Subthalamic nucleus and sensorimotor cortex activity during speech production

Abstract

The sensorimotor cortex is somatotopically organized to represent the vocal tract articulators, such as lips, tongue, larynx, and jaw. How speech and articulatory features are encoded at the subcortical level, however, remains largely unknown. We analyzed local field potential (LFP) recordings from the subthalamic nucleus (STN) and simultaneous electrocorticography recordings from the sensorimotor cortex of 11 patients (1 female) with Parkinson's disease during implantation of deep brain stimulation (DBS) electrodes, while patients read aloud threephoneme words. The initial phonemes involved either articulation primarily with the tongue (coronal consonants) or the lips (labial consonants). We observed significant increases in high gamma (60-150 Hz) power in both the STN and the sensorimotor cortex that began before speech onset and persisted for the duration of speech articulation. As expected from previous reports, in the sensorimotor cortex, the primary articulator involved in the production of the initial consonant was topographically represented by high gamma activity. We found that STN high gamma activity also demonstrated specificity for the primary articulator, although no clear topography was observed. In general, subthalamic high gamma activity varied along the ventraldorsal trajectory of the electrodes, with greater high gamma power recorded in the more dorsal locations of the STN. These results demonstrate that articulator-specific speech information is contained within high gamma activity of the STN, with similar temporal but less specific topographical organization, compared to similar information encoded in the sensorimotor cortex.

Acute effects of adaptive Deep Brain Stimulation in Parkinson’s disease

“…Studies using more sophisticated methods, such as articulography [ 42 ] or speech signal processing [ 43 ], might reveal even more insights about the potential benefits of aDBS. In addition to this, other activities in the STN LFP or biomarkers from the motor cortex could be used to monitor speech articulation, in order to further improve the efficacy of aDBS [ 44 ]. However, this is yet to be tested.…”

Thalamic encoding of lexical status is lateralized during reading aloud

“…Significant increases in broadband gamma activity began before but were predominantly locked to speech onset. Given that broadband gamma activity is thought to index synchronized local neuronal firing (25,26) and is associated with the functional activation of relevant brain regions during a wide range of sensorimotor and cognitive tasks, including speech and language processing (11,16,(27)(28)(29), our data suggest that the ventral lateral thalamus tracks speech production.…”

“…We recently developed a protocol to study subcortical activity during single-syllable word/nonword reading, in patients undergoing DBS lead implantation (15,16). Here, we explore whether the thalamus participates in the encoding of lexical status, by recording local field potentials (LFP) in patients undergoing DBS lead implantation for essential tremor targeting the ventral intermediate nucleus of the thalamus (Vim, which corresponds to the ventral portion of the ventral lateral posterior nucleus (VLp) (17)).…”

Deep Brain Stimulation Does Not Modulate Auditory-Motor Integration of Speech in Parkinson's Disease

“…Recent work suggested that the subthalamic nucleus (STN) is also involved in speech production. Increased activity in the gamma band in the STN was shown before speech onset and during articulation, similar to the sensorimotor cortex ( 14 ). In fact, DBS of the STN can alleviate specific speech symptoms like hypophonia and voice tremor ( 15 ).…”