ERP Correlates of Inhibitory Control and Theory of Mind Are Associated with Each Other and with ASD Symptoms

Background:

Both Theory of Mind (ToM) and Executive Functioning (EF) impairments have been argued to play a causal role in ASD. Interestingly, over the years, there has been growing support for a link between EF and ToM, and EF has been mentioned as an ‘enabling factor’ in the development of ToM. It is suggested that specifically inhibitory control is needed for successful ToM, as mentalizing almost always requires overriding a prepotent response (e.g., overriding own belief in false-belief tasks). Indeed, some studies have shown correlations between ToM and inhibitory ability, and fMRI studies have shown overlapping brain activation during ToM and inhibition tasks.  Still, studies attempting to directly test the link between inhibitory control and ToM are scarce, especially at the neural level, but may be of much importance to better understand ToM deficits in ASD. 

Objectives:  

The aim of the current study was to investigate the relationship between neural correlates of inhibitory control and ToM, using EEG. In addition, correlational analyses were conducted to relate the ERP findings to ASD symptoms in a neurotypical population. 

Methods:

22 neurotypical participants carried out a ToM task and a Go/No-Go task while their EEG activity was being recorded. The Go/No-Go task required participants to respond to a certain letter (80%, Go), and to inhibit responding to another letter (20%, No-Go). The ToM task consisted of watching short videos, in which both the participant and another agent formed a belief about the location of a ball. During the outcome phase, participants had to respond in accordance with what the agent had believed, enabling false- versus true-belief analyses. ERP components were calculated for No-Go versus Go trials, and for false- versus true-belief trials. These were subsequently related to ASD symptomatology assessed by means of the Autism Spectrum Quotient (AQ). 

Results:  

For the Go/No-Go task, the typical pattern of N2 and P3 components was found, with expected differences between Go- and No-Go-trials. In the outcome phase of the ToM task, a P3-like component could be observed at the midline, for the false-belief versus true-belief trials. A strong positive and specific correlation was found between the false-belief (versus true-belief) related P3 component and the No-Go (versus Go) P3 component (r = 0.50); no link was found with the N2. In addition, both the false-belief P3 and No-Go P3 were moderately and negatively correlated with ASD symptoms (r = -0.35 and r = -0.32 respectively).

Conclusions:  

The finding that ERP indices of inhibitory control and mentalizing are positively correlated suggests that general inhibitory control plays a significant role in Theory of Mind tasks. Both ERP indices were found to be associated with ASD symptoms, with smaller amplitudes for adults with more ASD symptoms. Although we used a dimensional approach in a neurotypical population and replication of the findings is warranted in individuals with a formal diagnosis of ASD, these findings may help to better understand ToM deficits in ASD.