// .277 ms
bool neuron_state_update( REAL exc_input, REAL inh_input, neuron_pointer_t neuron ) {
bool spike = false;
REAL V_last = neuron->V_membrane;
neuron->refract_timer -= refractory_time_update; // countdown refractory timer
if( neuron->refract_timer < 1 ) { // test for outside refractory time
input_this_timestep = exc_input - inh_input + neuron->I_offset; // now adding offset current - all need to be in nA
lif_neuron_closed_form( neuron, V_last, -neuron->refract_timer );
// ode_solve_fix_ss_expl( RK_METHOD, NO_OF_EXPL_FIX_STEPS, EXPL_FIX_STEP_SIZE, neuron );
// ode_solve_fix_ss_expl_rk2_v1( NO_OF_EXPL_FIX_STEPS, EXPL_FIX_STEP_SIZE, neuron );
spike = REAL_COMPARE( neuron->V_membrane, >=, neuron->V_thresh ); // has it spiked?
#ifdef CORRECT_FOR_THRESHOLD_GRANULARITY
if( spike ) {
REAL A, B, thresh;
// calculate the two simple linear indicators of where the threshold was cut
thresh = neuron->V_thresh;
A = neuron->V_membrane - thresh;
B = thresh - V_last;
if ( A >= 2*B ) neuron->prev_spike_code = 2; // it spiked in first third
else if ( B >= 2*A ) neuron->prev_spike_code = 0; // it spiked in last third
else neuron->prev_spike_code = 1; // it spiked near middle
// io_printf( IO_STD, " A %9.4k B %9.4k code %u \n", A, B, neuron->prev_spike_code );
neuron_discrete_changes( neuron );
}
#else // works for both no correction and simple correction case
if( spike ) neuron_discrete_changes( neuron );
#endif
}
bool neuron_state_update( REAL exc_input, REAL inh_input, REAL external_bias, neuron_pointer_t neuron ) {
input_this_timestep = exc_input - inh_input + external_bias + neuron->I_offset; // all need to be in nA
rk2_kernel_midpoint( neuron->this_h, neuron ); // the best AR update so far
// create noisy membrane voltage by adding Gaussian noise with SD = membrane_noise_sd
REAL noisy_membrane = neuron->V + norminv_urb( mars_kiss32() ) * neuron->membrane_noise_sd;
// compare noisy membrane voltage with threshold
bool spike = REAL_COMPARE( noisy_membrane, >=, V_threshold );
if( spike ) {
neuron_discrete_changes( neuron );
neuron->this_h = machine_timestep * SIMPLE_TQ_OFFSET; //REAL_CONST( 1.85 ); // simple threshold correction - next timestep (only) gets a bump
}
else
neuron->this_h = machine_timestep;
return spike;
}
