Precision and neuronal dynamics in the human posterior parietal cortex during evidence accumulation.
Bottom Line: Precision, as reflected by the gain on pyramidal cell activity, was strongly correlated with both the speed of decision making and the slope of PPC ramping activity.Our findings indicate that the dynamics of neuronal activity in the human PPC during perceptual decision-making recapitulate those observed in the macaque, and in so doing we link observations from primate electrophysiology and human choice behaviour.Moreover, the synaptic gain control modulating these dynamics is consistent with predictive coding formulations of evidence accumulation.
Affiliation: Wellcome Trust Centre for Neuroimaging, London WC1N 3BG, UK. Electronic address: email@example.com.Show MeSH
Mentions: To provide a qualitative illustration of the effects of varying the intrinsic gain and forward connection parameters, we performed a contribution or sensitivity analysis (the change in response with respect to the change in a parameter). Here, we simulated data using the winning network structure (Fig. 4), with all the parameters set to their Bayesian model average across subjects. We then increased the strength of the intrinsic connection within the parietal cortex by a small amount, and used the difference between the ensuing responses to assess the effects of intrinsic gain on PPC activity. To compare these effects to those generated by altering forward connections strengths, we repeated this analysis for the forward connection from MT to PPC. For graphical illustration, the sensitivity to changes in parameters was normalised to the maximum response.
Affiliation: Wellcome Trust Centre for Neuroimaging, London WC1N 3BG, UK. Electronic address: firstname.lastname@example.org.