In a parity judgment task, the ERPs at parietal electrode sites become the more negative the more mental rotation has to be executed. In two experiments, it was investigated whether a temporal relationship exists between the onset of this amplitude modulation and the moment when mental rotation is executed. Therefore, the duration of processing stages located before mental rotation was manipulated. The amplitude modulation was delayed when either the perceptual quality of the stimulus was reduced (Experiment 1) or when character discrimination was more difficult (Experiment 2). The results suggest that the onset of the rotation-related negativity might be used as a chronopsychophysiological marker for the onset of the cognitive process of mental rotation.

The mammalian auditory system contains descending pathways that originate in the cortex and relay at various intermediate levels before reaching the peripheral sensory organ of Corti. The last link in this chain consists of the olivocochlear bundle. The activity of this bundle can be measured through otoacoustic emissions, which are acoustic signatures of the cochlear biomechanical activity. In the present study, it was hypothesized that frequency-specific activation of the olivocochlear bundle in the contralateral ear would show up as frequency-specific variations in otoacoustic emission amplitude in the ipsilateral ear. Two groups of young adult subjects participated in this experiment. Evoked otoacoustic emissions were recorded in the ipsilateral ear at two test frequencies (1 and 2 kHz). Subjects had to detect probe tones at a given frequency in background noise in the contralateral ear. Larger efferent activation was measured at test frequencies on which attention is focused. This result provides evidence for an influence of attention on the auditory periphery via descending projections.

Although memory has been widely studied using event-related potentials, memory-related changes in the electroencephalogram (EEG) have been relatively neglected. The aim of this study was to determine whether evidence could be found for memory-related changes in the EEG. EEG was recorded from a sample of healthy volunteers while they performed word and face recognition memory tasks. Data were analyzed using the method of event-related desynchronization. In the theta frequency range there was a short-duration increase in power that occurred in the first 250 ms that was maximal at temporal sites (T5/T6). For words, but not faces, there was a repetition effect in theta such that new words elicited greater synchronization than old words at the midline frontal electrode (Fz). In the alpha frequency range there was a lateralized repetition effect, which occurred from 750 ms. In upper alpha this effect was lateralized in the expected way with greater desynchronization at temporo-parietal sites on the left for words and on the right for faces. For lower alpha, the lateralization was reversed. The meanings of these findings are interpreted in the light of existing models of recognition memory.

Temporal stability is an important fundamental quality when measuring sleep parameters, yet it has been infrequently assessed. Generalizability theory was used to estimate the short-term temporal stability of five variables commonly used to characterize insomnia: sleep onset latency, total sleep time, wake after sleep onset, time in bed, and sleep efficiency. Estimates were calculated for 32 elderly primary insomniacs and 32 elderly normal sleepers, both in the lab and at home, using both sleep logs and polysomnography (PSG). A week of recording using either PSG or sleep logs was typically sufficient to achieve adequate stability (defined as G coefficient of at least 0.80) with some notable exceptions: (a) when using log-derived measures with insomniacs, a 3-week average was necessary for wake after sleep onset and (b) more than a 2-week average was necessary for sleep onset latency. Because of the substantial commitment involved in the physiological recording of sleep, alternative forms of aggregation are considered with the intent of improving temporal stability.

The effects of attention were assessed on novelty P3 amplitude and scalp distribution elicited by environmental sounds in young and elderly volunteers who participated in either actively attended or ignored oddball conditions. For the young, novelty P3 amplitude decreased with time on task during both attend and ignore sequences. Amplitude decrements were greatest at frontal sites during the attend condition, but at all sites during the ignore condition. A reliable amplitude decrement was not observed for the elderly in either the attend or ignore oddball series. The data suggest that attention differentially activates multiple generators that contribute to scalp-recorded novelty P3 activity. The lack of novelty P3 habituation seen in the elderly is consistent with changes in frontal lobe function as age increases.

Accurate and early diagnosis of Alzheimer's Disease (AD) with reliable and noninvasive methods is of great importance for clinical practice as effective and specific antidementive therapies become available. The aim of the study was to evaluate the clinical relevance of event-related P300 in the early diagnosis of AD. Thirty patients with AD, 26 patients with mild cognitive impairment (MCI) from our Memory Clinic and 26 age-matched healthy controls (HC) were studied with event-related P300 potentials. Amplitudes of temporo-basal dipoles (TB-P300) were significantly diminished in AD compared to HC and MCI. Furthermore, latencies of temporo-superior dipoles (TS-P300) were significantly prolonged in AD compared with HC. Sensitivity was 90.0% for the differentiation of patients with AD from HC (specificity 79.1%) using reduced TB-P300 amplitudes and prolonged TS-P300 latencies. Similar results were found using Pz amplitudes as well as Fz latencies. Our data suggest that TB-P300 amplitudes and TS-P300 latencies may be an accurate clinically available, nonexpensive, noninvasive, and reliable marker for AD.

Carotid baroreceptor stimulation has been shown to dampen pain. This study tested, in 40 normotensive adults, the hypothesis that pain is lower during systole when arterial baroreceptor stimulation is maximal than diastole when stimulation is minimal. The sural nerve was stimulated electrocutaneously to obtain a nociceptive flexion reflex (NFR) threshold, and then stimulation was delivered for 28 trials at 100% NFR threshold at seven intervals after the R-wave. Nociceptive responding was indexed by electromyographic (EMG) activity elicited in the biceps femoris. Significant variations in EMG activity occurred across the cardiac cycle, with less activity midcycle, indicating that the NFR response was attenuated during systole compared to diastole. Stimulation of baroreceptors by natural changes in blood pressure during the cardiac cycle dampened nociception, and accordingly, the data support the arterial baroreflex mechanism of hypertensive hypoalgesia.

The bandwidth for the recording of the orbicularis oculi blink reflex electromyogram (EMG) response is optimal when low-frequency artifacts, such as motion artifacts and cross-talk from other muscles, are maximally suppressed, whereas true EMG signal power is maximally retained. The optimal bandwidth was investigated for acoustic, electrocutaneous, and photic blink reflexes. Reflexes were recorded with varying bandwidth and interelectrode distances of 12 and 36 mm. Power spectra of the EMG signals were calculated and compared with a theoretical spectrum of the uncontaminated EMG signal. For both electrode distances, the optimal bandwidth was on the average 28–500 Hz for acoustic and electrocutaneous blink reflexes and 12–500 Hz for photic blinks. Using photic stimuli, however, a high-pass filter frequency larger than 12 Hz (probably at least 30 Hz) in combination with occlusion of the eye will be necessary to avoid influences of retinal potentials. Given the optimal bandwidth, a larger electrode spacing may be expected to moderately improve the detectability of small blinks in all stimulus conditions.

In a within-subjects design, event-related potentials were compared for two types of sentence-final syntactic errors: Incorrect verb inflection and incorrect word category (phrase structure). In a grammatical judgment task, these errors triggered robust N400 and P600 components. To assess the degree of automaticity of the underlying linguistic processes, the N400 and P600 effects were measured in a task for which the participants judged whether a word in a sentence was printed in upper case. In this physical judgment task, the N400 and P600 following verb inflection errors were greatly attenuated or absent, whereas those elicited by word category violation were only slightly diminished in amplitude. The data suggest that word category information is processed more automatically than inflectional information. The P600 appears to reflect a relatively controlled language-related process.

Electroencephalogram (EEG) alpha power has been demonstrated to be inversely related to mental activity and has subsequently been used as an indirect measure of brain activation. The thalamus has been proposed as an important site for modulation of rhythmic alpha activity. Studies in animals have suggested that cortical alpha rhythms are correlated with alpha rhythms in the thalamus. However, little empirical evidence exists for this relation in humans. In the current study, resting EEG and a fluorodeoxyglucose positron emission tomography scan were measured during the same experimental session. Over a 30-min period, average EEG alpha power across 28 electrodes from 27 participants was robustly inversely correlated with glucose metabolic activity in the thalamus. These data provide the first evidence for a relation between alpha EEG power and thalamic activity in humans.

Event-related potentials (ERPs) were recorded in male and female participants in response to 32 male and 32 female faces. Participants were instructed to simply look carefully at each face; after ERP collection they were asked to rate each face on a 5-point attractiveness scale. A positive correlation between average rating and average P300 scores to opposite sex faces was observed in male (r = .40) and in preovulatory (r = .41) and postovulatory (r = .44) female subjects. Correlations to same sex faces were only found in postovulatory females (r = .61). Male participants showed a much larger average P300 than did female participants, and the P300 evoked in female participants was unexpectedly larger to female than to male faces. Neither task relevance nor stimulus probability is a plausible explanations for these findings because they were experimentally controlled. These results support the emotional value hypothesis, according to which classical P300 processes reflect an affective evaluation of the stimulus, which in turn produces context updating.

The effects of prior task exposure on cardiovascular reactivity to stress were examined in two experiments by randomly assigning participants to repeated exposure groups that performed mental arithmetic pretest and test tasks versus delayed exposure groups that performed only the test task after prolonged rest. Impedance cardiographic and blood pressure measures were recorded continuously from 60 undergraduate men in Experiment 1 and 112 undergraduate men and women in Experiment 2. Task repetition attenuated cardiovascular reactivity and improved task performance in repeated exposure groups (p < .001), suggesting an integrated process of behavioral adaptation. During the test task, delayed exposure groups showed greater cardiac reactivity (p < .01), but not vascular reactivity, than repeated exposure groups. Thus, cardiac reactivity varied as a specific function of prior task exposure, whereas vascular reactivity varied as a general function of time.

This study examined the effect of response selection and execution on P3 latency during the performance of simple reaction time (RT) and stimulus–response compatibility tasks. Response time on these tasks was defined in terms of RT and movement time (MT). Event-related brain potentials were recorded from 67 female participants concurrently with the performance measures. On the simple RT task, the distance of the response button from the home button was varied (7, 15, and 23 cm). When stimulus evaluation demands were minimal, response execution affected P3 latency, with increased response button distance resulting in increased P3 latency. However, these movement effects were modest, and in most protocols, would not be a confounding factor. The stimulus–response compatibility task examined the interaction of stimulus evaluation demands and response requirements. RT, MT, and P3 latency were affected by stimulus congruency, whereas RT and P3 amplitude were affected by response compatibility.

We evaluated the feasibility of recording multiple physiological anxiety measures during a flight and how well they could distinguish flight phobics from controls. Benefits of baseline adjustment and transformation for all variables and adjustment of heart rate by ventilation to give additional heart rate were calculated. Effect size, one measure of the power to discriminate groups, was between 1.1 and 1.7 for heart rate measures. Although respiratory rate and minute ventilation, indicators of hyperventilation, did not differ between groups, phobics paused more during inspiration than did controls. Phobics also showed more skin conductance fluctuations and less respiratory sinus arrhythmia. Self-reported anxiety was a more powerful discriminator than physiological measures, a result that may be partially explained by how phobics were selected. These results indicate that monitoring of multiple physiological systems outside the laboratory is practical and informative. Physiological measures of psychological importance can be quantified accurately in a noisy, changing, unsupervised ambulatory setting.

Effects of movement advance information were assessed on the prestimulus amplitude of the lateralized readiness potential (LRP), on the contingent negative variation (CNV), and on reaction time (RT). In a precuing paradigm with movement parameters hand, direction, and force, partial precues provided advance information about either hand alone, hand plus force, or hand plus direction, and the full precue specified all response parameters. The full precue produced the shortest RTs and the largest CNV amplitude, precuing hand and force or hand and movement direction produced somewhat slower RTs and a somewhat smaller CNV amplitude, and precuing only hand yielded slowest RTs and the smallest CNV amplitude. In contrast, the LRP amplitude was largest for the full precue and was the same for the remaining precues. The CNV appears to index the central assembling of a motor program, and the LRP represents the implementation of the program at more peripheral levels.

An experiment with N = 56 university students investigated the joint effects of manipulated mood state and task difficulty on cardiovascular and electrodermal reactivity during mood inductions and performance on a letter cancellation task. We tested our theory-based prediction that moods per se do not involve autonomic adjustments whereas mood and task difficulty interact during task performance to determine autonomic reactivity with respect to active coping. Specifically, we anticipated for an easy task weaker reactivity in a positive mood (due to low subjective demand) than in a negative mood (due to high subjective demand). Conversely, we expected, for a difficult task, stronger reactivity in a positive mood (high, but not yet too high, subjective demand) than in a negative mood (too high subjective demand). Adjustments of systolic blood pressure, diastolic blood pressure, and tonic skin conductance level described exactly the predicted pattern. Furthermore, task performance was associated with autonomic reactivity in the difficult conditions.

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.

Studies that measure the onset of the lateralized readiness potential (LRP) could well provide researchers with important new data concerning the information-processing locus of experimental effects of interest. However, detecting the onset of the LRP has proved difficult. The present study used computer simulations involving both human and artificial data, and both stimulus- and response-locked effects, to compare a wide variety of techniques for detecting and estimating differences in the onset latency of the LRP. Across the two sets of simulations, different techniques were found to be the most accurate and reliable for the analysis of stimulus- and response-locked data. On the basis of these results, it is recommended that regression-based methods be used to analyze most LRP data.

Startle modulation was investigated as participants first anticipated and then viewed affective pictures in order to determine whether affective modulation of the startle reflex is similar in these different task contexts. During a 6-s anticipation period, a neutral light cue signaled whether the upcoming picture would portray snakes, erotica, or household objects; at the end of the anticipatory period, a picture in the signaled category was viewed for 6 s. Male participants highly fearful of snakes were recruited to maximize emotional arousal during anticipation and perception. Results indicated that the startle reflex was potentiated when anticipating either unpleasant (phobic) or pleasant (erotic) pictures, compared to neutral stimuli, whereas during perception, reflexes were potentiated when viewing unpleasant stimuli, and reduced when viewing pleasant pictures. The startle reflex is modulated by hedonic valence in picture perception, and by emotional arousal in a task context involving picture anticipation.

A problem confronting the search for psychopathology-related genes concerns the difficulty identifying gene carriers. Psychiatric diagnosis provides imperfect identification of affected individuals, and unaffected gene carriers go undetected. Psychophysiological measures may assist molecular genetic investigations by indicating genetic susceptibility for psychopathology, thus increasing the probability of identifying affected and unaffected gene carriers. Research strategies based on these premises are applied to the study of psychoactive substance use disorders and schizophrenia. Data are presented illustrating (1) that individual differences in inhibitory control involving autonomic and antisaccade eye movement measures and the P3 component of the event-related potential may be sensitive to susceptibility for substance use disorders, and (2) that eye tracking variables may identify genetic risk for schizophrenia.