


Multi-taper coherency matrix - point process times
Usage:
[C,phi,S12,f,zerosp,confC,phistd,Cerr]=cohmatrixpt(data,params,fscorr)
Input:
data (structure array of spike times with dimension channels) - required
params: structure with fields tapers, pad, Fs, fpass, err
- optional
tapers (precalculated tapers from dpss, or in the form [NW K] e.g [3 5]) -- optional. If not
specified, use [NW K]=[3 5]
pad (padding factor for the FFT) - optional (can take values -1,0,1,2...).
-1 corresponds to no padding, 0 corresponds to padding
to the next highest power of 2 etc.
e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT
to 512 points, if pad=1, we pad to 1024 points etc.
Defaults to 0.
Fs (sampling frequency) - optional. Default 1.
fpass (frequency band to be used in the calculation in the form
[fmin fmax])- optional.
Default all frequencies between 0 and Fs/2
err (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars
[0 p] or 0 - no error bars) - optional. Default 0.
fscorr (finite size corrections, 0 (don't use finite size corrections) or 1 (use finite size corrections) - optional
(available only for spikes). Defaults 0.
Output:
C (magnitude of coherency frequency x channels x channels)
phi (phase of coherency frequency x channels x channels)
S12 (cross-spectral matrix frequency x channels x channels)
f (frequencies)
zerosp (1 for channels where no spikes were found, zero otherwise)
confC (confidence level for C at 1-p %) - only for err(1)>=1
phistd - theoretical/jackknife (depending on err(1)=1/err(1)=2) standard deviation for phi - Note that
phi + 2 phistd and phi - 2 phistd will give 95% confidence
bands for phi - only for err(1)>=1
Cerr (Jackknife error bars for C - use only for Jackknife - err(1)=2)

0001 function [C,phi,S12,f,zerosp,confC,phistd,Cerr]=cohmatrixpt(data,params,fscorr) 0002 % Multi-taper coherency matrix - point process times 0003 % 0004 % Usage: 0005 % 0006 % [C,phi,S12,f,zerosp,confC,phistd,Cerr]=cohmatrixpt(data,params,fscorr) 0007 % Input: 0008 % data (structure array of spike times with dimension channels) - required 0009 % params: structure with fields tapers, pad, Fs, fpass, err 0010 % - optional 0011 % tapers (precalculated tapers from dpss, or in the form [NW K] e.g [3 5]) -- optional. If not 0012 % specified, use [NW K]=[3 5] 0013 % pad (padding factor for the FFT) - optional (can take values -1,0,1,2...). 0014 % -1 corresponds to no padding, 0 corresponds to padding 0015 % to the next highest power of 2 etc. 0016 % e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT 0017 % to 512 points, if pad=1, we pad to 1024 points etc. 0018 % Defaults to 0. 0019 % Fs (sampling frequency) - optional. Default 1. 0020 % fpass (frequency band to be used in the calculation in the form 0021 % [fmin fmax])- optional. 0022 % Default all frequencies between 0 and Fs/2 0023 % err (error calculation [1 p] - Theoretical error bars; [2 p] - Jackknife error bars 0024 % [0 p] or 0 - no error bars) - optional. Default 0. 0025 % fscorr (finite size corrections, 0 (don't use finite size corrections) or 1 (use finite size corrections) - optional 0026 % (available only for spikes). Defaults 0. 0027 % Output: 0028 % C (magnitude of coherency frequency x channels x channels) 0029 % phi (phase of coherency frequency x channels x channels) 0030 % S12 (cross-spectral matrix frequency x channels x channels) 0031 % f (frequencies) 0032 % zerosp (1 for channels where no spikes were found, zero otherwise) 0033 % confC (confidence level for C at 1-p %) - only for err(1)>=1 0034 % phistd - theoretical/jackknife (depending on err(1)=1/err(1)=2) standard deviation for phi - Note that 0035 % phi + 2 phistd and phi - 2 phistd will give 95% confidence 0036 % bands for phi - only for err(1)>=1 0037 % Cerr (Jackknife error bars for C - use only for Jackknife - err(1)=2) 0038 0039 if isstruct(data) 0040 Ch=length(data); 0041 if Ch==1; error('Need at least 2 channels'); end; 0042 else 0043 error('Need at least two channels of data in the a structural array'); 0044 end; 0045 if nargin < 2; params=[]; end; 0046 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params); 0047 clear trialave params 0048 if nargin < 3 || isempty(fscorr); fscorr=0; end; 0049 0050 [mintime,maxtime]=minmaxsptimes(data); 0051 dt=1/Fs; % sampling time 0052 t=mintime:dt:maxtime+dt; % time grid for prolates 0053 N=length(t); % number of points in grid for dpss 0054 nfft=max(2^(nextpow2(N)+pad),N); % number of points in fft of prolates 0055 [f,findx]=getfgrid(Fs,nfft,fpass); % get frequency grid for evaluation 0056 tapers=dpsschk(tapers,N,Fs); % check tapers 0057 [J,Msp,Nsp]=mtfftpt(data,tapers,nfft,t,f,findx); % mt fft for point process times 0058 C1=size(J,3); 0059 zerosp=zeros(1,C1); % initialize the zerosp variable 0060 zerosp(Nsp==0)=0; % set the zerosp variable 0061 if err(1)==0; 0062 [C,phi,S12]=cohmathelper(J,err); 0063 elseif err(1)==1; 0064 if fscorr==0; 0065 [C,phi,S12,confC,phistd]=cohmathelper(J,err); 0066 else 0067 [C,phi,S12,confC,phistd]=cohmathelper(J,err,Nsp); 0068 end; 0069 elseif err(1)==2; 0070 if fscorr==0; 0071 [C,phi,S12,confC,phistd,Cerr]=cohmathelper(J,err); 0072 else 0073 [C,phi,S12,confC,phistd,Cerr]=cohmathelper(J,err,Nsp); 0074 end; 0075 end 0076 clear Msp