Effects of high frequency flash stimulation on the capacity of learning memory and autonomous exploratory in young rats / 中华行为医学与脑科学杂志

Objective:To investigate the effects of 40 Hz and 70 Hz frequency flash stimulation on the ability of learning memory and autonomous exploratory in young rats.Methods:Twenty-seven SPF grade male SD rats aged 19-21 days were divided into control group (Ctr group), 40 Hz group and 70 Hz group with 9 in each group according to the random number table.The rats in Ctr group were not given flash stimulation, while rats in the 40 Hz and 70 Hz group were received 40 Hz, 70 Hz flash stimulation (1.5 h/d for 39 days), respectively.The Morris water maze experiment was used to assess the learning and memory ability of rats, and the open field experiment was used to evaluate the ability of autonomous exploratory of rats.Nissl staining was used to assess the morphology of Nissl bodies in the hippocampus CA1 region of the rats.The local field potentials (LFPs) collected from the primary visual cortex (V1 area) region by electrophysiological experiments was used to verify the synchronization of flash evoked neural oscillations.SPSS 23.0 software was used for statistical analysis.The repeated measures ANOVA and one-way ANOVA were used to analyze normal distribution measurement data, and LSD and Tamhane tests were used for further pairwise comparison.The Kruskal-Wallis test was used for non-normal distribution measurement data.Results:(1) The flash stimulation of 40 Hz and 70 Hz both can effectively caused synchronization of neural oscillations in the primary visual cortex of healthy young rats.(2) The results of repeated measures ANOVA analysis showed that there was no interaction effect of grouping and time in the escape latency of young rats in the Morris water maze positioning navigation phase( F=1.326, P>0.05 ). The escape latency had time main effect ( F=40.025, P<0.05), but no grouping main effect ( F=2.039, P>0.05). With the increase of learning days, the escape latency of young rats in each group decreased significantly.There was no interaction effect of grouping and time in the total distance of young rats ( F=2.029, P>0.079). It had time main effect ( F=32.052, P<0.05), but not grouping main effect ( F=2.390, P>0.05) on total distance.With the increase of learning days, the total distance of young rats in each group significantly shortened.On the 6th day of the Morris water maze experiment, there was no statistically significant difference among groups in terms of time in the target quadrant and the number of crossing platforms ( F=2.511, 0.802, both P>0.05). The results of the open field experiment showed that the total distance traveled in the center of young rats in each group was statistically significant ( H=8.935, P<0.05), the total distance traveled in the center in the 70 Hz group (3.80 (2.25, 6.93) m)was significantly longer than that in the 40 Hz group (0.80 (0.72, 1.46) m), P<0.05). The percentage of time spent in the center was statistically significant in the three groups ( H=11.050, P<0.05). Young rats in the 70 Hz group spent significantly higher percentage of time in the center(3.20(2.43, 8.30)) than those in the 40 Hz group (0.95 (0.37, 1.06 ), P<0.05 ). (3) Nissl staining results showed that Nissl bodies in the hippocampal CA1 area of young rats in Ctr, 40 Hz and 70 Hz group were all arranged neatly and tightly, no edema was found in the surrounding stroma, and no obvious inflammatory cell infiltration was found. Conclusion:70 Hz frequency flash stimulation may promote the ability of learning memory and autonomous exploratory of young rats.

Analysis of electroencephalography brain rhythms in the reading process / Análise dos ritmos cerebrais de eletroencefalografia no processo de leitura

ABSTRACT Objective: To verify if, by three distinct quantifiers, the measured electroencephalographic signal at rest is different from the signal measured during a word reading situation, especially considering the faster rhythms, gamma and high-gamma, as it occurs in clinical rhythms (delta to beta). Methods: A total of 96 electroencephalographic signals measured from neurologically healthy volunteers were evaluated at two moments: resting and word reading. Each signal segment was measured by three quantifiers that separately assess normalized power, percent power, and right and left hemisphere coherence. The Mann-Whitney test was used to compare the results of the quantifiers in each brain range. Results: The gamma and high-gamma rhythms presented a more distinct behavior when comparing the analyzed moments (resting and reading) than the clinical rhythms. Conclusion: This finding contributes to the scarce literature on faster rhythms, which can contain information that is normally disregarded in neurological clinical practice.

RESUMO Objetivo: Verificar se, por meio de três quantificadores distintos, o sinal eletroencefalográfico medido em repouso é diferente do sinal medido durante o processo de leitura, especialmente considerando os ritmos rápidos, gama e supergama, assim como ocorre nos ritmos clínicos delta a beta. Métodos: Foram avaliados 96 sinais eletroencefalográficos medidos em voluntários neurologicamente saudáveis, em dois momentos: repouso e leitura de palavras. Cada trecho do sinal foi mensurado por três quantificadores que medem, de maneira isolada, a potência normalizada e a potência percentual, bem como a coerência entre os hemisférios direito e esquerdo. O teste estatístico de Mann-Whitney foi usado para comparar os resultados dos quantificadores em cada faixa cerebral. Resultados: Os ritmos gama e supergama apresentaram comportamento mais distinto entre os momentos analisados (repouso e leitura) que os ritmos clinicamente analisados. Conclusão: Esse achado contribui com a escassa literatura segundo a qual os ritmos rápidos podem conter informações que normalmente são descartadas na neurologia clínica.

BrainTV: a novel approach for online mapping of human brain functions

Our understanding of the brain's functional organisation has greatly benefited from occasional exploratory sessions during electrophysiological studies, trying various manipulations of an animal's environment to trigger responses in particular neurons. Famous examples of such exploration have unveiled various unexpected response properties, such as those of mirror neurons. This approach, which relies on the possibility to test online the reactivity of precise neural populations has no equivalent so far in humans. The present study proposes and applies a radically novel framework for mapping human brain functions in ecological situations based on a combination of a) exploratory sessions, using real-time electrophysiology to formulate hypotheses about the functional role of precise cortical regions and b) controlled experimental protocols specifically adapted to test these hypotheses. Using this two-stage approach with an epileptic patient candidate for surgery and implanted with intracerebral electrodes, we were able to precisely map high-level auditory functions in the patients' superior temporal lobe. We propose that this procedure constitutes at the least a useful complement of electrical cortical stimulations to map eloquent brain areas in epileptic patients before their surgery, but also a path of discovery for human functional brain mapping.

Changes of Quantitative EEG after Donepezil Treatment in Alzheimer's Disease

BACKGROUND: Though symptomatic improvements after treatment of donepezil is well documented in Alzheimer's disease (AD), the electrophysiological change have not yet been elucidated. Among the parameters of quantitative electroen-cephalography (q-EEG), high frequency activity, especially gamma rhythm, may play a role in normal cognitive function including the integration of sensory processing, association, coupling or selective attention, which are characteristically impaired in AD. METHODS: In order to define the profile of q-EEG changes including gamma rhythm after donepezil treatment, we followed 17 AD patients for 12 weeks. We analyzed the spectra power taken from 16 derivations by averaging twenty-2-sec epoch in normal controls and AD patients. After logarithmic transformation of spectra power, statistical test was done and the effect of donepezil treatment on q-EEG profile was analyzed during follow up period. RESULTS: Before medication of donepezil, AD patients had a significantly lower alpha spectra power as well as a significant higher delta spectra power, compared with normal control. After medication of donepezil in AD patients, compared to base-line q-EEG, gamma spectra power was significantly increased, whereas delta spectra power was significantly reduced. Compared to absolute power, relative power was more sensitive in detecting change of EEG after donepezil treatment. CONCLUSIONS: This study suggests that donepezil significantly change delta and gamma spectra power in q-EEG, and the increase in gamma rhythm may be correlated with the clinical improvements after donepezil treatment. (J Korean Neurol Assoc 19(3):245~250, 2001)