ABSTRACT
Gamma band oscillation (GBO) and sensory gating (SG) are associated with many cognitive functions. Ketamine induces deficits of GBO and SG in the prefrontal cortex (PFC). However, the time-courses of the effects of different doses of ketamine on GBO power and SG are poorly understood. Studies have indicated that GBO power and SG have a common substrate for their generation and abnormalities. In this study, we found that (1) ketamine administration increased GBO power in the PFC in rats differently in the low- and high-dose groups; (2) auditory SG was significantly lower than baseline in the 30 mg/kg and 60 mg/kg groups, but not in the 15 mg/kg and 120 mg/kg groups; and (3) changes in SG and basal GBO power were significantly correlated in awake rats. These results indicate a relationship between mechanisms underlying auditory SG and GBO power.
Subject(s)
Animals , Male , Rats , Acoustic Stimulation , Analysis of Variance , Dose-Response Relationship, Drug , Electroencephalography , Excitatory Amino Acid Antagonists , Pharmacology , Gamma Rhythm , Ketamine , Pharmacology , Prefrontal Cortex , Rats, Sprague-Dawley , Sensory Gating , Sleep Stages , Statistics as Topic , Time Factors , WakefulnessABSTRACT
OBJECTIVE: To analyze changes in gamma band absolute power in motor cortical areas, before and after a condition of hand immobilization for 48 hours. METHOD: Fifteen healthy volunteers, aged between 20 and 30, were submitted to EEG assessment before and after 48 hours of immobilization of the dominant hand, while performing a motor task triggered by a visual stimulus. A two-way repeated measures ANOVA with two within-group factors (moment x condition), each one with two levels (before vs. after visual stimuli; before vs. after 48-hour HI, respectively) was used to test for changes in beta band absolute power. RESULTS: Statistical analysis revealed that hand immobilization caused changes in cortical areas. A significant increase in gamma band absolute power was found after hand immobilization at electrodes F3 (p = 0.001) at F4 (p = 0.001) and at Fz (p = 0.001), at C3 (p = 0.001), C4 (p = 0.001) and Cz (p = 0.001). CONCLUSION: These results reveal that oscillations of the gamma band can be a cortical strategy to solve the effect of less activation due to movement restriction. Knowledge of the functioning of motor cortical areas after a condition of immobilization can lead to more effective strategies in rehabilitation.
OBJETIVO: O objetivo deste estudo foi analisar mudanças na potência absoluta da banda gamma em áreas corticais motoras, antes e depois de uma condição de imobilização da mão por 48 horas. MÉTODO: Quinze voluntários saudáveis, com idades entre 20 e 30 anos, foram submetidos a avaliação eletroencefalográfica antes e depois da imobilização, durante a execução de uma tarefa motora desencadeada por um estímulo visual. Uma análise de variância com dois fatores (ANOVA two-way) foi empregada para investigar o fator momento (antes e depois do estímulo visual) e o fator condição (antes e depois da imobilização). RESULTADOS: Um aumento significativo na potencia absoluta da banda gamma foi encontrado após imobilização da mão nos elétrodos (ou derivações) F3, F4, FZ, C3, C4 e Cz. CONCLUSÃO: Estes resultados revelam que as oscilações na banda gama podem ser uma estratégia cortical para resolver o efeito de menor ativação devido à restrição de movimento. Um melhor conhecimento do funcionamento de áreas corticais motoras após uma condição de imobilização pode orientar estratégias mais eficazes na reabilitação.
Subject(s)
Electroencephalography/methods , Hand/physiopathology , Immobilization/methods , Neuronal Plasticity , Analysis of VarianceABSTRACT
OBJECTIVE: Healthy individuals show stronger gamma-band activities (GBAs) for socially relevant stimuli (human faces) than for non-relevant ones. This study aimed to examine whether this gamma-band preference occurs in patients with schizophrenia. METHODS: EEG was recorded for 24 patients with schizophrenia and 23 healthy controls while they viewed pictures of human faces, chairs, and nature scenes. The spectral powers of high-beta (20-30 Hz) and gamma (30-80 Hz) frequencies were analyzed along 3 midline cortical regions, and phase synchronization was calculated. RESULTS: Compared to the response to non-facial stimuli, higher event related deactivation to facial stimuli was observed for the high-beta frequency across groups. For the gamma frequency, early-stage GBA was increased and late-stage GBA was decreased for all 3 stimuli in patients with schizophrenia compared to healthy controls. Preferential GBA patterns (100-200 and 200-300 ms) were found in healthy controls, but not in patients with schizophrenia. Significant correlation existed between negative symptoms and GBA in the frontal region for chair and scene stimuli. There was no significant intergroup difference in phase synchronization pattern. CONCLUSION: Our results suggest that patients with schizophrenia have deficits in the preferential pattern of GBA for human faces and the deficits in the preferential pattern were mainly influenced by over-response to socially non-relevant stimuli.