//genesis
/* FILE INFORMATION
** The 1991 Traub set of voltage and concentration dependent channels
** Implemented as tabchannels by : Dave Beeman
** R.D.Traub, R. K. S. Wong, R. Miles, and H. Michelson
** Journal of Neurophysiology, Vol. 66, p. 635 (1991)
**
** This file depends on functions and constants defined in defaults.g
** As it is also intended as an example of the use of the tabchannel
** object to implement concentration dependent channels, it has extensive
** comments. Note that the original units used in the paper have been
** converted to SI (MKS) units. Also, we define the ionic equilibrium
** potentials relative to the resting potential, EREST_ACT. In the
** paper, this was defined to be zero. Here, we use -0.060 volts, the
** measured value relative to the outside of the cell.
*/
/* November 1999 update for GENESIS 2.2: Previous versions of this file used
a combination of a table, tabgate, and vdep_channel to implement the
Ca-dependent K Channel - K(C). This new version uses the new tabchannel
"instant" field, introduced in GENESIS 2.2, to implement an
"instantaneous" gate for the multiplicative Ca-dependent factor in the
conductance. This allows these channels to be used with the fast
hsolve chanmodes > 1.
*/
// Now updated for Traub et al. J Neurophysiol 2003;89:909-921.
// And for LTS and FS interneurons - Cunningham et al. PNAS 2004;101:7152-7157.
// CONSTANTS
float EREST_ACT = -0.070 /* cell resting potential */
float ENATCR = 0.120 + EREST_ACT // 0.050
float EKTCR = -0.025 + EREST_ACT // -0.095
float ECATCR = 0.195 + EREST_ACT // 0.125
float EARTCR = 0.035 + EREST_ACT // -0.035
float SOMA_A = 3.320e-9 // soma area in square meters
/*
For these channels, the maximum channel conductance (Gbar) has been
calculated using the CA3 soma channel conductance densities and soma
area. Typically, the functions which create these channels will be used
to create a library of prototype channels. When the cell reader creates
copies of these channels in various compartments, it will set the actual
value of Gbar by calculating it from the cell parameter file.
*/
//========================================================================
// Tabchannel gNa-transient, gNa(F) 2005/03
//========================================================================
function make_NaF20
if ({exists NaF20})
return
end
create tabchannel NaF20
setfield NaF20 \
Ek 0.05 \
Ik 0 \
Xpower 3 \
Ypower 1
setfield NaF20 \
Gbar 1875 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call NaF20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
if ({ v - 5.5 } < -30 )
tau = 0.025 + 0.14 * { exp { {{v - 5.5} + 30} / 10} }
else
tau = 0.02 + {0.145} * { exp { -1 * {{v - 5.5} + 30} / 10} }
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
v = v * 1000 // v to units of equation
inf = 1 / { 1 + {exp { { -1 * {v - 5.5} - 38} / 10}} }
v = v * 0.001 // reset v
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield NaF20 X_A->table[{i}] {alpha}
setfield NaF20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield NaF20 X_A->calc_mode 1 X_B->calc_mode 1
// Creating table for gate h, using name Y for it here
float dv = ({v_max} - {v_min})/{tab_divs}
call NaF20 TABCREATE Y {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
tau = 0.15 + 1.15 / { 1 + { exp {{ v + 37 } / 15} } }
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
v = v * 1000 // v to units of equation
inf = 1 / { 1 + {exp {{v + 55.9} / 10.7}} }
v = v * 0.001 // reset v
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield NaF20 Y_A->table[{i}] {alpha}
setfield NaF20 Y_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield NaF20 Y_A->calc_mode 1 Y_B->calc_mode 1
end
//========================================================================
// Tabchannel gNa-persistent (non-inactivating), gNa(P) 2005/03
//========================================================================
function make_NaP20
if ({exists NaP20})
return
end
create tabchannel NaP20
setfield NaP20 \
Ek 0.05 \
Ik 0 \
Xpower 1
setfield NaP20 \
Gbar 1875 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call NaP20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
if ({ v + 7 } < -30 )
tau = 0.025 + 0.14 * { exp { {{v + 7} + 30} / 10} }
else
tau = 0.02 + 0.145 * { exp { -1 * {{v + 7} + 30} / 10} }
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
v = v * 1000 // v to units of equation
inf = 1 / { 1 + {exp { { -1 * {v + 7} - 38} / 10}} }
v = v * 0.001 // reset v
//alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield NaP20 X_A->table[{i}] {alpha}
setfield NaP20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield NaP20 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Tabchannel Anomalous Rectifier, gAR 2005/03
//========================================================================
function make_AR20
if ({exists AR20})
return
end
create tabchannel AR20
setfield AR20 \
Ek -0.035 \
Ik 0 \
Xpower 1
setfield AR20 \
Gbar 2.5 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call AR20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // temporarily set v to units of equation...
tau = 1 /{{exp {-14.6 - {0.086 * v} }} + {exp {-1.87 + {0.07 * v}}}}
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = 5.5, Vhalf = -75, in physiological units
// A = 1, B = 0.0055, Vhalf = -0.075
inf = 1 / ( {exp {(v + 0.075) / 0.0055}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield AR20 X_A->table[{i}] {alpha}
setfield AR20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield AR20 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Tabchannel gK-delayed rectifier, gK(DR) 2005/03
//========================================================================
function make_KDR20
if ({exists KDR20})
return
end
create tabchannel KDR20
setfield KDR20 \
Ek -0.095 \
Ik 0 \
Xpower 4
setfield KDR20 \
Gbar 1250 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KDR20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
if (v < -10 )
tau = 0.25 + 4.35 * {exp {{ v + 10 }/10}}
else
tau = 0.25 + 4.35 * {exp {{- v - 10}/ 10}}
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = -10, Vhalf = -29.5, in physiological units
// A = 1, B = -0.01, Vhalf = -0.0295
inf = 1 / ( {exp {(v + 0.0295) / -0.01}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield KDR20 X_A->table[{i}] {alpha}
setfield KDR20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KDR20 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Tabchannel gK-transient, gK(A) 2005/03
//========================================================================
function make_KA20
if ({exists KA20})
return
end
create tabchannel KA20
setfield KA20 \
Ek -0.095 \
Ik 0 \
Xpower 4 \
Ypower 1
setfield KA20 \
Gbar 300 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KA20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
tau = 0.185 + 0.5 / {{exp {{ v + 35.8 }/19.7}} + {exp {{-v - 79.7}/12.7}}}
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = -8.5, Vhalf = -60, in physiol units
// A = 1, B = -0.0085, Vhalf = -0.06
inf = 1 / ( {exp {(v + 0.06) / -0.0085}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield KA20 X_A->table[{i}] {alpha}
setfield KA20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KA20 X_A->calc_mode 1 X_B->calc_mode 1
// Creating table for gate h, using name Y for it here
float dv = ({v_max} - {v_min})/{tab_divs}
call KA20 TABCREATE Y {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // temporarily set v to units of equation...
if (v < -63.0 )
tau = 0.5 / {{exp {{ v + 46 }/5}} + {exp {{ -v - 238 }/37.5}}}
else
tau = 9.5
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = 6, Vhalf = -78, in physiol units
// A = 1, B = 0.006, Vhalf = -0.078
inf = 1 / ( {exp {(v + 0.078) / 0.006}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield KA20 Y_A->table[{i}] {alpha}
setfield KA20 Y_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KA20 Y_A->calc_mode 1 Y_B->calc_mode 1
end
//========================================================================
// Tabchannel gK2-slow, gK2 2005/03
//========================================================================
function make_K220
if ({exists K220})
return
end
create tabchannel K220
setfield K220 \
Ek -0.095 \
Ik 0 \
Xpower 1 \
Ypower 1
setfield K220 \
Gbar 1 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call K220 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation...
tau = 4.95 + 0.5 / { {exp { {v - 81} / 25.6}} + {exp { {- v - 132} / 18 }}}
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = -17, Vhalf = -10, in physiol units
// A = 1, B = -0.017, Vhalf = -0.01
inf = 1 / ( {exp {(v + 0.01) / -0.017}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield K220 X_A->table[{i}] {alpha}
setfield K220 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield K220 X_A->calc_mode 1 X_B->calc_mode 1
// Creating table for gate h, using name Y for it here
float dv = ({v_max} - {v_min})/{tab_divs}
call K220 TABCREATE Y {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // temporarily set v to units of equation...
tau = 60 + 0.5 / {{exp {{ v - 1.33 }/200}} + {exp {{- v - 130}/ 7.1}}}
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = 10.6, Vhalf = -58, in physiol units
// A = 1, B = 0.0106, Vhalf = -0.058
inf = 1 / ( {exp {(v + 0.058) / 0.0106}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield K220 Y_A->table[{i}] {alpha}
setfield K220 Y_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield K220 Y_A->calc_mode 1 Y_B->calc_mode 1
end
//========================================================================
// Tabchannel gK-muscarinic receptor supressed, gK(M) 2005/03
//========================================================================
function make_KM20
if ({exists KM20})
return
end
create tabchannel KM20
setfield KM20 \
Ek -0.095 \
Ik 0 \
Xpower 1
setfield KM20 \
Gbar 75 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KM20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// alpha
float alpha
// A = 0.02, B = -5, Vhalf = -20, in physiol units
// A = 20, B = -0.005, Vhalf = -0.02
alpha = 20 / ( {exp {(v + 0.02) / -0.005}} + 1)
// beta
float beta
// A = 0.01, B = -18, Vhalf = -43, in physiol units
// A = 10, B = -0.018, Vhalf = -0.043
beta = 10 * {exp {(v + 0.043) / -0.018}}
// alpha and beta
float tau = 1/(alpha + beta)
setfield KM20 X_A->table[{i}] {alpha}
setfield KM20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KM20 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Tabchannel gCa(L)-low threshold, transient, gCa(L) 2005/03
//========================================================================
function make_CaL20
if ({exists CaL20})
return
end
create tabchannel CaL20
setfield CaL20 \
Ek 0.125 \
Ik 0 \
Xpower 2 \
Ypower 1
setfield CaL20 \
Gbar 1 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call CaL20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // v to units of equation
tau = 0.204 + 0.333 / { {exp {{v + 15.8} / 18.2 }} + {exp {{- v - 131} / 16.7}} }
v = v * 0.001 //reset v
// Set correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = -6.2, Vhalf = -56.0, in physiol units
// A = 1, B = -0.0062, Vhalf = -0.056
inf = 1 / ( {exp {(v + 0.056) / -0.0062}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield CaL20 X_A->table[{i}] {alpha}
setfield CaL20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield CaL20 X_A->calc_mode 1 X_B->calc_mode 1
// Y table for gate h
float dv = ({v_max} - {v_min})/{tab_divs}
call CaL20 TABCREATE Y {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// tau
float tau
v = v * 1000 // temporarily set v to units of equation...
if (v < -81.0 )
tau = 0.333 * {exp {{ v + 466 } / 66.6}}
else
tau = 9.32 + 0.333 * {exp {{ - v - 21 } / 10.5}}
end
v = v * 0.001 // reset v
// correct units of tau
tau = tau * 0.001
// inf
float inf
// A = 1, B = 4, Vhalf = -80, in physiological units
// A = 1, B = 0.004, Vhalf = -0.08
inf = 1 / ( {exp {(v + 0.08) / 0.004}} + 1)
// alpha and beta
float alpha
float beta
alpha = inf / tau
beta = (1- inf)/tau
setfield CaL20 Y_A->table[{i}] {alpha}
setfield CaL20 Y_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield CaL20 Y_A->calc_mode 1 Y_B->calc_mode 1
end
//==========================================================================
// Tabchannel gCaH-high threshold calcium, gCa(L) "long" 2003/05
//==========================================================================
function make_CaH20
if ({exists CaH20})
return
end
create tabchannel CaH20
setfield CaH20 \
Ek 0.125 \
Ik 0 \
Xpower 2
setfield CaH20 \
Gbar 5 \
Gk 0
float tab_divs = 741
float v_min = -0.12
float v_max = 0.06
float v, dv, i
// X table for gate me
float dv = ({v_max} - {v_min})/{tab_divs}
call CaH20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// alpha
float alpha
// A = 1.6, B = -13.888889, Vhalf = 5 in physiological units
// A = 1600, B = -0.013888889000000001, Vhalf = 0.005
alpha = 1600 / ( {exp {(v - 0.005) / -0.013888889000000001}} + 1)
// beta
float beta
// A = 0.1, B = -5, Vhalf = -8.9, in physiol units
// A = 100, B = -0.005, Vhalf = -0.0089
if ( {abs {(v + 0.0089)/ -0.005}} < 1e-6)
beta = 100 * (1 + (v + 0.0089)/-0.005/2)
else
beta = 100 * ((v + 0.0089) / -0.005) /(1 - {exp {-1 * (v + 0.0089)/-0.005}})
end
// alpha and beta & tabels
float tau = 1/(alpha + beta)
setfield CaH20 X_A->table[{i}] {alpha}
setfield CaH20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield CaH20 X_A->calc_mode 1 X_B->calc_mode 1
end
//========================================================================
// Ca conc, Traub et al. J Neurophysiol 2003;89:909-921.
//========================================================================
/****************************************************************************
Next, we need an element to take the Calcium current calculated by the Ca
channel and convert it to the Ca concentration. The "Ca_concen" object
solves the equation dC/dt = B*I_Ca - C/tau, and sets Ca = Ca_base + C. As
it is easy to make mistakes in units when using this Calcium diffusion
equation, the units used here merit some discussion.
With Ca_base = 0, this corresponds to Traub's diffusion equation for
concentration, except that the sign of the current term here is positive, as
GENESIS uses the convention that I_Ca is the current flowing INTO the
compartment through the channel. In SI units, the concentration is usually
expressed in moles/m^3 (which equals millimoles/liter), and the units of B
are chosen so that B = 1/(ion_charge * Faraday * volume). Current is
expressed in amperes and one Faraday = 96487 coulombs. However, in this
case, Traub expresses the concentration in arbitrary units, current in
microamps and uses tau = 13.33 msec (50 msec soma, 20 msec dendrites in the
2003 J Neurophys paper). If we use the same concentration units,
but express current in amperes and tau in seconds, our B constant is then
10^12 times the constant (called "phi") used in the paper. The actual value
used will typically be determined by the cell reader from the cell
parameter file (will vary inversely with surface area of compartment).
However, for the prototype channel we wlll use Traub's
corrected value for the soma. (An error in the paper gives it as 17,402
rather than 17.402.) In our units, this will be 17.402e12.
****************************************************************************/
function make_Ca_s20
if ({exists Ca_s20})
return
end
create Ca_concen Ca_s20
setfield Ca_s20 \
tau { 1.0 / 20 } \
Ca_base 0
addfield Ca_s20 addmsg1
setfield Ca_s20 \
addmsg1 "../CaH20 . I_Ca Ik"
// addfield Ca_s20 addmsg2
// setfield Ca_s20 \
// addmsg2 "../CaL20 . I_Ca Ik"
end
/*
This Ca_concen element should receive an "I_Ca" message from the calcium
channel, accompanied by the value of the calcium channel current. As we
will ordinarily use the cell reader to create copies of these prototype
elements in one or more compartments, we need some way to be sure that the
needed messages are established. Although the cell reader has enough
information to create the messages which link compartments to their channels
and to other adjacent compartments, it must be provided with the information
needed to establish additional messages. This is done by placing the
message string in a user-defined field of one of the elements which is
involved in the message. The cell reader recognizes the added field names
"addmsg1", "addmsg2", etc. as indicating that they are to be
evaluated and used to set up messages. The paths are relative to the
element which contains the message string in its added field. Thus,
"../Ca_hip_traub91" refers to the sibling element Ca_hip_traub91 and "."
refers to the Ca_hip_conc element itself.
*/
/****************************************************************************/
function make_Ca_d20
if ({exists Ca_d20})
return
end
create Ca_concen Ca_d20
setfield Ca_d20 \
tau { 1.0 / 50 } \
Ca_base 0
addfield Ca_d20 addmsg1
setfield Ca_d20 \
addmsg1 "../CaH20 . I_Ca Ik"
// addfield Ca_d20 addmsg2
// setfield Ca_d20 \
// addmsg2 "../CaL20 . I_Ca Ik"
end
/*
This Ca_concen element should receive an "I_Ca" message from the calcium
channel, accompanied by the value of the calcium channel current. As we
will ordinarily use the cell reader to create copies of these prototype
elements in one or more compartments, we need some way to be sure that the
needed messages are established. Although the cell reader has enough
information to create the messages which link compartments to their channels
and to other adjacent compartments, it must be provided with the information
needed to establish additional messages. This is done by placing the
message string in a user-defined field of one of the elements which is
involved in the message. The cell reader recognizes the added field names
"addmsg1", "addmsg2", etc. as indicating that they are to be
evaluated and used to set up messages. The paths are relative to the
element which contains the message string in its added field. Thus,
"../Ca_hip_traub91" refers to the sibling element Ca_hip_traub91 and "."
refers to the Ca_hip_conc element itself.
*/
//===============================================================================
// Ca-dependent K Channel - K(C) - (vdep_channel with table and tabgate)2005/03
//===============================================================================
/*
The expression for the conductance of the potassium C-current channel has a
typical voltage and time dependent activation gate, where the time dependence
arises from the solution of a differential equation containing the rate
parameters alpha and beta. It is multiplied by a function of calcium
concentration that is given explicitly rather than being obtained from a
differential equation. Therefore, we need a way to multiply the activation
by a concentration dependent value which is determined from a lookup table.
This is accomplished by using the Z gate with the new tabchannel "instant"
field, introduced in GENESIS 2.2, to implement an "instantaneous" gate for
the multiplicative Ca-dependent factor in the conductance.
*/
function make_KCs20
if ({exists KCs20})
return
end
create tabchannel KCs20
setfield KCs20 \
Ek -0.095 \
Ik 0 \
Xpower 1 \
Zpower 1
setfield KCs20 \
Gbar 120 \
Gk 0
float tab_divs = 1041
float v_min = -0.12
float v_max = 0.14
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KCs20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// alpha
float alpha
v = v * 1000 // v to units of equation
if (v < -10 )
alpha = {2 / 37.95} * { exp { {{v + 50 } / 11} - {{ v + 53.5} / 27} } }
else
alpha = 2 * {exp { { {-1 * v} - 53.5 } / 27 }}
end
v = v * 0.001 // reset v
// correct units of alpha
alpha = alpha * 1000
// beta
float beta
v = v * 1000 // v to units of equation
alpha = alpha * 0.001 // alpha to units of equation
if (v < -10 )
beta = 2 * {exp { { {-1 * v} - 53.5 } / 27 }} - alpha
else
beta = 0.0
end
v = v * 0.001 // reset v
alpha = alpha * 1000 // resetting alpha
// correct units of beta
beta = beta * 1000
// alpha and beta
float tau = 1/(alpha + beta)
setfield KCs20 X_A->table[{i}] {alpha}
setfield KCs20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KCs20 X_A->calc_mode 1 X_B->calc_mode 1
// voltage indep. concentration var
float conc_min = 0
float conc_max = 1000
float dc = ({conc_max} - {conc_min})/{tab_divs}
float ca_conc = {conc_min}
call KCs20 TABCREATE Z {tab_divs} {conc_min} {conc_max}
float const_state
for (i = 0; i <= ({tab_divs}); i = i + 1)
ca_conc = ca_conc * 0.000001 // ca_conc to units of equation
if (ca_conc < 0.00025 )
const_state = {ca_conc / 0.00025}
else
const_state = 1
end
ca_conc = ca_conc * 1000000 // reset ca_conc
setfield KCs20 Z_A->table[{i}] {0}
setfield KCs20 Z_B->table[{i}] {const_state}
ca_conc= ca_conc + dc
end
tweaktau KCs20 Z
addfield KCs20 addmsg1
setfield KCs20 addmsg1 "../Ca_s20 . CONCEN Ca"
end
function make_KCd20
if ({exists KCd20})
return
end
create tabchannel KCd20
setfield KCd20 \
Ek -0.095 \
Ik 0 \
Xpower 1 \
Zpower 1
setfield KCd20 \
Gbar 120 \
Gk 0
float tab_divs = 1041
float v_min = -0.12
float v_max = 0.14
float v, dv, i
// X table for gate m
float dv = ({v_max} - {v_min})/{tab_divs}
call KCd20 TABCREATE X {tab_divs} {v_min} {v_max}
v = {v_min}
for (i = 0; i <= ({tab_divs}); i = i + 1)
// alpha
float alpha
v = v * 1000 // v to units of equation
if (v < -10 )
alpha = {2 / 37.95} * { exp { {{v + 50 } / 11} - {{ v + 53.5} / 27} } }
else
alpha = 2 * {exp { { {-1 * v} - 53.5 } / 27 }}
end
v = v * 0.001 // reset v
// correct units of alpha
alpha = alpha * 1000
// beta
float beta
v = v * 1000 // v to units of equation
alpha = alpha * 0.001 // alpha to units of equation
if (v < -10 )
beta = 2 * {exp { { {-1 * v} - 53.5 } / 27 }} - alpha
else
beta = 0.0
end
v = v * 0.001 // reset v
alpha = alpha * 1000 // resetting alpha
// correct units of beta
beta = beta * 1000
// alpha and beta
float tau = 1/(alpha + beta)
setfield KCd20 X_A->table[{i}] {alpha}
setfield KCd20 X_B->table[{i}] {alpha + beta}
v = v + dv
end // end of for (i = 0; i <= ({tab_divs}); i = i + 1)
setfield KCd20 X_A->calc_mode 1 X_B->calc_mode 1
// voltage indep. concentration var
float conc_min = 0
float conc_max = 1000
float dc = ({conc_max} - {conc_min})/{tab_divs}
float ca_conc = {conc_min}
call KCd20 TABCREATE Z {tab_divs} {conc_min} {conc_max}
float const_state
for (i = 0; i <= ({tab_divs}); i = i + 1)
ca_conc = ca_conc * 0.000001 // ca_conc to units of equation
if (ca_conc < 0.00025 )
const_state = {ca_conc / 0.00025}
else
const_state = 1
end
ca_conc = ca_conc * 1000000 // reset ca_conc
setfield KCd20 Z_A->table[{i}] {0}
setfield KCd20 Z_B->table[{i}] {const_state}
ca_conc= ca_conc + dc
end
tweaktau KCd20 Z
addfield KCd20 addmsg1
setfield KCd20 addmsg1 "../Ca_d20 . CONCEN Ca"
end
//========================================================================
// Tabulated Ca-dependent K AHP Channel,gK(AHP) 2003/05
//========================================================================
/* This is a tabchannel which gets the calcium concentration from Ca_hip_conc
in order to calculate the activation of its Z gate. It is set up much
like the Ca channel, except that the A and B tables have values which are
functions of concentration, instead of voltage.
*/
function make_KAHPs20
if ({exists KAHPs20})
return
end
create tabchannel KAHPs20
setfield KAHPs20 \
Ek -0.095 \
Ik 0 \
Zpower 1
setfield KAHPs20 \
Gbar 1 \
Gk 0
float tab_divs = 1041
float c
float conc_min = 0
float conc_max = 1000
float dc = ({conc_max} - {conc_min})/{tab_divs}
float ca_conc = {conc_min}
call KAHPs20 TABCREATE Z {tab_divs} {conc_min} {conc_max}
for (c = 0; c <= ({tab_divs}); c = c + 1)
// alpha
float alpha
// ca_conc converton to units of equ.
ca_conc = ca_conc * 0.000001
if (ca_conc < 0.0005 )
alpha = ca_conc/0.05
else
alpha = 0.01
end
ca_conc = ca_conc * 1000000 // resetting ca_conc
// correct units of alpha
alpha = alpha * 1000
// beta
float beta
beta = 0.001
// Set correct units of beta
beta = beta * 1000
//alpha and beta
float tau = 1/(alpha + beta)
setfield KAHPs20 Z_A->table[{c}] {alpha}
setfield KAHPs20 Z_B->table[{c}] {alpha + beta}
ca_conc = ca_conc + dc
end // end of for (c = 0; c <= ({tab_divs}); c = c + 1)
setfield KAHPs20 Z_conc 1
setfield KAHPs20 Z_A->calc_mode 1 Z_B->calc_mode 1
addfield KAHPs20 addmsg1
setfield KAHPs20 \
addmsg1 "../Ca_s20 . CONCEN Ca"
end
function make_KAHPd20
if ({exists KAHPd20})
return
end
create tabchannel KAHPd20
setfield KAHPd20 \
Ek -0.095 \
Ik 0 \
Zpower 1
setfield KAHPd20 \
Gbar 1 \
Gk 0
float tab_divs = 1041
float c
float conc_min = 0
float conc_max = 1000
float dc = ({conc_max} - {conc_min})/{tab_divs}
float ca_conc = {conc_min}
call KAHPd20 TABCREATE Z {tab_divs} {conc_min} {conc_max}
for (c = 0; c <= ({tab_divs}); c = c + 1)
// alpha
float alpha
// ca_conc converton to units of equ.
ca_conc = ca_conc * 0.000001
if (ca_conc < 0.0005 )
alpha = ca_conc/0.05
else
alpha = 0.01
end
ca_conc = ca_conc * 1000000 // resetting ca_conc
// correct units of alpha
alpha = alpha * 1000
// beta
float beta
beta = 0.001
// Set correct units of beta
beta = beta * 1000
//alpha and beta
float tau = 1/(alpha + beta)
setfield KAHPd20 Z_A->table[{c}] {alpha}
setfield KAHPd20 Z_B->table[{c}] {alpha + beta}
ca_conc = ca_conc + dc
end // end of for (c = 0; c <= ({tab_divs}); c = c + 1)
setfield KAHPd20 Z_conc 1
setfield KAHPd20 Z_A->calc_mode 1 Z_B->calc_mode 1
addfield KAHPd20 addmsg1
setfield KAHPd20 \
addmsg1 "../Ca_d20 . CONCEN Ca"
end