Contributions of the multiple demand network to emergent and skilled reading.

Reading is an acquired skill that must engage brain networks initially evolved for other functions, integrating visual, language, and executive systems. However, it is still unclear how evolutionary-defined brain networks are leveraged to scaffold reading skills. Here, we focus on emergent reading in an artificial alphabetic writing system - a process that is heavily based on phonological decoding. We examine whether such emergent reading co-opts portions of the language and multiple demand (MD) networks, and whether it activates constituents of a network associated with skilled reading. Adult participants (n = 32) completed training in the artificial alphabet and ten reading sessions over the course of several weeks. After that, participants' brain activity was recorded with the fMRI as they read words in the new alphabet. We found substantial overlap between regions activated during emergent reading and the MD network, but only minor overlap with the language network. Identified regions also overlapped with the skilled reading network, albeit showing sites of divergence. Furthermore, we observed differences in the relative engagement of the MD and language networks during emergent vs. skilled reading, suggesting that configurations of neural systems change with reading experience, with greater contributions from the language network to more skilled reading processes.