Transformation of Context-dependent Sensory Dynamics into Motor Behavior
Figure 3
The behavior of the model network.
Left panels: Routine swimming activity pattern, in the absence of the hunting neuron excitation (c.f. Figure 1, left panel). Right panels: Search hunting behavior activity pattern when the hunting neuron is activated (c.f. Figure 1, right panel). (A) Behavior of the SRC model network. During routine swimming the model statocyst network shows a winner take-all dynamics. Only the SRC pressed by the statolith fires (and thus inhibits other SRCs connected to it). In the first part of the time series, the active neuron in the statocyst network is SRC01. A simulation of body orientation change by exciting SRC06 (denoted by the arrow) makes the new pressed SRC fire immediately while SRC01 becomes silent like the rest of the SRCs. The winnerless competition dynamics (WLC) appears in the statocyst model when the hunting neuron is activated. The irregular sequential activations of the WLC activity displayed by the model are very similar to the one observed in the biological circuit (see Figure 2). (B) Behavior of the CG network located between the statocyst and the wing CPG. During routine swimming either CG1 or CG2 is active, depending on which of the SRCs receives the excitation from the statolith. The CG3 cell integrates and sends this information to the CPG. When a deviation from the preferred position occurs, the identity of the active SRC pressed by the statolith changes and the cerebral interneurons interpret this change (see panel C). During hunting, both CG1 and CG2 cells are active. (C) Behavior of the wing CPG model responsible for generating the periodic wing beating rhythm. As in the biological circuit (Figure 6) the activity of the wing CPG model is affected by the statocyst dynamics which is evoked by the behavioral context. During routine swimming, the model CPG generates a regular rhythm. During the hunting behavior the pattern is faster and highly irregular. Note that during routine swimming, when a change of posture is simulated, the sensory information received in the wing CPG immediately generates a corrective activity. Here, for example, the change from SCR01 to SCR06 produces a short change in the frequency and shape of the rhythm. Afterward, the typical repetitive rhythm is restored.