Examinando por Autor "Fernandez-del-Olmo, Miguel"

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Acute kinematic and neurophysiological effects of treadmill and overground walking in Parkinson’s disease
(SAGE, 2019-06-20) Fernandez-Lago, Helena; Bello, Olalla; Salgado , AV; Fernandez-del-Olmo, Miguel
BACKGROUND: The use of the treadmill as a gait rehabilitation tool has provided novel options for treatment of gait impairments in Parkinson's Disease (PD). However, the neural mechanisms underlying these therapeutic effects in PD remain unknown and whether any therapeutic effects from treadmill training can be reproduced on overground walking. OBJECTIVE: To examine the immediate short-term effects of a single session of treadmill and overground walking on gait, spinal and corticospinal parameters in PD.METHODSPD participants (N = 15) were evaluated in two separate sessions under two walking conditions: walking over a treadmill and walking overground. Overground walking performance, the Soleus H-reflex, Reciprocal Ia-Inhibition, Intracortical Facilitation (ICF) and Short Intracortical Inhibition (SICI), were evaluated before and after each condition. RESULTS: Gait speed and stride length improved in post-treadmill compared with pre-treadmill. No significant changes in these gait parameters were found for the pre vs. post-overground condition. ICF values and Hmax/Mmax ratio decreased after, compared with before, the two walking conditions. CONCLUSIONS: Treadmill walking, but not overground walking, lead to an improvement in the stride length and gait speed in the PD patients without evidence of different modulation on spinal and corticospinal parameters.
An Integrative Clustering Approach to tDCS Individual Response Variability in Cognitive Performance: Beyond a Null Effect on Working Memory
(PERGAMON-ELSEVIER SCIENCE LTD, 2020-07-28) Luque-Casado, Antonio; Rodríguez-Freiría, Rocio; Fogelson, Noa; Iglesias-Soler, Eliseo; Fernandez-del-Olmo, Miguel
Despite the growing interest in the use of transcranial direct current stimulation (tDCS) for the modulation of human cognitive function, there are contradictory findings regarding the cognitive benefits of this technique. Inter-individual response variability to tDCS may play a significant role. We explored the effects of anodal versus sham tDCS over the left prefrontal cortex (LPFC) on working memory performance, taking into account the inter-individual variability. Twenty-nine healthy volunteers received an 'offline' anodal tDCS (1.5 mA, 15 min) to the left prefrontal cortex (F3 electrode site) in an intra-individual, cross-over, sham-controlled experimental design. n-back and Sternberg task performance was assessed before (baseline), immediately after tDCS administration (T1) and 5 min post-T1 (T2). We applied an integrative clustering approach to characterize both the group and individual responses to tDCS, as well as identifying naturally occurring subgroups that may be present within the total sample. Anodal tDCS failed to improve working memory performance in the total sample. Cluster analysis identified a subgroup of 'responders' who significantly improved their performance after anodal (vs. sham) stimulation, although not to a greater extent than the best baseline or sham condition. The proportion of 'responders' ranged from 15% to 59% across task conditions and behavioral outputs. Our findings show a high inter-individual variability of the tDCS response, suggesting that the use of tCDS may not be an effective tool to improve working memory performance in healthy subjects. We propose that the use of clustering methods is more suitable in identifying 'responders' and for evaluating the efficacy of this technique.
Differences in the effects of a startle stimulus on rate of force development between resistance-trained rock climbers and untrained individuals: Evidence for reticulospinal adaptations?
(WILEY, 2023-03-23) Colomer-Poveda, David; Lopez-Rivera, Eva; Hortobagyi, Tibor; Márquez, Gonzalo; Fernandez-del-Olmo, Miguel
The aim of the present cross-sectional study was to determine if chronic rock climbing and climbing-specific resistance training (RT) would modify the reticulospinal tract (RST) efficacy. Sixteen healthy, elite level climbers (CL; n = 16, 5 F; 29.8 ± 6.7 years) with 12 ± 7 years of climbing and climbing-specific RT experience and 15 healthy recreationally active participants (CON; n = 15, 4 F; 24.6 ± 5.9 years), volunteered for the study. We quantified RST efficacy by comparing the effects of a startle stimulus over reaction time (Rtime ) and measured rate of force development (RFD) and surface electromyography (sEMG) in representative muscles during powerful hand grip contractions. Both groups performed two Rtime tasks while performing rapid, powerful gripping with the right hand (Task 1) or during 3-s-long maximal voluntary right hand grip contractions in response to an imperative visual signal alone (V), or combined with a auditory-non startle stimulus (A) or/and startling auditory stimulus (S). We also tested the reproducibility of these responses on two separate days in CON. Intersession reliability ranged from 0.34 to 0.96 for all variables. The CL versus CON was 37% stronger (p = 0.003). The S stimulus decreased Rtime and increased RFD and sEMG in both groups during both tasks (all p < 0.001). Rtime was similar between groups in all conditions. However, CL had a greater RFD from 50 to 100 ms compared with CON only after the S stimulus in both tasks (p < 0.05, d = 0.85-0.96). The data tentatively suggest that chronic rock climbing and climbing-specific RT might improve RST efficacy, by increasing RST input to the α-motoneurons.
Exploring the effects of Transcranial Direct Current Stimulation over the prefrontal cortex on working memory: A cluster analysis approach
(ELSEVIER IRELAND LTD, 2019-08-06) Luque-Casado, Antonio; Fogelson, Noa; Iglesias-Soler, Eliseo; Fernandez-del-Olmo, Miguel
BACKGROUND: The interest in the use of anodal transcranial direct current stimulation (tDCS) for the enhancement of cognitive functioning has increased significantly in recent years. However, the efficacy of this technique remains to be established. OBJECTIVE: The current study explored the effects of anodal vs. sham tDCS over the left dorsolateral prefrontal cortex (DLPFC) during the performance of the digit span backwards task. METHODS: 30 healthy participants received 'offline' anodal tDCS (1.5 mA, 15 min) to the left DLPFC in an intra-individual, cross-over, sham-controlled experimental design. Memory span performance was assessed before (baseline), immediately after tDCS administration (T1) and 10 min post-T1 (T2). We applied cluster analysis in order to characterize individual responses to tDCS, and in order to identify naturally occurring subgroups that may be present. RESULTS: Analysis of all the subjects showed that anodal tDCS failed to improve memory span performance. Cluster analysis revealed the presence of a subgroup of 'responders' that significantly improved their performance after anodal (vs. sham) tDCS in T1 (47%) and T2 (46%). However, there was no significant improvement in performance after anodal tDCS compared to the best baseline performance. CONCLUSION: Our findings suggest that tDCS does not improve memory span performance and highlights the need for better ways to optimize methodological approaches in order to account for inter-individual variability and accurately assess the evidential value of tDCS-linked cognitive outcomes.
Small Enhancement of Bimanual Typing Performance after 20 Sessions of tDCS in Healthy Young Adults
(PERGAMON-ELSEVIER SCIENCE LTD, 2021-05-08) Sevilla-Sánchez, Marta; Hortobágyi, Tibor; Fogelson, Noa; Iglesias-Soler, Eliseo; Carballeira, Eduardo; Fernandez-del-Olmo, Miguel
Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that may improve motor learning. However, the long-term effects of tDCS have not been explored, and the ecological validity of the evaluated tasks was limited. To determine whether 20 sessions of tDCS over the primary motor cortex (M1) would enhance the performance of a complex life motor skill, i.e., typing, in healthy young adults. Healthy young adults (n = 60) were semi-randomly assigned to three groups: the tDCS group (n = 20) received anodal tDCS over M1; the SHAM group (n = 20) received sham tDCS, both while performing a typing task; and the Control group (CON, n = 20) only performed the typing task. Typing speed and errors at maximum (mTT) and submaximal (iTT) speeds were measured before training, and after 10 and 20 sessions of tDCS. Every subject increased maximum typing speed after 10 and 20 tDCS sessions, with no significant differences (p > 0.05) between the groups. The number of errors at submaximal rates decreased significantly (p < 0.05) by 4% after 10 tDCS sessions compared with the 3% increase in the SHAM and the 2% increase in the CON groups. Between the 10th and 20th tDCS sessions, the number of typing errors increased significantly in all groups. While anodal tDCS reduced typing errors marginally, such performance-enhancing effects plateaued after 10 sessions without any further improvements in typing speed. These findings suggest that long-term tDCS may not have functionally relevant effects on healthy young adults' typing performance.
Test-retest reliability of stride length-cadence gait relationship in Parkinson’s disease
(Elsevier, 2019-05-03) Ambrus, Mira; Sanchez-Molina, Jose Andrés; Fernandez-del-Olmo, Miguel
INTRODUCTION: The gait pattern in Parkinson´s disease (PD) subjects is characterized by a specific deficit of the internal regulation of the stride length (SL), while the control of the cadence (Cad) remains intact. The purpose of the present study was to evaluate the reliability of the stride length-cadence relationship (SLCrel) in a group of PD subjects. METHODS: Thirty five PD subjects performed two sessions, separated by a three month resting period. In each session Gait speed, SL and Cad were evaluated at five different self-selected speed conditions: preferred, slow, very slow, fast and very fast. Linear regression analysis was used to explore the SLCrel and to determine the slope, intercept and coefficient of determination (R2) for each participant. Test-retest reliability for the slope and intercept was calculated using intra-class correlation coefficient (ICC), 95% confidence interval (CI), and standard error of mean (SEM). RESULTS: There were no significant differences in the slope and intercept between the two sessions. The overall speed was significantly faster in the second session compared with the first one (F = 4.60, p = 0.03). The SLCrel showed high reliability across the sessions (ICC = 0.89 and ICC = 0.91; 95% CI = 0.80-0.95 and 95% CI = 0.82-0.95; SEM = 0.002 and SEM = 0.073, for the slope and interception, respectively). CONCLUSIONS: The SLCrel in Parkinsonian gait is a reproducible measure across a period of three months, and may be a useful tool to explore the specificity of gait rehabilitation interventions in PD subjects.