R. Koray Çiftçi

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Functional near-infrared spectroscopy (fNIRS) is an emerging technique for monitoring the concentration changes of oxy- and deoxy-hemoglobin (oxy-Hb and deoxy-Hb) in the brain. An important consideration in fNIRS-based neuroimaging modality is to conduct group-level analysis from a set of time series measured from a group of subjects. We investigate the(More)
Functional near-infrared spectroscopy (fNIRS) is an optical imaging method, which monitors the brain activation by measuring the successive changes in the concentration of oxy- and deoxyhemoglobin in real time. In this study, we present a method to investigate the functional connectivity of prefrontal cortex (PFC) Sby applying a Gauss-Markov model to fNIRS(More)
—In this study, we investigate the clustering information of alpha band brain networks during memory load task. For this purpose, short time memory task which includes memory load varieties is implemented to the subjects. To calculate mutual information, time and frequency information is both taken into consideration due to Cohen class time-frequency(More)
We propose a method to do constrained parameter estimation and inference from neuroimaging data using general linear model (GLM). Constrained approach precludes unrealistic hemodynamic response function (HRF) estimates to appear at the outcome of the GLM analysis. The permissible ranges of waveform parameters were determined from the study of a repertoire(More)
Functional clustering is used to identify strongly interacting regions in the brain. In this study, functional clustering approach is applied to near infrared spectroscopy (NIRS) signals obtained during mental arithmetic task. Being a stress inducing task, mental arithmetic is known to cause a right lateral activation in the brain. We hypothesized that(More)
The main hypothesis tested in this study is that cognitive activity causes a change in the complexity of functional near-infrared spectroscopy (fNIRS) signals. We calculated neural complexity (C N) of fNIRS signals obtained during mental arithmetic task and monitored the time course of change in neural complexity. Considerable increases in neu-ral(More)
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