Prefrontal EEG correlation during Tower of Hanoi and WCST performance: effect of emotional visual stimuli.

INTRODUCTION: Emotional stimuli elicit changes in the electroencephalographic (EEG) activity of several brain structures. Prefrontal cortex is involved in the processing of emotional stimuli and executive functions. The correlation analysis of EEG provides information about the functional coupling between areas. It is reasonable to expect that emotional activation will modify prefrontal coupling during the performance of executive tasks such as Tower of Hanoi or Wisconsin Card Sorting Test (WCST). AIM: Determine whether the prefrontal EEG correlation during the performance of the Tower of Hanoi and WCST is affected by previous exposure to videos with sexual or aggressive content. MAIN OUTCOME MEASURES: Prefrontal EEG coupling was determined by the Pearson correlation. Valence and general arousal were evaluated by the Self-Assessment Manikin Scale and sexual arousal with a Sexual Arousal Scale. Computerized versions of the Towers of Hanoi and WCST provided data on prefrontal executive functions. METHODS: EEG from the left and right prefrontal zones was recorded during the performance of the Tower of Hanoi and WCST immediately after the subjects were exposed to one of the videos (neutral, aggressive, and erotic). RESULTS: There was no difference between videos in the task performance parameters. Only the erotic video produced an increased prefrontal coupling in the slow bands (delta and theta) during the performance of the Tower of Hanoi, whereas a decreased coupling in the delta, theta, and alpha bands was observed during the WCST. CONCLUSIONS: Prefrontal coupling was changed after exposure to the erotic video, and it is likely that enhanced sexual arousal was the main cause of this change. The correlation patterns obtained could be associated with particular cognitive strategies or to functional adaptations while being sexually aroused. The results of this study may contribute to an understanding of the central nervous mechanisms underlying the cognitive effects of sexual arousal.

Effects of alcohol on the performance of the Tower of London task in relation to the menstrual cycle: an electroencephalographic study.

It is well known that the metabolism of alcohol and cognitive functions can vary during the menstrual cycle. Also, both alcohol ingestion and hormonal variations during menstruation have been associated with characteristic changes in electroencephalographic (EEG) activity. The aim of the present study was to determine whether EEG activity during the performance of the Tower of London (TOL) task is affected by previous ingestion of alcohol and whether these EEG patterns vary in relation to different phases of the menstrual cycle. For this purpose, female participants consumed a moderate dose of alcohol or placebo during the follicular and early luteal phases of the menstrual cycle and then, 35 min after liquid ingestion, EEG activity was recorded during the performance of TOL. A deleterious effect of alcohol on TOL performance was potentiated in the follicular phase, related to a higher α1 relative power, probably as a result of the low progesterone levels characteristic of this menstrual phase. These data show the feasibility of examining the interaction of alcohol and menstrual cycle phases on cognitive performance by means of EEG recording, and contribute toward a better understanding of the brain mechanisms that underlie the cognitive changes that occur during the menstrual cycle under the effects of alcohol.

Effects of red wine on the electrical activity and functional coupling between prefrontal-parietal cortices in young men.

The effects of low-dose red wine on cortical electroencephalogram (EEG) and the functional coupling between the frontal and parietal cortices during the first minutes after ingestion were studied. In a first experiment, 38 male volunteers participated in a wine/water challenge protocol in which each subject served as his own control. Wine-induced EEG changes appeared immediately after ingestion and continued for 40 min. These changes were characterized by an increase in the absolute power (AP) and relative power (RP) of fast frequencies (alpha1, alpha2, beta1 and beta2), a decrease of low frequencies (delta and theta) and a specific decrease in the degree of coupling between cortices at 20 min after wine ingestion. To determine if EEG changes were produced by the alcohol in the red wine, in a second experiment, 24 male volunteers participated in an independent wine/placebo group protocol. At 20 min post-ingestion, the red wine group showed higher power in the alpha band, lower RP of low frequencies and decreased correlation, as compared to the placebo group. These findings show that low-dose red wine produces a rapid cortical activation and decreased synchronization between the prefrontal and parietal areas, which could be associated with aroused states or altered cognitive processes, as has been described in other studies.

Brain electrical activity changes in treatment refractory schizophrenics after olanzapine treatment.

The aim of the present study was to identify brain electrical activity changes generated by olanzapine (OLZ) in treatment refractory schizophrenics (TRS). 14 paranoid TRS (31.5+/-8.39 years old) were evaluated before and after 8 weeks of OLZ treatment. Psychopathology was evaluated by means of total BPRS and PANSS scores. Resting EEG was recorded in the pre (under typical neuroleptics) and post (under OLZ) sessions. A good response to OLZ was observed in 57% of TRS. A significant reduction in positive and negative symptoms scales of PANSS was found. Absolute power of theta1, theta2, alpha1 bands increased after treatment, while beta2 power showed a decrease. Intrahemispheric correlation increased between different zones of the frontal areas and between frontal and posterior areas, while interhemispheric correlation decreased in theta2. EEG changes were more evident in those patients who had a better response to OLZ. OLZ showed to be effective in TRS, improving psychiatric symptoms and increasing activity synchronization between different areas within each hemisphere that may indicate a functional reorganization, particularly in good responders.

Relationship between resting alpha activity and the ERPs obtained during a highly demanding selective attention task.

In spite of previous reports on the relationship between ongoing EEG and ERPs, there remains a lack of agreement on the nature of their nexuses. The aim of the present study was to evaluate the relationship between resting EEG and the ERP components in two groups of healthy subjects with different levels of performance in a highly demanding selective visual attention task. Young adults were classified according to the amount of their correct responses in the task, into high (HP; averaged hits (AH): 86%) and low performance groups (LP; AH: 59%). EEG was recorded during rest, prior to task performance and absolute (AP) and relative power (RP), as well as inter- (rTER) and intrahemispheric (rTRA) correlation were calculated. ERPs during task performance were also obtained and their amplitude and latency measures were assessed. Results showed that individuals with better behavioral performance had a higher synchronization between both hemispheres during rest as well as higher amplitude and shorter latencies of N2 and P3. Principal Component Analysis revealed that alpha2 AP and RP were inversely related to P2 and N2 latency. Higher values of alpha1 and alpha2 rTER were clustered with higher P3 amplitude and shorter reaction time. In conclusion, the differences in the cortical organization of HP and LP at rest (EEG) seem to be associated to the way the brain reacts during information processing (ERPs).

Effects of musical tempi on visual attention ERPs.

The purpose of this work was to examine whether fast and slow musical tempi have different effects on selective attention evaluated through ERPs and task performance. A high demanding visual selective attention task was performed by the subjects: without music (BL) and with Bach's music in slow (ST) and fast tempi (FT). Difference waves were obtained substracting non-target from target. FT caused a reduction in reaction time and N2d and P3d latencies and in P3d amplitude. N2d latency was longer in ST than BL and FT. Music played in FT induced a faster stimuli evaluation and response than ST.