Information Processing, Neural Connectivity, and Neuronal Organization

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

Children with autism spectrum disorder (ASD) show marked difficulties in reading comprehension, a complex cognitive skill fundamental to successful daily functioning that is associated with core executive functions. However, the neurophysiological mechanisms underlying reading comprehension deficits in these children remain elusive. Twenty-one right-handed males with high-functioning ASD (mean age = 10.24 years) and 23 age-, IQ-, educational level-, sex- and handedness-matched typically developing (TD; mean age = 10.14 years) individuals underwent a reading comprehension test and the semantic verbal fluency test that tapped core executive functions underlying reading comprehension during concurrent prefrontal functional near-infrared spectroscopy (fNIRS) measurement. Participants' information processing efficiency was also assessed. High-functioning ASD children exhibited general reading comprehension [main effect of group: F (1,40) = 7.58, p = 0.009], selective verbal fluency deficits [Group × category interaction: F (1,42) = 4.90, p = 0.032] and slower processing speed (t 42 = 2.36, p = 0.023). Regarding the hemodynamics of the prefrontal cortex (PFC), although ASD individuals showed comparable patterns of PFC brain activation to their healthy counterparts, lower PFC intrahemispheric [main effect of group: F (1,42) = 11.36, p = 0.002] and interhemispheric [main effect of group: F (1,42) = 7.79, p = 0.008] functional connectivity were evident during the semantic verbal fluency test. At the whole-group level, poorer reading comprehension performance was associated with poorer performance in the semantic verbal fluency test (r 42 = 0.508, p < 0.001). Moreover, poorer semantic verbal fluency test performance was associated with slower information processing speed (r 42 = -0.312, p = 0.044), which is associated with reduced left medial PFC functional connectivity (r 42 = -0.319, p = 0.040). Abnormal intrahemispheric and interhemispheric prefrontal hypoconnectivity is associated with deficits in executive processes essential for reading comprehension in ASD. Our study has provided important implications for the neuropsychological and neurophysiological mechanisms underlying reading comprehension deficits in ASD.

Autistic Adults are Not Impaired at Maintaining or Switching Between Counterfactual and Factual Worlds: An ERP Study

We report an event-related brain potential (ERP) experiment that tests whether autistic adults are able to maintain and switch between counterfactual and factual worlds. Participants (N = 48) read scenarios that set up a factual or counterfactual scenario, then either maintained the counterfactual world or switched back to the factual world. When the context maintained the world, participants showed appropriate detection of the inconsistent critical word. In contrast, when participants had to switch from a counterfactual to factual world, they initially experienced interference from the counterfactual context, then favoured the factual interpretation of events. None of these effects were modulated by group, despite group-level impairments in Theory of Mind and cognitive flexibility among the autistic adults. These results demonstrate that autistic adults can appropriately use complex contextual cues to maintain and/or update mental representations of counterfactual and factual events.

Investigating the Use of World Knowledge During On-line Comprehension in Adults with Autism Spectrum Disorder

The on-line use of world knowledge during reading was examined in adults with autism spectrum disorder (ASD). Both ASD and typically developed adults read sentences that included plausible, implausible and anomalous thematic relations, as their eye movements were monitored. No group differences in the speed of detection of the anomalous violations were found, but the ASD group showed a delay in detection of implausible thematic relations. These findings suggest that there are subtle differences in the speed of world knowledge processing during reading in ASD.

Would Adults with Autism be less likely to Bury the Survivors? An Eye Movement Study of Anomalous Text Reading

In a single eye movement experiment we investigated the effects of context on the time course of local and global anomaly processing during reading in adults with Autism Spectrum Disorder (ASD). In one condition short paragraph texts contained anomalous target words. Detection of the anomaly was only possible through evaluation of word meaning in relation to the global context of the whole paragraph (Passage Level Anomalies). In another condition the anomaly could be detected via computation of a local thematic violation within a single sentence embedded in the paragraph (Sentence Level Anomalies). For the sentence level anomalies the ASD group, in contrast with the typically developing (TD) group, showed early detection of the anomaly as indexed by regressive eye movements from the critical target word upon fixation. Conversely, for the passage level anomalies, and in contrast with the ASD group, the TD group showed early detection of the anomaly, with increased regressive eye movements once the critical word had been fixated. The reversal of the pattern of regression path data for the two groups, for the sentence and passage level anomalies, is discussed in relation to cognitive accounts of ASD.