Parametric computation and persistent gamma in a cortical model (Chambers et al. 2012)

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Using the Traub et al (2005) model of the cortex we determined how 33 synaptic strength parameters control gamma oscillations. We used fractional factorial design to reduce the number of runs required to 4096. We found an expected multiplicative interaction between parameters.
1 . Chambers JD, Bethwaite B, Diamond NT, Peachey T, Abramson D, Petrou S, Thomas EA (2012) Parametric computation predicts a multiplicative interaction between synaptic strength parameters that control gamma oscillations. Front Comput Neurosci 6:53 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network; Axon; Synapse; Channel/Receptor; Dendrite;
Brain Region(s)/Organism:
Cell Type(s): Neocortex L5/6 pyramidal GLU cell; Neocortex L2/3 pyramidal GLU cell; Neocortex V1 interneuron basket PV GABA cell; Neocortex fast spiking (FS) interneuron; Neocortex spiny stellate cell; Neocortex spiking regular (RS) neuron; Neocortex spiking low threshold (LTS) neuron;
Channel(s): I A; I K; I K,leak; I K,Ca; I Calcium; I_K,Na;
Gap Junctions: Gap junctions;
Receptor(s): GabaA; AMPA; NMDA;
Transmitter(s): Gaba; Glutamate;
Simulation Environment: NEURON;
Model Concept(s): Oscillations; Parameter sensitivity;
Implementer(s): Thomas, Evan [evan at]; Chambers, Jordan [jordandchambers at];
Search NeuronDB for information about:  Neocortex L5/6 pyramidal GLU cell; Neocortex L2/3 pyramidal GLU cell; Neocortex V1 interneuron basket PV GABA cell; GabaA; AMPA; NMDA; I A; I K; I K,leak; I K,Ca; I Calcium; I_K,Na; Gaba; Glutamate;
balcomp.hoc *
defvar.hoc *
lbcreate.hoc *
mscreate.hoc *
traubcon.hoc *
traubcon_net.hoc *
proc load_balanced_create() {local host, gid, usx, sx, si, sb, c, cc, ptree \
  localobj cell, sr
	host =[$1]
	gid = load_balance_.gid.x[$1]
	sx = load_balance_.splitx.x[$1]
	usx = load_balance_.unsplitx.x[$1]
	si = load_balance_.spliti.x[$1]
	sb = load_balance_.splitb.x[$1]

	cell = cells.object(cells.count-1)

	if (sx < 0) { // entirely on this cpu
		c = load_balance_.cell_complexity(cell)
		sr = ldbal_reconnect(si, abs(sb))
// following tests must be carried out with point process complexities in mcomplex.dat = 0
//sr.sec printf("%d a split %s %g %g    %g %g   %d %d %d %d\n",, secname(), usx, c, sx, usx - sx, host, gid, si, sb)
		ptree = 0 if (sb < 0) { ptree = 1 }
		ldbal_split(sr, host, gid, ptree, cell)
//c = load_balance_.cell_complexity(cell)
//if (host == { cc = sx } else { cc = usx - sx }
//ptree = 0 if (!pc.gid_exists(gid)) ptree = 1
//printf("%d split %s %d %d %g %g\n",, cell, gid, ptree, c, cc)

//reconnect so a split at the returned
// SectionRef corresponds to the complexity desired
// ptree = 1 means the parent tree will go on the host
obfunc ldbal_reconnect() {local i  localobj sp, bs, sr, sc
	ip = load_balance_.parent_vec_.x[$1]
	if (ip  == -1) {
		execerror("cannot split at original root", "")
	sp = load_balance_.secref(ip)
	// the branch set (in the proper order)
	bs = load_balance_.parent_vec_.indvwhere("==", ip)
	// disconnect all the children
	// assume all children effectively connected at their 0 end to the trueparent
	// at the 1 end
	for i=0, bs.size-1 {
		sr = load_balance_.secref(bs.x[i])
		sr.sec { disconnect() }
	if ($2 <= bs.size) { // is it an individual?
		// then all get connected to the trueparent and return
		// the individual
		for i=0, bs.size-1 {
			sr = load_balance_.secref(bs.x[i])
			sp.sec connect sr.sec (0), 1
		sc = load_balance_.secref(bs.x[$2-1])
	}else{ // it is a sum
		sc = load_balance_.secref(bs.x[0])
		sp.sec connect sc.sec (0), 1
		n = $2 - bs.size // 1 means 0+1
		for i=1, n { // connect to the 0 child
			sr = load_balance_.secref(bs.x[i])
			sc.sec connect sr.sec (0), 0
		for i=n+1, bs.size-1 { // connect to the trueparent
			sr = load_balance_.secref(bs.x[i])
			sp.sec connect sr.sec (0), 1
	return sc

proc ldbal_split() {
	if ($4 == 0) {
		$o1.sec pnm.splitcell($2, $2+1)
		$o1.sec pnm.splitcell($2+1, $2)
	if (section_exists("comp", $o5.presyn_comp ,$o5)) {
		pc.set_gid2node($3 + splitbit,
		gidvec.append($3 + splitbit)

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