GABA synapsesΒΆ

GABA receptors are the most common type of inhibitory ionotropic receptors in the brain. They have fast kinetics and are responsible for inhibitory synaptic transmission.

In this example we show:

  • How to add and activate GABA synapses at various model compartments.

  • How to adjust the synaptic conductance and kinetics of GABA synapses.

import brian2 as b
from brian2.units import ms, mV, nS, pF

from dendrify import Dendrite, NeuronModel, Soma

b.prefs.codegen.target = 'numpy'  # faster for simple simulations

# Create a simple 3-compartment neuron model
soma = Soma('soma', cm_abs=100*pF, gl_abs=10*nS)
dend1 = Dendrite('dend1', cm_abs=50*pF, gl_abs=5*nS)
dend2 = Dendrite('dend2', cm_abs=50*pF, gl_abs=5*nS)

# Add GABA synapse with rise and decay kinetics to dend1
dend1.synapse('GABA', tag='slow', g=1*nS, t_rise=2*ms, t_decay=5*ms)

# Add GABA synapse with instantaneous rise and decay kinetics to dend2
dend2.synapse('GABA', tag='fast', g=1*nS,  t_decay=5*ms)

# Merge the compartments into a single neuron model
model = NeuronModel([(soma, dend1, 10*nS),
                     (dend1, dend2, 10*nS)],
                    v_rest=-60*mV)

# Create 2 neurons (no somatic spiking for simplicity)
neurons = model.make_neurongroup(2, method='euler')

# Each neuron receives a spike at t=10ms at different dendrites
input_spikes = b.SpikeGeneratorGroup(2, [0, 1], [10, 10]*ms)
slow_gaba = b.Synapses(input_spikes, neurons, on_pre='s_GABA_slow_dend1 += 1')
slow_gaba.connect(i=0, j=0)
fast_gaba = b.Synapses(input_spikes, neurons, on_pre='s_GABA_fast_dend2 += 1')
fast_gaba.connect(i=1, j=1)

# Create monitors
variables = ['V_dend1', 'V_dend2', 'I_GABA_slow_dend1', 'I_GABA_fast_dend2']
M = b.StateMonitor(neurons, variables, record=True)

# Run the simulation
b.run(80*ms)

# Visualize results
time = M.t/ms
vd1 = M.V_dend1[0]/mV
vd2 = M.V_dend2[1]/mV
ampa1 = M.I_GABA_slow_dend1[0]/nS
ampa2 = M.I_GABA_fast_dend2[1]/nS

fig, axes = b.subplots(2, 1, sharex=True, figsize=(6, 6))
ax0, ax1 = axes

ax0.set_title('Inhibitory postsynaptic potentials')
ax0.plot(time, vd1, label='Dendrite 1 (slow rise)')
ax0.plot(time, vd2, label='Dendrite 2 (instant rise)')
ax0.set_ylabel('Membrane potential (mV)')
ax0.legend()

ax1.set_title('Inhibitory postsynaptic currents')
ax1.plot(time, ampa1, c='black', label='slow rise')
ax1.plot(time, ampa2, c='crimson', label='instant rise')
ax1.set_xlabel('Time (ms)')
ax1.set_ylabel('Current (nS)')
ax1.legend()

fig.tight_layout()
b.show()
../_images/syn_gaba.png