Banca de DEFESA: Gabriel Menezes da Cruz

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Gabriel Menezes da Cruz
DATE: 28/02/2024
TIME: 10:30
LOCAL: Ambiente Virtual Teams
TITLE:

INVESTIGATION OF THE NEUROPHYSIOLOGICAL MECHANISM RESPONSIBLE FOR MODULATING  REFLEX EXCITABILITY AFTER CONTINUOUS ELECTRIC CURRENT STIMULATION APPLIED IN THE LOWER LIMBS

KEY WORDS:

Eletromiography, H Reflex, Pre synaptic inhibition, Spinal cord, Threshold Tracking

PAGES: 65
BIG AREA: Ciências da Saúde
AREA: Educação Física
SUMMARY:

Introduction: Plasticity is defined as structural changes in certain regions of the central nervous system resulting from some intervention, such as direct electrical current stimulation (DCS). The mechanisms involved in these adaptations have been studied using experimental paradigms to evaluate inhibitory pathways involved in the modulation of reflex excitability. The conditioning-test paradigm for evaluating the presynaptic inhibition pathway (IPS) has proven to be efficient in enhancing responses according to the intervention applied. Furthermore, techniques such as threshold tracking (THTR) allow working with the same population of motoneurons (motor neuron that controls muscle skeletal  movement) even when using different current intensities. Furthermore, neuroplasticity (a process involved in motor learning) can be assessed through electromyographic (EMG) responses resulting from electrical stimulation of the Ia afferents of the neuromuscular spindles, either at rest (H reflex) or during maximum voluntary contraction (V wave ). These responses allow us to infer the excitability of the medullary and cortical-spinal pathways, respectively. Objectives: To study the effects of direct electrical current stimulation on the neurophysiology of the spinal cord, added with stimulation of the common peroneal nerve (FIB). Methods: The intervention consisted of 2 sessions with a one-week interval between them. Each session consisted of 3 protocols at 3 different times: 1) 60 responses: 20 control H reflex responses, 20 H reflex responses conditioned by the FIB and 20 H reflex responses conditioned by the FIB + threshold tracking technique; 2) Recruitment curve (CR); 3) Wave V. The times were divided into: PRE) before stimulation with REAL or SHAM ECC; DUR) during stimulation with ECC REAL or SHAM; POS) after REAL or SHAM stimulation. Electromyographic variables were analyzed before (PRE), during (DUR), and after (POS) each moment of stimulation on each day. The variables investigated were: 1) Parameters extracted from the H-reflex recruitment curve (CR); 2) Amplitude of wave V; 3) Level of presynaptic inhibition (GIPS); 4) THTR current change. Results: The intervention was not effective in generating significant changes in the curve parameters and wave V Amplitude. However, it was efficient in presenting significant differences between GIPS PRE compared to POS in the REAL condition. Furthermore, significant differences were found between THTR PRE x POS and THTR DUR x THTR POS (p<0.05). The results suggest that ECC added to the FIB stimulus produces a potentiated inhibition of the H reflex. Conclusion: The use of anodal ECC in the lower limbs added to an IPS protocol significantly reduces the amplitude of the H reflex. The two-session protocol was effective in generating effects on GIPS and THTR, but not on the curve parameters or V Wave. The use of this intervention should be considered in studies of the mechanisms that govern descending commands in the lower limbs, since the intervention is simple to perform, the equipment is low cost and the protocol is relatively easy.

 

 

 

 

COMMITTEE MEMBERS:
Externo ao Programa - 2354637 - FABIO VIEGAS CAIXETA - UnBExterno à Instituição - FERNANDO HENRIQUE MAGALHÃES - USP
Externa ao Programa - 2794682 - LUCIANA HAGSTROM BEX - nullPresidente - 1979784 - RINALDO ANDRE MEZZARANE