Science of Aphasia 5 Cross Linguistic Aspects of Aphasia ...

PERCEPTION OF SIGN-LEXEMES VERSUS NON-VERBAL MOVEMENT OF HANDS
AND ARMS IN DEAF SIGNERS AND HEARING NON-SIGNERS: AN FMRI-STUDY
Juliane Klann (*#§), Frank Kastrau (*), Walter Huber (#)
*: Interdisciplinary Centre of Clinical Research \"CNS\", University Hospital Aachen; #: Neurolinguistics at the
Dept. of Neurology, University Hospital Aachen; §: Dept. of Linguistics, University of Cologne
Introduction:
Sign languages make extensive use of hand- and arm-movements in three-dimensional space. This implies, that
production and perception of sign language requires systems, whose functions are represented in different neural
networks, namely the planning respectively the analysis of hand- and arm-movements, that is known to be
represented in parietal cortex and the processing of language, that is represented in a perisylvian network mainly
concerning frontal and temporal cortical regions. This well established dissociation of neuro-anatomical
correlates leads to the assumption, that deaf signers may recruit both systems when they process sign language,
whereas hearing non-signers should activate parietal regions only, since they are not familiar with sign language
as a natural language system.
Lesion data as well as imaging studies document that deaf signers do not recruit parietal cortex for the
processing of sign lexemes. In order to pursue these issues further, we compared the processing of verbal and
non-verbal hand- and arm- movements in deaf signers and hearing non-signers. To gain an insight in anatomical
localization, functional Magnetic Resonance Imaging (fMRI) was conducted.
Subjects:
The participants were 11 prelingually deaf, age ranging from 22 to 43 years, with primary competence in
German Sign Language (DGS = Deutsche Gebärden Sprache). The control-group consists of 11 hearing,
matched for sex, age and education, with no competence in DGS. All subjects were right-handed.
Methods:
The same task was offered to all participants, hearing as well as deaf, in DGS and written German. Both
conditions were presented separately, each condition in one block. The first block included written nouns,
pseudo- and non-words. The second block contained videotaped single signs, pseudo-signs and non-verbal hand-
/arm-movements and non-signs. The participants were instructed to hit a button when they identified a known
sign or word.
The stimuli were linguistically parallel in both tasks. We chose 60 sign-lexemes, representing objects, 30
pseudo-signs and 30 non-signs. For the written material condition we presented 60 nouns, 30 pseudo-words and
30 non-words. All signs and words consisted of a linguistically simple structure (no compounds) and represented
high frequent nouns. The length of written words, pseudo- and non-words varied between four and nine letters.
The stimuli were presented pseudorandomized in an event related design. Imaging is done with a Philips 1.5
Tesla Gyruscan NT with standard bird-cage headcoil using a multishot T2* weighted gradient echo EPI
sequence. Image analysis and statistical evaluation will be carried out using SPM2 (Welcome
Department of Cognitive Neurology).
Preliminary Results:
Data analysis is not yet finished. Inspection of nine deaf individuals demonstrates indeed activation of temporal
regions with no activation of parietal cortex.