James E. Arruda

Effects of aerobic exercise and gender on visual and auditory P300, reaction time, and accuracy

Abstract Visual and auditory reaction times (RTs) have been reported to decrease during moderate aerobic exercise, and this has been interpreted as reflecting an exercise-induced activation (EIA) of cognitive information processing. In the present study we examined changes in several independent measures of information processing (RT, accuracy, P300 latency and amplitude) during exercise, and their relationship to visual or auditory modalities and to gender. P300 latencies offer independent measures of cognitive speed that are unrelated to motor output, and P300 amplitudes have been used as measures of attentional allocation. Twenty-four healthy college students [mean (SD) age 20 (2) years] performed auditory and visual “oddball” tasks during resting baseline, aerobic exercise, and recovery periods. Consistent with previous studies, both visual and auditory RTs during exercise were significantly shortened compared to control and recovery periods (which did not differ from each other). We now report that, paralleling the RT changes, auditory and visual P300 latencies decreased during exercise, indicating the occurrence of faster cognitive information processing in both sensory modalities. However, both auditory and visual P300 amplitudes decreased during exercise, suggesting diminished attentional resource allocation. In addition, error rates increased during exercise. Taken together, these results suggest that the enhancement of cognitive information processing speed during moderate aerobic exercise, although operating across genders and sensory modalities, is not a global facilitation of cognition, but is accompanied by decreased attention and increased errors.

Measurement of mood states in stroke patients: validation of the visual analog mood scales.

OBJECTIVE The Visual Analog Mood Scales (VAMS) were recently developed by Stern and colleagues to assess mood state in neurologically impaired patients. These brief scales require that a patient place a single pen mark along a 100mm vertical line to indicate how he or she presently feels. Although previous studies have garnered evidence in support of the validity of these brief scales when administered to psychiatric patients and healthy young adult and geriatric control subjects, it is presently unknown whether the VAMS are valid measures of internal mood state in neurologically impaired stroke patients. The purpose of the present investigation was to assess reliability and validity of the VAMS in a stroke-patient population. PARTICIPANTS Participants were 41 (21 men and 20 women) inpatients admitted for either acute stroke or rehabilitation following stroke. DESIGN Participants completed both the VAMS and a modified version of the Profile of Mood States (POMS). Nonparametric multitrait-multimethod analyses were performed using the Pearson correlations among and between the six subscales of the VAMS and the POMS. CONCLUSION The VAMS possess good convergent and discriminant validity when administered to stroke inpatients, providing further support for the utility of these brief, easily administered scales.

Standardization and validation of the visual analog mood scales

Abstract The Visual Analog Mood Scales (VAMS) have recently been developed to better understand and assess mood disturbance in neurologically impaired patients who, because of communication and cognitive deficits, cannot complete more lengthy, verbally demanding measures of mood states. In the present study, normative data from age-, gender- and race-stratified general adult (n = 400) and geriatric (n = 175) standardization samples are presented. In addition, validation evidence for the VAMS, using a multitrait, multimethod paradigm, is reported and the underlying content structure of VAMS items, using principal components analysis, is presented. The VAMS scores correlated significantly (rs ranging from .55 to 30) with other measures of mood disturbance. Principal components analysis resulted in a two-component solution, which was labeled “Negative Mood” and “Energy”. The VAMS appear to be brief, easily administered, and valid measures of mood states. The normative data presented allow for improved inter...

Neurobehavioral functioning in asymptomatic HIV-1 infected women.

Numerous reports have assessed the neuropsychological functioning of medically asymptomatic HIV-1 infected men. However, to date there have been no published studies of the neuropsychological functioning of asymptomatic HIV-1 infected women, even though women represent the fastest-growing demographic group of HIV-1 infected individuals. In this investigation, 31 women (17 asymptomatic HIV-1 seropositive, 14 seronegative) were administered a battery of neurocognitive and neuropsychiatric instruments. Participants in both groups were matched for age, education, months since injection drug use, and substance use. Group comparisons revealed no significant differences in any of the neurocognitive or neuropsychiatric measures. The results of this preliminary study suggest that clinically significant differences in neurobehavioral function are unlikely in medically asymptomatic HIV-1 infected women compared to seronegative controls. However, additional studies are needed with larger sample sizes and with careful attention to possible confounding or masking variables.

A guide for applying principal-components analysis and confirmatory factor analysis to quantitative electroencephalogram data

Principal-components analysis (PCA) has been used in quantitative electroencephalogram (qEEG) research to statistically reduce the dimensionality of the original qEEG measures to a smaller set of theoretically meaningful component variables. However, PCAs involving qEEG have frequently been performed with small sample sizes, producing solutions that are highly unstable. Moreover, solutions have not been independently confirmed using an independent sample and the more rigorous confirmatory factor analysis (CFA) procedure. This paper was intended to illustrate, by way of example, the process of applying PCA and CFA to qEEG data. Explicit decision rules pertaining to the application of PCA and CFA to qEEG are discussed. In the first of two experiments, PCAs were performed on qEEG measures collected from 102 healthy individuals as they performed an auditory continuous performance task. Component solutions were then validated in an independent sample of 106 healthy individuals using the CFA procedure. The results of this experiment confirmed the validity of an oblique, seven component solution. Measures of internal consistency and test-retest reliability for the seven component solution were high. These results support the use of qEEG data as a stable and valid measure of neurophysiological functioning. As measures of these neurophysiological processes are easily derived, they may prove useful in discriminating between and among clinical (neurological) and control populations. Future research directions are highlighted.

Validation of a right hemisphere vigilance system as measured by principal component and factor analyzed quantitative electroencephalogram

Arruda and colleagues [Arruda, J.E., Weiler, M.D., Valentino, D.A. et al., 1996. A guide for applying principal-component analysis and confirmatory factor analysis to qEEG data. Int. J. Psychophysiol. 23, 63-81.] recently described seven neurophysiological measures that were previously derived and confirmed using factor analytic procedures and the quantitative electroencephalogram (EEG) sampled from 208 normal controls during an auditory continuous performance test (CPT). The purpose of the present investigation was to further test the validity of these empirically derived measures by examining each measures relationship with CPT-related declines in performance. Participants were 48 right-handed men (n = 13) and women (n = 35) who reported being free of any neurological condition, birthing complications, or loss of consciousness greater than 2 min. After completing an eyes-closed resting condition, participants performed a 23-min CPT while both quantitative EEG and behavioral performance were measured at 45, 405, 765 and 1125 s into the CPT. Bipolar recordings were gathered using the International 10-20 system, from eight sites: frontal, fronto-temporal, temporal and temporal-occipital. Multivariate and follow-up univariate tests suggest the existence of a neurophysiological system located within the right temporal region that appears essential for the maintenance of a sustained attentional state. If confirmed, the further quantification of this neurocognitive system may prove useful as part of a clinical diagnostic workup.

Assessment of Mood State in Dementia by Use of the Visual Analog Mood Scales (VAMS)

OBJECTIVE The assessment of mood states in individuals with dementia is a challenging yet clinically useful task. The purpose of the present study was to examine the validity of the Visual Analog Mood Scales (VAMS) in individuals with dementia. METHODS Thirty-one patients who met diagnostic criteria for dementia completed the VAMS and a modified Profile of Mood States. RESULTS Authors found good convergent validity between all monotrait-heteromethod mood states. Excellent discriminant validity was found for VAMS Happy, Confused, Angry, and Energetic scales. CONCLUSION These results provide evidence for the validity of the VAMS in patients with dementia.

Rhythmic oscillations in the performance of a sustained attention task

Attempts to sustain a narrow focus of attention over a long period of time are effortful and are punctuated by lapses. Most studies of sustained attention performance obscure the presence and pattern of lapses by reporting measures that are summed across the entire period of an individuals performance, or that are average scores for blocks of trials across many participants. In the present study we attempted to explore fluctuation in the attention of individual participants over the course of a vigilance task and to quantify its periodicity, if any exists. Normal university students listened to letters of the alphabet, arranged randomly and presented at a rate of 2 per second for 20 min. They were instructed to press a hand-held button when they detected a target (two consecutive identical letters). Continuous estimates of performance accuracy (correctly detected targets) at regularly spaced time intervals were created for each participant using a moving time window. The resulting functions were analyzed in order to detect and quantify periodicity using a Fast Fourier Transform (FFT). The most often observed rhythms for those participants with adequate FFT power congregated at 1–2 min, 4–7 min and greater than 10 min. Performance functions from 36 of the 40 subjects displayed at least two of these frequencies. Other studies have identified cycles in performance during similar vigilance challenges, but without particular rhythms or with no particular shared frequencies amongst participants. The possible sources of these fluctuations and the differences in the findings of these studies and the present study are discussed.

Concurrent visual task effects on evoked and emitted auditory p300 in adolescents

Using an oddball stimulus presentation paradigm, the effects of divided attention on auditory P300s were studied. Auditory attention was either divided or focused, depending on the demands placed on subjects during the performance of a concomitantly presented visual task. Two types of auditory tasks were performed under each of the two auditory attention conditions. In one, subjects responded to infrequently presented high pitched tones (oddball stimuli). In the other they responded to the occasional omission of a stimulus in an otherwise rhythmically presented chain of stimuli. P300s and reaction times were recorded to both the rare tones and the omissions. The Sternberg visual memory task was used to manipulate the subjects auditory attention state. Subjects actively performed the Sternberg task during the divided auditory attention condition, whereas during the focused attention condition they were not required to respond to the visual stimuli. During focused auditory attention, evoked auditory P300s were both larger and faster than their emitted counterparts. During divided attention, auditory P300s were reduced in amplitude but latency was unaffected. Evoked auditory P300s showed evidence of containing P300a as well as P300b components, particularly when attention was shared with the visual task.

Measures of Variations in Performance During a Sustained Attention Task

In this study the authors developed and explored measures of short-term variations in accuracy on a test of sustained attention, a departure from traditional measures of average performance over long periods. The study participants were normal young adults, actively engaged in a continuous performance test (CPT). Both correct (hits) and incorrect (misses) responses to CPT targets appeared to aggregate in runs (2 or more consecutive hits or misses). Results of a Monte-Carlo procedure indicated that these runs were longer and fewer than would occur if hits and misses were randomly distributed. Average accuracy decreased between the first and second 5-min quarter of the test, then remained level. The length of hit runs followed the same pattern. However, other aspects of performance continued to change. The amount of time participants spent in miss runs began to increase significantly in the third quarter, and the frequency of miss runs did not increase until the fourth quarter. Explanations of these findings based upon changes in perceptual sensitivity or upon phasic increases in arousal caused by hits were rejected by further analysis. There was evidence that the length of miss runs was limited by a target-expectancy effect created by the specific parameters of our CPT. The authors conclude that measures of variations in performance reveal aspects of vigilance that are not tapped by traditional measures, and that factors that initiate, sustain and terminate both hit and miss runs are important targets of future research. Additional research is needed to determine whether or not the particular measures developed in this study may contribute to the understanding of attention problems in clinical populations.