COBA

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COBA#

class brainpy.state.COBA(E)#

Conductance-based (COBA) synaptic output.

Converts synaptic conductance into post-synaptic current using the driving-force model. The output current depends on the difference between the membrane potential and the reversal potential:

\[I_{\mathrm{syn}}(t) = g_{\mathrm{syn}}(t) \, (E - V(t))\]

where \(g_{\mathrm{syn}}\) is the instantaneous synaptic conductance, \(E\) is the reversal potential, and \(V\) is the post-synaptic membrane potential.

Parameters:

E (ArrayLike) – Reversal potential of the synapse. Typical values: 0 mV for excitatory (AMPA/NMDA) and -80 mV for inhibitory (GABAa) synapses.

See also

CUBA

Current-based synaptic output (potential-independent).

MgBlock

Conductance-based output with voltage-dependent Mg2+ block.

Notes

  • When \(V < E\), the driving force \((E - V)\) is positive, producing a depolarizing (excitatory) current. When \(V > E\), the current is hyperpolarizing (inhibitory).

  • The COBA model is more biologically realistic than CUBA because the synaptic current magnitude depends on the membrane potential, providing automatic gain control and preventing reversal of current direction past the equilibrium potential [1].

References

Examples

>>> import brainpy
>>> import saiunit as u
>>> # Excitatory COBA synapse with reversal at 0 mV
>>> coba_exc = brainpy.state.COBA(E=0. * u.mV)
>>> # Inhibitory COBA synapse with reversal at -80 mV
>>> coba_inh = brainpy.state.COBA(E=-80. * u.mV)
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