tDCS and local scalp cooling do not change corticomotor and intracortical excitability in healthy humans

Author(s)

Souza, Victor H. ; de Castro, Kamyle Villa-Flor ; de Melo-Carneiro, Pedro ; Gomes, Iago de Oliveira ; Camatti, Janine Ribeiro ; de Oliveira, Iasmyn Adelia Victor Fernandes ; Sa, Katia Nunes ; Baptista, Abrahao Fontes ; Lucena, Rita ; Zugaib, Joao

• Document type: Journal article
• Source: CLINICAL NEUROPHYSIOLOGY; v. 168, p. 9-pg., 2024-10-09.

Abstract

Objective: Scalp cooling might increase the long-term potentiation (LTP)-like effect of transcranial direct current stimulation (tDCS) by reducing the threshold for after-effects according to metaplasticity and increasing electrical current density reaching the cortical neurons. We aimed to investigate whether priming scalp cooling potentiates the tDCS after-effect on motor cortex excitability. Methods: This study had a randomized, parallel-arms, sham-controlled, double-blinded design with an adequately powered sample of 105 healthy subjects. Corticomotor and intracortical excitability were assessed with motor evoked potentials (MEP) from transcranial magnetic stimulation (TMS) in shortinterval intracortical inhibition (SICI) and intracortical facilitation (ICF) paradigms. Subjects were randomly allocated into six intervention groups, including anodal and cathodal tDCS (1-mA/20-min), scalp cooling, and sham. MEPs were recorded before, immediately, and 15 min after the interventions. Results: We did not observe changes in MEP amplitude from single-pulse TMS, SICI, and ICF with any intervention protocol. Conclusion: Anodal and cathodal tDCS did not have an LTP-like neuromodulatory effect on corticospinal and did not provide detectable GABAergic and glutamatergic neurotransmission changes, which were not influenced by priming scalp cooling. Significance: We provide strong evidence that tDCS (1-mA/20-min) does not alter corticomotor and intracortical excitability with or without priming scalp cooling. (c) 2024 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). (AU)

• FAPESP's process: 13/07559-3 - BRAINN - The Brazilian Institute of Neuroscience and Neurotechnology
• Grantee: Fernando Cendes
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC