Abstract

This study involved the design and preliminary testing of an audiovisual paradigm that proved effective in measuring the psychological functions and the underlying neural mechanisms associated with mental state attribution and contextual memory processes. The experiment required participants to categorise sound stimuli of distinct levels of dissonance (i.e. emotion recognition in sound) employing a theory of mind task. Subjects viewed an invariant still image of a radio-telescope, and were given the following instruction: “A radio-telescope located in Cambridge captured a series of radio signals from outer space. You will listen to these sounds and your task is to think and decide if they were produced by good or bad aliens. You will hear 24 different sounds in total”. Separate behavioural and neuroscientific (fMRI) experiments were conducted. Sound categories were highly ambiguous. The degree of perceptual uncertainty involved was reflected in post-experimental discussions, which showed participants under the impression of being randomly rating the sounds. Results, however, showed a significant difference in the judgements. Consonant sounds were clearly ascribed to good aliens whereas dissonant sounds were attributed to bad aliens. The results of the neuroscientific (fMRI) experiment demonstrated that distinct levels of dissonance exerted differential modulatory influences on the right angular gyrus (AG), an area in the right temporo-parietal junction (rTPJ) that has been implicated in mental state attribution processes (Saxe et al., 2005). Notably, a multiple regression analysis incorporating the Autism Spectrum Quotient test scores (or AQ test) (Baron-Cohen, Wheelwright, Skinner, Martin & Clubley, 2001), which aims to investigate whether adults of average intelligence have symptoms of autism spectrum conditions; indicated that participants with higher levels of autistic traits, especially within the social skills dimension, presented significant difficulties in the recognition of positive valence in consonant sound patterns. An analysis of the neural mechanisms engaged while participants were judging these consonant sounds revealed a marked coactivation between the parahippocampal cortex (PHC) and the rTPJ. Given the involvement of the PHC in storage and recall of long-term associations built up over repeated exposure (e.g. consonant sounds cue retrieval of positive valence associations) (Gosselin et al., 2006; Aminoff et al., 2013) and the role of the rTPJ in reasoning about the others’ mental states (e.g. intentions), the findings were considered to suggest an active process in which contextual associations for the consonant sound patterns (e.g. pleasantness, smoothness) were being retrieved to emotionally qualify the intentions represented at the level of the rTPJ. Following extensive functional and effective connectivity analyses, I proposed that a compromised use of associative memory to affectively contextualise mental state attributions may underlie the difficulties observed in participants with more autistic traits in recognising positive valence in consonant sounds.

Refs. Aminoff, M., Kveraga, K., Bar, M. (2013). The role of the parahippocampal cortex in cognition, Trends in Cognitive Sciences, Volume 17, Issue 8, August 2013, Pages 379-390, ISSN 1364 -6613. Baron-Cohen, S., Wheelwright, S., Skinner, R., Martin, J., Clubley, E. (2001). The autism-spectrum quotient (AQ): evidence from Asperger syndrome/high-functioning autism, males and females, scientists and mathematicians. J Autism Dev Disorders, 31, 5-17. Gosselin, N., Samson, S., Adolphs, R., Noulhiane, M., Roy, M., Hasboun, D., Baulac, M., Peretz, I. (2006). Emotional responses to unpleasant music correlates with damage to the parahippocampal cortex. Brain, 129, 2585-2592.