Edmond and Lily Safra International Institute for Neuroscience of Natal

Natal, Brazil

Edmond and Lily Safra International Institute for Neuroscience of Natal

Natal, Brazil
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Pais-Vieira M.,Duke University | Lebedev M.A.,Duke University | Wiest M.C.,Wellesley College | Nicolelis M.A.L.,Duke University | Nicolelis M.A.L.,Edmond and Lily Safra International Institute for Neuroscience of Natal
Journal of Neuroscience | Year: 2013

The rat somatosensory system contains multiple thalamocortical loops (TCLs) that altogether process, in fundamentally different ways, tactile stimuli delivered passively or actively sampled. To elucidate potential top-down mechanisms that governTCLprocessing in awake, behaving animals, we simultaneously recorded neuronal ensemble activity across multiple cortical and thalamic areas while rats performed an active aperture discrimination task. Single neurons located in the primary somatosensory cortex (S1), the ventroposterior medial, and the posterior medial thalamic nuclei of the trigeminal somatosensory pathways exhibited prominent anticipatory firing modulations before the whiskers touching the aperture edges. This cortical and thalamic anticipatory firing could not be explained by whisker movements or whisker stimulation, because neither trigeminal ganglion sensory-evoked responses nor EMG activity were detected during the same period. Both thalamic and S1 anticipatory activity were predictive of the animal's discrimination accuracy. Inactivation of the primary motor cortex (M1) with muscimol affected anticipatory patterns in S1 and the thalamus, and impaired the ability to predict the animal's performance accuracy based on thalamocortical anticipatory activity. These findings suggest that neural processing in TCLs is launched in anticipation of whisker contact with objects, depends on top-down effects generated in part by M1 activity, and cannot be explained by the classical feedforward model of the rat trigeminal system. Copyright © 2013 the authors.

Pessin G.,Vale Institute of Technology | Osorio F.S.,University of Sao Paulo | Ueyama J.,University of Sao Paulo | Wolf D.F.,University of Sao Paulo | And 2 more authors.
Proceedings of the ACM Symposium on Applied Computing | Year: 2014

This work combines wireless networks (WLAN) (Wireless LAN IEEE 802.11 b/g) with learning and evolution of artificial neural networks. Our main objective is to propose an architecture for a self-adaptive system, addressing alternative methods to the usage of GPS for self-localisation in autonomous mobile robots either in indoor or outdoor environments. We seek to describe alternatives and evaluation methods for localisation of mobile agents using the strength signal from Access Points (APs). The results show that the proposed method used with autonomous mobile robots does not require the use of special hardware, and hence is low cost, easy to operate, and fully autonomous. Copyright 2014 ACM.

Thomson E.,Duke University | Thomson E.,Edmond and Lily Safra International Institute for Neuroscience of Natal | Lou J.,Duke University | Sylvester K.,Duke University | And 4 more authors.
Journal of Neurophysiology | Year: 2014

The nucleus basalis (NB) is a cholin-ergic neuromodulatory structure that projects liberally to the entire cortical mantle and regulates information processing in all cortical layers. Here, we recorded activity from populations of single units in the NB as rats performed a whisker-dependent tactile discrimination task. Over 80% of neurons responded with significant modulation in at least one phase of the task. Such activity started before stimulus onset and continued for seconds after reward delivery. Firing rates monotonically increased with reward magnitude during the task, suggesting that NB neurons are not indicating the absolute deviation from expected reward amounts. Individual neurons also encoded significant amounts of information about stimulus identity. Such robust coding was not present when the same stimuli were delivered to lightly anesthetized animals, suggesting that the NB neurons contain a sensorimotor, rather than purely sensory or motor, representation of the environment. Overall, these results support the hypothesis that neurons in the NB provide a value-laden representation of the sensorimotor state of the animal as it engages in significant behavioral tasks. © 2014 the American Physiological Society.

Pais-Vieira M.,Duke University | Kunicki C.,Edmond and Lily Safra International Institute for Neuroscience of Natal | Tseng P.-H.,Duke University | Martin J.,Duke University | And 3 more authors.
Journal of Neurophysiology | Year: 2015

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 (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 and state dependent and that its dynamics depend on the asynchronous convergence of modulations originating from ipsilateral M1 and contralateral S1. © 2015 the American Physiological Society.

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