Research on Language and Brain Waves

Principal Investigator: Prof. William S-Y WANG
Department of Electronic Engineering of CUHK

Background

The central goal of this project is to understand the biological and cultural bases of human behavior in terms of the underlying mental activities.  More specifically, our goal is to study linguistic behavior, particularly with reference to the distinctive features of the Chinese language.

In the proposed study we will look into brain activities through electroencephalograph (EEG) which records the changes in electric potential on one’s scalp during which one undergoes designated cognitive tasks. When these “brain waves” are properly time-locked they become Event Related Potentials (ERP) which is an established method in cognitive neuroscience, beginning with a paper by Sutton et al in Science in 19651 where they reported the discovery of an ERP component later called the P300. Since then, ERP has become a “non-invasive, high resolution, way to look at the human brain in action”2.

Language and the Brain

Language is an extremely complex behavior that involves sensory-motor circuits for its reception and transmission, as well as a variety of memorial and computational circuits for analyzing and comprehending the input and packaging and synchronizing the output. These numerous circuits are distributed in diverse regions of the central nervous system, each serving other non-linguistic functions as well3,4.
The challenge is to factor out significant linguistic features from language and to identify the corresponding signatures in the brain waves which appear when these features are processed. Ideally, the neurological sources of these signatures can be discovered by a combination of fMRI observations and computer modeling.
Our focus will be on the Chinese language, which has several features not found in other major languages of the world. These include lexical tone5, abundant ambiguity6,7, and morpho-syllabic writing8. We will begin our project with experiments which investigate these three features, each time building and extending on established studies done in the context of European languages.

Equipment

We are equipped with a 128-channels Geodesic EEG System manufactured by Electrical Geodesics, Inc. that gives EEG recordings with up to a 1ms temporal resolution. As for the purpose of looking into the sources of brain activities in space, we will employ Brain Electrical Source Analysis (BESA) which is a well recognized approach in the field. This gives us a basis to further our investigation with our collaborators in The University of Hong Kong8 where functional Magnetic Resonance Imaging (fMRI) facilities there could provide high spatial resolution as a nice complement with our ERP facilities.

References

1 Sutton, S., Braren, M., Zubin, J., & John, E. R. (1965). Evoked-Potential correlates of stimulus uncertainty. Science, 150(3700), 1187-1188.
2 Donchin, E. (2006). fMRI: Not the only way to look at the human brain Observer, 19(11).
3 Tzeng, O.J.L and W.S-Y. Wang. (1983). Search for a common neurocognitive mechanism for language and movements. American Journal of Physiology 246.R904-R911.
4 Polich, J.M., G. McCarthy, W.S-Y. Wang and E. Donchin. (1983). When words collide: orthographic and phonological interference during word processing. Biological Psychology 16.155-80.
5 Luo, H., Ni, J-T., Li, Z-H., Li, X-O., Zhang, D-R., Zeng, F-G., Lin Chen,L. (2006) Opposite patterns of hemisphere dominance for early auditory processing of lexical tones and consonants. PNAS, 103(51),19558-19563.
6 Eckstein, K. and Friederici, A. D. (2006). It’s early: Event-related potential evidence for initial interaction of syntax and prosody in speech comprehension. Journal of Cognitive Neuroscience 18(10): 1696-1711.
7 Lee, T. H. T. (2007). Garden-path sentences in Chinese. Festschrift in Honor of Professor Ting Pang-Hsin. Institute of Linguistics. Academia Sinica. Taiwan.
8 Tan, L.H., Spinks, J.A., Eden, G., Perfetti, C.A., & Siok, W.T. (2005). Reading depends on writing, in Chinese PNAS 102, 8781-8785.