A person's cognitive state determines how their brain responds to visual stimuli. The most common such effect is a response enhancement when stimuli are task relevant and attended rather than ignored. In this fMRI study, we report a surprising twist on such attention effects in the visual word form area (VWFA), a region that plays a key role in reading. We presented participants with strings of letters and visually similar shapes, which were either relevant for a specific task (lexical decision or gap localization) or ignored (during a fixation dot color task). In the VWFA, the enhancement of responses to attended stimuli occurred only for letter strings, whereas non-letter shapes evoked smaller responses when attended than when ignored. The enhancement of VWFA activity was accompanied by strengthened functional connectivity with higher-level language regions. These task-dependent modulations of response magnitude and functional connectivity were specific to the VWFA and absent in the rest of visual cortex. We suggest that language regions send targeted excitatory feedback into the VWFA only when the observer is trying to read. This feedback enables the discrimination of familiar and nonsense words and is distinct from generic effects of visual attention.
Bibliographical noteFunding Information:
We are grateful to Brian Wandell, Kalanit Grill-Spector, and Anthony Norcia for help designing the study, and to Vassiki Chauhan for writing advice. Funding provided by NIH R00 EY029366 , R01 HD095861 , and P41 EB027061 ; NSF IIS-1822683 and IIS-1822929 . Thanks also to Kalanit Grill-Spector and Kevin Weiner for permission to re-analyze their 2015 data, funded by NIH R01 EY02391501A1 and RO1 EY03164.
© 2023 Elsevier Inc.
- functional connectivity
- task effects
- ventral temporal cortex
- visual attention
- visual word form area
- visual word recognition
PubMed: MeSH publication types
- Journal Article
- Research Support, N.I.H., Extramural
- Research Support, U.S. Gov't, Non-P.H.S.