  Lateral Inhibition (LI) phenomena occur in a wide range of sensory modalities
and are most famously described in the human visual system. In LI the activity
of a stimulated neuron is itself excited and suppresses the activity of its
local neighbours via inhibitory connections, increasing the contrast between
spatial environmental stimuli. Simple or- ganisms, such as the single-celled
slime mould Physarum polycephalum possess no neural tissue yet, despite this,
are known to exhibit complex computational behaviour. Could simple organisms
such as slime mould approximate LI without recourse to neural tissue? We
describe a model whereby LI can emerge without explicit inhibitory wiring,
using only bulk transport effects. We use a multi-agent virtual material model
of slime mould to reproduce the characteristic contrast amplification response
of LI using excitation via attractant stimuli. Restoration of baseline activ-
ity occurs when the stimuli are removed. We also explore an opposite
counterpart behaviour, Lateral Activation (LA), using repellent stimuli. These
preliminary results suggest that simple organisms without neural tissue may
approximate sensory contrast enhancement using alternative analogues of LI and
suggests novel approaches towards generating collec- tive contrast enhancement
in distributed computing and robotic devices.
