Pesquisador Vinculado
Professor Associado de Engenharia Biomédica junto ao Departamento de Eletrônica e Engenharia Biomédica (DEEB), Faculdade de Engenharia Elétrica e de Computação (FEEC), Universidade Estadual de Campinas (UNICAMP). Ex-Coordenador (2017-2023) e atual Coordenador Associado (2023-2027) do Centro de Engenharia Biomédica (CEB), UNICAMP. Fundador e Coordenador do Laboratório de Pesquisa em Neuroengenharia (NER Lab). Sua pesquisa na área de neuroengenharia está focada em investigações teórico-computacionais e experimentais que visam entender como diferentes elementos do sistema neuromusculoesquelético interagem durante o controle do movimento humano em condições normais e patológicas. Graduado em Engenharia Elétrica pela Universidade Federal de Goiás (2008). Mestre e Doutor em Engenharia Biomédica pela Escola Politécnica da Universidade de São Paulo (2010 e 2013, respectivamente). Realizou estágio pós-doutoral no Laboratório de Engenharia Biomédica (LEB), Escola Politécnica da Universidade de São Paulo (2013-2015). Foi Pesquisador Visitante junto ao Department of Neurorehabilitation Engineering, Georg-August University (Göttingen, Alemanha, 2015). Recebeu o título de Livre-Docente em Engenharia Biomédica pela UNICAMP (2022). É membro da International MotoNeuron Society, IEEE + IEEE Engineering in Medicine Biology Society (EMBS), Organization for Computational Neurosciences (OCNS), Sociedade Brasileira para o Progresso da Ciência (SBPC) e Sociedade Brasileira de Engenharia Biomédica (SBEB). Atualmente é Diretor Financeiro da SBEB e membro do Board of Reviewing Editors do periódico eLife, atuando nas áreas de Neurociência e Biologia Computacional.
Neuroengenharia
Neurociência Computacional ➠ Neurofisiologia Humana ➠ Neuromecânica ➠ Processamento de Sinais Neurais ➠ Neurotecnologia ➠ Neuropróteses ➠ Interfaces Neurais
(19) 3521-3756
leoelias@unicamp.br
Publicações
2022
Batista-Ferreira, Leandra; Rabelo, Natielle Ferreira; da Cruz, Gabriel Menezes; de Almeida Costa, Juliana Nunes; Elias, Leonardo Abdala; Mezzarane, Rinaldo André
Effects of voluntary contraction on the soleus H-reflex of different amplitudes in healthy young adults and in the elderly Journal Article
Em: Front Hum Neurosci, vol. 16, pp. 1039242, 2022, ISSN: 1662-5161.
Resumo | Links | BibTeX | Tags:
@article{pmid36590063,
title = {Effects of voluntary contraction on the soleus H-reflex of different amplitudes in healthy young adults and in the elderly},
author = {Leandra Batista-Ferreira and Natielle Ferreira Rabelo and Gabriel Menezes da Cruz and Juliana Nunes de Almeida Costa and Leonardo Abdala Elias and Rinaldo André Mezzarane},
doi = {10.3389/fnhum.2022.1039242},
issn = {1662-5161},
year = {2022},
date = {2022-01-01},
urldate = {2022-01-01},
journal = {Front Hum Neurosci},
volume = {16},
pages = {1039242},
abstract = {A number of H-reflex studies used a moderate steady voluntary contraction in an attempt to keep the motoneuron pool excitability relatively constant. However, it is not clear whether the voluntary muscle activation itself represents a confounding factor for the elderly, as a few ongoing mechanisms of reflex modulation might be compromised. Further, it is well-known that the amount of either inhibition or facilitation from a given conditioning depends on the size of the test H-reflex. The present study aimed at evaluating the effects of voluntary contraction over a wide range of reflex amplitudes. A significant reflex facilitation during an isometric voluntary contraction of the soleus muscle (15% of the maximal voluntary isometric contraction-MVC) was found for both young adults and the elderly ( < 0.05), regardless of their test reflex amplitudes (considering the ascending limb of the H-reflex recruitment curve-RC). No significant difference was detected in the level of reflex facilitation between groups for all the amplitude parameters extracted from the RC. Simulations with a computational model of the motoneuron pool driven by stationary descending commands yielded qualitatively similar amount of reflex facilitation, as compared to human experiments. Both the experimental and modeling results suggest that possible age-related differences in spinal cord mechanisms do not significantly influence the reflex modulation during a moderate voluntary muscle activation. Therefore, a background voluntary contraction of the ankle extensors (e.g., similar to the one necessary to maintain upright stance) can be used in experiments designed to compare the RCs of both populations. Finally, in an attempt to elucidate the controversy around changes in the direct motor response (M-wave) during contraction, the maximum M-wave (Mmax) was compared between groups and conditions. It was found that the Mmax significantly increases ( < 0.05) during contraction and decreases ( < 0.05) with age arguably due to muscle fiber shortening and motoneuron loss, respectively.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A number of H-reflex studies used a moderate steady voluntary contraction in an attempt to keep the motoneuron pool excitability relatively constant. However, it is not clear whether the voluntary muscle activation itself represents a confounding factor for the elderly, as a few ongoing mechanisms of reflex modulation might be compromised. Further, it is well-known that the amount of either inhibition or facilitation from a given conditioning depends on the size of the test H-reflex. The present study aimed at evaluating the effects of voluntary contraction over a wide range of reflex amplitudes. A significant reflex facilitation during an isometric voluntary contraction of the soleus muscle (15% of the maximal voluntary isometric contraction-MVC) was found for both young adults and the elderly ( < 0.05), regardless of their test reflex amplitudes (considering the ascending limb of the H-reflex recruitment curve-RC). No significant difference was detected in the level of reflex facilitation between groups for all the amplitude parameters extracted from the RC. Simulations with a computational model of the motoneuron pool driven by stationary descending commands yielded qualitatively similar amount of reflex facilitation, as compared to human experiments. Both the experimental and modeling results suggest that possible age-related differences in spinal cord mechanisms do not significantly influence the reflex modulation during a moderate voluntary muscle activation. Therefore, a background voluntary contraction of the ankle extensors (e.g., similar to the one necessary to maintain upright stance) can be used in experiments designed to compare the RCs of both populations. Finally, in an attempt to elucidate the controversy around changes in the direct motor response (M-wave) during contraction, the maximum M-wave (Mmax) was compared between groups and conditions. It was found that the Mmax significantly increases ( < 0.05) during contraction and decreases ( < 0.05) with age arguably due to muscle fiber shortening and motoneuron loss, respectively.
2021
Ranieri, Caetano M.; Pimentel, Jhielson M.; Romano, Marcelo R.; Elias, Leonardo Abdala; Romero, Roseli A. F.; Lones, Michael A.; Araujo, Mariana F. P.; Vargas, Patricia A.; Moioli, Renan C.
A Data-Driven Biophysical Computational Model of Parkinson’s Disease Based on Marmoset Monkeys Journal Article
Em: IEEE Access , vol. 9, pp. 122548 - 122567, 2021, ISSN: 2169-3536.
Resumo | Links | BibTeX | Tags:
@article{nokey,
title = {A Data-Driven Biophysical Computational Model of Parkinson’s Disease Based on Marmoset Monkeys},
author = {Caetano M. Ranieri and Jhielson M. Pimentel and Marcelo R. Romano and Leonardo Abdala Elias and Roseli A. F. Romero and Michael A. Lones and Mariana F. P. Araujo and Patricia A. Vargas and Renan C. Moioli},
doi = {10.1109/ACCESS.2021.3108682},
issn = {2169-3536},
year = {2021},
date = {2021-08-30},
urldate = {2021-08-30},
journal = {IEEE Access },
volume = {9},
pages = {122548 - 122567},
abstract = {In this work we propose a new biophysical computational model of brain regions relevant to Parkinson's Disease (PD) based on local field potential data collected from the brain of marmoset monkeys. PD is a neurodegenerative disorder, linked to the death of dopaminergic neurons at the substantia nigra pars compacta, which affects the normal dynamics of the basal ganglia-thalamus-cortex (BG-T-C) neuronal circuit of the brain. Although there are multiple mechanisms underlying the disease, a complete description of those mechanisms and molecular pathogenesis are still missing, and there is still no cure. To address this gap, computational models that resemble neurobiological aspects found in animal models have been proposed. In our model, we performed a data-driven approach in which a set of biologically constrained parameters is optimised using differential evolution. Evolved models successfully resembled spectral signatures of local field potentials and single-neuron mean firing rates from healthy and parkinsonian marmoset brain data. This is the first computational model of PD based on simultaneous electrophysiological recordings from seven brain regions of Marmoset monkeys. Results indicate that the proposed model may facilitate the investigation of the mechanisms of PD and eventually support the development of new therapies. The DE method could also be applied to other computational neuroscience problems in which biological data is used to fit multi-scale models of brain circuits.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this work we propose a new biophysical computational model of brain regions relevant to Parkinson's Disease (PD) based on local field potential data collected from the brain of marmoset monkeys. PD is a neurodegenerative disorder, linked to the death of dopaminergic neurons at the substantia nigra pars compacta, which affects the normal dynamics of the basal ganglia-thalamus-cortex (BG-T-C) neuronal circuit of the brain. Although there are multiple mechanisms underlying the disease, a complete description of those mechanisms and molecular pathogenesis are still missing, and there is still no cure. To address this gap, computational models that resemble neurobiological aspects found in animal models have been proposed. In our model, we performed a data-driven approach in which a set of biologically constrained parameters is optimised using differential evolution. Evolved models successfully resembled spectral signatures of local field potentials and single-neuron mean firing rates from healthy and parkinsonian marmoset brain data. This is the first computational model of PD based on simultaneous electrophysiological recordings from seven brain regions of Marmoset monkeys. Results indicate that the proposed model may facilitate the investigation of the mechanisms of PD and eventually support the development of new therapies. The DE method could also be applied to other computational neuroscience problems in which biological data is used to fit multi-scale models of brain circuits.
Germer, Carina M; Farina, Dario; Elias, Leonardo A; Nuccio, Stefano; Hug, François; Vecchio, Alessandro Del
Surface EMG cross talk quantified at the motor unit population level for muscles of the hand, thigh, and calf Journal Article
Em: J Appl Physiol (1985), vol. 131, não 2, pp. 808–820, 2021, ISSN: 1522-1601.
Resumo | Links | BibTeX | Tags:
@article{pmid34236246,
title = {Surface EMG cross talk quantified at the motor unit population level for muscles of the hand, thigh, and calf},
author = {Carina M Germer and Dario Farina and Leonardo A Elias and Stefano Nuccio and François Hug and Alessandro Del Vecchio},
doi = {10.1152/japplphysiol.01041.2020},
issn = {1522-1601},
year = {2021},
date = {2021-08-01},
urldate = {2021-08-01},
journal = {J Appl Physiol (1985)},
volume = {131},
number = {2},
pages = {808--820},
abstract = {Cross talk is an important source of error in interpreting surface electromyography (EMG) signals. Here, we aimed at characterizing cross talk for three groups of synergistic muscles by the identification of individual motor unit action potentials. Moreover, we explored whether spatial filtering (single and double differential) of the EMG signals influences the level of cross talk. Three experiments were conducted. Participants (total 25) performed isometric contractions at 10% of the maximal voluntary contraction (MVC) with digit muscles and knee extensors and at 30% MVC with plantar flexors. High-density surface EMG signals were recorded and decomposed into motor unit spike trains. For each muscle, we quantified the cross talk induced to neighboring muscles and the level of contamination by the nearby muscle activity. We also estimated the influence of cross talk on the EMG power spectrum and intermuscular correlation. Most motor units (80%) generated significant cross-talk signals to neighboring muscle EMG in monopolar recording mode, but this proportion decreased with spatial filtering (50% and 42% for single and double differential, respectively). Cross talk induced overestimations of intermuscular correlation and has a small effect on the EMG power spectrum, which indicates that cross talk is not reduced with high-pass temporal filtering. Conversely, spatial filtering reduced the cross-talk magnitude and the overestimations of intermuscular correlation, confirming to be an effective and simple technique to reduce cross talk. This paper presents a new method for the identification and quantification of cross talk at the motor unit level and clarifies the influence of cross talk on EMG interpretation for muscles with different anatomy. We proposed a new method for the identification and quantification of cross talk at the motor unit level. We show that surface EMG cross talk can lead to physiological misinterpretations of EMG signals such as overestimations in the muscle activity and intermuscular correlation. Cross talk had little influence on the EMG power spectrum, which indicates that conventional temporal filtering cannot minimize cross talk. Spatial filter (single and double differential) effectively reduces but not abolish cross talk.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Cross talk is an important source of error in interpreting surface electromyography (EMG) signals. Here, we aimed at characterizing cross talk for three groups of synergistic muscles by the identification of individual motor unit action potentials. Moreover, we explored whether spatial filtering (single and double differential) of the EMG signals influences the level of cross talk. Three experiments were conducted. Participants (total 25) performed isometric contractions at 10% of the maximal voluntary contraction (MVC) with digit muscles and knee extensors and at 30% MVC with plantar flexors. High-density surface EMG signals were recorded and decomposed into motor unit spike trains. For each muscle, we quantified the cross talk induced to neighboring muscles and the level of contamination by the nearby muscle activity. We also estimated the influence of cross talk on the EMG power spectrum and intermuscular correlation. Most motor units (80%) generated significant cross-talk signals to neighboring muscle EMG in monopolar recording mode, but this proportion decreased with spatial filtering (50% and 42% for single and double differential, respectively). Cross talk induced overestimations of intermuscular correlation and has a small effect on the EMG power spectrum, which indicates that cross talk is not reduced with high-pass temporal filtering. Conversely, spatial filtering reduced the cross-talk magnitude and the overestimations of intermuscular correlation, confirming to be an effective and simple technique to reduce cross talk. This paper presents a new method for the identification and quantification of cross talk at the motor unit level and clarifies the influence of cross talk on EMG interpretation for muscles with different anatomy. We proposed a new method for the identification and quantification of cross talk at the motor unit level. We show that surface EMG cross talk can lead to physiological misinterpretations of EMG signals such as overestimations in the muscle activity and intermuscular correlation. Cross talk had little influence on the EMG power spectrum, which indicates that conventional temporal filtering cannot minimize cross talk. Spatial filter (single and double differential) effectively reduces but not abolish cross talk.
Germer, Carina Marconi; Moreira, Luciana Sobral; Elias, Leonardo Abdala
Assessment of force control improvement induced by sinusoidal vibrotactile stimulation in dominant and non-dominant hands Journal Article
Em: Res. Biomed. Eng., vol. 37, não 1, pp. 95–103, 2021, ISSN: 2446-4740.
@article{Germer2020,
title = {Assessment of force control improvement induced by sinusoidal vibrotactile stimulation in dominant and non-dominant hands},
author = {Carina Marconi Germer and Luciana Sobral Moreira and Leonardo Abdala Elias},
doi = {10.1007/s42600-020-00111-6},
issn = {2446-4740},
year = {2021},
date = {2021-03-00},
journal = {Res. Biomed. Eng.},
volume = {37},
number = {1},
pages = {95--103},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2020
Moreira, Luciana S; Elias, Leonardo A; Germer, Carina M; Palomari, Evanisi T
Reliable measurement of incisal bite force for understanding the control of masticatory muscles Journal Article
Em: Arch Oral Biol, vol. 112, pp. 104683, 2020, ISSN: 1879-1506.
Resumo | Links | BibTeX | Tags:
@article{pmid32120053,
title = {Reliable measurement of incisal bite force for understanding the control of masticatory muscles},
author = {Luciana S Moreira and Leonardo A Elias and Carina M Germer and Evanisi T Palomari},
doi = {10.1016/j.archoralbio.2020.104683},
issn = {1879-1506},
year = {2020},
date = {2020-04-01},
urldate = {2020-04-01},
journal = {Arch Oral Biol},
volume = {112},
pages = {104683},
abstract = {OBJECTIVE: In the present study, we aimed at evaluating the steadiness of incisal bite force during isometric contractions of masticatory muscles.nnDESIGN: Two separate experiments were carried out in 11 healthy young women. A first experiment was performed to test the reliability of our protocol for measurement of incisal bite force steadiness. The second experiment aimed to evaluate the steadiness of incisal bite force at four submaximal (i.e., percentage of maximum voluntary contraction, MVC) levels (5 %MVC, 10 %MVC, 15 %MVC, and 20 %MVC), along with the bilateral myoelectric activity of two masticatory muscles (temporalis and masseter).nnRESULTS: The results from the first experiment showed that our protocol is substantially reliable (intraclass correlation coefficient, ICC > 0.80) for estimating force variability and moderate reliable (0.60 < ICC < 0.80) for estimating spectral properties of force signals. In the second experiment, we found that force standard deviation (SD) increased proportionally to the power of mean force, and coefficient of variation (CoV) was higher at low-intensity contractions and maintained at an approximately constant level for high-intensity contractions. The force-EMG relationships were linear for both muscles at the contraction intensities evaluated in the study (5 %MVC to 20 %MVC), and the median frequency did not change with contraction intensity.nnCONCLUSION: Therefore, we presented a reliable method to estimate the incisal bite force, along with additional data on force control and myoelectric activity of jaw elevator muscles during isometric steady contractions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
OBJECTIVE: In the present study, we aimed at evaluating the steadiness of incisal bite force during isometric contractions of masticatory muscles.nnDESIGN: Two separate experiments were carried out in 11 healthy young women. A first experiment was performed to test the reliability of our protocol for measurement of incisal bite force steadiness. The second experiment aimed to evaluate the steadiness of incisal bite force at four submaximal (i.e., percentage of maximum voluntary contraction, MVC) levels (5 %MVC, 10 %MVC, 15 %MVC, and 20 %MVC), along with the bilateral myoelectric activity of two masticatory muscles (temporalis and masseter).nnRESULTS: The results from the first experiment showed that our protocol is substantially reliable (intraclass correlation coefficient, ICC > 0.80) for estimating force variability and moderate reliable (0.60 < ICC < 0.80) for estimating spectral properties of force signals. In the second experiment, we found that force standard deviation (SD) increased proportionally to the power of mean force, and coefficient of variation (CoV) was higher at low-intensity contractions and maintained at an approximately constant level for high-intensity contractions. The force-EMG relationships were linear for both muscles at the contraction intensities evaluated in the study (5 %MVC to 20 %MVC), and the median frequency did not change with contraction intensity.nnCONCLUSION: Therefore, we presented a reliable method to estimate the incisal bite force, along with additional data on force control and myoelectric activity of jaw elevator muscles during isometric steady contractions.
Germer, Carina Marconi; Vecchio, Alessandro Del; Negro, Francesco; Farina, Dario; Elias, Leonardo Abdala
Neurophysiological correlates of force control improvement induced by sinusoidal vibrotactile stimulation Journal Article
Em: J Neural Eng, vol. 17, não 1, pp. 016043, 2020, ISSN: 1741-2552.
Resumo | Links | BibTeX | Tags:
@article{pmid31791034,
title = {Neurophysiological correlates of force control improvement induced by sinusoidal vibrotactile stimulation},
author = {Carina Marconi Germer and Alessandro Del Vecchio and Francesco Negro and Dario Farina and Leonardo Abdala Elias},
doi = {10.1088/1741-2552/ab5e08},
issn = {1741-2552},
year = {2020},
date = {2020-01-01},
journal = {J Neural Eng},
volume = {17},
number = {1},
pages = {016043},
abstract = {OBJECTIVE: An optimal level of vibrotactile stimulation has been shown to improve sensorimotor control in healthy and diseased individuals. However, the underlying neurophysiological mechanisms behind the enhanced motor performance caused by vibrotactile stimulation are yet to be fully understood. Therefore, here we aim to evaluate the effect of a cutaneous vibration on the firing behavior of motor units in a condition of improved force steadiness.nnAPPROACH: Participants performed a visuomotor task, which consisted of low-intensity isometric contractions of the first dorsal interosseous (FDI) muscle, while sinusoidal (175 Hz) vibrotactile stimuli with different intensities were applied to the index finger. High-density surface electromyogram was recorded from the FDI muscle, and a decomposition algorithm was used to extract the motor unit spike trains. Additionally, computer simulations were performed using a multiscale neuromuscular model to provide a potential explanation for the experimental findings.nnMAIN RESULTS: Experimental outcomes showed that an optimal level of vibration significantly improved force steadiness (estimated as the coefficient of variation of force). The decreased force variability was accompanied by a reduction in the variability of the smoothed cumulative spike train (as an estimation of the neural drive to the muscle), and the proportion of common inputs to the FDI motor nucleus. However, the interspike interval variability did not change significantly with the vibration. A mathematical approach, together with computer simulation results suggested that vibrotactile stimulation would reduce the variance of the common synaptic input to the motor neuron pool, thereby decreasing the low frequency fluctuations of the neural drive to the muscle and force steadiness.nnSIGNIFICANCE: Our results demonstrate that the decreased variability in common input accounts for the enhancement in force control induced by vibrotactile stimulation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
OBJECTIVE: An optimal level of vibrotactile stimulation has been shown to improve sensorimotor control in healthy and diseased individuals. However, the underlying neurophysiological mechanisms behind the enhanced motor performance caused by vibrotactile stimulation are yet to be fully understood. Therefore, here we aim to evaluate the effect of a cutaneous vibration on the firing behavior of motor units in a condition of improved force steadiness.nnAPPROACH: Participants performed a visuomotor task, which consisted of low-intensity isometric contractions of the first dorsal interosseous (FDI) muscle, while sinusoidal (175 Hz) vibrotactile stimuli with different intensities were applied to the index finger. High-density surface electromyogram was recorded from the FDI muscle, and a decomposition algorithm was used to extract the motor unit spike trains. Additionally, computer simulations were performed using a multiscale neuromuscular model to provide a potential explanation for the experimental findings.nnMAIN RESULTS: Experimental outcomes showed that an optimal level of vibration significantly improved force steadiness (estimated as the coefficient of variation of force). The decreased force variability was accompanied by a reduction in the variability of the smoothed cumulative spike train (as an estimation of the neural drive to the muscle), and the proportion of common inputs to the FDI motor nucleus. However, the interspike interval variability did not change significantly with the vibration. A mathematical approach, together with computer simulation results suggested that vibrotactile stimulation would reduce the variance of the common synaptic input to the motor neuron pool, thereby decreasing the low frequency fluctuations of the neural drive to the muscle and force steadiness.nnSIGNIFICANCE: Our results demonstrate that the decreased variability in common input accounts for the enhancement in force control induced by vibrotactile stimulation.