Thalamic encoding of lexical status is lateralized during reading aloud

To explore whether the thalamus participates in lexical status encoding,
local field potentials were recorded in patients undergoing deep brain
stimulation lead implantation while they read aloud single-syllable words
and nonwords. Bilateral decreases in thalamic beta (12-30Hz) activity were
preferentially locked to stimulus presentation, and these decreases were
greater when nonwords were read. Increased broadband gamma (70-150Hz)
activity also was locked preferentially to speech onset bilaterally, but
greater nonword-related increases in this activity were observed only on
the left, demonstrating lateralization of thalamic broadband gamma
selectivity for lexical status. In addition, this lexical status effect
was strongest in more anterior thalamic locations, regions which are more
likely to receive pallidal than cerebellar afferents. These results
provide evidence from intracranial thalamic recordings for the
lateralization and topography of subcortical lexical status processing.