Adolescent resting state networks and their associations to schizotypal trait expression

Lagioia Lagioia

doi:10.3389/fnsys.2010.00035

Abstract

The rising interest in temporally coherent brain networks during baseline adult cerebral activity finds convergent evidence for an identifiable set of resting state networks (RSNs). To date, little is know concerning the earlier developmental stages of functional connectivity in RSNs. This study's main objective is to characterize the RSNs in a sample of adolescents. We further examine our data from a developmental psychopathology perspective of psychosis-proneness, by testing the hypothesis that early schizotypal symptoms are linked to disconnection in RSNs. In this perspective, this study examines the expression of adolescent schizotypal traits and their potential associations to dysfunctional RSNs. Thirty-nine adolescents aged between 12 and 20 years old underwent an 8-min functional magnetic resonance imaging (fMRI) “resting state” session. In order to explore schizotypal trait manifestations, the entire population was assessed by the Schizotypal Personality Questionnaire (SPQ). After conventional processing of the fMRI data, we applied group-level independent component analysis (ICA). Twenty ICA maps and associated time courses were obtained, among which there were RSNs that are consistent with findings in the literature. We applied a regression analysis at group level between the energy of RSN-associated time courses in different temporal frequency bins and the clinical measures (3 in total). Our results highlight the engagement of six relevant RSNs; (1) a default-mode network (DMN); (2) a dorso-lateral attention network; (3) a visual network (VN); (4) an auditory network (AN); (5) a sensory motor network (SMN); (6) a self-referential network (SRN). The regression analysis reveals a statistically significant correlation between the clinical measures and some of the RSNs, specifically the visual and the AN. In particular, a positive correlation is obtained for the VN in the low frequency range (0.05 Hz) with SPQ measures, while the AN correlates negatively in the high frequency range (0.16–0.19 Hz). Trend-like significance for the SRN may hint to its implication in disorganized thoughts and behaviors during adolescence. Unlike DMN activity in schizophrenic patients, adolescent DMN was unrelated to schizotypal trait expression. This suggests that relationships between the DMN and schizotypy may be modified in later developmental stages of both functional connectivity and psychotic expression. These results are discussed in light of RSNs literature involving children, adults, and individuals with schizophrenia.

Highlights

Over the past 15 years, functional magnetic resonance imaging studies have devoted sustained interest in the intrinsic baseline activity of the brain, referred to as the brain’s resting state or its default-mode activity
Consistent resting state networks found across adolescents Peak activity were obtained by the implement of Statistical Parametric Mapping (SPM) 5 one sample t-test run for each relevant RSN
The results are explained on the base of past evidence of RSNs and they www.frontiersin.org are described by highlighting the functional system they sustain RSN 1

Summary

Introduction

Over the past 15 years, functional magnetic resonance imaging (fMRI) studies have devoted sustained interest in the intrinsic baseline activity of the brain, referred to as the brain’s resting state or its default-mode activity. The brain’s blood oxygen level-dependent (BOLD) signal displays spontaneous fluctuations in its low or high frequencies showing a high degree of temporal correlation across separated cortical areas These temporal correlations underline intrinsic functional connectivity between functional networks which are crucial for processes such as vision, auditory processing, language, (Hampson et al, 2002; Beckmann et al, 2005); in particular the default-mode network (DMN) has constituted the main interest of past studies that implemented seedvoxel techniques (Biswal et al, 1995; Raichle et al, 2001) as well as independent component analysis (ICA) (Greicius et al, 2004; van de Ven et al, 2004; Beckmann et al, 2005). Other networks have been identified, including a self-referential system engaging the medial prefrontal regions, a posterior network involved in visual processing, an attention network engaging superior frontal and parietal cortex, a superior temporal system and a network engaging precentral and postcentral cortex (Gusnard et al, 2001; Greicius et al, 2003; Fox and Raichle, 2007; Mantini et al, 2007)

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