Authors: Aboud, Katherine S., Laura A. Barquero and Laurie E. Cutting..
Article: Prefrontal mediation of the reading network predicts intervention response in dyslexia.
Publication: Cortex (Elsevier). 101: 96-106, April 2018 | DOI: 10.1016/j.cortex.2018.01.009
A primary challenge facing the development of interventions for dyslexia is identifying effective predictors of intervention response. While behavioral literature has identified core cognitive characteristics of response, the distinction of reading versus executive cognitive contributions to response profiles remains unclear, due in part to the difficulty of segregating these constructs using behavioral outputs. In the current study we used functional neuroimaging to piece apart the mechanisms of how/whether executive and reading network relationships are predictive of intervention response. We found that readers who are responsive to intervention have more typical pre-intervention functional interactions between executive and reading systems compared to nonresponsive readers. These findings suggest that intervention response in dyslexia is influenced not only by domain-specific reading regions, but also by contributions from intervening domain-general networks. Our results make a significant gain in identifying predictive bio-markers of outcomes in dyslexia, and have important implications for the development of personalized clinical interventions.
- The role of executive networks in reading intervention response is unclear.
- Intervention response is predicted by prefrontal mediation of the reading network.
- At baseline, responders have more typical prefrontal mediation than nonresponders.
- Executive areas provide a scaffold for better intervention response in dyslexia.
The current study consequently re-frames neural resilience to learning disorders, such as dyslexia, in the context of the presence or absence of an appropriate executive “scaffold”. By identifying neural circuits of intervention response, the current findings take steps to help identify neurobiological patterns of distinct reader subpopulations—groups which likely have different interventional needs.
Specifically, in DYS-R only, left dlPFC activation corresponded with increased correlations between left vMTG/left vIFG semantic seeds and the left IPL. The left IPL clusters mapped closely to coordinates that are functionally and structurally reduced in readers with dyslexia (Hoeft et al., 2007). In the context of word reading, this area is thought to support phonological processing, as well as mapping orthographic and phonological information (Celsis et al., 1999; Price, 2012; Vigneau et al., 2006). The current results point to a unique relationship in DYS-R, as compared to DYS-NR, between left dlPFC activity and attainment of stronger phonological-semantic communication— processes that are degraded in the face of poor orthographic representations of words (Perfetti, 2007).
However, DYS-NR appears to recruit the left dlPFC to support classic compensatory reading circuits in the right hemisphere (Pugh et al., 2000; Shaywitz et al., 1998; Waldie, Haigh, Badzakova-Trajkov, Buckley, & Kirk, 2013). Consequently, unlike the utilization of the left dlPFC in DYS-R, these pathways do not result in increased communication between canonical reading areas, possibly reflecting less efficiency in DYS-NR.
It is perhaps for this reason that some of the most effective reading interventions include executive components such as explicit strategy instruction and self-regulated learning (Wanzek, Wexler, Vaughn, & Ciullo, 2010). We therefore propose that cognitive control systems play an essential, albeit a “behind the scenes” role in resiliency in learning.
Rather, the focus would need to shift in terms of how to strengthen and facilitate connections and interactions between critical cognitive control networks and reading systems that may allow for alternate learning pathways. In particular, readers who are non-responsive to traditional interventions may benefit from existing interventions that emphasize both reading and executive functions.