trigavg

Vector

SYNTAX

v1.trigavg(data,trigger,pre,post)

DESCRIPTION

Perform an event-triggered average of <data> using times given by <trigger>. The duration of the average is from -<pre> to <post>. This is useful, for example, in calculating a spike triggered stimulus average.

spikebin

Vector

SYNTAX

v.spikebin(data,thresh)

DESCRIPTION

Used to make a binary version of a spike train. <data> is a vector of membrane potential. <thresh> is the voltage threshold for spike detection. <v> is set to all zeros except at the onset of spikes (the first dt which the spike crosses threshold)

psth

Vector

SYNTAX

vmeanfreq = vdest.psth(vsrchist,dt,trials,size)

DESCRIPTION

The name of this function is somewhat misleading, since its input, vsrchist, is a finely-binned post-stimulus time histogram, and its output, vdest, is an array whose elements are the mean frequencies f_mean[i] that correspond to each bin of vsrchist.

For bin i, the corresponding mean frequency f_mean[i] is determined by centering an adaptive square window on i and widening the window until the number of spikes under the window equals size. Then f_mean[i] is calculated as

f_mean[i] = N[i] / (m dt trials)

where 

  f_mean[i] is in spikes per _second_ (Hz).
  N[i] = total number of events in the window
           centered on bin i
  m = total number of bins in the window
           centered on bin i
  dt = binwidth of vsrchist in _milliseconds_
           (so m dt is the width of the window in milliseconds)
  trials = an integer scale factor

trials is used to adjust for the number of traces that were superimposed to compute the elements of vsrchist. In other words, suppose the elements of vsrchist were computed by adding up the number of spikes in n traces 

              n
  v1.x[i] = SUMMA # of spikes in bin i of trace j
            j = 1
Then trials would be assigned the value n. Of course, if the elements of vsrchist are divided by n before calling psth(), then trials should be set to 1.

Acknowledgment: The documentation and example for psth was prepared by Ted Carnevale.

BUGS

The total number of spikes in vsrchist must be greater than size.

EXAMPLES

execute following example 
VECSIZE = 200
MINSUM = 50
DT = 1000	// ms per bin of v1 (vsrchist)
TRIALS = 1

objref v1, v2
v1 = new Vector(VECSIZE)
  
objref r
r = new Random()
           
  
for (ii=0; ii<VECSIZE; ii+=1) {
	v1.x[ii] = int(r.uniform(0,10))
}
v1.plot(g1)

v2 = new Vector()
v2.psth(v1,DT,TRIALS,MINSUM)
v2.plot(g2)

inf

Vector

SYNTAX

v.inf(i,dt,gl,el,cm,th,res,[ref])

DESCRIPTION

Simulate a leaky integrate and fire neuron. <i> is a vector containing the input. <dt> is the timestep. <gl> and <el> are the conductance and reversal potential of the leak term <cm> is capacitance. <th> is the threshold voltage and <res> is the reset voltage. <ref>, if present sets the duration of ab absolute refractory period. N.b. Currently working with forward Euler integration, which may give spurious results.

resample

Vector

SYNTAX

v1.resample(v2,rate)

DESCRIPTION

Resamples the vector at another rate -- integers work best.

SEE ALSO

copy

neuron/general/classes/vector/vneur.hel : May 13 2012