ECSS Paris 2023: OP-BM15
INTRODUCTION: Emotional memory refers to the recollection of emotionally significant experiences, which tend to persist longer than neutral experiences and influence behavior by modulating motor control. Previous research has shown that recalling negative emotional memories enhances corticospinal excitability (CSE), a key mechanism underlying motor control [1]. However, given the variety of daily emotions, the impact of discrete emotions (e.g., sadness, anger) on CSE is unclear and requires further investigation. Furthermore, while the effects of emotional memories on CSE have been studied in upper limb muscles, their impact on lower limb muscles remains unexplored. Thus, this study aimed to investigate the effects of discrete emotional memory recall on CSE in lower limb muscles. METHODS: Twenty-one healthy males (18–29 years old) participated in this study. CSE was assessed using motor-evoked potential (MEP) amplitudes elicited by transcranial magnetic stimulation applied to the primary motor cortex. MEPs were recorded from the soleus, tibialis anterior, medial and lateral gastrocnemius, and rectus femoris muscles. While recalling episodes of happiness, sadness, fear, anger, and neutral (morning routine), 12 MEPs were recorded per condition. Participants rated arousal (high–low) and valence (pleasant–unpleasant) levels of their recalled episodes using the Self-Assessment Manikin. Statistical analyses included a two-way ANOVA with an aligned rank transform to examine the effects of five muscles and five emotions on MEP amplitudes, followed by a post-hoc contrast test using the ART-C procedure. Additionally, a repeated measures correlation (rmcorr) was conducted to explore relationships between MEP amplitudes and valence/arousal levels. The level of statistical significance was set at p < 0.05. RESULTS: The two-way ANOVA showed a significant main effect of emotions (p < 0.01) but not of muscles (p = 0.99) or their interaction (p = 0.82). Post-hoc contrast tests revealed that recalling emotional memories—whether happiness, sadness, fear, or anger—significantly increased MEP amplitudes compared to neutral (all p < 0.05). Given the lack of a significant main effect of muscles, the rmcorr was conducted using mean MEP amplitudes across all muscles and revealed a significant positive correlation between MEP amplitudes and arousal levels (r = 0.34, p < 0.01). CONCLUSION: The results indicate that recalling emotional memories enhances CSE in lower limb muscles. Although no significant differences were observed among discrete emotions, MEP amplitudes were positively correlated with arousal levels. These findings suggest that subjective arousal levels rather than emotion types modulate CSE in lower limb muscles. This study advances our understanding of the interplay between emotional memories and motor control, with potential implications for sports performance and rehabilitation strategies. REFERENCE: 1. Mineo et al., Neuropsychologia, 2018.
Read CV Yume MashikiECSS Paris 2023: OP-BM15
INTRODUCTION: Transcutaneous spinal cord stimulation (tSCS) is an emerging stimulation technique which has known a great interest in the neuromuscular field. It presents the advantage of evoking concomitant responses in multiple muscles of the lower limb, known as posterior root muscle (PRM) reflexes (Minassian et al., 2007). Although the nature of these last is complex, stemming from sensory and/or motor solicitation, they present some similarities with the H-reflex that is evoked by peripheral nerve stimulation (PNS). Conversely to PRM reflex, the H-reflex results mainly from Ia afferents depolarization and its amplitude is modulated by external interventions, known to activate Ia afferents, such as neuromuscular electrical stimulation (NMES) (Vitry et al., 2019), local vibration (LV, Abbruzzese et al., 2001) as well as muscle lengthening (Budini & Tilp, 2016). The aim of this study was to determine whether the modulations observed for the H-reflex are also present for the PRM reflex. METHODS: Fourteen volunteers participated in two experimental sessions. For both sessions, tSCS electrodes were placed at the L1-L2 level of the spinal cord and under the umbilicus to evoke soleus PRM reflex, while PNS was applied to the posterior tibial nerve, to evoke soleus H-reflex. Amplitudes of H- and PRM reflexes were matched at 85%Hmax. For the first experiment, H- and PRM reflexes were delivered before, during and after 3min of Achilles tendon vibration and 1min of plantar-flexor muscles stretching (amplitude: 20°, speed: 30°/s). For the second experiment, both reflexes were delivered before and following 20-s of NMES applied at a frequency of 20 and 100Hz. The evolution of the amplitude of H- and PRM reflexes was explored before, during (for the first experiment only) and after each intervention. RESULTS: Results showed similar modulations of the responses evoked by PNS and tSCS for the four interventions that were tested. Indeed, both H- and PRM reflexes were decreased during LV and stretching (P < 0.001) with a return to baseline values following the interventions. For the NMES trains, a decrease was observed following the 20-Hz train (P < 0.02) while no modulation was revealed for either reflex for the 100-Hz condition (P = 0.51). CONCLUSION: Present results show that H- and PRM reflex are modulated in the same way by different external interventions known to solicitate Ia afferents. This suggests that similar mechanisms, most probably presynaptic inhibitory mechanisms, are responsible for both H- and PRM reflexes modulations during these different interventions. This study provides new proof of the similarities between the two types of reflexes and a better understanding of the nature of PRM reflexes.
Read CV Julia SORDETECSS Paris 2023: OP-BM15