Navegando por Autor "Blanco, Wilfredo"
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Artigo Computational models of memory consolidation and long-term synaptic plasticity during sleep(2018-10-11) Rennó-Costa, César; Silva, Ana Cláudia Costa da; Blanco, Wilfredo; Ribeiro, Sidarta Tollendal GomesThe brain stores memories by persistently changing the connectivity between neurons. Sleep is known to be critical for these changes to endure. Research on the neurobiology of sleep and the mechanisms of long-term synaptic plasticity has provided data in support of various theories of how brain activity during sleep affects long-term synaptic plasticity. The experimental findings – and therefore the theories – are apparently quite contradictory, with some evidence pointing to a role of sleep in the forgetting of irrelevant memories, whereas other results indicate that sleep supports the reinforcement of the most valuable recollections. A unified theoretical framework is in need. Computational modeling and simulation provide grounds for the quantitative testing and comparison of theoretical predictions and observed data, and might serve as a strategy to organize the rather complicated and diverse pool of data and methodologies used in sleep research. This review article outlines the emerging progress in the computational modeling and simulation of the main theories on the role of sleep in memory consolidationArtigo Cyclic alternation of quiet and active sleep states in the octopus(Elsevier BV, 2021-03-25) Medeiros, Sylvia Lima de Souza; Paiva, Mizziara Marlen Matias de; Lopes, Paulo Henrique; Blanco, Wilfredo; Lima, Françoise Dantas de; Oliveira, Jaime Bruno Cirne de; Medeiros, Inácio Gomes; Sequerra, Eduardo Bouth; Souza, Sandro José de; Leite, Tatiana Silva; Ribeiro, Sidarta Tollendal GomesPrevious observations suggest the existence of ‘Active sleep’ in cephalopods. To investigate in detail the behavioral structure of cephalopod sleep, we video-recorded four adult specimens of Octopus insularis and quantified their distinct states and transitions. Changes in skin color and texture and movements of eyes and mantle were assessed using automated image processing tools, and arousal threshold was measured using sensory stimulation. Two distinct states unresponsive to stimulation occurred in tandem. The first was a ‘Quiet sleep’ state with uniformly pale skin, closed pupils, and long episode durations (median 415.2 s). The second was an ‘Active sleep’ state with dynamic skin patterns of color and texture, rapid eye movements, and short episode durations (median 40.8 s). ‘Active sleep’ was periodic (60% of recurrences between 26 and 39 min) and occurred mostly after ‘Quiet sleep’ (82% of transitions). These results suggest that cephalopods have an ultradian sleep cycle analogous to that of amniotesArtigo Dream characteristics in a Brazilian sample: an online survey focusing on lucid dreaming(2013-12) Rolim, Sérgio A. Mota; Targino, Zé H.; Souza, Bryan C.; Blanco, Wilfredo; Araujo, John F.; Ribeiro, SidartaDuring sleep, humans experience the offline images and sensations that we call dreams, which are typically emotional and lacking in rational judgment of their bizarreness. However, during lucid dreaming (LD), subjects know that they are dreaming, and may control oneiric content. Dreaming and LD features have been studied in North Americans, Europeans and Asians, but not among Brazilians, the largest population in Latin America. Here we investigated dreams and LD characteristics in a Brazilian sample (n = 3,427; median age = 25 years) through an online survey. The subjects reported recalling dreams at least once a week (76%), and that dreams typically depicted actions (93%), known people (92%), sounds/voices (78%), and colored images (76%). The oneiric content was associated with plans for the upcoming days (37%), memories of the previous day (13%), or unrelated to the dreamer (30%). Nightmares usually depicted anxiety/fear (65%), being stalked (48%), or other unpleasant sensations (47%). These data corroborate Freudian notion of day residue in dreams, and suggest that dreams and nightmares are simulations of life situations that are related to our psychobiological integrity. Regarding LD, we observed that 77% of the subjects experienced LD at least once in life (44% up to 10 episodes ever), and for 48% LD subjectively lasted less than 1 min. LD frequency correlated weakly with dream recall frequency (r = 0.20, p < 0.01), and LD control was rare (29%). LD occurrence was facilitated when subjects did not need to wake up early (38%), a situation that increases rapid eye movement sleep (REMS) duration, or when subjects were under stress (30%), which increases REMS transitions into waking. These results indicate that LD is relatively ubiquitous but rare, unstable, difficult to control, and facilitated by increases in REMS duration and transitions to wake state. Together with LD incidence in USA, Europe and Asia, our data from Latin America strengthen the notion that LD is a general phenomenon of the human species.Artigo Dream characteristics in a Brazilian sample: an online survey focusing on lucid dreaming(Frontiers in Human Neuroscience, 2013-12-10) Mota-Rolim, Sérgio A.; Targino, Zé H.; Souza, Bryan C.; Blanco, Wilfredo; Araujo, John F.; Ribeiro, Sidarta Tollendal GomesArtigo Electrophysiological evidence that the retrosplenial cortex displays a strong and specific activation phased with hippocampal theta during paradoxical (REM) sleep(2017-07-20) Koike, Bruna Del Vechio; Farias, Kelly Soares; Billwiller, Francesca; Almeida-Filho, Daniel; Libourel, Paul-Antoine; Tiran-Cappello, Alix; Parmentier, Régis; Blanco, Wilfredo; Ribeiro, Sidarta Tollendal Gomes; Luppi, Pierre-Herve; Queiroz, Claudio Marcos Teixeira deIt is widely accepted that cortical neurons are similarly more activated during waking and paradoxical sleep (PS, aka REM) than during slow wave sleep (SWS). However, we recently reported using Fos labeling that only a few limbic cortical structures including the retrosplenial (RSC) and anterior cingulate (ACA) cortices contain a large number of neurons activated during PS hypersomnia. Our aim in the present study was to record local field potentials (LFPs) and unit activity from these two structures across all vigilance states in freely moving male rats to determine whether the RSC and the ACA are electrophysiologically specifically active during basal PS episodes. We found that theta power was significantly higher during PS than during active waking (aWK) similarly in the RSC and hippocampus (HPC) but not in ACA. Phase-amplitude coupling between HPC theta and gamma oscillations strongly and specifically increased in RSC during PS compared with aWK. It did not occur in ACA. Further, 68% and 43% of the units recorded in the RSC and ACA were significantly more active during PS than during aWK and SWS, respectively. In addition, neuronal discharge of RSC but not of ACA neurons increased just after the peak of hippocampal theta wave. Our results show for the first time that RSC neurons display enhanced spiking in synchrony with theta specifically during PS. We propose that activation of RSC neurons specifically during PS may play a role in the offline consolidation of spatial memories, and in the generation of vivid perceptual scenery during dreaming.Artigo Gain of transcription factor binding sites is associated to changes in the expression signature of human brain and testis and is correlated to genes with higher expression breadth(2019-03-22) Silva, Vandeclécio Lira da; Santos, André Mauricio Ribeiro dos; Blanco, Wilfredo; Souza, Sandro José deThe gain of transcription factor binding sites (TFBS) is believed to represent one of the major causes of biological innovation. Here we used strategies based on comparative genomics to identify 21,822 TFBS specific to the human lineage (TFBS-HS), when compared to chimpanzee and gorilla genomes. More than 40% (9,206) of these TFBS-HS are in the vicinity of 1,283 genes. A comparison of the expression pattern of these genes and the corresponding orthologs in chimpanzee and gorilla identified genes differentially expressed in human tissues. These genes show a more divergent expression pattern in the human testis and brain, suggesting a role for positive selection in the fixation of TFBS gains. Genes associated with TFBS-HS were enriched in gene ontology categories related to transcriptional regulation, signaling, differentiation/development and nervous system. Furthermore, genes associated with TFBS-HS present a higher expression breadth when compared to genes in general. This biased distribution is due to a preferential gain of TFBS in genes with higher expression breadth rather than a shift in the expression pattern after the gain of TFBS.Artigo Hippocampal functional organization: a microstructure of the place cell network encoding space(2019-04-06) Pavlides, Constantine; Donishi, Tomohiro; Ribeiro, Sidarta Tollendal Gomes; Mello, Claudio V.; Blanco, Wilfredo; Ogawa, SonokoA clue to hippocampal function has been the discovery of place cells, leading to the ‘spatial map’ theory. Although the firing attributes of place cells are well documented, little is known about the organization of the spatial map. Unit recording studies, thus far, have reported a low coherence between neighboring cells and geometric space, leading to the prevalent view that the spatial map is not topographically organized. However, the number of simultaneously recorded units is severely limited, rendering construction of the spatial map nearly impossible. To visualize the functional organization of place cells, we used the activity-dependent immediate-early gene Zif268 in combination with behavioral, pharmacological and electrophysiological methods, in mice and rats exploring an environment. Here, we show that in animals confined to a small part of a maze, principal cells in the CA1/CA3 subfields of the dorsal hippocampus immunoreactive (IR) for Zif268 adhere to a ‘cluster-type’ organization. Unit recordings confirmed that the Zif268 IR clusters correspond to active place cells, while blockade of NMDAR (which alters place fields) disrupted the Zif268 IR clusters. Contrary to the prevalent view that the spatial map consists of a non-topographic neural network, our results provide evidence for a ‘cluster-type’ functional organization of hippocampal neurons encoding for space.Artigo Synaptic Homeostasis and Restructuring across the Sleep-Wake Cycle(Aldo A Faisal, Imperial College London, UNITED KINGDOM, 2015-05-28) Blanco, Wilfredo; M. Pereira, Catia; R. Cota, Vinicius; C. Souza, Annie; Rennó-Costa, César; Santos, Sharlene; Dias, Gabriella; Guerreiro, Ana M. G.; Tort, Adriano Bretanha Lopes; D. Neto, Adrião; Ribeiro, Sidarta Tollendal GomesArtigo The Effects of GABAergic Polarity Changes on Episodic Neural Network Activity in Developing Neural Systems(2017-09-29) Blanco, Wilfredo; Bertram, Richardson; Tabak, JoelEarly in development, neural systems have primarily excitatory coupling, where even GABAergic synapses are excitatory. Many of these systems exhibit spontaneous episodes of activity that have been characterized through both experimental and computational studies. As development progress the neural system goes through many changes, including synaptic remodeling, intrinsic plasticity in the ion channel expression, and a transformation of GABAergic synapses from excitatory to inhibitory. What effect each of these, and other, changes have on the network behavior is hard to know from experimental studies since they all happen in parallel. One advantage of a computational approach is that one has the ability to study developmental changes in isolation. Here, we examine the effects of GABAergic synapse polarity change on the spontaneous activity of both a mean field and a neural network model that has both glutamatergic and GABAergic coupling, representative of a developing neural network. We find some intuitive behavioral changes as the GABAergic neurons go from excitatory to inhibitory, shared by both models, such as a decrease in the duration of episodes. We also find some paradoxical changes in the activity that are only present in the neural network model. In particular, we find that during early development the inter-episode durations become longer on average, while later in development they become shorter. In addressing this unexpected finding, we uncover a priming effect that is particularly important for a small subset of neurons, called the “intermediate neurons.” We characterize these neurons and demonstrate why they are crucial to episode initiation, and why the paradoxical behavioral change result from priming of these neurons. The study illustrates how even arguably the simplest of developmental changes that occurs in neural systems can present non-intuitive behaviors. It also makes predictions about neural network behavioral changes that occur during development that may be observable even in actual neural systems where these changes are convoluted with changes in synaptic connectivity and intrinsic neural plasticity.