Banca de QUALIFICAÇÃO: Leonardo Amorim Ribeiro

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Leonardo Amorim Ribeiro
DATE: 24/10/2024
TIME: 10:00
LOCAL: ambiente virtual Teams
TITLE:

Acute Neuromuscular adaptations after combined motor cortex and spinal cord direct current stimulation

KEY WORDS:

Neuroplasticity; neurostimulation; neurorehabilitation; ergogenic effect.

PAGES: 50
BIG AREA: Ciências da Saúde
AREA: Educação Física
SUMMARY:

INTRODUCTION: Direct current stimulation is a non-invasive neuromodulation technique.
The facilitation or inhibition of neurons in the underlying regions depends on the electrode
configuration, that is, the relative positioning of the anode and cathode nearest to the target
region (considered as "anodal" and "cathodal" stimulation, respectively). The stimulation can
be applied on the scalp (transcranial direct current stimulation – tDCS) or on the spinal cord
(transcutaneous spinal cord direct current stimulation – tsDCS). Anodal tDCS and cathodal
tsDCS have shown effects on cortical and medullary circuits, respectively. The devices are
considered low-cost, and the interventions demonstrate a range of benefits for patients with
various neuromotor conditions, such as stroke, multiple sclerosis, Parkinson's, spinal cord
injuries, etc. Additionally, studies have shown potential effects on athletic performance, such
as increased muscle strength and power. Although the benefits of tDCS and tsDCS applied
individually are well elucidated, few studies investigated the effects of the association of both
interventions. No studies were found evaluating the effects of dual stimulation (combined
tDCS + tsDCS) on, for example, spinal cord excitability. OBJECTIVE: To compare the
acute neuromuscular effects following stimulation performed only on the motor cortex, only
on the spinal cord, or on both simultaneously. METHODS: Twelve young, healthy
volunteers will be recruited to undergo four laboratory visits for 20 minutes of intervention
each day. The following combinations will be used: I) anodal tDCS + cathodal tsDCS; II)
anodal tDCS + sham tsDCS (placebo); III) sham tDCS + cathodal tsDCS; IV) sham tDCS +
sham tsDCS. Neurophysiological parameters and strength, as well as variables extracted from
the soleus muscle H-reflex recruitment curve, will be assessed before (PRE) and immediately
after (POST) each intervention. Post-activation depression (or homosynaptic depression, HD)
expressed by the frequency-dependent percentage reduction of the H-reflex will also be
measured. The V-wave, which represents the excitability of the supraspinal pathways,
obtained through the H-reflex technique but with supramaximal stimulation during a maximal
voluntary isometric contraction (MVIC), will be assessed. During the same test, the peak
torque (PT) of the plantar flexors will be obtained before the electrical stimulus and
characterized as a measure of maximum strength. Additionally, the rate of force development
(RFD) of this signal will be analyzed at 30, 50, 100, and 200 ms. Furthermore, a muscle
endurance test will be conducted with contractions of intensity between 40 to 60% of the
maximum torque obtained during the MVIC of the plantar flexors. The maximum time to
failure (5 seconds below 40% MVIC), mean frequency (Fmean), and median frequency
(Fmedi) of the soleus muscle EMG spectrum will be calculated as variables of endurance and
fatigue monitoring, respectively. A two-way mixed-design ANOVA will be used to compare
considering factors as times (PRE and POST) and types of stimulation (I, II, III, and IV). Any
significant differences will be further interpreted using the post hoc least significant
difference (LSD) test. EXPECTED RESULTS: It is expected that gains in strength, power,
and endurance will be greater in combined stimulation (tDCS + tsDCS) compared to isolated
stimulations on the motor cortex or spinal cord applied separately. Additionally, it is also
expected a neuronal facilitation indicated by an increase in the amplitude of the H-reflex and
V-wave, along with a decrease in HD level. We believe the results obtained will be useful in
helping to explain the mechanisms responsible for the potential greater gain in strength and
power after conjugated direct current stimulation (tDCS and tsDCS).

COMMITTEE MEMBERS:
Externa à Instituição - ANA CAROLINA PANHAN - UNICAMP
Externo ao Programa - 2354637 - FABIO VIEGAS CAIXETA - nullExterna ao Programa - 2794682 - LUCIANA HAGSTROM BEX - nullPresidente - 1979784 - RINALDO ANDRE MEZZARANE