuminate presetting processes that prepare the motor system for action, to demonstrate the presence of the transmission of partial information in the cognitive system, and to identify processes responsible for the inhibition of responses. The lateralized readiness potential appears to reflect activity in motor areas of cortex. Thus, this measure, along with other psychophysiological measures, can be used to understand how the functions of the mind are implemented in the brain potential.
The Timing of Bedtime and Waketime Decisions in Free‐Running Subjects
Authors: Monk Timothy H. , Moline Margaret L. 
Published: February 2007

ABSTRACTTwelve “free‐running’ temporal isolation studies were performed using healthy human subjects aged 20–81 years (4 males, 8 females). Circadian rhythms were measured in subjective alertness (using a visual analogue scale technique) and rectal temperature. In all 12 subjects best fitting rhythm periods were found to be shorter for rectal temperature (mean = 24.3 hours) than for subjective alertness (mean = 24.8 hours). Both rhythms were predictive of bedtime and waketime decisions. Bedtime decisions tended to cluster on the falling arm of the temperature and alertness cycles (modal times = 120 degrees (temperature) and 140 degrees (alertness) after acrophase); waketime decisions on the rising arm (modal times = 240 degrees (temperature) and 300 degrees (alertness) after acrophase). When this pattern was violated, sleep episodes were significantly more variable in length and disturbed by intruding wakefulness.
Quantitative Measurements of Finger Blood Flow During Behavioral Treatments for Raynaud's Disease
Authors: Freedman Robert R. 
Published: February 2007

ABSTRACTQuantitative measurements of finger blood flow have not been performed during temperature biofeedback or other treatments for Raynaud's disease. In the present investigation, finger blood flow was determined with venous occlusion plethysmography, in addition to measurements of finger temperature, heart rate, blood pressure, and skin conductance level. After a maximum vasodilation test, subjects received 10 sessions of finger temperature biofeedback or autogenic training. There were no group differences during the maximum vasodilation test. During training, temperature feedback subjects showed significant elevations in finger blood flow, finger temperature, and skin conductance level, whereas those who received autogenic training did not. These findings could not be explained by group differences in other cardiovascular measures and are consistent with previous studies suggesting the involvement of an active vasodilating mechanism in temperature feedback.
Brain Potentials During Selective Attention, Memory Search, and Mental Rotation
Authors: Wijers Albertus A. , Otten Leun J. , Feenstra Steven , Mulder Gijsbertus , Mulder Lambertus J.M. 
Published: February 2007

ABSTRACTEvent‐related potentials were measured in a task that combined the classic selective attention paradigm with memory search and mental rotation paradigms. Subjects were required to attend to stimulus letters in one color and to ignore stimuli in a different color. Within the attended category subjects searched for target letters from a prememorized set (the memory set) and indicated whether they were presented normally or in mirror‐image. Letters in all stimulus categories were presented randomly in either their upright position or rotated over 60°, 120°, or 180°.The event‐related potentials showed that the earliest effect of attending to color was a positivity at the anterior electrodes and a negativity at Oz (onset about 150 ms), followed by the enhancement of a central N2 component (N2b, onset about 220 ms). The early effect is thought to reflect selective processing of elementary stimulus features, the later N2b the covert orienting of attention. A later, prolonged central negativity elicited by attended stimuli covaried with the duration of the memory search process. Target detection resulted in a parietal P3b component, and also in an earlier negativity (in the range approximately 200–300 ms) to both attended and unattended targets, suggesting an early preattentive target classification. There were two effects of the rotation of stimuli. First there was an early occipital effect (about 200–300 ms), irrespective of attention and stimulus categories. It was argued that this effect reflected the preattentive identification of the orientation of the stimulus letters. A later (onset about 350–400 ms) parietal effect consisted of an increase in negativity as a function of the angle over which letters were rotated. This prolonged negativity had a later onset latency than the search‐related negativity, and was restricted to the event‐related potentials to target letters in the attended input channel. It was suggested that this component is the manifestation of a mental rotation process. It was argued that rotation‐related negativity and memory search‐related activity reflect operations in distinct working memory subsystems.