Ers in Human Neuroscience www.frontiersin.orgMay Volume ArticleMartins et al.Observing PointLights Depicting Postural Adjustements(Figure), totaling presentations of every stimulus.PLD presentation and EEG recordings had been synchronized by way of a digital trigger signal.Every single PLD lasted , ms and was preceded by a fixation cross (interstimulus), presented to get a variable time period (involving , and , ms), to avoid any anticipation or expectancy effects regarding the upcoming animation.The fixation cross was set to help the subjects position their gaze for the duration of the experiment, minimizing eye movements, plus the final ms of this interstimulus period was also applied as a baseline situation.The total duration from the experimental session was roughly min.Soon after the experimental session, the participants were asked about their subjective perception in the balanceimbalance level presented in every biological stimulus, similarly to that described previously (see “Preliminary evaluation with the stimuli” section).To examine the BMS-3 SDS scores obtained from QB and UB, we made use of the nonparametric Wilcoxon test, assuming p .postural adjustments, we applied a statistical strategy similar to that of Foxe and Simpson and Krakowski et al..Pointbypoint pairedT tests (thinking about the whole , ms trial) were calculated amongst EEG time series acquired in each and every condition (quiet vs.unstable) and in each patterns of pointlight motion applied PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/21529310 (biological and scrambled stimuli).Differences have been regarded important only when the following spatialtemporal condition was satisfied let Tk (t) be the Tscore of electrode k at time t, and let Wk (t) be this worth averaged over consecutive time points ( ms), prior to and immediately after t (Equation), Wk (t) neig sTk (t s) .and let Wk (t) be the following average more than the three nearest neighbors of electrode k (equation).WkneigAcquisition on the EEG SignalFor EEG data recording we utilised a channel device (Geodesic HidroCel GSN EGI, Electrical Geodesic Inc) constructed within a soft cap.The signal was amplified by an optic isolated system of higher impedance ( M) with a converter AD of bits, in addition to a nominal gain of x.The acquisition was performed at a sampling frequency of Hz, and the signal was analogically filtered (Butterworth first order bandpass filter of .Hz; Geodesic EEG Method , Electrical Geodesic Inc).The impedance with the electrodes was maintained under k for all the recordings.The electrode positioned on the vertex (Cz) was utilized as a reference for the duration of the acquisition.(t) max Wl (t) Wm (t) Wn (t) , l,m,nPreprocessing from the EEG SignalFirstly, the recorded signal was rereferenced from Cz to the typical reference using NetStation software program (Electrical Geodesic Inc).Following this process, the data was analyzed offline applying EEGLab in MatLab’s atmosphere (Math Performs, Version a).The raw information was segmented in events of , ms, discarding the initial , ms on the fixation cross along with the final , ms from the PLD of each and every occasion.This segment duration was chosen thinking of a window of interest of your 1st , ms following the stimuli onset (see also Hirai et al ; Jokisch et al Krakowski et al Saunier et al).A proportional segment (ms) of fixation cross period was employed to calculate the baseline.Subsequent, a baseline correction was applied making use of the last ms of your fixation cross signal period.Immediately after that, the signal was digitally filtered in a .Hz band (FIR filter) in addition to a notch filter amongst and Hz was applied to reduce electrical interferences from the energy gri.
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