Carolina Kunicki - Academia.edu (original) (raw)

Papers by Carolina Kunicki

Tactile information processing requires the integration of sensory, motor, and cognitive informat... more Tactile information processing requires the integration of sensory, motor, and cognitive information. Width discrimination has been extensively studied in rodents, but not in humans. Here, we describe Electroencephalography (EEG) signals in humans performing a tactile width discrimination task. Comparison of changes in Spectral Power Density during two different periods of the task corresponding to the discrimination of the tactile stimulus and the motor response, revealed the engagement of a complex network associated with the electrodes recording from fronto-temporo-parieto-occipital areas and across multiple frequency bands. Analysis of ratios of higher [Ratio1:(0.5-20Hz)/(0.5-45Hz)] or lower frequencies [Ratio2: (0.5-4.5Hz)/(0.5-9Hz)], also revealed that the periods of tactile discrimination and motor response, were accompanied by changes in these ratios. Further analysis of the tactile discrimination period demonstrated that ratios of frequencies recorded from electrodes locate...

2018 International Joint Conference on Neural Networks (IJCNN)

Understanding, mapping, and repairing the central nervous system would benefit from a better comp... more Understanding, mapping, and repairing the central nervous system would benefit from a better comprehension of how sensory stimuli information is conveyed by the neural activity underlying animal behavior. In this way, a promising approach, neural decoding, include machine-learning methods that associate patterns of brain activity with sensory stimuli. By solving a regression or classification problem, decoding contributes to highlighting the features from neural activity that best relate to a target variable. In this work, we built a support vector machine decoder coupled with a recursive feature selection algorithm to investigate the relevance of three distinct aspects of neural activity in an active tactile discrimination experiment involving rodents. Considering simultaneous recordings from a population of single-neuron spikes and local field potentials from the prefrontal, posterior parietal, primary sensory and visual cortices of nine Long-Evans rats, we were able to decode animal behavioral choices with approximately 95% of accuracy. When only the 30 most informative features from neural activity were used, accuracy values marginally decreased, indicating that a reduced set of features convey most of stimuli information, at least from the decoder perspective. Importantly, all regions contributed with features, and no single feature was associated to high classification accuracy. In addition to further unveiling the distributed nature of information processing in the brain, our results suggest that efficient brain-machine interfaces may be built with a reduced set of features.

XXVI Brazilian Congress on Biomedical Engineering

Spinal cord stimulation has become a widely used and efficient alternative for the management of ... more Spinal cord stimulation has become a widely used and efficient alternative for the management of neurological disorders such as refractory chronic pain. The implanted devices likely induce activation of microglia, the cells responsible for the initiation of inflammatory response in the central nervous system. However, so far there are no available data on the microglial response following spinal cord epidural implants. This study intended to characterize the acute microglial response after spinal cord electrode implantation. To evaluate the acute response, a custom-made flat bipolar platinum electrode was implanted in the epidural space under the thoracic vertebra 4 (T4) in Wistar rats. Two days after implantation, morphological changes of microglia were evaluated by immunohistochemistry staining for ionized calcium-binding adaptor protein-1 (IBA-1) in spinal cord sections. Substantial loss of microglia ramification was found throughout the spinal cord at the implant site (T4). In contrast, microglia was not activated in areas distant from the implant such as cervical vertebra 4 (C4) and thoracic vertebra 11 (T11). This result interestingly demonstrates that semi-invasive implants in the spinal cord are able to induce the activation of microglial cells at the implant region. This work is the first step towards understanding the impact of epidural implants in spinal cord tissue.

XXVII Brazilian Congress on Biomedical Engineering

XXVII Brazilian Congress on Biomedical Engineering

Miguel Pais-Vieira, Carolina Kunicki, Po-He Tseng, Joel Martin, Mikhail Lebedev, and 6 Miguel A.L... more Miguel Pais-Vieira, Carolina Kunicki, Po-He Tseng, Joel Martin, Mikhail Lebedev, and 6 Miguel A.L. Nicolelis 7 8 Departments of Neurobiology, Biomedical Engineering, and Psychology and Neuroscience 9 and Center for Neuroengineering, Duke University, Durham, North Carolina 27710; and 10 Edmond and Lily Safra International Institute for Neuroscience of Natal, Natal, Brazil 11 12 13 Corresponding Author: 14 Miguel A. L. Nicolelis 15 Box 3209, Dept. of Neurobiology 16 Duke University 17 Durham, NC 27710 18 nicoleli@neuro.duke.edu 19 (919) 684-4580 20 21 Number of Pages: 78 22 Number of Figures: 17 23 Number of Tables: 5 24 Number of Movies: 6 25 Number of Supporting Figures: 8 26 27 Number of words abstract: 244 28 Number of words introduction: 514 29 Number of words discussion: 3678 30 31 32 33 34 35 Articles in PresS. J Neurophysiol (July 15, 2015). doi:10.1152/jn.00108.2015

Journal of Visualized Experiments

Journal of Visualized Experiments, 2019

Scientific Reports, 2019

Processing of tactile sensory information in rodents is critically dependent on the communication... more Processing of tactile sensory information in rodents is critically dependent on the communication between the primary somatosensory cortex (S1) and higher-order integrative cortical areas. Here, we have simultaneously characterized single-unit activity and local field potential (LFP) dynamics in the S1, primary visual cortex (V1), anterior cingulate cortex (ACC), posterior parietal cortex (PPC), while freely moving rats performed an active tactile discrimination task. Simultaneous single unit recordings from all these cortical regions revealed statistically significant neuronal firing rate modulations during all task phases (anticipatory, discrimination, response, and reward). Meanwhile, phase analysis of pairwise LFP recordings revealed the occurrence of long-range synchronization across the sampled fronto-parieto-occipital cortical areas during tactile sampling. Causal analysis of the same pairwise recorded LFPs demonstrated the occurrence of complex dynamic interactions between c...

Brain Sciences, 2019

Microelectrode implants are an important tool in neuroscience research and in developing brain–ma... more Microelectrode implants are an important tool in neuroscience research and in developing brain–machine interfaces. Data from rodents have consistently shown that astrocytes are recruited to the area surrounding implants, forming a glial scar that increases electrode impedance and reduces chronic utility. However, studies in non-human primates are scarce, with none to date in marmosets. We used glial fibrillary acidic protein (GFAP) immunostaining to characterize the acute and chronic response of the marmoset brain to microelectrodes. By using densitometry, we showed that marmoset astrocytes surround brain implants and that a glial scar is formed over time, with significant increase in the chronic condition relative to the acute condition animal.

Frontiers in neural circuits, 2017

Accumulating evidence suggests that neural interactions are distributed and relate to animal beha... more Accumulating evidence suggests that neural interactions are distributed and relate to animal behavior, but many open questions remain. The neural assembly hypothesis, formulated by Hebb, states that synchronously active single neurons may transiently organize into functional neural circuits-neuronal assemblies (NAs)-and that would constitute the fundamental unit of information processing in the brain. However, the formation, vanishing, and temporal evolution of NAs are not fully understood. In particular, characterizing NAs in multiple brain regions over the course of behavioral tasks is relevant to assess the highly distributed nature of brain processing. In the context of NA characterization, active tactile discrimination tasks with rats are elucidative because they engage several cortical areas in the processing of information that are otherwise masked in passive or anesthetized scenarios. In this work, we investigate the dynamic formation of NAs within and among four different c...

Brazilian Journal of Medical and Biological Research, 2009

The fractal dimension has been employed as a useful parameter in the diagnosis of retinal disease... more The fractal dimension has been employed as a useful parameter in the diagnosis of retinal disease. Avakian et al. (Curr Eye Res 2002; 24: 274-280), comparing the vascular pattern of normal patients with mild to moderate non-proliferative diabetic retinopathy (NPDR), found a significant difference between them only in the macular region. This significant difference in the box-counting fractal dimension of the macular region between normal and mild NPDR patients has been proposed as a method of precocious diagnosis of NPDR. The aim of the present study was to determine if fractal dimensions can really be used as a parameter for the early diagnosis of NPDR. Box-counting and information fractal dimensions were used to parameterize the vascular pattern of the human retina. The two methods were applied to the whole retina and to nine anatomical regions of the retina in 5 individuals with mild NPDR and in 28 diabetic but opthalmically normal individuals (controls), with age between 31 and 86 years. All images of retina were obtained from the Digital Retinal Images for Vessel Extraction (DRIVE) database. The results showed that the fractal dimension parameter was not sensitive enough to be of use for an early diagnosis of NPDR.

A minha avó, Eunice, a minha mãe, Marta e as minhas tias, Arminda e Neusa. "De tudo ficaram três ... more A minha avó, Eunice, a minha mãe, Marta e as minhas tias, Arminda e Neusa. "De tudo ficaram três coisas... A certeza de que estamos começando... A certeza de que é preciso continuar... A certeza de que podemos ser interrompidos antes de terminar... Façamos da interrupção um novo caminho... Da queda, um passo de dança... Do medo, uma escada... Do sonho, uma ponte... Da procura, um encontro"

Journal of Neurophysiology, 2015

Tactile information processing in the rodent primary somatosensory cortex (S1) is layer specific ... more Tactile information processing in the rodent primary somatosensory cortex (S1) is layer specific and involves modulations from both thalamocortical and cortico-cortical loops. However, the extent to which these loops influence the dynamics of the primary somatosensory cortex while animals execute tactile discrimination remains largely unknown. Here, we describe neural dynamics of S1 layers across the multiple epochs defining a tactile discrimination task. We observed that neuronal ensembles within different layers of the S1 cortex exhibited significantly distinct neurophysiological properties, which constantly changed across the behavioral states that defined a tactile discrimination. Neural dynamics present in supragranular and granular layers generally matched the patterns observed in the ventral posterior medial nucleus of the thalamus (VPM), whereas the neural dynamics recorded from infragranular layers generally matched the patterns from the posterior nucleus of the thalamus (P...

Scientific Reports, 2013

A brain-to-brain interface (BTBI) enabled a real-time transfer of behaviorally meaningful sensori... more A brain-to-brain interface (BTBI) enabled a real-time transfer of behaviorally meaningful sensorimotor information between the brains of two rats. In this BTBI, an ''encoder'' rat performed sensorimotor tasks that required it to select from two choices of tactile or visual stimuli. While the encoder rat performed the task, samples of its cortical activity were transmitted to matching cortical areas of a ''decoder'' rat using intracortical microstimulation (ICMS). The decoder rat learned to make similar behavioral selections, guided solely by the information provided by the encoder rat's brain. These results demonstrated that a complex system was formed by coupling the animals' brains, suggesting that BTBIs can enable dyads or networks of animal's brains to exchange, process, and store information and, hence, serve as the basis for studies of novel types of social interaction and for biological computing devices.

2014 IEEE 16th International Conference on e-Health Networking, Applications and Services (Healthcom), 2014

The anatomical and functional characterization of neuronal assemblies (NAs) is a major challenge ... more The anatomical and functional characterization of neuronal assemblies (NAs) is a major challenge in neuroscience. Principal component analysis (PCA) is a widely used method for feature detection, however, when dealing with neuronal data analysis, its limitations have not yet been fully understood. Our work complements previous PCA studies which, in general, characterise NAs based solely on excitatory neuronal interactions. We analysed the performance of PCA in two neglected scenarios: assemblies containing patterns of neural interactions (1) with inhibition and (2) with delays. The analyses considered two types of artificially generated data, one drawn from a traditional Poissonian model, and the other drawn from a latent multivariate Gaussian model; in both models, data from a behaving Wistar rat was used for parameter tuning. Our results highlight scenarios in which neglecting complex interactions between neurons can lead to false conclusions when using PCA to detect NAs. Also, we reinforce the importance of more realistic simulations in the evaluation of neuronal signal processing algorithms.

Einstein (São Paulo), 2012

OBJECTIVE: The hippocampus has an important role in the acquisition and recall of aversive memori... more OBJECTIVE: The hippocampus has an important role in the acquisition and recall of aversive memories. The objective of this study was to investigate the relationship among hippocampal rhythms. METHODS: Microeletrodes arrays were implanted in the hippocampus of Wistar rats. The animals were trained and tested in a contextual fear conditioning task. The training consisted in applying shocks in the legs. The memory test was performed 1 day (recent memory) or 18 days (remote memory) after training. We proposed a measure based on the FFT power spectrum, denominated "delta-theta ratio", to characterize the different behaviors (active exploration and freezing) and the memories types. RESULTS: The delta-theta ratio was able to distinguish recent and remote memories. In this study, the ratio for the 18-day group was smaller than for the 1-day group. Moreover, this measure was useful to distinguish the different behavior states – active exploration and freezing. CONCLUSIONS: The resu...

Veterinary Ophthalmology, 2008

To study the applicability of the fractal dimension as a parameter for describing retinal vessel ... more To study the applicability of the fractal dimension as a parameter for describing retinal vessel patterns in ophthalmically normal dogs. The following strategy was adopted: (i) development of an experimental procedure to obtain digitalized photographs of the fundus; (ii) development of software to segment retinal vessel images and calculate the box-counting and radius of gyration fractal dimensions of the retinal vessels and diffusion-limited aggregation (DLA), a process with similar characteristics to retinal vessel morphology, and (iii) establishment of a standard curve for the fractal dimensions of segmented vessels. Digitalized photographs of the fundus showed an adequate contrast between the vessels and the rest of the fundus for numerical analysis. The software developed produced a binary image of the retinal vessels permitting calculation of the fractal dimension. The mean values of the fractal dimensions calculated by the methods of box-counting and radius of gyration for the DLA were significantly different (t = -40.33, P approximately 0). The radius of gyration method was found to be more suitable for documenting the dimension of the DLA and, consequently, of the dog's retinal vessels. This methodology may be useful to differentiate between normal and pathologic states of canine retinal vascularization.

Scientific Reports, 2019

Stress responses are associated with elevations in corticosterone levels and, as a consequence, i... more Stress responses are associated with elevations in corticosterone levels and, as a consequence, increases in glutamate in the central nervous system which can lead to neurological impairment. Ceftriaxone promotes glutamate transport and has been used to reduce glutamate toxicity, but so far it is not known whether ceftriaxone is able to reverse the effects of corticosterone administration. Here we describe the separate and combined effects of acute ceftriaxone and acute corticosterone administration in local field potentials (LFPs) recorded from the somatosensory cortex (S1) of anesthetized mice. For this, LFPs were recorded from groups of anesthetized mice injected with saline, corticosterone, ceftriaxone, or both. Comparison of global state maps, and their displacements, as measured by ratios of different frequency bands (Ratio 1: 0.5–20 Hz/0.5–45 Hz; and Ratio 2: 0.5–4.5 Hz/0.5–9 Hz) revealed distinct and opposite effects for corticosterone and for ceftriaxone. Corticosterone spe...

Journal of Neurophysiology, 2015

Tactile information processing in the rodent primary somatosensory cortex (S1) is layer-specific ... more Tactile information processing in the rodent primary somatosensory cortex (S1) is layer-specific and involves modulations from both thalamocortical and cortico-cortical loops. However, the extent to which these loops influence the dynamics of the primary somatosensory cortex while animals execute tactile discrimination remains largely unknown. Here, we describe neural dynamics of S1 layers across the multiple epochs defining a tactile discrimination task. We observed that neuronal ensembles within different layers of the S1 cortex exhibited significantly distinct neurophysiological properties, which constantly changed across the behavioral states that defined a tactile discrimination. Neural dynamics present in supragranular and granular layers generally matched the patterns observed in the ventral posterior medial nucleus of the thalamus (VPM), while the neural dynamics recorded from infragranular layers generally matched the patterns from the posterior nucleus of the thalamus (POM). Selective inactivation of contralateral S1 specifically switched infragranular neural dynamics from POM-like to those resembling VPM neurons. Meanwhile ipsilateral M1 inactivation profoundly modulated the firing suppression observed in infragranular layers. This latter effect was counterbalanced by contralateral S1 block. Tactile stimulus encoding was layer specific and selectively affected by M1 or contralateral S1 inactivation. Lastly, causal information transfer occurred between all neurons in all S1 layers but was maximal from infragranular to the granular layer. These results suggest that tactile information processing in the S1 of awake behaving rodents is layer specific, state-dependent, and that its dynamics depend on the asynchronous convergence of modulations originating from ipsilateral M1 and contralateral S1.

Tactile information processing requires the integration of sensory, motor, and cognitive informat... more Tactile information processing requires the integration of sensory, motor, and cognitive information. Width discrimination has been extensively studied in rodents, but not in humans. Here, we describe Electroencephalography (EEG) signals in humans performing a tactile width discrimination task. Comparison of changes in Spectral Power Density during two different periods of the task corresponding to the discrimination of the tactile stimulus and the motor response, revealed the engagement of a complex network associated with the electrodes recording from fronto-temporo-parieto-occipital areas and across multiple frequency bands. Analysis of ratios of higher [Ratio1:(0.5-20Hz)/(0.5-45Hz)] or lower frequencies [Ratio2: (0.5-4.5Hz)/(0.5-9Hz)], also revealed that the periods of tactile discrimination and motor response, were accompanied by changes in these ratios. Further analysis of the tactile discrimination period demonstrated that ratios of frequencies recorded from electrodes locate...

2018 International Joint Conference on Neural Networks (IJCNN)

Understanding, mapping, and repairing the central nervous system would benefit from a better comp... more Understanding, mapping, and repairing the central nervous system would benefit from a better comprehension of how sensory stimuli information is conveyed by the neural activity underlying animal behavior. In this way, a promising approach, neural decoding, include machine-learning methods that associate patterns of brain activity with sensory stimuli. By solving a regression or classification problem, decoding contributes to highlighting the features from neural activity that best relate to a target variable. In this work, we built a support vector machine decoder coupled with a recursive feature selection algorithm to investigate the relevance of three distinct aspects of neural activity in an active tactile discrimination experiment involving rodents. Considering simultaneous recordings from a population of single-neuron spikes and local field potentials from the prefrontal, posterior parietal, primary sensory and visual cortices of nine Long-Evans rats, we were able to decode animal behavioral choices with approximately 95% of accuracy. When only the 30 most informative features from neural activity were used, accuracy values marginally decreased, indicating that a reduced set of features convey most of stimuli information, at least from the decoder perspective. Importantly, all regions contributed with features, and no single feature was associated to high classification accuracy. In addition to further unveiling the distributed nature of information processing in the brain, our results suggest that efficient brain-machine interfaces may be built with a reduced set of features.

XXVI Brazilian Congress on Biomedical Engineering

Spinal cord stimulation has become a widely used and efficient alternative for the management of ... more Spinal cord stimulation has become a widely used and efficient alternative for the management of neurological disorders such as refractory chronic pain. The implanted devices likely induce activation of microglia, the cells responsible for the initiation of inflammatory response in the central nervous system. However, so far there are no available data on the microglial response following spinal cord epidural implants. This study intended to characterize the acute microglial response after spinal cord electrode implantation. To evaluate the acute response, a custom-made flat bipolar platinum electrode was implanted in the epidural space under the thoracic vertebra 4 (T4) in Wistar rats. Two days after implantation, morphological changes of microglia were evaluated by immunohistochemistry staining for ionized calcium-binding adaptor protein-1 (IBA-1) in spinal cord sections. Substantial loss of microglia ramification was found throughout the spinal cord at the implant site (T4). In contrast, microglia was not activated in areas distant from the implant such as cervical vertebra 4 (C4) and thoracic vertebra 11 (T11). This result interestingly demonstrates that semi-invasive implants in the spinal cord are able to induce the activation of microglial cells at the implant region. This work is the first step towards understanding the impact of epidural implants in spinal cord tissue.

XXVII Brazilian Congress on Biomedical Engineering

XXVII Brazilian Congress on Biomedical Engineering

Miguel Pais-Vieira, Carolina Kunicki, Po-He Tseng, Joel Martin, Mikhail Lebedev, and 6 Miguel A.L... more Miguel Pais-Vieira, Carolina Kunicki, Po-He Tseng, Joel Martin, Mikhail Lebedev, and 6 Miguel A.L. Nicolelis 7 8 Departments of Neurobiology, Biomedical Engineering, and Psychology and Neuroscience 9 and Center for Neuroengineering, Duke University, Durham, North Carolina 27710; and 10 Edmond and Lily Safra International Institute for Neuroscience of Natal, Natal, Brazil 11 12 13 Corresponding Author: 14 Miguel A. L. Nicolelis 15 Box 3209, Dept. of Neurobiology 16 Duke University 17 Durham, NC 27710 18 nicoleli@neuro.duke.edu 19 (919) 684-4580 20 21 Number of Pages: 78 22 Number of Figures: 17 23 Number of Tables: 5 24 Number of Movies: 6 25 Number of Supporting Figures: 8 26 27 Number of words abstract: 244 28 Number of words introduction: 514 29 Number of words discussion: 3678 30 31 32 33 34 35 Articles in PresS. J Neurophysiol (July 15, 2015). doi:10.1152/jn.00108.2015

Journal of Visualized Experiments

Journal of Visualized Experiments, 2019

Scientific Reports, 2019

Processing of tactile sensory information in rodents is critically dependent on the communication... more Processing of tactile sensory information in rodents is critically dependent on the communication between the primary somatosensory cortex (S1) and higher-order integrative cortical areas. Here, we have simultaneously characterized single-unit activity and local field potential (LFP) dynamics in the S1, primary visual cortex (V1), anterior cingulate cortex (ACC), posterior parietal cortex (PPC), while freely moving rats performed an active tactile discrimination task. Simultaneous single unit recordings from all these cortical regions revealed statistically significant neuronal firing rate modulations during all task phases (anticipatory, discrimination, response, and reward). Meanwhile, phase analysis of pairwise LFP recordings revealed the occurrence of long-range synchronization across the sampled fronto-parieto-occipital cortical areas during tactile sampling. Causal analysis of the same pairwise recorded LFPs demonstrated the occurrence of complex dynamic interactions between c...

Brain Sciences, 2019

Microelectrode implants are an important tool in neuroscience research and in developing brain–ma... more Microelectrode implants are an important tool in neuroscience research and in developing brain–machine interfaces. Data from rodents have consistently shown that astrocytes are recruited to the area surrounding implants, forming a glial scar that increases electrode impedance and reduces chronic utility. However, studies in non-human primates are scarce, with none to date in marmosets. We used glial fibrillary acidic protein (GFAP) immunostaining to characterize the acute and chronic response of the marmoset brain to microelectrodes. By using densitometry, we showed that marmoset astrocytes surround brain implants and that a glial scar is formed over time, with significant increase in the chronic condition relative to the acute condition animal.

Frontiers in neural circuits, 2017

Accumulating evidence suggests that neural interactions are distributed and relate to animal beha... more Accumulating evidence suggests that neural interactions are distributed and relate to animal behavior, but many open questions remain. The neural assembly hypothesis, formulated by Hebb, states that synchronously active single neurons may transiently organize into functional neural circuits-neuronal assemblies (NAs)-and that would constitute the fundamental unit of information processing in the brain. However, the formation, vanishing, and temporal evolution of NAs are not fully understood. In particular, characterizing NAs in multiple brain regions over the course of behavioral tasks is relevant to assess the highly distributed nature of brain processing. In the context of NA characterization, active tactile discrimination tasks with rats are elucidative because they engage several cortical areas in the processing of information that are otherwise masked in passive or anesthetized scenarios. In this work, we investigate the dynamic formation of NAs within and among four different c...

Brazilian Journal of Medical and Biological Research, 2009

The fractal dimension has been employed as a useful parameter in the diagnosis of retinal disease... more The fractal dimension has been employed as a useful parameter in the diagnosis of retinal disease. Avakian et al. (Curr Eye Res 2002; 24: 274-280), comparing the vascular pattern of normal patients with mild to moderate non-proliferative diabetic retinopathy (NPDR), found a significant difference between them only in the macular region. This significant difference in the box-counting fractal dimension of the macular region between normal and mild NPDR patients has been proposed as a method of precocious diagnosis of NPDR. The aim of the present study was to determine if fractal dimensions can really be used as a parameter for the early diagnosis of NPDR. Box-counting and information fractal dimensions were used to parameterize the vascular pattern of the human retina. The two methods were applied to the whole retina and to nine anatomical regions of the retina in 5 individuals with mild NPDR and in 28 diabetic but opthalmically normal individuals (controls), with age between 31 and 86 years. All images of retina were obtained from the Digital Retinal Images for Vessel Extraction (DRIVE) database. The results showed that the fractal dimension parameter was not sensitive enough to be of use for an early diagnosis of NPDR.

A minha avó, Eunice, a minha mãe, Marta e as minhas tias, Arminda e Neusa. "De tudo ficaram três ... more A minha avó, Eunice, a minha mãe, Marta e as minhas tias, Arminda e Neusa. "De tudo ficaram três coisas... A certeza de que estamos começando... A certeza de que é preciso continuar... A certeza de que podemos ser interrompidos antes de terminar... Façamos da interrupção um novo caminho... Da queda, um passo de dança... Do medo, uma escada... Do sonho, uma ponte... Da procura, um encontro"

Journal of Neurophysiology, 2015

Tactile information processing in the rodent primary somatosensory cortex (S1) is layer specific ... more Tactile information processing in the rodent primary somatosensory cortex (S1) is layer specific and involves modulations from both thalamocortical and cortico-cortical loops. However, the extent to which these loops influence the dynamics of the primary somatosensory cortex while animals execute tactile discrimination remains largely unknown. Here, we describe neural dynamics of S1 layers across the multiple epochs defining a tactile discrimination task. We observed that neuronal ensembles within different layers of the S1 cortex exhibited significantly distinct neurophysiological properties, which constantly changed across the behavioral states that defined a tactile discrimination. Neural dynamics present in supragranular and granular layers generally matched the patterns observed in the ventral posterior medial nucleus of the thalamus (VPM), whereas the neural dynamics recorded from infragranular layers generally matched the patterns from the posterior nucleus of the thalamus (P...

Scientific Reports, 2013

A brain-to-brain interface (BTBI) enabled a real-time transfer of behaviorally meaningful sensori... more A brain-to-brain interface (BTBI) enabled a real-time transfer of behaviorally meaningful sensorimotor information between the brains of two rats. In this BTBI, an ''encoder'' rat performed sensorimotor tasks that required it to select from two choices of tactile or visual stimuli. While the encoder rat performed the task, samples of its cortical activity were transmitted to matching cortical areas of a ''decoder'' rat using intracortical microstimulation (ICMS). The decoder rat learned to make similar behavioral selections, guided solely by the information provided by the encoder rat's brain. These results demonstrated that a complex system was formed by coupling the animals' brains, suggesting that BTBIs can enable dyads or networks of animal's brains to exchange, process, and store information and, hence, serve as the basis for studies of novel types of social interaction and for biological computing devices.

2014 IEEE 16th International Conference on e-Health Networking, Applications and Services (Healthcom), 2014

The anatomical and functional characterization of neuronal assemblies (NAs) is a major challenge ... more The anatomical and functional characterization of neuronal assemblies (NAs) is a major challenge in neuroscience. Principal component analysis (PCA) is a widely used method for feature detection, however, when dealing with neuronal data analysis, its limitations have not yet been fully understood. Our work complements previous PCA studies which, in general, characterise NAs based solely on excitatory neuronal interactions. We analysed the performance of PCA in two neglected scenarios: assemblies containing patterns of neural interactions (1) with inhibition and (2) with delays. The analyses considered two types of artificially generated data, one drawn from a traditional Poissonian model, and the other drawn from a latent multivariate Gaussian model; in both models, data from a behaving Wistar rat was used for parameter tuning. Our results highlight scenarios in which neglecting complex interactions between neurons can lead to false conclusions when using PCA to detect NAs. Also, we reinforce the importance of more realistic simulations in the evaluation of neuronal signal processing algorithms.

Einstein (São Paulo), 2012

OBJECTIVE: The hippocampus has an important role in the acquisition and recall of aversive memori... more OBJECTIVE: The hippocampus has an important role in the acquisition and recall of aversive memories. The objective of this study was to investigate the relationship among hippocampal rhythms. METHODS: Microeletrodes arrays were implanted in the hippocampus of Wistar rats. The animals were trained and tested in a contextual fear conditioning task. The training consisted in applying shocks in the legs. The memory test was performed 1 day (recent memory) or 18 days (remote memory) after training. We proposed a measure based on the FFT power spectrum, denominated "delta-theta ratio", to characterize the different behaviors (active exploration and freezing) and the memories types. RESULTS: The delta-theta ratio was able to distinguish recent and remote memories. In this study, the ratio for the 18-day group was smaller than for the 1-day group. Moreover, this measure was useful to distinguish the different behavior states – active exploration and freezing. CONCLUSIONS: The resu...

Veterinary Ophthalmology, 2008

To study the applicability of the fractal dimension as a parameter for describing retinal vessel ... more To study the applicability of the fractal dimension as a parameter for describing retinal vessel patterns in ophthalmically normal dogs. The following strategy was adopted: (i) development of an experimental procedure to obtain digitalized photographs of the fundus; (ii) development of software to segment retinal vessel images and calculate the box-counting and radius of gyration fractal dimensions of the retinal vessels and diffusion-limited aggregation (DLA), a process with similar characteristics to retinal vessel morphology, and (iii) establishment of a standard curve for the fractal dimensions of segmented vessels. Digitalized photographs of the fundus showed an adequate contrast between the vessels and the rest of the fundus for numerical analysis. The software developed produced a binary image of the retinal vessels permitting calculation of the fractal dimension. The mean values of the fractal dimensions calculated by the methods of box-counting and radius of gyration for the DLA were significantly different (t = -40.33, P approximately 0). The radius of gyration method was found to be more suitable for documenting the dimension of the DLA and, consequently, of the dog's retinal vessels. This methodology may be useful to differentiate between normal and pathologic states of canine retinal vascularization.

Scientific Reports, 2019

Stress responses are associated with elevations in corticosterone levels and, as a consequence, i... more Stress responses are associated with elevations in corticosterone levels and, as a consequence, increases in glutamate in the central nervous system which can lead to neurological impairment. Ceftriaxone promotes glutamate transport and has been used to reduce glutamate toxicity, but so far it is not known whether ceftriaxone is able to reverse the effects of corticosterone administration. Here we describe the separate and combined effects of acute ceftriaxone and acute corticosterone administration in local field potentials (LFPs) recorded from the somatosensory cortex (S1) of anesthetized mice. For this, LFPs were recorded from groups of anesthetized mice injected with saline, corticosterone, ceftriaxone, or both. Comparison of global state maps, and their displacements, as measured by ratios of different frequency bands (Ratio 1: 0.5–20 Hz/0.5–45 Hz; and Ratio 2: 0.5–4.5 Hz/0.5–9 Hz) revealed distinct and opposite effects for corticosterone and for ceftriaxone. Corticosterone spe...

Journal of Neurophysiology, 2015

Tactile information processing in the rodent primary somatosensory cortex (S1) is layer-specific ... more Tactile information processing in the rodent primary somatosensory cortex (S1) is layer-specific and involves modulations from both thalamocortical and cortico-cortical loops. However, the extent to which these loops influence the dynamics of the primary somatosensory cortex while animals execute tactile discrimination remains largely unknown. Here, we describe neural dynamics of S1 layers across the multiple epochs defining a tactile discrimination task. We observed that neuronal ensembles within different layers of the S1 cortex exhibited significantly distinct neurophysiological properties, which constantly changed across the behavioral states that defined a tactile discrimination. Neural dynamics present in supragranular and granular layers generally matched the patterns observed in the ventral posterior medial nucleus of the thalamus (VPM), while the neural dynamics recorded from infragranular layers generally matched the patterns from the posterior nucleus of the thalamus (POM). Selective inactivation of contralateral S1 specifically switched infragranular neural dynamics from POM-like to those resembling VPM neurons. Meanwhile ipsilateral M1 inactivation profoundly modulated the firing suppression observed in infragranular layers. This latter effect was counterbalanced by contralateral S1 block. Tactile stimulus encoding was layer specific and selectively affected by M1 or contralateral S1 inactivation. Lastly, causal information transfer occurred between all neurons in all S1 layers but was maximal from infragranular to the granular layer. These results suggest that tactile information processing in the S1 of awake behaving rodents is layer specific, state-dependent, and that its dynamics depend on the asynchronous convergence of modulations originating from ipsilateral M1 and contralateral S1.