: \$Id: netstim.mod,v 1.2 2003/03/31 13:27:47 hines Exp \$ : comments at end NEURON { ARTIFICIAL_CELL stim RANGE y, frequency, number, start, noise, change, event, flag, hey, on, end } PARAMETER { frequency = 1 (1/s) <1e-9,1e9>: mean frequency of spiking = 1000/interval (from netstim.mod) number = 10 <0,1e9> : number of spikes start = 50 (ms) : start of first spike noise = 0 <0,1> : amount of randomeaness (0.0 - 1.0) } ASSIGNED { y event (ms) on end (ms) change (ms) : the frequency will change at thist time, so recalculate hey } PROCEDURE seed(x) { set_seed(x) : VERBATIM : printf("Seed is %g\n", _lx); : ENDVERBATIM } INITIAL { on = 0 y = 0 if (noise < 0) { noise = 0 } if (noise > 1) { noise = 1 } if (start >= 0 && number > 0) { : randomize the first spike so on average it occurs at : start + noise*(1/frequency)*(1000) event = start + invl((1/frequency)*(1000)) - (1/frequency)*(1000)*(1. - noise) : but not earlier than 0 if (event < 0) { event = 0 } if (event > change) { init_sequence(t) net_send(change-t, 4) hey = 4} : next spike is after frequency change, so it must be recalculated else { net_send(event-t, 3) hey = 3} } } PROCEDURE init_sequence(t(ms)) { if (number > 0) { on = 1 event = t end = t + 1e-6 + invl((1/frequency)*(1000))*(number-1) : controls how many spikes are generated by defining mean : time to stop spiking - so with noise = 0, it's exact, with noise number becomes a mean number of spikes } } FUNCTION invl(mean (ms)) (ms) { if (mean <= 0.) { mean = .01 (ms) : I would worry if it were 0. } if (noise == 0) { invl = mean }else{ invl = (1. - noise)*mean + noise*mean*exprand(1) } } PROCEDURE event_time() { if (number > 0) { event = event + invl((1/frequency)*(1000)) } if (event > end) { on = 0 : stop spiking (based on number?) } } NET_RECEIVE (w) { if (flag == 0) { : external event y = 2 net_event(t) : sends event at time t to all processes connected to jstim net_send(.1, 2) : spike ends in 0.1 ms hey = 2 } if (flag == 3) { : from INITIAL if (on == 0) { init_sequence(t) net_send(0, 1) : net_send(interval, flag) is self event to arrive at t+interval hey = 1 } } if (flag == 1 && on == 1) { y = 2 net_event(t) : sends event at time t to all processes connected to jstim event = t event_time() if (event > change) { net_send(change-t, 4) : at time of frequency change, recalculate next spike w/ new frequency hey = 4 } else { if (on == 1) { net_send(event - t, 1) hey = 1 } } net_send(.1, 2) : spike ends in 0.1 ms hey = 2 } if (flag == 2) { y = 0 } if (flag == 4) { event = t event_time() : recalculate next event time with new frequency if (on == 1) { if (event > change) { net_send(change - t, 4) : at time of frequency change, recalculate next spike w/ new frequency hey = 4 } else { net_send(event - t, 1) hey = 1 } } } } COMMENT Presynaptic spike generator --------------------------- This mechanism has been written to be able to use synapses in a single neuron receiving various types of presynaptic trains. This is a "fake" presynaptic compartment containing a spike generator. The trains of spikes can be either periodic or noisy (Poisson-distributed) Parameters; noise: between 0 (no noise-periodic) and 1 (fully noisy) interval: mean time between spikes (ms) number: mean number of spikes Written by Z. Mainen, modified by A. Destexhe, The Salk Institute Modified by Michael Hines for use with CVode The intrinsic bursting parameters have been removed since generators can stimulate other generators to create complicated bursting patterns with independent statistics (see below) Modified by Michael Hines to use logical event style with NET_RECEIVE This stimulator can also be triggered by an input event. If the stimulator is in the on=0 state and receives a positive weight event, then the stimulator changes to the on=1 state and goes through its entire spike sequence before changing to the on=0 state. During that time it ignores any positive weight events. If, in the on=1 state, the stimulator receives a negative weight event, the stimulator will change to the off state. In the off state, it will ignore negative weight events. A change to the on state immediately fires the first spike of its sequence. ENDCOMMENT