  Inhibition is considered to shape neural activity, and broaden its pattern
repertoire. In the sensory organs, where the anatomy of neural circuits is
highly structured, lateral inhibition sharpens contrast among stimulus
properties. The impact of inhibition on stimulus processing and the involvement
of lateral inhibition is less clear when activity propagates to the
less-structured relay stations. Here we take a synthetic approach to
disentangle the impacts of inhibition from that of specialized anatomy on the
repertoire of evoked activity patterns, and as a result, the network capacity
to uniquely represent different stimuli. To this aim, we blocked inhibition in
randomly rewired networks of cortical neurons in-vitro, and quantified response
variability and stimulus discrimination among stimuli provided at different
spatial loci, before and after the blockade. We show that blocking inhibition
quenches variability of responses evoked by repeated stimuli through any
spatial source; for all tested response features. Despite the sharpening role
of inhibition in the highly structured sensory organs, in these random networks
we find that blocking inhibition enhances stimulus discrimination between
spatial sources of stimulation, when based on response features that emphasize
the relation among spike times recorded through different electrodes. We
further show that under intact inhibition, responses to a given stimulus are a
noisy version of those revealed by blocking inhibition; such that intact
inhibition disrupts an otherwise coherent, wave propagation of activity.
