// $Id: background_layer.g,v 16.1 2000/03/02 14:43:39 ajay Exp $
// background_layer.g  HIPPO model
// Used to provide random background activity to the pyr cell network. The level of activity
// is determined by the rate of the randomspike elements.
// Note: Background activity is not provided to ILNs (even though one randomspike and one
//       pulsegen element is created for every pyr cell. See function 'set_bkgnd_conn' below).

// background layer is a layer of pulsegens (one pulsegen for each pyr cell), that gives
// a brief, large depol pulse to pyr cells to make them spike. The pulses are given randomly.
// The pulsegens receive a trigger input from a layer of randomspike elements (one for each
// pulsegen).

// make layer of randomspike elements that trigger the pulsegens
create neutral /library/bkgnd_rs
create  randomspike	/library/bkgnd_rs/randspike
setfield /library/bkgnd_rs/randspike  \
	min_amp		1.0 \
	max_amp		1.0 \
	reset		1 \
	reset_value	0 \ 
	abs_refract     {5e-3}   \   // max rate 200 Hz.
	rate		20  // Hz. This should allow 10% of pop. to be active

createmap /library/bkgnd_rs /bkgnd_rs_layer   {CA3_NX}   {CA3_NY}


// make layer of pulsegen elements that provide depol to pyr cells
create neutral /library/bkgnd_pulse
create      pulsegen      /library/bkgnd_pulse/pulse
setfield      /library/bkgnd_pulse/pulse   \
	level1          1.0e-8 \   // 1e-8, since duration brief, large amp.
	width1          1e-3  \
	delay1          0  \ 
	baselevel       0 \
	trig_mode       1 // ext. trig mode

createmap /library/bkgnd_pulse /bkgnd_pulse_layer   {CA3_NX}   {CA3_NY}

// connect randomspike elements to pulsegens and pulsegens to pyr cells, one-to-one
// Do not provide random input to ILNs (input layer neurons that code afferent input).
function set_bkgnd_conn
  int i

  for (i=num_ILN; i < NPYR; i=i+1) // pyr[0-24] are used as ILN to code 5 patterns
    addmsg /bkgnd_rs_layer/bkgnd_rs[{i}]/randspike   /bkgnd_pulse_layer/bkgnd_pulse[{i}]/pulse \
		INPUT state
    addmsg /bkgnd_pulse_layer/bkgnd_pulse[{i}]/pulse   /pyr_layer/pyr[{i}]/soma \
		INJECT output
  end

end
// set_bkgnd_conn