Feed-forward, feed-back, and distributed feature representation during visual word recognition revealed by human intracranial neurophysiology

Kaneshiro

Strauber

et al. 2021

Sci Rep

EEG has been central to investigations of the time course of various neural functions underpinning visual word recognition. Recently the steady-state visual evoked potential (SSVEP) paradigm has been increasingly adopted for word recognition studies due to its high signal-to-noise ratio. Such studies, however, have been typically framed around a single source in the left ventral occipitotemporal cortex (vOT). Here, we combine SSVEP recorded from 16 adult native English speakers with a data-driven spatial filtering approach—Reliable Components Analysis (RCA)—to elucidate distinct functional sources with overlapping yet separable time courses and topographies that emerge when contrasting words with pseudofont visual controls. The first component topography was maximal over left vOT regions with a shorter latency (approximately 180 ms). A second component was maximal over more dorsal parietal regions with a longer latency (approximately 260 ms). Both components consistently emerged across a range of parameter manipulations including changes in the spatial overlap between successive stimuli, and changes in both base and deviation frequency. We then contrasted word-in-nonword and word-in-pseudoword to test the hierarchical processing mechanisms underlying visual word recognition. Results suggest that these hierarchical contrasts fail to evoke a unitary component that might be reasonably associated with lexical access.

Section: Discussionmentioning

confidence: 99%

Distinct neural sources underlying visual word form processing as revealed by steady state visual evoked potentials (SSVEP)

Kaneshiro

Strauber

et al. 2021

Sci Rep

“…Finding of a second component is consistent with the increasing evidence showing that visual word recognition is not only limited to the left vOT. Instead, other higher-level linguistic representation areas also support final word recognition 13,14,62 . For example, a recent fMRI study showed that, connected with the middle and anterior vOT, other language areas (e.g., the supramarginal, angular gyrus, and inferior frontal gyrus) are responsible for lexical information processing especially for real words 13 .…”

Section: Discussionmentioning

confidence: 99%

“…As a result, the sensitivity of neurons increases from familiar letter fragments and fragments combinations to more complex letter strings (e.g, bigrams and morphemes) and whole words. However, given the functional and structural connections between vOT (especially anterior regions) and other language areas mentioned above (i.e., AG, SMG, and STS), a considerable number of studies support the interactive theory in which feed-forward and feed-back processing mechanisms together contribute to final recognition of a word 5,6,45,62 . Specifically, the forward pathway conveys bottom-up progression from early visual cortex (e.g., visual area 4, V4) to vOT, which accumulates inputs about the elementary forms of words 73 , and continually from vOT to higher-level linguistic representation areas, which enable integration of orthographic stimuli with phonological and lexical representations 14 .…”

Section: Discussionmentioning

confidence: 99%

Neural Sources Underlying Visual Word Form Processing as Revealed by Steady State Visual Evoked Potentials (SSVEP)

Kaneshiro

Strauber

et al. 2021

Preprint

EEG has been central to investigations of the time course of various neural functions underpinning visual word recognition. Recently the steady-state visual evoked potential (SSVEP) paradigm has been increasingly adopted for word recognition studies due to its high signal-to-noise ratio. Such studies, however, have been typically framed around a single source in the left ventral occipitotemporal cortex (vOT). Here, we combine SSVEP recorded from 16 adult native English speakers with a data-driven spatial filtering approach - Reliable Components Analysis (RCA) - to elucidate distinct functional sources with overlapping yet separable time courses and topographies that emerge when contrasting words with pseudofont visual controls. The first component topography was maximal over left vOT regions with an shorter latency (approximately 180 msec). A second component was maximal over more dorsal parietal regions with a longer latency (approximately 260 msec). Both components consistently emerged across a range of parameter manipulations including changes in the spatial overlap between successive stimuli, and changes in both base and deviation frequency. We then contrasted word-in-nonword and word-in-pseudoword to test the hierarchical processing mechanisms underlying visual word recognition. Results suggest that these hierarchical contrasts fail to evoke a unitary component that might be reasonably associated with lexical access.

“…Finding of a second component is consistent with the increasing evidence showing that visual word recognition is not only limited to the left vOT. Instead, other higher-level linguistic representation areas also support final word recognition (Long et al, 2020;Lerma-Usabiaga et al, 2018;Price & Devlin, 2011).…”

Section: Low-level Visual Processing Implicates Medial Occipital Areasmentioning

confidence: 99%

“…As a result, the sensitivity of neurons increases from familiar letter fragments and fragments combinations to more complex letter strings (e.g, bigrams and morphemes) and whole words. However, given the functional and structural connections between vOT (especially anterior regions) and other language areas mentioned above (i.e., AG, SMG, and STS), a considerable number of studies support the interactive theory in which feed-forward and feed-back processing mechanisms together contribute to final recognition of a word (Dehaene et al, 2005;Dehaene et al, 2015;Long et al, 2020). Specifically, the forward pathway conveys bottom-up progression from early visual cortex (e.g., visual area 4, V4) to vOT, which accumulates inputs about the elementary forms of words (Schurz et al, 2014), and continually from vOT to higher-level linguistic representation areas, which enable integration of orthographic stimuli with phonological and lexical representations (Price & Devlin, 2011).…”

Section: Low-level Visual Processing Implicates Medial Occipital Areasmentioning

confidence: 99%

Neural Sources Underlying Visual Word Form Processing as Revealed by Steady State Visual Evoked Potentials (SSVEP)

Kaneshiro²,

Strauber³

et al. 2021

Preprint

EEG has been central to investigations of the time course of various neural functions underpinning visual word recognition. Recently the steady-state visual evoked potential (SSVEP) paradigm has been increasingly adopted for word recognition studies due to its high signal-to-noise ratio. Such studies, however, have been typically framed around a single source in the left ventral occipitotemporal cortex (vOT). Here, we combine SSVEP recorded from 16 adult native English speakers with a data-driven spatial filtering approach - Reliable Components Analysis (RCA) - to elucidate distinct functional sources with overlapping yet separable time courses and topographies that emerge when contrasting words with pseudofont visual controls. The first component topography was maximal over left vOT regions with an early latency (approximately 180 msec). A second component was maximal over more dorsal parietal regions with a longer latency (approximately 260 msec). Both components consistently emerged across a range of parameter manipulations including changes in the spatial overlap between successive stimuli, and changes in both base and deviation frequency. We then contrasted word-in-nonword and word-in-pseudoword to test the hierarchical processing mechanisms underlying visual word recognition. Results suggest that these hierarchical contrasts fail to evoke a unitary component that might be reasonably associated with lexical access.