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Disruption of the right temporoparietal junction impairs probabilistic belief updating

Generating and updating probabilistic models of the environment is a fundamental modus operandi of the human brain. Though crucial for various cognitive functions, the neural mechanisms of these inference processes remain to be elucidated. Here, we show the causal involvement of the right temporoparietal junction (rTPJ) in updating probabilistic beliefs and we provide new insights into the chronometry of the process by combining online transcranial magnetic stimulation (TMS) with computational modelling of behavioral responses. Since neuroimaging has suggested that rTPJ is implicated in divergent cognitive domains, the demonstration of an involvement in updating internal models provides a novel unifying explanation for these findings.
Participants performed a modified location-cueing paradigm, where false information about the percentage of cue validity (%CV) was provided in half of the experimental blocks to prompt updating of prior expectations (see Figure 1).
 

Mengotti 2017

Figure 1. Timeline of the experimental paradigm for a validly cued trial. At the beginning of each block the %CV (either true or false) was shown. This value was used a prior before the observation of the first trial in the modelling approach. On each trial, participants indicated whether the upper or lower corner of the target was missing. Central fixation was maintained throughout the experiment. Double-pulse online TMS (with 100 ms ISI) was delivered in every trial, either at 300 ms or at 50 ms after target appearance, in different sessions. Both active TMS and sham stimulation were performed, in two different runs, in each session.


Online double-pulse TMS over rTPJ 300 ms (but not 50 ms) after target appearance selectively decreased participants’ updating of false prior beliefs concerning %CV, reflected in a decreased learning rate α of a Rescorla-Wagner model (see Figure 2). Online TMS over rTPJ also impacted on participants’ explicit beliefs, causing them to overestimate %CV.

Mengotti 2017

Figure 2. Learning rate α for all stimulation (TMS at 300 ms, TMS at 50 ms, sham) and prior (blocks with true or false information concerning the % CV) conditions. Error bars indicate SEM.

 

These results confirm the involvement of rTPJ in updating of probabilistic beliefs, thereby advancing our understanding of this area's function during cognitive processing.


Publication:

Mengotti, P., Dombert, P. L., Fink, G. R., & Vossel, S. (2017). Disruption of the right temporoparietal junction impairs probabilistic belief updating. Journal of Neuroscience, 37(22), 5419-5428.


Correspondence to:

Dr. Paola Mengotti


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