Article
The Centromedian-Parafascicular Complex may signal behaviorally relevant events
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Published: | June 9, 2017 |
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Objective: The centromedian-parafascicular complex (CM-Pf) of the intralaminar thalamus was shown to be activated during attentional orienting and processing of behaviorally relevant stimuli. Therefore, the CM-Pf was suggested to be a part of a subcortical cognitive control loop. Here, we investigated the human CM-Pf and its involvement in processing of task relevant information during an auditory three-class oddball paradigm with simultaneous cortical recordings.
Methods: Simultaneous intracranial local field potentials (LFPs) and scalp electroencephalographic (EEG) recordings were obtained in 6 patients (2 woman; mean age=48±12 years) who received deep brain stimulation (DBS) electrodes in the CM-Pf for the treatment of their pain syndromes. Within 2 days after surgery, they performed an auditory three-class oddball paradigm with externalized DBS electrodes. Subcortical and cortical event-related potentials (ERPs) were analyzed upon presentation of one frequent standard stimulus (900Hz; 72%) and two infrequent stimuli (600Hz and 1200Hz; 14%), either being a relevant or a distractor stimulus.
Results: Analysis revealed high accuracy (>70%) for all participants. As expected, the rare relevant stimuli elicited a P3 response over parietal regions in the EEG. The P3 component of an ERP is known to reflect attentional processes in tasks requiring stimulus detection and discrimination. Recordings in the CM-Pf revealed highest amplitudes to the relevant stimuli as well. Interestingly, peak latencies of the CM-Pf precede the cortical P3 response.
Conclusion: The CM-Pf seems to be involved in goal-oriented action selection and attentional mechanisms. Importantly, subcortical responses in the CM-Pf precede cortical responses, suggesting that auditory information is labelled as behavioral relevant from subcortical circuits and is then distributed to cortical areas; possibly via thalamo-striatal loop mechanisms.