Can Sequential Processing be Enhanced As a Way to Improve Language and Communication Functions?

Background:  One of the core symptoms of Autism Spectrum Disorder (ASD) is "persistent deficits in social communication and social interaction across multiple contexts," and can include an impairment to language (5th ed.; Diagnostic and Statistical Manual of Mental Disorders; American Psychiatric Association, 2013). Rather than relying on standard therapeutic approaches that focus on behavioral outcomes, it may be beneficial to develop interventions that attempt to modify the underlying neurocognitive mechanisms that are the basis for the language and communication symptoms observed in ASD. One possible explanation for the observed pattern of deficits in language and communication functions is that ASD is associated with impaired “sequential processing” abilities. Sequential processing (SP) is a domain-general mechanism used to perceive and learn environmental patterns of stimuli unfolding in time, especially in the domains of language, social, and motor cognition (Cleeremans et al., 1998; Conway et al., 2010). Both high-functioning and lower-functioning children with ASD have been shown to be impaired on sequential processing tasks (Gordon & Stark, 2007; Maister & Plaisted-Grant, 2011; Mostofsky et al., 2000). Thus, because of the established link between SP and language in typically-developing (TD) children and adults (Conway et al., 2010) and the evidence suggesting an impairment of various aspects of SP in ASD, it is possible that impairments to SP are a contributing factor to the observed difficulties in language and communication. 

Objectives:  Under this view, a potentially promising treatment approach is to enhance SP in order to improve language and communication skills in individuals with autism. 

Methods:  In order to test the feasibility of this approach we developed a novel computerized training task to attempt to enhance SP in healthy TD adults. Participants (n=24) were quasi-randomly assigned to a SP training group, active control group, or passive control group. The SP training involved a computerized visual-spatial sequence reproduction task that incorporated underlying structured patterns in the input sequences. We used event-related potentials (ERP) to explore the neural changes to SP and language resulting from the sequence training. Participants were first assessed on several baseline behavioral and ERP measures of SP and language and then following 10 days of training or control tasks, participants were reassessed with the same baseline measures.

Results:  Results indicated training-related behavioral enhancements to SP and language. In addition, sequence training led to a frontal functional neural reorganization of SP, a region of the brain known to be important for executive functions, controlled attention, and language.

Conclusions:  Overall, these findings demonstrate the feasibility of using this intervention to alleviate the most central deficits of autism. Specifically, a targeted intervention strategy that focuses on training underlying SP mechanisms could provide benefits to the quality of life for individuals with ASD by improving their ability to acquire the subtle patterns embedded in language, and possibly other domains where such learning is important, such as pragmatics and social interactions.