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Beyond the Visual Word Form Area: Rethinking the Dorsal Stream’s Role in Reading
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Organizer: Sachi Paul1; 1University of Pittsburgh
Presenters: Sachi Paul, Sabrina Turker, Oscar Woolnough, Peter Turkeltaub, Jacqueline Cummine
For decades, the neurobiology of reading has been dominated by a “ventral-centric” model focused on the visual word form area and its connections into temporal lobe regions associated with phonological and semantic processing. This symposium challenges the status quo by highlighting the neurobiological mechanisms—particularly within the inferior parietal lobe—that integrate speech-related representations into models of visual word recognition. Bringing together speakers with backgrounds in cognitive neuroscience, speech sciences, and neurology, we will explore how regions within the inferior parietal lobe, such as supramarginal gyrus, form a dorsal interface between reading and speech production. Speakers will examine the functional necessity of this interface across tasks and populations. We will use live digital polling to gather audience “hot take” questions, leading into a collaborative debate between presenters and audience. To further extend engagement, we will host a post-conference meetup and circulate key readings in advance, welcoming attendees of all career stages.
Presentations
What is SMG doing during speech and reading?: An integrative review
Sachi Paul1, Julie Fiez1; 1University of Pittsburgh
Through the history of research in the neurobiology of language, reading has been organized around a ventral-centric framework, with the visual word form area serving as the canonical entry point into orthographic, phonological, and semantic processing. Yet, mounting evidence implicates dorsal stream regions in skilled reading, raising questions about what exactly these regions contribute and why dominant models have underemphasized them. SMG is one region that is widely mentioned in speech and reading literature—it appears to be robustly recruited during pseudoword reading and phonological manipulation tasks, yet focal lesions often leave basic speech production relatively intact. Drawing on a systematic review of converging evidence across neuroimaging, lesion-symptom mapping, TMS, and intracranial electrophysiology, this talk argues that SMG functions as a dynamic dorsal interface between speech production and reading, most critically when phonological demands are novel or effortful. This framework motivates the perspectives and cross-method evidence that follow.
Beyond the Reading Brain: The Neural Manifestation of Dyslexia
Sabrina Turker1; 1University of Vienna
The neurobiological manifestations of developmental dyslexia, a common learning disability affecting reading and writing, include reduced activation of core reading regions and altered communication between them. These neurofunctional differences are strongly influenced by (a) task demands and difficulty, (b) language experience (e.g., multilingualism), and (c) individual symptom severity. While neurostimulation targeting reading regions can modulate connectivity and improve reading performance, converging evidence suggests that dyslexia is not confined to localized deficits in single reading areas. Rather, it reflects broader alterations in large-scale brain networks involved in cognition and early sensory processing. In recent work, we provide first evidence for atypical network organization in adults with dyslexia, characterized by reduced activation and weaker coupling within and between networks, such as the salience and ventral visual networks.
Distributed Spatiotemporal Networks for Reading Aloud
Oscar Woolnough1; 1University of Texas Health Science Center at Houston
Fluent literacy is dependent on the rapid coordination of distributed, functionally distinct hubs across the brain. Direct intracranial recordings in large populations provide a high spatiotemporal resolution window to probe this network during reading aloud. As patients read aloud both known and novel words, we see dynamic interactions between the frontoparietal dorsal stream and the frontotemporal ventral stream. Dorsal stream regions are initially sensitive to sub-lexical factors driving reading speed of novel words before receiving word frequency information, a driver of known word reading speed, propagating from the visual word form area. Within the dorsal stream, inferior parietal sulcus and precentral sulcus facilitate the bidirectional mapping between written and spoken language, allowing patients to construct novel phonologies for written words, and access the spellings of spoken words. This work demonstrates the importance of the dynamic coordination of dorsal and ventral stream activity for the interface between reading and speech.
Reading between the lines: Dissecting the neurocognitive architecture of reading through studies of alexia
Peter Turkeltaub1; 1Georgetown University
Humans did not evolve to read. Reading coopts brain networks that evolved for object recognition, language, and speech. Current neurocognitive models of speech processing suggest a highly modular organization for translating between auditory targets and motor speech acts, supported by a distributed cortical and subcortical network. Although reading must rely on this underlying speech architecture, neurocognitive models of reading remain comparatively simple, composed only of orthographic, semantic, and phonological representations and intervening units. A disconnect has thus emerged between theories of speech and reading. Current models of reading were inspired by behavioral dissociations in alexia. I will discuss a series of recent studies in which we combine detailed behavioral assessment, computational modeling, and modern lesion-symptom mapping methods to identify brain structures and connections where lesions cause deficits in reading and speech subprocesses. Collectively, the findings help to align our understanding of reading with current models of speech and language.
Rethinking the Supramarginal Gyrus: From Speech Sensorimotor Control to Reading
Jacqueline Cummine1; 1University of Alberta
The supramarginal gyrus (SMG) is frequently discussed in the reading literature as a phonological processing region, yet this characterization overlooks its well-established role in speech production as a sensorimotor interface supporting the generation and monitoring of articulatory commands. I argue that insights from the speech production literature offer a critical framework for reinterpreting SMG function in reading. Across a series of studies, we examine how somatosensory perturbations and speech production demands modulate SMG activity and its connectivity with frontal speech regions. Findings demonstrate that SMG activity is dynamically shaped by somatosensory feedback and sensorimotor integration during speech tasks. I then extend this framework to reading, proposing that SMG may support mapping between orthographic, phonological, and articulatory representations through the same sensorimotor mechanisms that support speech production. This perspective challenges dominant phonological-only interpretations and suggests that reading models should incorporate the SMG as a core component of the speech sensorimotor system.