Frontal asymmetry index in Williams syndrome: Evidence for altered emotional brain circuitry?

Abstract

Asymmetrical frontal electroencephalography (EEG) activity is associated with motivational neural systems of approach/withdrawal behaviors. Greater left frontal EEG has been linked to increased appetitive tendencies whereas increased right frontal activity is related to the activation of avoidance mechanisms. Williams syndrome (WS) is a genetic condition characterized by a highly sociable personality manifested by a propensity to approach strangers and decreased social fear. Consequently, the current study was designed to investigate the frontal cortical activity during resting state, indexed by relative alpha power, in adults with WS as compared to typically developing (TD) controls, and a subgroup of TD extraverts. Results indicated that participants with WS produced attenuated left frontal activity relative to TD peers, or TD extraverts in particular; yet, no groups differed in their degree of right frontal activity. Finally, while both TD group and the extravert subset showed trends of greater left over right frontal activity, the WS participants demonstrated opposing effect of increased right over left frontal EEG. Importantly, individuals with WS produced deviating frontal activity patterns compared to TD extraverts despite exhibiting common social-affiliative tendencies, underscoring that neural mechanisms that give rise to extraversion in WS may not function similarly to those subserving this personality trait expressed in TD.

Keywords: Alpha power; Extraversion; Resting EEG; Social neuroscience; Williams syndrome.

Figure 1

Correlation between age, left and right frontal alpha power during resting state, and alpha power asymmetry in Typically Developing participants (N=16) versus adults with Williams Syndrome (N=9).

Figure 2

Alpha power of left and right frontal region during resting state in typically developing participants (N = 16), a subset of typically developing extraverts (N = 9), and adults with Williams syndrome (N = 9). Increased ln transformed alpha power values denote less cortical activity.

Figure 3

Alpha power asymmetry during resting state in participants with Williams syndrome (N = 9) versus typically developing extraverts (N = 9). Greater asymmetry values denote more left frontal activity at resting state.