Poster A52, Tuesday, August 20, 2019, 10:15 am – 12:00 pm, Restaurant Hall
Picture naming yields highly reproducible cortical activation patterns: test-retest reliability of MEG recordings
Heidi Ala-Salomäki1, Jan Kujala1,2, Mia Liljeström1, Riitta Salmelin1;1Aalto University, 2University of Jyväskylä, Finland
Language production deficits occur frequently in patients with brain injury, e.g. following stroke. Magnetoencephalography (MEG) provides a direct measure of cortical processing, unaffected by the neurovascular disruption that occurs after stroke, and is thus well suited for assessment of functional brain damage in post-stroke patients. For this purpose, reliable measures of brain activity related to language production in individual participants are paramount. It is, however, unclear how reproducible the MEG activations are in various language-related tasks. In this MEG study, the aim was to identify source-localized naming-related evoked activity and modulations of cortical oscillatory activity that show high test-retest reliability across measurement days in healthy individuals. For patients with a severe speech production disorder picture naming can be a challenging task. Therefore, we also determined whether a semantic judgment task would suffice to induce comparably consistent activity. We analyzed MEG data collected from 19 healthy participants on two separate days. To identify activity related to picture naming (“Name the object in the picture”) or semantic judgment (“Is this a picture of a living object (‘yes/no’)?”) task, we compared these tasks with a visual task (“Say ‘yes’ when there is a red cross in the middle of the picture”). We identified task-related activity that was statistically significant (p<0.001, uncorrected, repeated measures t-test) on both measurement days and further used ICC (intraclass correlation coefficient) (Shrout and Fleiss, 1979) to determine the task-related activity that was consistent (ICC>0.4) in individual participants across measurement days. Analyses were performed for selected time windows (200–400 ms, 400–600 ms and 600–800 ms) time-locked to stimulus presentation, based on a neurocognitive model of speech production (Indefrey and Levelt, 2004) and earlier MEG findings (Salmelin et al., 1994; Vihla et al., 2006). The source-localized evoked activity related to the picture naming task was found to be highly consistent across measurement days in the left frontal (400–600 ms), central (400–800 ms), parietal (200–800 ms), temporal (200–800 ms), occipital (600–800 ms) and cingulate (600–800 ms) regions, as well as the right parietal (600–800 ms) region. In the semantic judgment task, consistent evoked activity was spatially and temporally more limited, occurring in the left parietal (600–800 ms), temporal (600–800 ms) and occipital (400–600 ms) areas, and the right parietal region (600–800 ms). Consistent modulations of oscillatory activity were observed mainly in the occipital cortex (400–800 ms) but not in cortical regions typically associated with language processing. The present study emphasizes the individual-level reproducibility of MEG evoked activity dynamics in picture naming. Due to the high test-retest reliability the task shows great promise for clinical evaluation of language function, as well as for longitudinal MEG studies of language production in clinical and healthy populations. References: Indefrey and Levelt (2004), Cognition, 92, 101–144. Salmelin, Hari, Lounasmaa, and Sams (1994), Nature, 368, 463–465. Shrout and Fleiss (1979), Psychological Bulletin, 86, 420–428. Vihla, Laine, and Salmelin (2006), Neuroimage, 33, 732–738.
Themes: Language Production, Methods
Method: Electrophysiology (MEG/EEG/ECOG)