Características electrofisiológicas del núcleo centromediano talámico humano

Abstract

The main goal of this thesis was the analysis of the electrophysiological features (properties of the action potential -AP- and pattern of discharge), by the extracellular recording of centromedian thalamic nucleus (Ce) in anesthetized patients. The theoretical trajectory of the electrodes on the different thalamic nuclei was reconstructed, assigning a nucleus to each depth of the trajectory. The analysis of the properties of each neuronal group that compose the most relevant thalamic nuclei was performed through a process of sorting and clustering. Results show significant differences between the subdomains of the Ce nucleus (magnocellular and parvocellular), both for the average morphological characteristics of the AP, and for the discharge properties. The analysis of the properties of the remaining nuclei of the thalamus also showed significant differences between Ce, ventral-intermediate nucleus (V.im.) and ventro-caudal nucleus (V.c.). In order to define the criteria for approaching Ce in relation to the V.c. nucleus, the response to electrical stimulation of the contralateral median nerve, recorded through microelectrodes (somatosensory evoked potentials, SSEP), was analyzed during the procedure. Three types of responses were found: (i) local field potentials (LFP), which are of complex morphology and a more or less localized distribution; (ii) high frequency oscillations (HFO), with a more widespread and nonspecific distribution; (iii) low-frequency oscillations (LFO), a response that has not been previously described in the literature, are more localized and are intimately related to V.c. This work demonstrates that the use of the electrophysiological characteristics of the extracellularly recorded APs, as well as those of the SSEPs, can improve the identification of the different thalamic nuclei, increasing the accuracy of Deep Brain Stimulation surgery