[Eeglablist] Creating epochs related to the gait cycle

[Chesney Craig]

Dear Makoto,

Thank you for your assistance. Yes, I have read a lot of Dr Wagner’s papers, so I would be keen to hear her recommendations too. Our lab is quite new to analysing EEG data, especially mobile EEG.

Kind regards,
Chesney

From: Makoto Miyakoshi [mailto:mmiyakoshi at ucsd.edu]
Sent: 18 February 2017 02:21
To: Chesney Craig <C.Craig at mmu.ac.uk>; Johanna Wagner <joa.wagn at gmail.com>
Cc: eeglablist at sccn.ucsd.edu
Subject: Re: [Eeglablist] Creating epochs related to the gait cycle

Dear Chesney,

I included my colleague Johanna Wagner for her advice. Probably you know her paper. Johanna, please help us here.

The time warping is only valid after time-frequency transform, if I understand correctly. If you stretch or shrink raw time series, it changes frequency! When you compute ERSP, there is 'timewarp' option. This can warp the ERSP results, if it works.

Makoto



On Tue, Feb 14, 2017 at 3:11 AM, Chesney Craig <C.Craig at mmu.ac.uk<mailto:C.Craig at mmu.ac.uk>> wrote:
Hi,

I would like to create epochs time-locked to each gait cycle, as has been done in previous papers (Gwin et al., 2010, 2011).

From my understanding, this was done previously by analysing each gait cycle as a single trial, as EEGLAB doesn’t allow epochs of different lengths. Is this correct?

These trials were then time-warped so that heel strikes occurred at the same adjusted latencies. However, could anyone provide more detail on how to perform such timewarping and what this function does? From my reading on the timewarp function, the original time series and warped time series must be the same length. However, I am unclear as to what this means. Does ‘original time series’ refer to your selected gait cycle to model the others on (e.g. gait cycle 1) and then the function will warp the following gait cycles to the same latencies, which would then result in epochs of the same length?

Following this, I assume I should append the epochs to perform ICA?

Any general advice on creating epochs related to the gait cycle would also be greatly appreciated.

Thanks in advance.

Kind regards,
Chesney Craig

Research Associate
Valentine 1-3
Department of Exercise and Sport Science
Manchester Metropolitan University Cheshire
Crewe Green Road
Crewe
Cheshire
CW1 5DU
Tel: 0161 247 5538

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--
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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