bluuebunny/crossref_metadata_2025 huggingface dataset:
Early morning driver sleepiness: Effectiveness of 200 mg caffeine
Authors: Reyner Louise A. , Horne James A.
Published: December 2004

Sleep‐related vehicle accidents are prevalent early morning, especially in younger drivers. In two independent studies following a night of either restricted or nil sleep, young experienced drivers drove for 2 hr (0600–0800h) continuously in an immobile car on an interactive, computer‐generated, dull, and monotonous roadway. This exercise followed ingestion (at 0530h) of 200 mg caffeine (= 2–3 cups coffee) versus placebo, counterbalanced, double blind. Driving incidents (lane drifting), subjective sleepiness, and 4–11 Hz electroencephalogram (EEG) activity were logged. In Study 1 (sleeping 0000–0500h), caffeine significantly reduced incidents and subjective sleepiness throughout the 2‐hr drive, and EEG power for the second 30‐min period. In Study 2 (no sleep), sleepiness affected all measures profoundly, and driving was terminated after 1 hr. Nevertheless, caffeine reduced incidents significantly for the first 30 min and subjective sleepiness for the hour. This caffeine dose, feasibly taken via coffee, effectively reduces early morning driver sleepiness for about 30 min following nil sleep, and for around 2 hr after sleep restriction.
Affective picture processing: The late positive potential is modulated by motivational relevance
Authors: Schupp Harald T. , Cuthbert Bruce N. , Bradley Margaret M. , Cacioppo John T. , Ito Tiffany , Lang Peter J.
Published: December 2004

Recent studies have shown that the late positive component of the event‐related‐potential (ERP) is enhanced for emotional pictures, presented in an oddball paradigm, evaluated as distant from an established affective context. In other research, with context‐free, random presentation, affectively intense pictures (pleasant and unpleasant) prompted similar enhanced ERP late positivity (compared with the neutral picture response). In an effort to reconcile interpretations of the late positive potential (LPP), ERPs to randomly ordered pictures were assessed, but using the faster presentation rate, brief exposure (1.5 s), and distinct sequences of six pictures, as in studies using an oddball based on evaluative distance. Again, results showed larger LPPs to pleasant and unpleasant pictures, compared with neutral pictures. Furthermore, affective pictures of high arousal elicited larger LPPs than less affectively intense pictures. The data support the view that late positivity to affective pictures is modulated both by their intrinsic motivational significance and the evaluative context of picture presentation.
Basic auditory dysfunction in dyslexia as demonstrated by brain activity measurements
Authors: Kujala Teija , Myllyviita Katja , Tervaniemi Mari , Alho Kimmo , Kallio Jari , Näätänen Risto
Published: December 2004

Although the generality of dyslexia and its devastating effects on the individual's life are widely acknowledged, its precursors and associated neural mechanisms are poorly understood. One of the two major competing views maintains that dyslexia is based primarily on a deficit in linguistic processing, whereas the other view suggests a more general processing deficit, one involving the perception of temporal information. Here we present evidence in favor of the latter view by showing that the neural discrimination of temporal information within complex tone patterns fails in dyslexic adults. This failure can be traced to early cortical mechanisms that process auditory information independently of attention.
Phasic heart period reactions to cued threat and nonthreat stimuli in generalized anxiety disorder
Authors: Thayer Julian F. , Friedman Bruce H. , Borkovec Thomas D. , Johnsen Bjorn H. , Molina Silvia
Published: December 2004

The hallmark of generalized anxiety disorder (GAD) is chronic uncontrollable worry. A preattentive bias toward threat cues and hypervigilance may support this ongoing state of apprehension. A study was conducted to bridge the attentional and physiological underpinnings of GAD by examining phasic heart period (HP) responses to cued threat and nonthreat stimuli. Thirty‐three GAD clients and 33 nonanxious control participants engaged in an S1‐S2 procedure that employed cued threat and nonthreat word stimuli, during which phasic HP reactions were recorded. As compared with the control group, the GAD group showed (1) smaller cardiac orienting responses and impaired habituation of cardiac orienting to neutral words, (2) HR acceleration in response to threat words, and (3) a conditioned anticipatory HR deceleration to threat words over repeated trials. The cardiac‐autonomic underpinnings of GAD appear to rigidly maintain precognitive defensive responses against threat. This portrayal is discussed in the context of an integrative model that depicts diminished global adaptive variability in GAD.
Automatic and controlled attentional processes in startle eyeblink modification: Effects of habituation of the prepulse
Authors: Schell Anne M. , Wynn Jonathan K. , Dawson Michael E. , Sinaii Ninet , Niebala Chris B.
Published: December 2004

The effect of prehabituation of the prepulse on startle eyeblink modification was studied in two experiments. In Experiment 1, college student participants were either prehabituated or nonhabituated to a tone that served as a prepulse in a startle modification passive attention paradigm. Neither short lead interval (60 and 120 ms) prepulse inhibition (PPI) nor long lead interval (2,000 ms) prepulse facilitation (PPF) was affected by the prehabituation procedure. In Experiment 2, participants were presented with an active attention paradigm in which one of two tone prepulses was attended while the other was ignored. One group was prehabituated to the prepulses and the other was not. Unlike the results with the passive paradigm in Experiment 1, prehabituation did significantly diminish attentional modulation of PPI and PPF. These results are consistent with the hypothesis that passive PPI and PPF are primarily automatic processes, whereas attentional modulation involves controlled cognitive processing.
Selective slow‐wave sleep deprivation and time‐of‐night effects on cognitive performance upon awakening
Authors: Ferrara Michele , de Gennaro Luigi , Casagrande Maria , Bertini Mario
Published: December 2004

We evaluated the effects of selective slow‐wave sleep (SWS) deprivation and time‐of‐night factors on cognitive performance upon awakening. Ten normal men slept for 6 consecutive nights in the laboratory: 1 adaptation, 2 baseline, 2 selective SWS deprivation, and 1 recovery night. Cognitive performance was assessed by means of a Descending Subtraction Task after 2, 5, and 7.5 h of sleep. There was an almost complete selective SWS suppression during both deprivation nights, and a significant SWS rebound during the recovery sleep. Regarding cognitive performance, a progressive linear decrease of sleep inertia upon successive awakenings was found during all experimental nights except for the recovery night. In addition, a significant decrease of sleep inertia was observed upon the morning awakening of the second deprivation night for the measure of performance speed, and a significant increase of sleep inertia upon the morning awakening of the recovery night for the measure of performance accuracy. The results show that cognitive performance upon awakening is adversely affected by sleep depth and that, during the sleep–wake transition, cognitive performance accuracy is more impaired than performance speed.
Magnetic brain activity evoked and induced by visually presented words and nonverbal stimuli
Authors: Eulitz Carsten , Eulitz Hind , Maess Burkhard , Cohen Rudolf , Pantev Christo , Elbert Thomas
Published: December 2004

Evoked and induced magnetic brain activity measured over the left hemisphere were tested for their specificity to language‐related processing. Induced activity refers to oscillatory alterations time locked but not phase locked to the stimulus. Words, false font stimuli, and two types of nonverbal patterns were presented visually while subjects performed a nonlinguistic visual feature detection task. The comparison of evoked and induced brain activity around 200 ms after stimulus onset revealed differential sensitivity to the stimuli. The M180 component of the evoked magnetic field was larger at the processing of words and false font stimuli compared with nonverbal stimuli. The induced magnetic brain activity in the 60‐Hz band at a compatible latency range was correlated with the familiarity of the visual Gestalt. Sensitivity to language‐specific information processing can be concluded if a parameter differentiates the word condition from the nonlexical conditions. Such a difference was observed at sensors located over the frontal‐temporal scalp regions for induced but not evoked magnetic brain activity. Thus, evoked and induced magnetic brain activity revealed a differential sensitivity to elements of cognitive processing during the given task.
On the reliable assessment of cardiovascular recovery: An application of curve‐fitting techniques
Authors: Christenfeld Nicholas , Glynn Laura M. , Gerin William
Published: December 2004

The underuse of cardiovascular recovery as an adjunct to reactivity may stem from a lack of research on how to assess the process reliably. We explore the test–retest reliability of three simple, intuitive approaches to measuring recovery, and of a more sophisticated curve‐fitting technique. Eighteen young normotensive subjects experienced three stressors twice each, with 10‐min baseline, 3‐min task, and 20‐min recovery periods and continuous monitoring of heart rate and blood pressure. Reactivity showed moderate reliability, but the three simple approaches to measuring recovery revealed essentially none. However, the curve‐fitting approach, using a three‐parameter (amount, speed, and level of recovery) logistic function was reliable. This approach, capturing the inherently dynamic process of cardiovascular recovery, may allow researchers to usefully add the assessment of recovery to paradigms exploring reactivity as a risk factor for cardiovascular disease.
Relationship between P300 amplitude and subsequent recall for distinctive events: Dependence on type of distinctiveness attribute
Authors: Otten Leun J. , Donchin Emanuel
Published: December 2004

Distinctive words elicit the P300 component of the event‐related brain potential, and are also likely to be recalled. Previous studies have shown that the larger the P300 elicited by distinctive words, the more likely it is that those words will be recalled. The present study addressed whether this relationship is affected by the manner in which distinctiveness is induced. Distinctiveness was manipulated either by varying the size of the characters in which a word was displayed, or by surrounding the word with a frame at close or far distance. All distinctiveness attributes resulted in improved recall performance. The words whose size was distinctive elicited a large P300, and P300 amplitude was larger for subsequently recalled words. The frame attributes elicited a small P300, and the amplitude of these P300s was not correlated with subsequent recall performance. Instead, a frontal slow wave was correlated with subsequent recall performance in the far frame group. It is concluded that the relationship between P300 amplitude and subsequent recall depends on the type of distinctiveness attribute, and should therefore not be ascribed to a generalized effect of distinctiveness on memory encoding processes.
Valence‐dependent modulation of psychophysiological measures: Is there consistency across repeated testing?
Authors: Manber Rachel , Allen John J.B. , Burton Keith , Kaszniak Alfred W.
Published: December 2004

The present study used the picture perception paradigm to examine the extent to which three well‐documented psychophysiological measures demonstrate consistency across time in response to emotional stimuli. The three measures were the eye‐blink startle response and the activation in two facial muscle regions (zygomatic and corrugator). Twenty‐seven young women were assessed on two occasions, 2 weeks apart. Whereas activation in the corrugator and zygomatic muscle regions demonstrated the predicted patterns at both assessments (with some attenuation in the zygomatic muscle regions), the startle response had limited consistency across the two assessments. The startle response revealed the predicted linear pattern of valence modulation during the first assessment. During the second assessment, startle magnitude response was a quadratic function of valence ratings and a linear function of arousal ratings. The unexpected pattern of startle response during the second session appeared to be related to the content of the pleasant slides, with action slides generating quadratic valence modulation and erotic slides continuing to exhibit the expected linear valence modulation.
Heritability of different measures of smooth pursuit eye tracking dysfunction: A study of normal twins
Authors: Katsanis Joanna , Taylor Jeanette , Iacono William G. , Hammer Micah A.
Published: December 2004

Research studies have found that smooth pursuit eye movement dysfunction may serve as an index of genetic liability to develop schizophrenia. The heritability of various measures of smooth pursuit eye tracking proficiency and the saccades that occur during smooth pursuit was examined in 64 monozygotic (MZ) and 48 dizygotic (DZ) twin pairs. Two age cohorts were assessed (11–12 and 17–18 years of age). Intraclass correlations indicated significant similarity in the MZ twins for almost all measures in both age cohorts, whereas few of the DZ twin correlations attained significance. Biometrical modeling indicated that genetic mechanisms influence performance on both global and specific eye tracking measures, accounting for about 40% to 60% of the variance. These findings suggest that the underlying brain systems responsible for smooth pursuit and saccade generation during pursuit are under partial genetic control.
Patterns of sympathetic and parasympathetic reactivity in a sample of children and adolescents
Authors: Salomon Kristen , Matthews Karen A. , Allen Michael T.
Published: December 2004

We hypothesized that patterns of sympathetic and parasympathetic reactivity observed in adults would be apparent in a sample of children and adolescents and that these patterns would be consistent across tasks. We explored the relationship between these patterns and psychosocial risk factors for cardiovascular disease. We measured preejection period (PEP) and an index of respiratory sinus arrhythmia (mean successive difference [MSD] statistic) during three reactivity tasks. We classified participants into four groups based on increases or decreases in PEP and MSD. Ninety percent of the sample exhibited the same pattern during at least two of the tasks. PEP and MSD demonstrated consistency, suggesting individual response stereotypy. Exhibiting a consistent pattern of decreased PEP and increased MSD was associated with less child‐ and parent‐reported family conflict. These results are discussed in the context of vagal regulation of environmental demands.
Immediate and delayed stimulus repetitions evoke different ERPs in a serial‐probe recognition task
Authors: Crites Stephen L. , Delgado Pedro , Devine James V. , Lozano Dora I.
Published: December 2004

In this study we examined whether event‐related potentials (ERPs) associated with stimulus repetition and recognition in a serial‐probe recognition task were comparable to ERPs in other tasks that are more typically used to investigate old/new ERP effects. The experiment consisted of 320 trials in which a recognition probe followed a four‐item memory set; 160 trials consisted of images depicting common objects that were easy to label (EL task), and 160 trials consisted of images depicting abstract patterns that were difficult to label (DL task). Nineteen participants indicated whether a probe that followed each memory set was or was not presented in the memory set. Half of the probes matched, and half did not match, an item in the preceding memory set. ERPs appeared to reflect two processes—one that differentiated between recently presented stimuli and other stimuli and another that distinguished between repeated stimuli and new stimuli. ERPs to recent probes were more positive than ERPs to other probes in the EL and DL tasks. ERPs to match (old) probes were more positive than ERPs to nonmatch (new) probes only in the EL task.
P300 and alpha event‐related desynchronization (ERD)
Authors: Yordanova Juliana , Kolev Vasil , Polich John
Published: December 2004

In the present study we evaluated the relationships between the P300 event‐related potential and event‐related desynchronization (ERD) of electroencephalographic alpha activity by simultaneously analyzing P300 as well as 7–10‐ and 10–14‐Hz alpha ERD responses from auditory passive and active oddball conditions. We compared the effects of task (target vs. nontarget) and electrode (Fz, Cz, Pz) on P300 and ERD, and correlated P300 amplitude/latency with ERD maximal amplitude/latency across individuals. The major findings were that P300 as well as slow and fast alpha ERD manifested similar task and electrode effects. P300 preceded ERD and predicted individual variance of both slow and fast alpha ERD. The relationships of P300 with alpha ERD were different for the slow and fast alpha frequencies. These findings indicate that P300 and ERD are related such that slow and fast alpha ERDs are specifically guided or modified by the internal event(s) indexed by P300.
Fleeting images: A new look at early emotion discrimination
Authors: Junghöfer Markus , Bradley Margaret M. , Elbert Thomas R. , Lang Peter J.
Published: December 2004

The visual brain quickly sorted stimuli for emotional impact despite high‐speed presentation (3 or 5 per s) in a sustained, serial torrent of 700 complex pictures. Event‐related potentials, recorded with a dense electrode array, showed selective discrimination of emotionally arousing stimuli from less affective content. Primary sources of this activation were over the occipital cortices, extending to right parietal cortex, suggesting a processing focus in the posterior visual system. Emotion discrimination was independent of formal pictorial properties (color, brightness, spatial frequency, and complexity). The data support the hypothesis of a very short‐term conceptual memory store (M. C. Potter, 1999)—shown here to include a fleeting but reliable assessment of affective meaning.
Development of prosaccade and antisaccade task performance in participants aged 6 to 26 years
Authors: Klein C. , Foerster F.
Published: December 2004

There are few studies on the development of oculomotor functions during childhood. B. Fischer, M. Biscaldi, and S. Gezeck (1997) reported improvement of antisaccade task performance between ages 6 and 16 years. The present study is a replication and extension of those results. In three age groups (6–7, 10–11, 18–26 years), saccades during pro‐ and antisaccade tasks with 200‐ms gap and overlap and during a fixation task were measured. Adults exhibited faster saccades and less prosaccades during the antisaccade tasks than 10–11‐year‐old children; these two groups had faster saccades during all tasks and less prosaccades during the anti‐ and the fixation task than 6–7‐year‐old subjects. Both children groups made more express saccades than adults. Results suggest different degrees of age‐related improvement for different saccadic parameters, the effects being greatest for prosaccade inhibition during the antisaccade task and in line with the assumed protracted development of prefrontal functions.
The effect of expressing anger on cardiovascular reactivity and facial blood flow in Chinese and Caucasians
Authors: Drummond Peter D. , Quah Saw Han
Published: December 2004

Blood pressure, heart rate, and changes in facial and finger blood flow were monitored in 24 male Chinese and 24 male Caucasians while they described anger‐provoking incidents and read out neutral material, either loudly and rapidly or softly and slowly. Describing the incidents loudly and rapidly heightened anger ratings and enhanced digital vasoconstriction but not blood pressure or heart rate; however, anger enhanced blood pressure during soft, slow speech. Facial blood flow increased during anger expression, irrespective of speech style, but decreased when neutral material was read out. The findings suggest that an increase in facial blood flow reduces peripheral vascular resistance during anger expression, and that baroreflexes attenuate increases in heart rate and blood pressure. Racial background did not influence subjective reports or physiological responses, possibly because the procedure did not draw strongly enough on cultural taboos.
Differentiation of deception using pupillary responses as an index of cognitive processing
Authors: Dionisio Daphne P. , Granholm Eric , Hillix William A. , Perrine William F.
Published: December 2004

The deception literature has predominantly focused on detection of guilty individuals using electrodermal measures. Little research has examined other psychophysiological measures or the mechanisms underlying deception. Therefore, the present study examined pupillary responses in a differentiation‐of‐deception paradigm. Twenty‐four undergraduate participants answered the same questions twice, once truthfully and once deceptively, while pupillary responses were recorded. Questions were based on recently learned (episodic) information from scenarios or on general (semantic) knowledge from long‐term memory. Task‐evoked pupil dilation was significantly greater when participants confabulated responses than when they told the truth for both episodic and semantic memory questions. Previous research has demonstrated that pupil size increases with increased cognitive processing load. The present study suggested that generating deceptive recall was associated with increased pupil size and required greater cognitive processing than truthful recall.
The effect of perceptual grouping on the mismatch negativity
Authors: Gaeta Helen , Friedman David , Ritter Walter , Cheng Jeff
Published: December 2004

The mismatch negativity (MMN) was used as a probe to evaluate changes, with age, of transient auditory memory. Subjects were 16 young (M= 23 years) and 16 old (M= 72 years) people. Standard auditory stimuli were presented in trains of eight tones (1000 Hz) with either a 1‐s or 8‐s intertrain interval (ITI). Occasionally, the first stimulus of a train was replaced with a 1200 Hz tone (deviant). The MMN was recorded while subjects watched a silent movie and ignored the sounds. Both groups of subjects showed an MMN response to deviant stimuli under the 1‐s ITI condition, but MMNs were only seen for some subjects under the 8‐s ITI condition. After MMN recording, subjects performed a discrimination task to the tones used for recording MMNs. Accuracy for both groups was near 100% at both ITIs. These results suggest that generation of MMN is a function of the perceptual grouping of the acoustical stimuli and that the integrity of perceptual grouping may be maintained with increased age.
Mismatch negativity and psychoacoustic measures of gap detection in normally hearing subjects
Authors: Bertoli Sibylle , Heimberg Stephan , Smurzynski Jacek , Probst Rudolf
Published: December 2004

Temporal auditory processing deficits are thought to play an important role in some pathologies of speech understanding difficulties. The purposes of the present study were to determine whether short silent gaps within a pure tone can be used to elicit mismatch negativity (MMN) as an objective measure of temporal resolution, and to investigate the relation between MMN and performance on a behavioral gap‐detection task. The stimuli used for both tasks were 1‐kHz sinusoids presented in a low‐pass masking noise. Behavioral gap‐detection thresholds were determined using an adaptive three‐alternative forced‐choice procedure. To elicit MMN, a series of deviant stimuli with varying gap durations was generated and presented in an oddball paradigm among standard stimuli without a gap. Only the gaps larger than the mean behavioral gap‐detection threshold evoked a clear MMN. There was no clear relation between psychoacoustic and MMN thresholds.
Spatiotemporal analysis of the late ERP responses to deviant stimuli
Authors: Spencer Kevin M. , Dien Joseph , Donchin Emanuel
Published: December 2004

We used a novel application of principal components analysis (spatiotemporal PCA) to decompose the event‐related brain potentials (ERPs) obtained with a dense electrode array, with the purpose of elucidating the late ERP components elicited by deviant stimuli under “attend” and “ignore” conditions. First, a “spatial” PCA was performed to identify a set of scalp distributions (spatial factors or “virtual electrodes”) that accounted for the spatial variance in the data set. The data were expressed as spatial factor scores or “virtual ERPs” measured at each of the virtual electrodes. These virtual ERPs were submitted to a “temporal” PCA, yielding a set of temporal factors or “virtual epochs.” Statistical analyses of the temporal factor scores found that (1) attended deviant stimuli elicited the P300 and Novelty P3 components, the latter being largest for highly salient nontargets; (2) “ignored” deviants elicited a small Novelty P3, and depending on the primary task, a small P300; and (3) the classical Slow Wave consisted of separate frontal‐negative and posterior‐positive components.
Contextual fear‐potentiated startle conditioning in humans: Replication and extension
Authors: Ameli Rezvan , Ip Chris , Grillon Christian
Published: December 2004

Contextual fear conditioning was examined using the startle reflex in two groups of participants over two sessions separated by 1/2 h. The conditioned stimulus (CS) was paired (paired group) or not (unpaired group) with an unpleasant shock during conditioning. The paired group showed conditioning to the CS that was well retained over the retention interval. Session 1 intertrial interval startles—a measure of contextual conditioning—were greater in the unpaired compared to the paired group. Context conditioning was retained in Session 2 and was present before the shock electrodes were attached. Self‐rating of state anxiety, arousal, and pleasure indicated differential changes in mood from Session 1 to Session 2 in the two groups, with the unpaired group showing relatively greater negative affects compared to the paired group. These results indicate that unpredictable shocks lead to greater context conditioning as measured by startle and self‐reports.
Saccadic inhibition among schizotypal personality disorder subjects
Authors: Brenner Colleen A. , McDowell Jennifer E. , Cadenhead Kristin S. , Clementz Brett A.
Published: December 2004

Schizotypal personality disorder (SPD) is theoretically part of the schizophrenia spectrum both clinically and neurobiologically. A liability for developing schizophrenia may be associated with dysfunction of dorsolateral prefrontal cortex (DLPFC) and its cortical and/or subcortical circuitry. If so, abnormalities on tasks associated with DLPFC functioning among SPD subjects would support the thesis that SPD is neurobiologically related to schizophrenia. Antisaccade and ocular motor delayed response performance, both of which are ostensibly supported by DLPFC circuitry, were assessed among 29 SPD, 17 schizophrenia, and 25 normal subjects. Generally, the SPD subjects' performance was more similar to normal than to schizophrenia groups. There was evidence, however, for inhibition abnormalities in a subgroup of SPD subjects. Antisaccade performance identified more SPD subjects as “abnormal” than delayed response measures.
Working memory processes show different degrees of lateralization: Evidence from event‐related potentials
Authors: Talsma Durk , Wijers Albertus A. , Klaver Peter , Mulder Gijsbertus
Published: December 2004

This study aimed to identify different processes in working memory, using event‐related potentials (ERPs) and response times. Abstract polygons were presented for memorization and subsequent recall in a delayed matching‐to‐sample paradigm. Two polygons were presented bilaterally for memorization and a cue indicated whether one (and if so, which one of the two) or both polygons had to be memorized. A subsequent test figure was presented unilaterally to the left or right visual field and had to be compared with the memorized figure(s). ERP results suggested that memorization takes place in a visual buffer in contralateral posterior brain areas, whereas identification of the test stimulus as a target appears to be mainly a left hemispheric process. Increased response times were found for nontarget test stimuli as compared to targets, and for target test stimuli that were presented contralaterally with respect to the location of the memorized stimulus. In addition, response times were slower when two figures were memorized than when only one was memorized.
Blood pressure, heart rate, and behavioral responses to psychological “novelty” stress in freely moving rats
Authors: van den Buuse Maarten , van Acker Saskia A.B.E. , Fluttert Marc , de Kloet E. Ronald
Published: December 2004

We developed a new model of psychological “open‐field” stress in freely moving rats. Blood pressure and heart rate of the rats were measured by radiotelemetry and behavior analyzed by video tracking software. Open‐field exposure induced marked increases in blood pressure and heart rate. Repeated daily exposure induced pressor responses that were slightly higher on Day 4 when compared to Day 1. Pretreatment with the β1‐adrenoceptor antagonist atenolol inhibited the tachycardia whereas the ganglion blocker pentolinium inhibited the pressor response, indicating involvement of the sympathetic nervous system. Pretreatment with diazepam prevented the novelty stress‐induced pressor response and reduced the tachycardia. These results show that the psychological stress of exposing rats to an open field induces marked cardiovascular effects that are mediated by sympathetic hyperactivity. This model is unique in that it focuses on psychological stress and allows concomitant measurement of blood pressure, heart rate, and behavior in freely moving rats.
Error‐related brain potentials are differentially related to awareness of response errors: Evidence from an antisaccade task
Authors: Nieuwenhuis Sander , Ridderinkhof K. Richard , Blom Jos , Band Guido P.H. , Kok Albert
Published: December 2004

The error negativity (Ne/ERN) and error positivity (Pe) are two components of the event‐related brain potential (ERP) that are associated with action monitoring and error detection. To investigate the relation between error processing and conscious self‐monitoring of behavior, the present experiment examined whether an Ne and Pe are observed after response errors of which participants are unaware. Ne and Pe measures, behavioral accuracy, and trial‐to‐trial subjective accuracy judgments were obtained from participants performing an antisaccade task, which elicits many unperceived, incorrect reflex‐like saccades. Consistent with previous research, subjectively unperceived saccade errors were almost always immediately corrected, and were associated with faster correction times and smaller saccade sizes than perceived errors. Importantly, irrespective of whether the participant was aware of the error or not, erroneous saccades were followed by a sizable Ne. In contrast, the Pe was much more pronounced for perceived than for unperceived errors. Unperceived errors were characterized by the absence of posterror slowing. These and other results are consistent with the view that the Ne and Pe reflect the activity of two separate error monitoring processes, of which only the later process, reflected by the Pe, is associated with conscious error recognition and remedial action.
G Theory and the reliability of psychophysiological measures: A tutorial
Authors: di Nocera Francesco , Ferlazzo Fabio , Borghi Valentina
Published: December 2004

For some years, the limits of classic reliability theory have been recognized in favor of the Generalizability Theory, which deals simultaneously with multiple sources of error. This measurement model can be particularly useful when applied to research in cognitive psychophysiology. Indeed, studies in this field often deal with estimated measures whose reliability is rarely taken into account. In this paper, we report two generalizability studies in order to investigate the usefulness of G theory in providing information about the reliability of experimental results. The first was carried out on P300 measured during an oddball task, and the second was carried out on ERPs recorded during a recognition memory task. As expected, results showed that P300 modulation was more reliable than ERP memory modulation. This suggests that G theory can be a useful tool to estimate the reliability of psychophysiological findings, complementing and extending results from conventional analyses.
Hypoalgesic effect of caffeine in normotensive men and women
Authors: Keogh Edmund , Witt Gerke
Published: December 2004

Evidence from both hypertensive and normotensive individuals indicate that elevated blood pressure is associated with decreased pain sensitivity. The current study sought to experimentally raise blood pressure using 250 mg caffeine, and investigate its effects on the cold pressor pain experiences of 25 men and 25 women. In a placebo‐controlled repeated‐measures experiment, caffeine increased systolic and diastolic blood pressure, as well as producing more clearheaded and energetic feelings. Caffeine produced higher pain threshold and pain tolerance levels compared to placebo, and women had a lower tolerance to pain than men. Finally, a significant association was found between caffeine‐related increase in systolic blood pressure and caffeine‐related increase in pain tolerance. Furthermore, this association was the strongest in women. These results are discussed in light of future directions for pain and hypertension research.
Selective attention and response inhibition alter phase‐dependent cardiac slowing
Authors: van der Veen Frederik M. , van der Molen Maurits W. , Jennings J. Richard
Published: December 2004

This study examined the effects of visual selective attention and stimulus discriminability on phasic heart rate changes. Grating stimuli consisting of four vertical bars were presented left or right from fixation. Participants attended to one side of the screen and responded with a button press to attended target stimuli that were defined by shorter middle bars. Stimulus discriminability was manipulated by increasing the length of the middle bars of targets. To examine the time course of response inhibition, participants had to respond to auditory probe stimuli that were presented occasionally and unpredictably at varying intervals following the visual stimulus. Responses to targets and probes following attended nontargets were slower in the difficult condition. Heart rate slowed in anticipation of a target and accelerated back to baseline afterwards. Phase‐dependent cardiac slowing was larger for attended nontargets compared to unattended nontargets and was more pronounced in the difficult condition. These findings were interpreted vis‐à‐vis inhibition accounts of phase‐dependent cardiac slowing.
The detection of constancy amidst change in children: A dissociation of preattentive and intentional processing
Authors: Molholm Sophie , Gomes Hilary , Ritter Walter
Published: December 2004

This study examined whether 7–9‐year‐old children preattentively build memories of constancy for individual stimulus features, and if these representations are affected by variability of other stimulus features. This was achieved by looking at the mismatch negativity (MMN) event‐related potential to a duration deviant occurring in a stimulus environment in which one or two other features constantly changed. Performance data were also collected, to look at the correspondence between the effects of this manipulation on preattentive and intentional deviance detection. MMN data indicated that the children built a preattentive feature‐based memory of constancy that was not affected by the number of varying features. In contrast, intentional deviance detection was considerably impaired by the introduction of feature variability. This dissociation is at variance with previous studies that usually report close association between MMN and behavior.
Event‐related potentials to auditory stimuli in female Vietnam nurse veterans with posttraumatic stress disorder
Authors: Metzger Linda J. , Carson Margaret A. , Paulus Lynn A. , Lasko Natasha B. , Paige Stephen R. , Pitman Roger K. , Orr Scott P.
Published: December 2004

Individuals with posttraumatic stress disorder (PTSD) have been found to show several event‐related brain potential (ERP) abnormalities including reduced target P3b amplitude, P50 suppression, and P2 amplitude/intensity slope. Female Vietnam nurse veterans with (n= 29) and without (n= 38) current PTSD completed P50 paired‐click, three‐tone “oddball” and four‐tone stimulus‐intensity modulation procedures. Opposite to previous findings, the current PTSD group had larger target P3b amplitudes and increased P2 amplitude/intensity slopes. Reduced P50 suppression was associated with increased severity of general psychopathology, but not with PTSD diagnosis. Findings suggest that target P3b amplitude and P2 amplitude/intensity slope abnormalities reflect different pathophysiological processes. Future research is needed to determine whether the opposite ERP abnormalities observed in this PTSD sample reflect gender‐, trauma‐, or sample‐specific findings.
Acute psychological stress reduces plasma triglyceride clearance
Authors: Stoney Catherine M. , West Sheila G. , Hughes Joel W. , Lentino Lisa M. , Finney Montenique L. , Falko James , Bausserman Linda
Published: December 2004

Acute stress elevates blood lipids, with the largest increases among men and postmenopausal women. The mechanisms for the effect are unknown, but may be due to altered lipid metabolism. This study investigated if acute stress induces transient reductions in triglyceride clearance in middle‐aged men and women, and determined if gender and menopause affect triglyceride metabolism. Of the 35 women, half were premenopausal, and half were naturally postmenopausal; men (n= 35) were age matched. Clearance of an intravenously administered fat emulsion was assessed twice: once during a nonstress session, and again during a stress‐testing session. During the stress session, a battery of behavioral stressors (serial subtraction, speech, mirror tracing, and Stroop) were performed for 40 min. The clearance rate of exogenous fat was significantly diminished during the stress, relative to the nonstress session. Women had more efficient clearance, relative to men, but there were no effects of menopausal status. The diminished ability to clear an intravenous fat emulsion during stress suggests one mechanism for stress‐induced elevations in lipids.
Aging and the Simon task
Authors: van der Lubbe Rob H.J. , Verleger Rolf
Published: December 2004

A visual Simon task was used to study the influence of aging on visuospatial attention and inhibitory control processes. Responses were much slower for elderly than for young participants. The delay in trials in which stimulus and response side did not correspond as compared to when they did correspond (the Simon effect) was larger for older people, even after correcting for general slowing due to aging. The slowing of responses reflected a slowing of internal processing, as indicated by progressively larger delays of the peak latencies of the N1, the posterior contralateral negativity (PCN), and P3. A comparison between the amplitudes of the PCN and early lateralized readiness potential (pre‐LRP) indicated that transmission from posterior sites (PCN) to the motor cortex may be affected by age. The data support the view that aging affects an inhibitory process that controls direct visuomotor transmission.
Power changes in infant EEG frequency bands during a spatial working memory task
Authors: Bell Martha Ann
Published: December 2004

Developmental psychophysiologists working with infants have no commonly accepted frequency definitions of EEG waves or rhythms. The purpose of this study was to investigate the task‐related power changes in three infant EEG frequency bands during the performance of a spatial working memory task by 8‐month‐old infants. EEG data were divided into three frequency bands: 3–5 Hz, 6–9 Hz, and 10–12 Hz. Although all three frequency bands showed some level of discrimination of baseline from task and among different processing stages of cognitive activity, only the 6–9 Hz band consistently exhibited these capabilities and distinguished the correct from incorrect responses. These data may form the foundation for defining EEG frequency bands that are appropriate for use with infant research participants and for understanding the function of these frequencies during cognitive activity.
Aversive Pavlovian conditioning in psychopaths: Peripheral and central correlates
Authors: Flor Herta , Birbaumer Niels , Hermann Christiane , Ziegler Silvio , Patrick Christopher J.
Published: December 2004

Differential aversive Pavlovian conditioning with a foul odor as unconditioned stimulus (US) and neutral faces as conditioned stimuli (CS) was compared between 9 noncriminal psychopaths as defined by the Hare Psychopathy Checklist Revised and 12 healthy controls. Event‐related potentials (ERP), heart rate, skin conductance response, corrugator EMG, and startle response potentiation as well as valence, arousal, and contingency of the CS were assessed. Whereas the healthy controls (HC) showed significant CS+/CS− differentiation, the psychopaths (PP) failed to exhibit a conditioned response although unconditioned responses were comparable between the groups. N100, P200, and P300 to the CSs revealed that psychopaths were not deficient in information processing and showed even better anticipatory responding than the HC group indicated by the terminal contingent negative variation (tCNV), that lacked, however, CS+ and CS− differentiation. These data indicate a deficit in association formation in psychopaths that may be related to deficient interaction of limbic‐subcortical and cortical structures.
Pericranial muscular, respiratory, and heart rate components of the orienting response
Authors: Stekelenburg J.J. , van Boxtel A.
Published: December 2004

We have earlier found that voluntary attention to weak auditory stimuli induces inhibition of respiration, heart rate, and electromyographic (EMG) activity of masticatory and lower facial muscles and that these responses lower the auditory threshold for low‐frequency sounds. In the current study, we examined whether this inhibitory response pattern also occurs during involuntary orienting to novel, nonsignal sounds. Environmental sounds of low intensity were presented unexpectedly during the performance of a reading task. Orienting responses (ORs) were elicited as indicated by heart rate deceleration and skin conductance responses. Inhibitory respiratory and pericranial EMG responses appeared to be intrinsic components of the OR. Together with the autonomic responses, they habituated when a nonsignal auditory stimulus was repeatedly presented. Our results also suggest that eye and pinna movements occurred toward the sound source. The results of the current study are consistent with the hypothesis of Sokolov (1963) that the primary function of the OR is enhancement of sensory sensitivity.
Stress and selective attention: The interplay of mood, cortisol levels, and emotional information processing
Authors: Ellenbogen Mark A. , Schwartzman Alex E. , Stewart Jane , Walker Claire‐Dominique
Published: December 2004

The effects of a stressful challenge on the processing of emotional words were examined in college students. Stress induction was achieved using a competitive computer task, where the individual either repeatedly lost or won against a confederate. Mood, attention, and cortisol were recorded during the study. There were four findings: (1) Participants in the negative stressor condition were faster to shift attention away from negative words than positive or neutral words; (2) attentional shifts away from negative words were associated with stress‐induced mood lowering; (3) participants in the negative stress condition with elevated scores on the Beck Depression Inventory were slow to disengage attention from all stimuli; and (4) elevated depression scores were associated with lower cortisol change from baseline during the experimental phase, and with higher cortisol levels during the recovery phase. These findings point to information‐processing strategies as a means to regulate emotion, and to atypical features of cognitive and adrenocortical function that may serve as putative risk markers of depression.
Best friends forever?: High school best friendships and the transition to college
Authors: Oswald Debra L. , Clark Eddie M.
Published: December 2004

The transition from high school to college is an important phase for adolescents in social as well as academic aspects. This study examined the changes that occur in high school best friendships during the first year of college. Results revealed that during the first year in college high school best friendships declined in satisfaction, commitment, rewards, and investments. During this period there was also an increase in costs and alternatives to best friend relationships. Proximity did not influence the friendships; however, level of communication did moderate friendship deterioration. Furthermore, individuals who continued their best friendship reported engaging in more maintenance behaviors of positivity, supportiveness, self‐disclosure, and interaction than individuals who reported a change in the relationship to close or casual friendship. Maintaining the best friendship also appeared to buffer adolescents from social loneliness. The results are discussed in terms of the implications of transitions on adolescent friendships.
Methodological issues in growth‐curve analyses with married couples
Authors: Kurdek Lawrence A.
Published: December 2004

Because longitudinal data are increasingly being used to test predictions regarding close relationships, researchers are also increasingly being confronted with methodological issues unique to the analysis of longitudinal data. In this paper, four issues in conducting growth‐curve analyses with married couples are examined: assessing statistical assumptions about homoscedastic and independent errors, handling information about missing data, dealing with couples with only one assessment, and estimating quadratic effects. Each issue is illustrated with actual data, and syntax from the multilevel module in LISREL 8.52 is provided for specific analyses. Guidelines are presented for helping researchers think through each issue with their own data set.