Table 2.

Overview of the mechanisms involved in the suppression of excitatory and inhibitory currents in HD RGCs and the degree to which these currents are suppressed

Response	Excitation suppression	Inhibition suppression	Mechanism of surround suppression
HD1
ON	85 ± 10%	5 ± 1%
OFF	75 ± 8%	8 ± 3%	Presynaptic and postsynaptic inhibition
HD2
ON	53 ± 7%	60 ± 6%
OFF	78 ± 4%	No inhibition	Presynaptic inhibition
UHD
ON	90 ± 7%	23 ± 7%
OFF	85 ± 4%	13 ± 3%	Strong presynaptic and postsynaptic inhibition