Table 1.

Model symbols.

Description	Symbol
Input stimuli to LGN cells	x
Input stimuli to ON LGN cells	xON
Input stimuli to OFF LGN cells	xOFF
Membrane time constant of LGN cells (12 ms)	τL
Membrane potentials of LGN cells	vL
Membrane potentials of ON LGN cells	${\text{v}}_{\text{ON}}^{\text{L}}$
Membrane potentials of OFF LGN cells	${\text{v}}_{\text{OFF}}^{\text{L}}$
Firing rates of LGN cells	sL
Firing rates of ON LGN cells	${\text{s}}_{\text{ON}}^{\text{L}}$
Firing rates of OFF LGN cells	${\text{s}}_{\text{OFF}}^{\text{L}}$
Spontaneous firing rate of LGN cells (2 Hz)	sb
Membrane time constant of cortical simple cells (12 ms)	τC
Membrane potentials of cortical simple cells	vC
Leakage voltages of cortical simple cells	${\text{v}}_{\text{leak}}^{\text{C}}$
Firing rates of cortical simple cells	sC
Excitatory connection: all LGN cells to simple cells	Au,+
Excitatory connection: ON LGN cells to simple cells	${\text{A}}_{\text{ON}}^{\text{u},+}$
Excitatory connection: OFF LGN cells to simple cells	${\text{A}}_{\text{OFF}}^{\text{u},+}$
Inhibitory connection: all LGN cells to simple cells	Au,−
Inhibitory connection: ON LGN cells to simple cells	${\text{A}}_{\text{ON}}^{\text{u},-}$
Inhibitory connection: OFF LGN cells to simple cells	${\text{A}}_{\text{OFF}}^{\text{u},-}$
Excitatory connection: simple cells to all LGN cells	Ad,+
Excitatory connection: simple cells to ON LGN cells	${\text{A}}_{\text{ON}}^{\text{d},+}$
Excitatory connection: simple cells to OFF LGN cells	${\text{A}}_{\text{OFF}}^{\text{d},+}$
Inhibitory connection: simple cells to all LGN cells	Ad,−
Inhibitory connection: simple cells to ON LGN cells	${\text{A}}_{\text{ON}}^{\text{d},-}$
Inhibitory connection: simple cells to OFF LGN cells	${\text{A}}_{\text{OFF}}^{\text{d},-}$
Sparsity level (0.6)	λ
Learning rate	η