Defensive responses are neurophysiological processes crucial for survival during threatening situations. Defensive immobility is a common adaptive response, in rodents, elaborated by ventrolateral periaqueductal gray matter (vlPAG) when threat is unavoidable. It is associated with somatosensory and autonomic reactions such as alteration in the sensation of pain and rate of respiration. In this study, defensive immobility was assessed by chemical stimulation of vlPAG with different doses of NMDA (0.1, 0.3, and 0.6 nmol). After elicitation of defensive immobility, antinociceptive and respiratory response tests were also performed. Results revealed that defensive immobility was followed by a decrease in the nociceptive perception. Furthermore, the lowest dose of NMDA induced antinociceptive response without eliciting defensive immobility. During defensive immobility, respiratory responses were also disturbed. Interestingly, respiratory rate was increased and interspersed with prolonged expiratory phase of breathing. These findings suggest that vlPAG integrates three different defensive behavioral responses, contributing to the most effective defensive strategies during threatening situations.

A Deus em primeiro lugar, pela intercessão de Maria de Nazaré e a São Bento.Ao Prof. Dr. Norberto Cysne Coimbra, pela dedicação, paciência e amizade em todo o processo de entendimento e execução do trabalho. Faltam-me palavras para descrever o quão importante o mesmo foi para mim em todo este percurso, tanto acadêmico quanto pessoal, meus agradecimentos sempre serão eternos. À Dra. Audrey Francheschi Biagioni, pelas palavras amigas, por toda dedicação e auxílio. Reitero, aqui, minha eterna gratidão e carinho que tenho por você.Aos membros da Banca examinadora, que aceitaram estar neste momento importante a mim, acrescentando, de forma muito profissional, críticas edificantes ao presente trabalho.Ao técnico Daoud Hibrahim Elias Filho e aos colegas do laboratório de neuroanatomia e neuropsicobiologia, do

Introduction: Neurofunctional rehabilitation often employs various approaches to enhance recruitment and muscle strength through overflow, a phenomenon that amplifies the motor response of homologous muscles in the contralateral segment. Overflow has been well documented in the literature, particularly in techniques like FNP and cross-education. Objectives: This study aimed to investigate the overflow mechanism in nonhomologous and ipsilateral muscles during an instructed handgrip task. Methods: We recruited 90 subjects of both genders between 18 and 30 years with right upper limb (RUL) motor preference. Each subject was seated with their lower limbs flexed at the hip, knee, and ankle to 90 degrees. We used a lower limb dynamometer to measure baseline strength by having the subjects perform three maximal left hip flexion contractions with 6-second contractions and 10-second intervals. For the second evaluation, the subjects performed three maximal handgrip contractions on a rigid dynamometer, followed by three maximal isometric contractions for left hip flexion (also with 6-second contractions and 10-second intervals). After a 10-minute rest period, we took new measurements of the maximum voluntary isometric contraction (MVIC) for both handgrip and hip flexion. We excluded subjects who were unable to produce 70% of their MVIC during testing. We conducted a statistical analysis using a multiple comparisons analysis of variance with a significance level of P < 0.05. Results: We found a decrease in strength between males and females during T3 (post-test) (P = 0.006), and an increase in strength between T3 and BL3 in female subjects (P = 0.045). Conclusion: Our study demonstrated an increase in hip flexor strength in women when subjected to a maximal isometric task with the ipsilateral upper limb.

Introduction: Neurofunctional rehabilitation often employs various approaches to enhance recruitment and muscle strength through overflow, a phenomenon that amplifies the motor response of homologous muscles in the contralateral segment. overflow has been well documented in the literature, particularly in techniques like FNP and cross-education. The phenomenon of overflow is known to facilitate muscle activity in muscles that are not actively stimulated, resulting in unintentional contractions during a resisted isometric activity. Objectives: The objective of this study was to investigate the overflow mechanisms of non-homologous contralateral muscles of the lower limb during an instructed handgrip task. Methods: A total of 90 individuals, with a motor preference for their right upper limb (RUL), were divided into control (CG) and resisted isometry group (RIG) and underwent a protocol involving three maximal hand grip contractions with their RUL and LUL. In assessment 2, the CG performed the same protocol as baseline, while the RIG group performed three maximal isometric contractions of left hip flexion with three maximal contractions of hand flexion with their RUL. statistical analysis was conducted by a multiple comparison analysis of variance with P < 0.05. Results: Observing the data from evaluation 1, both the CG and RIG showed a reduction in strength between the third and first attempt for both the left and right upper limbs (F = 1.07, F = 0.68, respectively). In evaluation 2, the decrease occurred only for the CG in both upper limbs (F = 0.15, F = 1.29, respectively). Conclusion: Our study revealed that maximal muscle strength was maintained in RIG individuals during assessment 2, indicating the existence of overflow when performing an isometric hip flexion task concomitantly with the palmar grip.