Biomedical subjects

Maurício Cagy

Publications and source records attributed to Maurício Cagy.

14 recordsLinked to original sources

PubMed2007

Effects of caffeine on electrophysiological and neuropsychological indices after sleep deprivation.

Caffeine is regarded as a central nervous system (CNS) stimulant. The goal of this study was to analyze electrophysiological, motor, cognitive and behavioral changes produced by caffeine ingestion after sleep deprivation. Ten subjects were evaluated after sleep deprivation, comparing the ingestion of either 400 mg of caffeine or placebo, in a double-blind randomized study. The variables analyzed were: quantitative EEG, the event-related potential (ERP-P300) and cognitive responses. The most significant quantitative EEG results, which were characterized by moment x treatment interactions, were seen in alpha and theta relative power variables. A significant decrease in relative alpha and theta was observed in the caffeine group after sleep deprivation. In relation to caffeine stimulant effects, there were no significant differences in the other parameters.

Adult↗

PubMed2006

Objective response detection technique in frequency-domain for reflecting changes in MLAEP.

The mid-latency auditory evoked potential (MLAEP) occurs within the interval 10-100ms post-stimulus and exhibits morphological changes due to coma, general anaesthesia and neurological and psychiatric diseases. This work evaluates an objective response detection technique in the frequency domain, the magnitude squared coherence (kappa(2)(f)), in reflecting MLAEPs changes in amplitude and latencies. Both simulation and EEG data were used in this investigation. The EEG during auditory stimulation in 10 volunteers under propofol-induced anaesthesia was acquired. Based on the null hypothesis of non-existing response, critical values have been derived in order to detect the auditory response. The alternative hypothesis was used to infer about maximal-response frequencies as well as to derive confidence intervals for the estimated values of kappa(2)(f) during anaesthesia. Changes in both simulated and real MLAEPs could be tracked by kappa(2)(f), even for low SNR. High degree of cortical activation occurred predominantly between 30 and 90Hz. This finding could be related to the sensory-originated phase-locked oscillation in the gamma band (30-70Hz). Hence, for applications where changes on MLAEPs should be assessed, the use of kappa(2)(f) as an objective statistical response detection technique is worth to be applied.

Algorithms↗

PubMed2006

Neuromodulatory effect of bromazepam on motor learning: an electroencephalographic approach.

To investigate the effects of bromazepam on motor performance and electroencephalographic activity (qEEG) in healthy subjects, during the process of learning a typewriting task, with a focused attention demand. A randomized double-blind model was used to allocate subjects in one of the following conditions: placebo (n=13), bromazepam 3 mg (n=13) or bromazepam 6 mg (n=13). Forty minutes after treatment administration, subjects were submitted to the motor task. EEG activity was recorded simultaneously. The analyzed variables were: number of errors and execution time, which were extracted from each block of the typewriting task, and mean relative power values in the beta band (13-35 Hz), extracted from the qEEG. A significantly lower number of typing errors was observed in both bromazepam conditions (Br 3 mg and Br 6 mg) when compared to the placebo. There was no difference between the two bromazepam conditions. For the execution time variable, a better performance was observed in the Br 3 mg condition, but with no statistical significance. The highest degree of cortical activation during the task was observed in Br 3 mg and Br 6 mg when compared to placebo. The medication's anxiolytic effect intensifies the attentional focus over predictable events occurring in reduced perceptual fields. The qEEG's accentuated response in pre-motor and primary motor areas suggests a greater effort directed to the most relevant aspects of the task. In short, the doses employed (3 and 6 mg) seem to enhance the learning of motor tasks that involve focused attention, such as typewriting.

Adult↗

PubMed2006

[Neuromodulatory effects of bromazepam when individuals were exposed to a motor learning task: quantitative electroencephalography (qEEG)].

The sedative effects of bromazepam on cognitive and performance have been widely investigated. A number of different approaches have assessed the influence of bromazepam when individuals are engaged to a motor task. In this context, the present study aimed to investigate electrophysiological changes when individuals were exposed to a typewriting task after taking 6 mg of bromazepam. qEEG data were simultaneously recorded during the task. In particular, relative power in delta band (0.5-3.5 Hz) was analyzed. Time of execution and errors during the task were registered as behavioral variables. The experimental group, bromazepam 6 mg, showed a better motor performance and higher relative power than control individuals (placebo). These results suggest that the use of bromazepam reduces anxiety levels as expected and thus, produces an increment in motor performance.

Alpha Rhythm↗

PubMed2006

The relation between EEG prefrontal asymmetry and subjective feelings of mood following 24 hours of sleep deprivation.

Several studies have investigated the relationship between asymmetrical EEG activity over the frontal cortex and mood. This study aimed at investigating the association between state fluctuations in frontal alpha EEG asymmetry and state changes followed by 24 h of sleep deprivation (SD). Our results show that sleep deprivation caused a significant alteration in the asymmetry values. Activation shifted from the left hemisphere, before SD, to the right hemisphere, after SD, in all frontal electrode pairs. In addition, according to the self-rating scale of SD-related mood effects, subjects became significantly less alerted and active, and sleepier. According to these results, increased right prefrontal activation might be potentially associated with the negative mood states typically seen after sleep deprivation, although the causal relationship is still uncertain. However, more studies will be necessary to establish the viability of EEG asymmetry and the cerebral lateralization hypothesis to explain the SD-related affective changes.

Adult↗

PubMed2006

Electroencephalographic changes after one night of sleep deprivation.

Total or partial sleep deprivation (SD) causes degrading effects on different cognitive and psychomotor functions that might be related to electrophysiological changes frequently observed. In the present study, we investigated the effects of one night of sleep deprivation on waking EEG. Experimental protocol consisted of recording electroencephalographic data from eleven healthy young subjects before (baseline) and after (time 2) one night of sleep deprivation. A natural log transformation was carried out and showed a significant increase in theta T6 (p=0.041), O2 (p=0.018) and OZ (p=0.028); and delta T6 (p=0.043) relative power; and a decrease in alpha Fp1 (p=0.040), F3 (p=0.013), Fp2 (p=0.033), T4 (p=0.050), T6 (p=0.018), O2 (p=0.011) and Oz (p=0.025) and beta (p=0.022) absolute power. These outcomes show that the EEG power spectra, after sleep deprivation, exhibit site-specific differences in particular frequency bands and corroborate for the premise of local aspects of brain adaptation after sleep deprivation, rather than global.

Adult↗

PubMed2006

[Procedural learning and anxiolytic effects: electroencephalographic, motor and attentional measures].

The objective of the present study was to evaluate attentional, motor and electroencephalographic (EEG) parameters during a procedural task when subjects have ingested 6 mg of bromazepam. The sample consisted of 26 healthy subjects, male or female, between 19 and 36 years of age. The control (placebo) and experimental (bromazepam 6 mg) groups were submitted to a typewriting task in a randomized, double-blind design. The findings did not show significant differences in attentional and motor measures between groups. Coherence measures (qEEG) were evaluated between scalp regions, in theta, alpha and beta bands. A first analysis revealed a main effect for condition (Anova 2-way--condition versus blocks). A second Anova 2-way (condition versus scalp regions) showed a main effect for both factors. The coherence measure was not a sensitive tool at demonstrating differences between cortical areas as a function of procedural learning.

Adult↗

PubMed2005

[Neuromodulatory effects of caffeine and bromazepam on visual event-related potential (P300): a comparative study].

UNLABELLED: The P300 component of the event-related potential (ERP) is a general measurement of "cognitive efficiency". It is an index of the ability of an individual's central nervous system (CNS) to process incoming information. OBJECTIVE: To compare the neuromodulatory effects of caffeine and bromazepam on the visual ERP (P300), in relation to a P300 normative database. METHOD: 15 right-handed individuals (7 male and 8 female), between 20 and 30 years of age, healthy, free of any cognitive impairment and not making use of psychoactive substances were studied. Participants were submitted to a visual discrimination task, which employed the "oddball" paradigm, after the administration of caffeine and bromazepam, in a randomized, double-blind design. RESULTS: Statistically significant differences were observed when the caffeine and bromazepam conditions were compared to the normative database. CONCLUSION: The present results suggest that caffeine and bromazepam have distinct modulatory effects on CNS functioning.

Adult↗

PubMed2005

[Electroencephalography measures in motor skill learning and effects of bromazepam].

Neuromodulators change brain's neural circuitry. Bromazepam is often been used in the pharmacological treatment of anxiety disorders. Few papers links this anxiolytic to motor tasks. The purpose of this study was to examine motor and electrophysiological changes produced by administration of bromazepam in differents doses (3 and 6 mg). The sample consisted of 39 healthy individuals, of both sexes, between 20 and 30 years of age. The control (placebo) and experimental (bromazepam 3mg and bromazepam 6 mg) groups were submitted to a typewriting task, in a randomized, double-blind design. The results did not reveal differences on score and time of the attention test. In the comportamental analysis was noticed blocks as main effect to behavioral variables (time and mistakes in the task). Electrophysiological data showed significants interactions to: laterally/condition/moment; laterally/condition; laterally/moment; condition/moment; condition/site.

Adult↗

PubMed2005

[Effects of Bromazepam in qEEG by type writing].

The efficiency with which an information is processed by the brain's neural circuitry can be altered by neuromodulators. The use of Bromazepam in the pharmacological treatment of anxiety disorders is due to its anxiolytic property. However, the effects of this benzodiazepine in motor learning tasks are not entirely understood. In this context, the goal of this study was to assess the effects of Bromazepam (6 mg) on psychophysiological, behavioral, and electrophysiological variables, during the process of learning a motor task. The sample consisted of 26 healthy individuals, of both sexes, between 19 and 36 years of age. The control (placebo) and experimental (Bromazepam 6 mg) groups were submitted to a typewriting task, in a randomized, double-blind design. The results did not reveal differences for phychophysiological and behavioral variables between the groups. Statistical tests pointed out to an interaction between condition and moment, and a hemisphere main effect, i.e. a reduction of relative power in the right hemisphere. This reduction suggests a specialization of the neural circuitry in the hemisphere contralateral to the finger used in the task. Such reduction is independent from the drug administration.

Adult↗

PubMed2004

Visual event-related potential (P300): a normative study.

UNLABELLED: The P300 component of the Event-Related Potential (ERP) is a general measurement of "cognitive efficiency". It is an index of the ability of an individual's Central Nervous System (CNS) to process incoming information. OBJECTIVE: To develop a normative database for the visual P300. METHODOLOGY: 30 right-handed individuals (same number of each sex), between 20 and 30 years of age, healthy, free of any cognitive impairment and not making use of psychoactive substances. Participants were submitted to a visual discrimination task, which employed the "oddball" paradigm. RESULTS: The expected scalp distribution trend was seen for latency but not for amplitude values. CONCLUSION: A high variability of latency and amplitude values was observed across the age span. Mean reaction time for the entire sample of the study was 391.56 +/- 37.03 ms.

Adult↗

PubMed2004

[Changes in cortical power distribution produced by memory consolidation as a function of a typewriting skill].

The present study aimed to investigate alterations in EEG patterns in normal, right-handed individuals, during the process of learning a specific motor skill (typewriting). Recent studies have shown that the cerebral cortex is susceptible to several changes during a learning process and that alterations in the brain's electrical patterns take place as a result of the acquisition of a motor skill and memory consolidation. In this context, subjects' brain electrical activity was analyzed before and after the motor task. EEG data were collected by a Braintech 3000 and analyzed by Neurometrics. For the statistical analysis, the behavioral variables "time" and "number of errors" were assessed by a one-way ANOVA. For the neurophysiological variable "Absolute Power", a paired t-Test was performed for each pair of electrodes CZ-C3/CZ-C4, in the theta and alpha frequency bands. The main results demonstrated a change in performance, through both behavioral variables ("time" and "number of errors"). At the same time, no changes were observed for the neurophysiological variable ("Absolute Power") in the theta band. On the other hand, a significant increase was observed in the alpha band in central areas (CZ-C3/CZ-C4). These results suggest an adaptation of the sensory-motor cortex, as a consequence of the typewriting training.

Adult↗

PubMed2004

Effects of caffeine on visual evoked potential (P300) and neuromotor performance.

The stimulant effects of caffeine on cognitive performance have been widely investigated. The visual evoked potential, specially the P300 component, has been used in studies that explain the stimulant mechanisms of caffeine through neurophysiological methods. In this context, the present study aimed to investigate electrophysiological changes (P300 latency) and modification of cognitive and motor performance produced by caffeine. Fifteen healthy volunteers, 9 women and 6 men (26 +/- 5 years, 67 +/- 12.5 kg) were submitted three times to the following procedure: electroencefalographic recording, Word Color Stroop Test, and visual discrimination task. Subjects took a gelatin caffeine capsule (400 mg) or a placebo (P1 and P2), in a randomized, crossover, double-blind design. A one-factor ANOVA and Tukey post hoc test were used to compare dependent variables on the C, P1 and P2 moments. The statistical analyses indicated a non-significant decrease in reaction time, Stroop execution time and latency at Cz on the caffeine moment when compared to the others. Moreover, a non-significant increase in Stroop raw score and latency at Pz could be observed. The only significant result was found at Fz. These findings suggest that the positive tendency of caffeine to improve cognitive performance is probably associated with changes in the frontal cortex, a widely recognized attention area.

Adult↗

PubMed2002

Unconsciousness indication using time-domain parameters extracted from mid-latency auditory evoked potentials.

OBJECTIVE: The mid-latency auditory evoked potential (MLAEP) has been used to indicate depth of anaesthesia, and is usually analysed in time-domain. This work compares three techniques: Wave Deformation Parameters (PDO), Auditory Evoked Potential Index (AEPidx) and an automatic Nb-wave latency estimator (Nb), in the assessment of unconsciousness onset based on EEG under auditory stimulation. METHODS: Ten normal adult volunteers, under no pre-anaesthetic drug administration, received propofol during two successive periods of 45 min each one (3 mg/Kg/h and 9 mg/Kg/h), being the EEG collected from 10 min previous to infusion beginning until the subjects woke up. From the time-evolution of MLAEP (averaging of successive sets of 1000 epochs) all the parameters were compared to thresholds (unconsciousness onset indication time) and the results were compared to the instant of pressing interruption of a soft-touch switch, when one assumed the volunteer became unconscious. RESULTS: The Wilcoxon Signed-Rank test points equivalence between each of the parameters and the switch for, say, alpha = 5%. Bland-Altman diagrams revealed that the Attenuation-PDO has better agreement to the switch than Nb and AEPidx. CONCLUSION: The results suggest that, at least to indicate unconsciousness, the most reliable effect of the anaesthetic drug on MLAEP would be the amplitude attenuation. Despite the high dependence on noise due to its time-domain basis, the Attenuation-PDO seems to be adequate to assess depth of anaesthesia.

Adult↗