Increased Preceuneus deactivation as a possible mechanism for enhanced preparatory suppression in people with high expression of autistic traits

Abstract

Previous evidence point to atypical attention processes in autism (and the broader autistic spectrum in neurotypical participants) particularly in conditions requiring distractor suppression. Further characterizing this atypicality, we have recently proposed (Abu-akel et al., 2016; Abu-Akel et al., VSS 2016) that Autistic traits are associated with a benefit when suppressing distractors in a preparatory manner but impairment when distractors are inhibited reactively (when more dynamic control of attention is required). In the present study we consider the Precuneus (Pc) as a candidate brain mechanism that may explain such a preparatory bias. The Pc is a potential candidate here as its deactivation (within the default mode network) is thought to facilitate performance in a preparatory way while its activation is thought to support dynamic switching between stimulus' aspects (Serences et al., 2004). To test whether Pc deactivation may explain preparatory biases in people with higher expression of autistic traits we assessed these traits in a total of 211 neurotypical adults who performed a blocked Global/Local task where target and distractor levels were known in advance (preparatory suppression). Next we examined the effect of Pc deactivation on task performance in a new cohort of ten participants using offline TMS over the Pc. We found reduced distractor interference in adults with high expression of autistic traits in the Global/Local task, irrespective of target level (global or local) or its relative salience. Importantly, a similar reduction in distractor interference was evident following TMS over the Pc, which again occurred irrespective of target level or saliency. Our findings point to the Pc as a potential brain mechanism underlying improved preparatory suppression. We speculate that high expression of autistic traits may be associated with increased deactivation of the Pc which in turn facilitates preparatory distractor suppression but is detrimental when dynamic control is needed.

Meeting abstract presented at VSS 2017