Behavioral and neurophysiologic response to therapy for chronic aphasia.

UNLABELLED: Breier JI, Juranek J, Maher LM, Schmadeke S, Men D, Papanicolaou AC. Behavioral and neurophysiologic response to therapy for chronic aphasia. OBJECTIVE: To characterize the relationship between neurophysiologic changes in the brain and behavioral response to constraint-induced language therapy (CILT) by using magnetoencephalography (MEG). DESIGN: Case series. SETTING: Medical school. PARTICIPANTS: Patients (N=23) with chronic aphasia after first-time unilateral stroke in the left hemisphere. INTERVENTIONS: Constraint-induced language therapy administered for 3 hours 4 times per week for 3 weeks. Language testing and functional imaging during a language comprehension task using MEG before, immediately after, and 3 months after CILT with a subgroup of patients undergoing additional MEG scanning and language testing 3 weeks before CILT. MAIN OUTCOME MEASURES: The percent of correct information units and the number of late dipoles normalized to total activation. RESULTS: Three patterns of behavioral and neurophysiologic response to CILT were identified. Patients with significant improvement in language immediately after CILT who lost these gains at follow-up had greater right hemisphere activation than other patients at all MEG scanning sessions. Patients with significant improvement in language immediately after CILT who maintained these gains at follow-up exhibited an increase in left temporal activation after CILT, whereas patients who did not exhibit significant improvement in language after CILT exhibited comparably greater activation in left parietal areas. CONCLUSIONS: Results suggest that although the right hemisphere may support recovery of language function in response to therapy, this recovery may not be stable, and some participation of perilesional areas of the left hemisphere may be necessary for a stable behavioral response.

Aberrant cortical functionality and somatosensory deficits after stroke.

Damage and/or disconnection of the primary somatosensory cortex (SI) after stroke leads to deficits in touch perception. We used magnetoencephalography to test whether specific patterns of functionality of the somatosensory cortex are associated with different degrees of postacute somatosensory deficit. Nineteen postacute unilateral stroke patients suffering different degrees of somatosensory deficit (six nonexistent, six moderate, and seven severe) and eight aged-matched controls underwent high-resolution MRI and whole-head magnetoencephalography recordings of somatosensory-evoked fields and of spontaneous slow oscillatory activity. Amplitude of SI activation after tactile stimulation in the affected and nonaffected hemispheres and delta dipole density (DDD) in the postcentral areas were estimated and compared across the four groups. Severe postacute somatosensory deficit was accompanied, in all cases, with absence of SI responses to stimulation in the affected hand and a significant asymmetry in postcentral DDD toward the affected hemisphere. Patients with moderate sensory loss showed asymmetry in their postcentral DDD (four cases toward the affected hemisphere and two toward the unaffected) but no atypical amplitudes in SI activation. Recordings in stroke patients without somatosensory deficit did not differ from those obtained in controls for SI amplitude or postcentral DDD. In stroke patients, amplitude of SI responses and postcentral DDD show a negative correlation. Lack of activation of SI cortex after stimulation of the affected hand and spontaneous slow oscillatory activity in postcentral areas are neurophysiological correlates of somatosensory deficit in the postacute phase of stroke.

A comparison of functional MRI and magnetoencephalography for receptive language mapping.

We compared functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) for the mapping of receptive language function. Participants performed the same language task in the two different imaging environments. MEG activation profiles showed prominent bilateral activity in superior temporal gyrus and left-lateralized activity in middle temporal gyrus. fMRI activation profiles revealed bilateral activity in prefrontal, superior temporal, middle temporal, and visual areas. Laterality quotients derived from the two modalities showed poor agreement between the two methods for commonly active regions of interest. Locations of peak activity also varied considerably within participants between the two methods.