Leminen, A. 1 , Leminen, M. 1, 2 , Lehtonen, M. 1, 3, 4 , Nevalainen, P. 5 , Ylinen, S. 1 , Kimppa, L. 1 , Sannemann, C. 1 , Mäkelä, J. 5 & Kujala, T. 1
1 Institute of Behavioural Sciences. University of Helsinki. Helsinki, Finland
2 Finnish Centre of Excellence in Interdisciplinary Music Research. Jyväskylä, Finland
3 Department of Psychology and Logopedics. Åbo Akademi University. Turku, Finland
4 Low Temperature Laboratory. Aalto University School of Science and Technology. Espoo, Finland
5 BioMag Laboratory. Hospital District of Helsinki and Uusimaa. Helsinki, Finland
The present study examined the time-course and the neural sources of recognition of spoken morphologically complex words. Ten participants listened to derived, inflected, and monomorphemic Finnish words and judged their acceptability while their electroencephalography (EEG) and magnetoencephalography (MEG) responses were simultaneously recorded. We also aimed to relate latencies to the point in time when the sensory information crucial to morphological processing or word recognition is available and to separate the base morpheme and suffix-related processes. To this end, the EEG and MEG responses were time-locked to the onset of the critical information (suffix onset for the complex words and uniqueness point for the monomorphemic words). The event-related potential (ERP) results showed that inflected words elicited a larger left-lateralized negativity than derived and monomorphemic words approximately 200 ms after the critical point, but no differences were observed between derived and monomorphemic words. Equivalent current dipole (ECD) modeling of the MEG responses showed that this negativity was explained by two bilateral sources in the temporal cortex, with inflected words showing larger source amplitudes than derived words. There were also significant differences in the dipole locations between inflected and derived words. Moreover, source modeling showed one bilateral source in the superior temporal area ~100 ms after the critical point, with derived words eliciting stronger source amplitudes than inflected and monomorphemic words in the right hemisphere. The current results provide electrophysiological evidence for distinct cortical processing of spoken inflected and derived words. In general, the results support models of morphological processing that state that during the recognition of inflected words, the constituent morphemes are accessed separately. The left-lateralization of the ERP responses suggests that the stem and suffix combination undergoes (morpho)syntactic licensing. With regard to derived words, stem and suffix morphemes might be at least initially activated along with the whole word representation.