1 INTRODUCTION

Childhood maltreatment (CM) is a common, detrimental public health concern (Gilbert et al., 2009). It is well established that CM confers vulnerability to maladaptive developmental outcomes (Morgan & Gayer-Anderson, 2016), such as deficits in cognitive, emotional, social, and behavioral functioning (Bick & Nelson, 2016), maladaptive personality traits (Fletcher & Schurer, 2017), and the vulnerability to development of psychopathology across a lifetime (Nusslock & Miller, 2016). However, through what mechanism does early adverse experiences so strongly impact development in later life has not been clearly examined. A key breakthrough discovery is that CM changes trajectories of brain development (Teicher & Samson, 2013). Brain injury in children due to maltreatment, from the slight to the glaringly clear, has been well documented from early childhood, and can continue to influence development into the third decade of life (Chong, Ng, Lee, & Zhou, 2017). Therefore, characterizing the long-term neurobiological consequence of CM is urgently needed for developing better prevention strategies and targeted treatment to reverse the CM-induced brain change (Teicher, Samson, Anderson, & Ohashi, 2016).

There is growing evidence that CM is associated with structural and functional changes in the human brain, particularly in the regions subserving social cognition and emotion, including prefrontal cortex (PFC; Teicher et al., 2016), hippocampus (Dahmen et al., 2018), amygdala, insula, and anterior cingulate cortex (ACC) (Dannlowski et al., 2012; Lim, Radua, & Rubia, 2014). However, the brain is a functionally interconnected network (Fornito, Bullmore, & Zalesky, 2017), thus, examining the CM-related neural connectome can advance our understanding of the neurodevelopmental consequences of CM. Recent functional connectivity (FC) studies have reported that CM was associated with increased amygdala FC with the hippocampus and PFC regions during an emotion-matching task in adults (Jedd et al., 2015), and reduced FC between ventromedial PFC and insula during fear facial stimuli in adolescents (Hart et al., 2018). Resting-state FC studies identified the CM-induced increased connectivity in salience network (SN), reduced connectivity within the default mode network (DMN), and between DMN and SN in both adolescents and adults (Goetschius et al., 2020; Marusak, Etkin, & Thomason, 2015; Philip, Sweet, et al., 2013). Moreover, decreased FC between medial PFC and amygdala and increased large-scale network modularity were associated with emotional abuse in girls (Cisler, 2017). The increased FC within theory of mind (ToM) network was influenced by the types and severity of abuse in women adults with CM (Boccadoro et al., 2019). The significant effect on a large of brain networks of CM was understandable due to the diverse influence in the social cognition–emotion processing of CM.

However, the abovementioned studies might miss critical neural signatures that existed outside such canonical networks as they focused on either priori defined seed regions or specific networks. Accordingly, an unbiased whole-brain connectivity may be a more effective way to holistically elucidate the impact of maltreatment experiences on the brain. In addition, as the neural alterations following CM are mostly in line with the findings described in psychiatric disorders, controlling the typically co-occurring psychiatric conditions is thus needed to determine the observed effects are a result of the maltreatment other than the associated psychiatric conditions or a combination or interaction of both (Hart & Rubia, 2012). Meanwhile, this can also provide new clues of latent vulnerability to the development of psychiatric disorders.

The present study aimed to use multivariate pattern analysis (MVPA), an unbiased whole-brain data-driven approach, to investigate the FC differences between healthy adults with and without a history of CM through resting-state functional magnetic resonance imaging (rs-fMRI) dataset. The utility of MVPA-informed FC analysis has already been demonstrated in various clinical contexts such as autism spectrum disorder (Anteraper et al., 2019) and major depressive disorder (Wang et al., 2019). Based on the aforementioned literatures, we hypothesized that adults with CM experience would show altered FC implicated in social cognition and emotion. Moreover, given the effect of CM on the formation of personality (Fletcher & Schurer, 2017), and the neural circuit basis underlying individual differences in personality (Pang et al., 2019), mediation analysis was employed to explore the associations between CM, FC measures, and personality profiles.