RT Journal Article
SR Electronic
T1 Integration of Direction Cues Is Invariant to the Temporal Gap between Them
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 16483
OP 16489
DO 10.1523/JNEUROSCI.2094-13.2013
VO 33
IS 42
A1 Kiani, Roozbeh
A1 Churchland, Anne K.
A1 Shadlen, Michael N.
YR 2013
UL http://www.jneurosci.org/content/33/42/16483.abstract
AB Many decisions involve integration of evidence conferred by discrete cues over time. However, the neural mechanism of this integration is poorly understood. Several decision-making models suggest that integration of evidence is implemented by a dynamic system whose state evolves toward a stable point representing the decision outcome. The internal dynamics of such point attractor models render them sensitive to the temporal gaps between cues because their internal forces push the state forward once it is dislodged from the initial stable point. We asked whether human subjects are as sensitive to such temporal gaps. Subjects reported the net direction of stochastic random dot motion, which was presented in one or two brief observation windows (pulses). Pulse strength and interpulse interval varied randomly from trial to trial. We found that subjects' performance was largely invariant to the interpulse intervals up to at least 1 s. The findings question the implementation of the integration process via mechanisms that rely on autonomous changes of network state. The mechanism should be capable of freezing the state of the network at a variety of firing rate levels during temporal gaps between the cues, compatible with a line of stable attractor states.