Navegando por Autor "Sameshima, Koichi"

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Comprehensive Analysis of Tissue Preservation and Recording Quality from Chronic Multielectrode Implants
(2011) Freire, Marco Aurelio M.; Morya, Edgard; Santos, Jose Ronaldo; Guimaraes, Joanilson S.; Lemos, Nelson A. M.; Sameshima, Koichi; Pereira, Antonio; Ribeiro, Sidarta Tollendal Gomes; Nicolelis, Miguel A. L.
Multielectrodes have been used with great success to simultaneously record the activity of neuronal populations in awake, behaving animals. In particular, there is great promise in the use of this technique to allow the control of neuroprosthetic devices by human patients. However, it is crucial to fully characterize the tissue response to the chronic implants in animal models ahead of the initiation of human clinical trials. Here we evaluated the effects of unilateral multielectrode implants on the motor cortex of rats weekly recorded for 1–6 months using several histological methods to assess metabolic markers, inflammatory response, immediate-early gene (IEG) expression, cytoskeletal integrity and apoptotic profiles. We also investigated the correlations between each of these features and firing rates, to estimate the impact of post-implant time on neuronal recordings. Overall, limited neuronal loss and glial activation were observed on the implanted sites. Reactivity to enzymatic metabolic markers and IEG expression were not significantly different between implanted and non-implanted hemispheres. Multielectrode recordings remained viable for up to 6 months after implantation, and firing rates correlated well to the histochemical and immunohistochemical markers. Altogether, our results indicate that chronic tungsten multielectrode implants do not substantially alter the histological and functional integrity of target sites in the cerebral cortex.
Corticalização de memória dependente do hipocampo durante o sono REM - Investigando as janelas temporais precoce (0 - 3 h) e tardia (8 - 16 h) após o aprendizado
(2019-02-25) Almeida Filho, Daniel Gomes de; Ribeiro, Sidarta Tollendal Gomes; ; ; Tort, Adriano Bretanha Lopes; ; Sameshima, Koichi; ; Moraes, Márcio Flávio Dutra; ; Pereira, Rodrigo Neves Romcy;
Sono e memória são dois aspectos essenciais na vida da maioria dos seres vivos. Durante o sono, nossos músculos e nossos órgãos internos repousam, o gasto de energia é reduzido, nosso sistema imunológico é recuperado e os metabólitos produzidos nos nossos cérebros durante a vigília são expurgados; todas atividades necessárias na preparação do nosso corpo para o próximo dia de experiências. Simultaneamente, a memória é uma função cognitiva que nos permite caracterizar padrões, armazená-los, construir e desenvolver ideias e definir quem somos. Curiosamente, as últimas décadas de pesquisa levaram à noção de que esses dois importantes processos fisiológicos podem andar de mãos dadas; ou seja, que a função do sono na memória não é meramente limpar informações desnecessárias e ajudar passivamente aumentando a relação sinal-ruído. As novas evidências sugerem um protagonismo do sono em trabalhar ativamente no processamento de memória. Além do abundante conjunto de evidências implicando uma fase específica do sono chamada de sono não-REM (movimento ocular rápido, do inglês rapid eye movement – REM) na consolidação da memória, o presente trabalho se concentra no entendimento do mecanismo pelo qual o sono REM beneficia o processamento de memória dependente do hipocampo. Fizemos uma extensa revisão da literatura, projetamos, realizamos e analisamos experimentos visando avançar na compreensão do papel do sono REM no processo de fazer memórias dependentes do hipocampo persistirem e dependerem gradualmente de estruturas neocorticais (corticalização) ao longo do tempo. Nossos resultados indicam que existem janelas temporais especiais relacionadas ao sono REM que auxiliam na promoção da plasticidade e corticalização do traço de memória após o aprendizado, com atenção especial para uma janela precoce 3 a 4 horas após o treinamento, e uma tardia cerca de 12 horas depois. Mostramos evidências de uma interação entre o hipocampo e o córtex retrosplenial (duas regiões intimamente relacionadas ao processamento de memória) durante o sono REM, e que essa interação durante a janela precoce está correlacionada com a expressão da memória. Nós também exibimos evidências que sugerem que o aumento da expressão de genes relacionados à plasticidade sináptica durante o período tardio, que tem sido consistentemente implicados na persistência da memória, pode depender do sono REM. Ao todo, os resultados relatados no presente trabalho suportam a noção de que as janelas de sono REM após o treinamento são importantes para o processamento de memória offline e para a corticalização. Eles também sugerem que os mecanismos da ação do sono REM compreendem a interação entre regiões corticais e subcorticais relacionadas à memória, e promover a expressão gênica induzida pelo aprendizado necessária para a remodelação otimizada de redes corticais, a fim de introduzir novas experiências no cabedal de conhecimento preexistente.
Experience-dependent upregulation of multiple plasticity factors in the hippocampus during early REM sleep
(Elsevier, 2015) Calais, Julien Braga; Ojopi, Elida Benquique; Morya, Edgard; Sameshima, Koichi; Ribeiro, Sidarta Tollendal Gomes
Is expression of synaptic plasticity-related genes modulated by exposure to novelty during subsequent sleep?
(2010-09) Calais, Julien Brag; Ojopi, Elida Benquique; Ribeiro, Sidarta Tollendal Gomes; Morya, Edgard; Nicolelis, Miguel Angelo Laporta; Sameshima, Koichi
Independent lines of evidence support the role of sleep in memory consolidation. However, some contradictory findings have been observed regarding how synaptic plasticity is modulated during sleep. Sleep deprivation studies have shown that the expression of genes related to long-term depression (LTD) is increased during sleep, while the expression of genes related to long-term potentiation (LTP) is increased during waking. However, experiments involving exposure to novelty and/or training in behavioral tasks prior to sleep have shown that immediate early genes (IEG) related to LTP maintenance, such Arc and Egr1, are reinduced during REM sleep. To further explore this question, we examined whether exposure to novelty influences the expression of genes related to LTP (Arc, Bdnf, Creb1, Egr1, Egr2, Fos, Nr4a1) or LTD (Camk4, Ppp2ca, Ppp2r2d). Behaviors and local field potentials (LFPs) were recorded from the hippocampus and primary somatosensory cortex of 30 adult male rats. Recordings were performed before, during and after 20 min of exposure to four novel objects. Animals were prevented from sleeping for 60 minutes after exposure, and were then allowed to sleep freely. Unexposed animals served as negative controls. Immediately after sleep deprivation (waking groups) or thirty minutes after entering sleep (slow wave sleep and REM sleep groups), animals were euthanized, and their brains were dissected into frozen samples of somatosensory cortex and hippocampus. Finally, plasticity-related genes had their expression levels analyzed by real time PCR. A bootstrap non-parametric two-way ANOVA (NANOVA) was performed on the data, followed when appropriate by the Tukey HSD test corrected for the number of comparisons (.α = 0.05). We observed an increase in gene expression in hippocampus of animals that were exposed to novel spatio-sensory stimuli in comparison to control animals after waking (Arc - p=0.001; Egr1 - p=0.005; Fos - p<0.001; Nr4a1 - p=0.006; Ppp2ca - p=0.018) and REM sleep (Arc - p=0.030; Egr1 - p=0.001; Fos - p<0.001; Ppp2ca - p=0.037; Ppp2r2d - p=0.010), but not after slow wave sleep. These findings corroborate the important role of REM sleep for memory consolidation. Most importantly, our results provide pioneering experimental evidence that synaptic potentiation and depression occur concomitantly during REM sleep.
Pitch and duration pattern sequence tests in 7- to 11-year-old children: results depend on response mode
(Journal of the American Academy of Audiology, 2019) Balen, Sheila Andreoli; Moore, David R.; Sameshima, Koichi; https://orcid.org/0000-0003-1353-4362
Background: Pitch pattern sequence (PPS) and duration pattern sequence (DPS) tests are frequently used in the assessment of auditory processing disorder. Current recommendations suggest alternate, interchangeable modes for responding to stimuli. Purpose: The objective of the study is to evaluate the influence of response mode (i.e., humming, pointing, and labeling) and age on PPS and DPS performance of 7- to 11-year-old children. Research Design: Laboratory-based testing of school children. Cross-sectional comparison of age, with repeated measures of age, test, ear, and response mode. Study Sample: From 452 children recruited, 228 right-handed children (109 girls) aged 7 years to 11 years 11 months (mean age 9 years 4 months) completed at least one test (PPS: 211, DPS: 198), and 181 children completed both tests. Audiology inclusion criteria include normal hearing thresholds (≤15 dB HL at octave frequencies 250–8000 Hz); word recognition in quiet ≥92%; tympanogram peak compensated static acoustic compliance 0.4–1.6 mmhos; and tympanometric peak pressure −100 to +50 daPa, all in both ears. Other inclusion criteria were Portuguese as first language; right handed; no musical training; no related, known, or observed phonological, learning, neurologic, psychiatric, or behavioral disorder; otologic history; and delayed neuropsychomotor or language development. Data Collection and Analysis: PPS: 30 trials per ear and response condition of three consecutive 500 msec duration intermixed high (1430 Hz) or low (880 Hz) frequency tones presented monaurally at 50 dB HL. The first response condition was humming followed by labeling (naming: high or low). DPS: As per PPS except 1000 Hz tones of intermixed 500 (long) and 250 msec (short) duration. First response was pointing (at a symbolic object) followed by labeling. Trends across age and between tests were assessed using repeated measures generalized linear mixed models. Correlation coefficients were calculated to assess relations among test scores. The two-sided significance level was 0.05. Results: Older children performed better than younger children in all tasks. Humming the tone pattern (PPS humming) produced generally better performance than either articulating the attributes of the tones (labeling) or pointing to objects representing tone duration. PPS humming produced ceiling performance for many children of all ages. For both labeling tasks and DPS pointing, performance was better on the PPS than on the DPS, for stimulation of the right than the left ear, and in boys than girls. Individual performance on the two tasks was highly correlated. Conclusions: Response mode does matter in the PPS and DPS. Results from humming should not be combined with or be a substitute for results obtained from a labeling response. Tasks that rely on labeling a tonal stimulus should be avoided in testing hearing in children or other special populations.

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Navegando por Autor "Sameshima, Koichi"