Figure 5.
Travel time governs both neuronal response gain and threshold. (a) Schematic of three possible mechanisms by which exogenous factors may govern a rise-to-threshold process. Shorter travel times can hasten patch-leaving (leftward movement on x axis) by increasing the rate of rise, reducing the threshold or elevating the baseline. (b,c) Evidence that travel times change rate of rise. Example neuron (b) and population (c) average regression slopes (beta weights) for firing rate as a function of time in patch. Beta weights fell as travel times rose, indicating that shorter travel time increases neuronal response gain. Error bars represent s.e.m. (d,e) Evidence that travel time influences firing threshold for patch abandonment. Firing rate on patch-leaving trial was taken as a proxy for threshold level. Example neuron (d) and population (e) show increasing firing rates on patch-leaving trial as travel time increases (black dots). Firing rate on penultimate trial also rose with travel time, consistent with a multi-trial integration process. Error bars represent s.e.m.