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Language experience modulates the activation of visual word form area: Evidence from functional MRI and stereotactic electroencephalography data

Mingyang Li1, Yangwen Xu1, Yi Liu1 and Zaizhu Han1*
  • 1 Beijing Normal University, China

Reading is supported by a distinctive brain network, which contains a critical node in the left middle fusiform gyrus, termed the “visual word form area” (VWFA, Cohen et al., 2000). The VWFA is highly responsive to words relative to objects (e.g., faces, animals, tools, buildings; Dehaene et al., 2010). One key outstanding question is what causes the apparent selectivity of the VWFA for words. There are two influential hypotheses for this question: shape and connectivity ones (Hannagan et al., 2015). The former assumes that the VWFA is highly specialized for recognizing the shapes of words (e.g., line junctions) rather than other categories (Dehaene and Cohen, 2011; Szwed et al., 2009). The latter postulates that the VWFA is constrained by its innate connectivity to high-level language regions. This region is dedicated to recognizing the form information of stimuli with language experience. One piece of supportive evidence for the connectivity hypothesis is that the activation intensity of the VWFA changed when subjects were trained to learn a novel stimulus (e.g., second language, artificial language, meaningless figures) as a word (Hashimoto and Sakai, 2004; Song et al., 2010; Xue et al., 2006). Given that the learning contexts for a novel stimulus were always specifically associated with a real word in participants’ native languages, it is unclear whether the change in the responsiveness of the VWFA was 1) specific to the novel stimulus or the native word, and 2) language-dependent or -independent. To deal with these limitations, the present study first conducted a functional MRI study comparing the activation pattern of the VWFA between when a meaningless figure was learnt as a word (by associating the figure with two lexical features: pronunciation, gender) and as an object (by associating with two object features: material property, other properties of objects). We found that the activation intensity of the VWFA significantly decreased only when the meaningless figures were learnt as words rather than objects. Furthermore, similar activation change was also observed in other language areas (e.g., Wernicke’s area, precentral gyrus, and supplementary motor area). Psychophysiological interaction (PPI) analysis further revealed that the strength of functional connectivity between the VWFA and Wernicke’s area was significantly enhanced for word training conditions. To further directly elaborate the dynamics of the information flow between the VWFA and other language areas in word recognition, we recruited a group of patients with intractable epilepsy, who were implanted with electrodes in the VWFA and other language areas. The patients’ stereotactic electroencephalography (SEEG) data were recorded as they performed a lexical task. Granger causality analysis for the SEEG data showed that the ventral occipital temporal cortex had strong interactions with Wernicke’s area, inferior frontal area, and anterior temporal lobe. The above findings underline the pivotal role of language experience in the plasticity of the VWFA, and highlight that this change is supported by the connectivity between this brain region and other language areas. This provides converging evidence for the connectivity hypothesis in word reading.

Acknowledgements

National Natural Science Foundation of China (21010063; 210100167).

References

Cohen, L., Dehaene, S., Naccache, L., Lehéricy, S., Dehaene-Lambertz, G., Hénaff, M.A., and Michel, F. (2000). The visual word form area. Spatial and temporal characterization of an initial stage of reading in normal subjects and posterior split-brain patients. Brain. Dehaene, S., and Cohen, L. (2011). The unique role of the visual word form area in reading. Trends Cogn. Sci. 15, 254–262. Dehaene, S., Pegado, F., Braga, L.W., Ventura, P., Nunes Filho, G., Jobert, A., Dehaene-Lambertz, G., Kolinsky, R., Morais, J., and Cohen, L. (2010). How learning to read changes the cortical networks for vision and language. Science (80-. ). 330, 1359–1364. Hannagan, T., Amedi, A., Cohen, L., Dehaene-Lambertz, G., and Dehaene, S. (2015). Origins of the specialization for letters and numbers in ventral occipitotemporal cortex. Trends Cogn. Sci. 19, 374–382. Hashimoto, R., and Sakai, K.L. (2004). Learning letters in adulthood: Direct visualization of cortical plasticity for forming a new link between orthography and phonology. Neuron. Song, Y., Hu, S., Li, X., Li, W., and Liu, J. (2010). The Role of Top-Down Task Context in Learning to Perceive Objects. J. Neurosci. 30, 9869–9876. Szwed, M., Cohen, L., Qiao, E., and Dehaene, S. (2009). The role of invariant line junctions in object and visual word recognition. Vision Res. Xue, G., Chen, C., Jin, Z., and Dong, Q. (2006). Language experience shapes fusiform activation when processing a logographic artificial language: An fMRI training study. Neuroimage 31, 1315–1326.

Keywords: VWFA, visual word form area, training, functional MRI, connectivity, SEEG (stereo-electroencephalography), Meaningless symbol

Conference: Academy of Aphasia 57th Annual Meeting, Macau, Macao, SAR China, 27 Oct - 29 Oct, 2019.

Presentation Type: Poster presentation

Topic: Not eligible for student award

Citation: Li M, Xu Y, Liu Y and Han Z (2019). Language experience modulates the activation of visual word form area: Evidence from functional MRI and stereotactic electroencephalography data. Front. Hum. Neurosci. Conference Abstract: Academy of Aphasia 57th Annual Meeting. doi: 10.3389/conf.fnhum.2019.01.00023

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Received: 05 May 2019; Published Online: 09 Oct 2019.

* Correspondence: Prof. Zaizhu Han, Beijing Normal University, Beijing, China, hanzaizhu@gmail.com