Inter-hemispheric coordination of maximal activity limits across spatially selective neurons.
If an activity limit implicates a diminishment or decay of activities over time, one question that arises is if accumulated activities and limits are: (a) coordinated across both hemispheres, (b) specific to each hemisphere, or (c) reflect a combination of coordinated and hemisphere-specific activities.
Activities consistent with coordinated activities or activities specific to each hemisphere are illustrated below, where increases in activity are modeled across IPD-selective neurons for 30 sequential interaural phase differences (IPD), starting at -0.25 cycles and ending at 0.25 cycles. Each increase is then followed by a proportional decrease or decay of activities across the neurons. Compounded decreases in activity are recorded in right-hand figures to show each prior IPD’s contribution to current activities.
Activities evoked across ‘labeled’ neurons (right panel) and each prior IPDs’ contribution to current activities (left panel). Activity limit = 5. Activities are coordinated across both hemispheres so that activities decay whenever activities in either hemisphere exceed limit. Inter-hemispheric coordination index (IHCI) = 1.
Activities evoked across ‘labeled’ neurons (right panel) and each prior IPDs’ contribution to current activities (left panel). Activity limit = 5. Activities are accumulated separately within each hemisphere so that activities decay whenever activities in that hemisphere exceed limit. Inter-hemispheric coordination index (IHCI) = 0.
The two dynamics demonstrated above (IHCI = 1 or IHCI = 0) differ mostly for peripheral IPDs that evoke smaller modeled activities when compared to central IPDs.
Edge model neural representations across frequency bands when activities are coordinated across both hemispheres (left panel, IHCI = 1) or accumulated separately within each hemisphere (right panel, IHCI = 0). Modeled activities evoked by experimental noise-bursts are plotted versus ITD-selective neurons ‘labeled’ by ITDs evoking half-maximal responses along their medial edges, in accord with the edge model.
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