Effects of working memory load on frontal connectivity in children with autism spectrum disorder: a fNIRS study

Abstract

Individuals with autism spectrum disorder (ASD) perform poorly in working memory (WM) tasks, with some literature suggesting that their impaired performance is modulated by WM load. While some neuroimaging and neurophysiological studies have reported altered functional connectivity during WM processing in individuals with autism, it remains largely unclear whether such alterations are moderated by WM load. The present study aimed to examine the effect of WM load on functional connectivity within the prefrontal cortex (PFC) in ASD using functional near-infrared spectroscopy (fNIRS). Twenty-two children with high-functioning ASD aged 8–12 years and 24 age-, intelligent quotient (IQ)-, sex- and handedness-matched typically developing (TD) children performed a number n-back task with three WM loads (0-back, 1-back, and 2-back). Hemodynamic changes in the bilateral lateral and medial PFC during task performance were monitored using a multichannel NIRS device. Children with ASD demonstrated slower reaction times, specifically during the “low load” condition, than TD children. In addition, the ASD and TD groups exhibited differential load-dependent functional connectivity changes in the lateral and medial PFC of the right but not the left hemisphere. These findings indicate that WM impairment in high-functioning ASD is paralleled by load-dependent alterations in right, but not left, intrahemispheric connectivity during WM processing in children with ASD. A disruption of functional neural connections that support different cognitive processes may underlie poor performance in WM tasks in ASD.

Neurophysiological measures and correlates of cognitive load in attention‐deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and dyslexia: A scoping review and research recommendations

“…Several studies found that, as cognitive load increased, individuals with ASD showed reduced recruitment and altered modulation of brain regions involved in working memory compared to neurotypical controls (Luna et al, 2002; Vogan et al, 2014, 2018). Other studies also found evidence of atypical lateralisation in ASD (Han et al, 2022; Koshino et al, 2005; Yeung et al, 2019). These neuroimaging findings align with behavioural research findings indicating that individuals with ASD perform poorly on working memory tasks, especially as cognitive load increases, and that ASD is associated with differences in working memory (Barendse et al, 2013; Habib et al, 2019; Steele et al, 2007; Wadhera & Kakkar, 2020).…”

“…In ASD, similar difficulties in recruiting WM‐related brain regions are reported in several studies: controls show increasing recruitment of these regions, whereas ASD participants do not show such modulation of increasing brain activation with increasing load (Luna et al, 2002; Vogan et al, 2014, 2018). In addition, ASD participants exhibit more right‐lateralised activation in WM‐related brain regions (Han et al, 2022; Koshino et al, 2005; Yeung et al, 2019).…”

“…This heterogeneity extends to gender‐specific effects, with male ADHD participants displaying lower WM‐related activity than their female counterparts (Valera et al, 2010). ASD was associated with more right‐lateralised activation in WM‐related regions, suggesting the use of distinct processing strategies in individuals with this condition (Han et al, 2022; Koshino et al, 2005; Yeung et al, 2019). There was a significant hypoactivation of WM‐related areas in dyslexia under increased cognitive load (Beneventi et al, 2010; Winn et al, 2006), but also an overactivation in specific regions such as the left superior and inferior frontal gyri (Vasic et al, 2008).…”

Visuo-motor updating in individuals with heightened autistic traits

“…Instead, when preparing for a saccade that must compensate for a preceding eye movement that altered the retinotopic representation of the target, those with more severe traits encounter difficulties. Likewise, the bias in localizing the target cannot be attributed to working memory deficits within our high-autism-like-symptom subsample; it is improbable that the mislocalization of the second target results solely from documented working memory deficits in ASD 39 .…”

Aberrant prefrontal functional connectivity during verbal fluency test is associated with reading comprehension deficits in autism spectrum disorder: An fNIRS study

“…fNIRS data preprocessing was performed using the AnalyzIR toolbox ( Santosa et al, 2018 ) in MATLAB 2019a (The Mathworks, Natick, MA). The preprocessing pipeline was reported elsewhere ( Chan et al, 2022 ; Han et al, 2022 ). First, bad channels were interpolated using the FixSatChans or FixFlatChans modules available in the toolbox.…”