Accumulation of evidence to a decision boundary in an active sensorimotor behavior
Abstract:
Behaviors in which subjects collect externally-generated streams of sensory evidence, such as judgment of random dot motion direction, are well explained by a bounded integration decision model. Does this model account for behavior in which the motor system generates evidence through interactions with the environment? In this study, rats palpated surfaces to identify the presented texture. We calculated the evidence for each candidate texture transmitted by whisker kinematics and by neurons in vibrissal somatosensory cortex. The instant of choice was fit by positing an integrator that gave greatest weight to vibrissal and neuronal evidence on the first touch and exponentially less weight to evidence on successive touches; the rat took a decision hen the accumulated quantity of evidence for one texture reached a boundary. The evidence actively generated by the vibrissal sensorimotor system appears to be accumulated downstream from sensory cortex until adequate to support a well grounded choice.