Browsing by Author "Figueroa-Taiba, Paulo"
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Publication Potentiation of Motor Adaptation Via Cerebellar tACS: Characterization of the Stimulation Frequency(2024) Figueroa-Taiba, Paulo; Álvarez-Ruf, Joel; Ulloa, Paulette; Bruna-Melo, Trinidad; Espinoza-Maraboli, Liam; Burgos, Pablo Ignacio; Mariman, Juan J.Motor adaptation is critical to update motor tasks in new or modified environmental conditions. While the cerebellum supports error-based adaptations, its neural implementation is partially known. By controlling the frequency of cerebellar transcranial alternating current stimulation (c-tACS), we can test the influence of neural oscillation from the cerebellum for motor adaptation. Two independent experiments were conducted. In Experiment 1, 16 participants received four c-tACS protocols (45 Hz, 50 Hz, 55 Hz, and sham) on four different days while they practiced a visuomotor adaptation task (30 degrees CCW) with variable intensity (within-subject design). In Experiment 2, 45 participants separated into three groups received the effect of 45 Hz, 55 Hz c-tACS, and sham, respectively (between-subject design), performing the same visuomotor task with a fixed intensity (0.9 mA). In Experiment 1, 45 Hz and 50 Hz of c-tACS accelerated motor adaptation when participants performed the task only for the first time, independent of the time interval between sessions or the stimulation intensity. The effect of active c-tACS was ratified in Experiment 2, where 45 Hz c-tACS benefits motor adaptation during the complete practice period. Reaction time, velocity, or duration of reaching are not affected by c-tACS. Cerebellar alternating current stimulation is an effective strategy to potentiate visuomotor adaptations. Frequency dependent effects on the gamma band, especially for 45 Hz c-tACS, ratify the oscillatory profile of cerebellar processes behind the motor adaptation. This can be exploited in future interventions to enhance motor learning.Publication White matter volume and microstructural integrity are associated with fatigue in relapsing multiple sclerosis(2025) Figueroa-Vargas, Alejandra; Navarrete-Caro, Sebastián; Cárcamo, Claudia; Ciampi, Ethel; Vásquez-Torres, Macarena; Soler, Bernardita; Montalba, Cristian; Iriarte-Carter, Matías; Martínez-Molina, María Paz; Carvajal-Paredes, Patricio; Ayala-Ochoa, Mariana; Márquez-Rodríguez, Víctor; Figueroa-Taiba, Paulo; Díaz-Díaz, Marcela; Herrero, Joaquín; Henríquez-Ch., Rodrigo; Stecher, Ximena; Manterola, Carla; Zamorano, Francisco; Guevara, Pamela; Aboitiz, Francisco; Billeke, PabloMultiple sclerosis (MS) is a prevalent neurological disorder marked by inflammation and demyelination, with fatigue being one of the most reported and debilitating symptoms. While fatigue occurs across various neurological conditions and even in healthy individuals, the specific mechanisms contributing to fatigue in each context remain unclear. In this study, we conducted a cross-sectional analysis involving 32 people with relapsing MS (PwRMS) and 29 healthy controls who reported fatigue. Participants underwent MRI scans, including T1-weighted and diffusion-weighted imaging. Additionally, the Modified Fatigue Impact Scale was utilized. We employed Bayesian LASSO and Spike-and-Slab LASSO regression models to investigate the hypothesis that fatigue correlates differently with brain structures in PwRMS. Our findings revealed brain regions associated with general and cognitive fatigue. In particular, reduced white matter volume and compromised microstructural integrity in specific areas—such as the cingulate gyrus, inferior frontal gyrus, and the banks of the superior temporal sulcus—showed significant associations with fatigue scores in PwRMS. These results suggest that alterations in specific brain regions may play a critical role in the clinical manifestation of fatigue in MS. Understanding these insights could help differentiate general mechanisms of fatigue from those affecting people with relapsing MS, which may guide future therapeutic strategies.