KOICHI SAMESHIMA
Projetos de Pesquisa
Unidades Organizacionais
Departamento de Radiologia, Faculdade de Medicina - Docente
LIM/43 - Laboratório de Medicina Nuclear, Hospital das Clínicas, Faculdade de Medicina - Líder
LIM/43 - Laboratório de Medicina Nuclear, Hospital das Clínicas, Faculdade de Medicina - Líder
31 resultados
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article 19 Citação(ões) na Scopus Alzheimer's disease qEEG Spectral analysis versus coherence. Which is the best measurement?(2011) ANGHINAH, Renato; KANDA, Paulo Afonso Medeiros; LOPES, Helder Frederico; BASILE, Luis Fernando Hindi; MACHADO, Sergio; RIBEIRO, Pedro.; VELASQUES, Bruna; SAMESHIMA, Koichi; TAKAHASHI, Daniel Yasumasa; PINTO, Lecio Figueira; CARAMELLI, Paulo; NITRINI, RicardoThere is evidence in electroencephalography that alpha, theta and delta band oscillations reflect cognitive and memory performances and that quantitative techniques can improve the electroencephalogram (EEG) sensitivity. This paper presents the results of comparative analysis of qEEG variables as reliable markers for Alzheimer's disease (AD). We compared the sensitivity and specificity between spectral analysis (spectA) and coherence (Coh) within the same group of AD patients. SpectA and Coh were calculated from EEGs of 40 patients with mild to moderate AD and 40 healthy elderly controls. The peak of spectA was smaller in the AD group than in controls. AD group showed predominance of slow spectA in theta and delta bands and a significant reduction of inter-hemispheric Coh for occipital alpha 2 and beta 1 and for frontal delta sub-band. ROC curve supported that alpha band spectA was more sensitive than coherence to differentiate controls from AD.- Editorial: Challenges to EEG/MEG graph analysis and how to face them(2023) BLINOWSKA, Katarzyna J.; BACCALA, Luiz A.; KAMINSKI, Maciej; SAMESHIMA, Koichi
- Pitch and Duration Pattern Sequence Tests in 7-to 11-Year-Old Children: Results Depend on Response Mode(2019) BALEN, Sheila Andreoli; MOORE, David R.; SAMESHIMA, KoichiBackground: 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.
- Functional Changes in Cortical Activity of Patients Submitted to Knee Osteoarthritis Treatment An Exploratory Pilot Study(2022) IUAMOTO, Leandro Ryuchi; IMAMURA, Marta; SAMESHIMA, Koichi; MEYER, Alberto; SIMIS, Marcel; BATTISTELLA, Linamara Rizzo; FREGNI, FelipeIntroduction There is evidence that brain plasticity is the central mechanism involved in the functional recovery process of patients with knee osteoarthritis. Studies involving the analysis of central nervous system mechanisms of pain control and recovery could provide more data on future therapeutic approaches. Objective The aim of the study was to explore possible functional changes in cortical activity of patients submitted to knee osteoarthritis standardized pain treatment using electroencephalography. Methodology Ten patients with clinical and radiological diagnosis of painful knee unilateral or bilateral osteoarthritis were recruited to participate in clinical (Pain's Visual Analog Scale), radiological (Kellgren-Lawrence Scale), and neurophysiological (electroencephalography) assessments to evaluate cortical activity during cortical pain modulation activity. The clinical and neurophysiological analyses were performed before and after standardized pain treatment. Results Eight patients participated in this study. A significant improvement in pain perception and relative increase in interhemispheric connectivity after therapies was observed. In electroencephalography analysis, tests with real movement showed a relative increase in density directed at Graph's analysis. Conclusions Relative increase density directed measures at connectivity analysis in electroencephalography after pain treatment can be possible parameters to be explored in future research with a larger number of patients.
- Partial directed coherence: twenty years on some history and an appraisal(2021) BACCALA, Luiz A.; SAMESHIMA, KoichiHere while we reminisce about how partial directed coherence was proposed, its motivation and evolution, we take the opportunity to relate it to some of its kin quantities and some of its offspring. Emphasis is placed on our development of asymptotic criteria to place it as a reliable investigation tool, where the connectivity detection problem is completely solved as opposed to what we call the characterization problem. We end by musing over some points now on our wishlist.
- On Neural Connectivity Estimation Problems(2015) BACCALA, Luiz A.; SAMESHIMA, KoichiAfter briefly recapping and reframing the problem of neural connectivity and its implications for today's brain mapping efforts, we argue that supplementing/replacing traditional conservative correlation based analysis methods requires active user understanding of the aims and limitations of the newly proposed multivariate analysis frameworks before the new methods can gain general acceptance and full profit can be made from the expanded descriptive opportunities they offer.
conferenceObject Functional convergence of parallel circuits within subthalamic nucleus: Intra-operative multichannel-microelectrode recording study during emotional, cognitive and motor tasks(2012) FONOFF, E. T.; EDGAR, M.; SAMESHIMA, K.; TEIXEIRA, M. J.; NICOLELIS, M. A. L.Objective: Demonstrate the convergence of circuit loops of basal ganglia within STN. Background: Specific cortical areas involved in the processing of motor, cognitive and emotional information are connected through parallel circuits to separate territories within basal ganglia suggesting a segregated model of information processing. However, behavioral changes in PD patients after STN DBS in the same subjects who experienced significant motor improvement suggest that the greatest convergence of different circuit loops is reached within STN. Methods: Twelve consecutive PD patients underwent multiunit recording through a 32-channel-microelectrode based in an assembly of microwires used for electrophysiological mapping of STN during stereotactic implantation of DBS electrodes in standard dorsolateral STN target. Once, the neurophysiologist recognized the neuron activity pattern typical of STN, the patient was asked to perform the tasks. Neuronal signal recording was time-locked with the interactive workstation that presented emotional valence images (IAPS Image Bank), a decision-making task and motion performance analysis of the contralateral hand. The signal was submitted to off-line spike-sorting analysis and correlated to behavioral responses to the three-modality tasks. Results: Twelve consecutive PD patients underwent multiunit recording through a 32-channel-microelectrode based in an assembly of microwires used for electrophysiological mapping of STN during stereotactic implantation of DBS electrodes in standard dorsolateral STN target. Once, the neurophysiologist recognized the neuron activity pattern typical of STN, the patient was asked to perform the tasks. Neuronal signal recording was time-locked with the interactive workstation that presented emotional valence images (IAPS Image Bank), a decision-making task and motion performance analysis of the contralateral hand. The signal was submitted to off-line spike-sorting analysis and correlated to behavioral responses to the three-modality tasks. Conclusions: This data is consistent with the hypothesis the basal ganglia modulates motor activity as complex behavioral series that are strongly influenced by the cognitive and emotional context in which they are executed.- Neuronal excitability level transition induced by electrical stimulation(2014) FLORENCE, G.; KURTHS, J.; MACHADO, B. S.; FONOFF, E. T.; CERDEIRA, H. A.; TEIXEIRA, M. J.; SAMESHIMA, K.In experimental studies, electrical stimulation (ES) has been applied to induce neuronal activity or to disrupt pathological patterns. Nevertheless, the underlying mechanisms of these activity pattern transitions are not clear. To study these phenomena, we simulated a model of the hippocampal region CA1. The computational simulations using different amplitude levels and duration of ES revealed three states of neuronal excitability: burst-firing mode, depolarization block and spreading depression wave. We used the bifurcation theory to analyse the interference of ES in the cellular excitability and the neuronal dynamics. Understanding this process would help to improve the ES techniques to control some neurological disorders.
- Brain network dynamics characterization in epileptic seizures(2014) RODRIGUES, A. C.; MACHADO, B. S.; FLORENCE, G.; HAMAD, A. P.; SAKAMOTO, A. C.; FUJITA, A.; BACCALA, L. A.; AMARO JR., E.; SAMESHIMA, K.Here we propose and evaluate a new approach to analyse multichannel mesial temporal lobe epilepsy EEG data from eight patients through complex network and synchronization theories. The method employs a Granger causality test to infer the directed connectivity graphs and a wavelet transform based phase synchronization measure whose characteristics allow studying dynamical transitions during epileptic seizures. We present a new combined graph measure that quantifies the level of network hub formation, called network hub out-degree, which closely reflects the level of synchronization observed during the ictus.
- GWAS of human bitter taste perception identifies new loci and reveals additional complexity of bitter taste genetics(2014) LEDDA, Mirko; KUTALIK, Zoltan; DESTITO, Maria C. Souza; SOUZA, Milena M.; CIRILLO, Cintia A.; ZAMBONI, Amabilene; MARTIN, Nathalie; MORYA, Edgard; SAMESHIMA, Koichi; BECKMANN, Jacques S.; COUTRE, Johannes le; BERGMANN, Sven; GENICK, Ulrich K.Human perception of bitterness displays pronounced interindividual variation. This phenotypic variation is mirrored by equally pronounced genetic variation in the family of bitter taste receptor genes. To better understand the effects of common genetic variations on human bitter taste perception, we conducted a genome-wide association study on a discovery panel of 504 subjects and a validation panel of 104 subjects from the general population of Sao Paulo in Brazil. Correction for general taste-sensitivity allowed us to identify a SNP in the cluster of bitter taste receptors on chr12 (10.88- 11.24 Mb, build 36.1) significantly associated (best SNP: rs2708377, P = 5.31 x 10(-13), r(2) = 8.9%, beta = -0.12, s.e. = 0.016) with the perceived bitterness of caffeine. This association overlaps with-but is statistically distinct from-the previously identified SNP rs10772420 influencing the perception of quinine bitterness that falls in the same bitter taste cluster. We replicated this association to quinine perception (P = 4.97 x 10(-37), r(2) = 23.2%, beta = 0.25, s.e. = 0.020) and additionally found the effect of this genetic locus to be concentration specific with a strong impact on the perception of low, but no impact on the perception of high concentrations of quinine. Our study, thus, furthers our understanding of the complex genetic architecture of bitter taste perception.