Navegando por Autor "Rodrigues, Ana João"
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Artigo Coupled variability in primary sensory areas and the hippocampus during spontaneous activity(Scientific Report, 2017-04-10) Vasconcelos, NivaldoA. P. de; Soares-Cunha, Carina; Rodrigues, Ana João; Ribeiro, Sidarta Tollendal Gomes; Sousa, NunoThe cerebral cortex is an anatomically divided and functionally specialized structure. It includes distinct areas, which work on different states over time. The structural features of spiking activity in sensory cortices have been characterized during spontaneous and evoked activity. However, the coordination among cortical and sub-cortical neurons during spontaneous activity across different states remains poorly characterized. We addressed this issue by studying the temporal coupling of spiking variability recorded from primary sensory cortices and hippocampus of anesthetized or freely behaving rats. During spontaneous activity, spiking variability was highly correlated across primary cortical sensory areas at both small and large spatial scales, whereas the cortico-hippocampal correlation was modest. This general pattern of spiking variability was observed under urethane anesthesia, as well as during waking, slow-wave sleep and rapid-eye-movement sleep, and was unchanged by novel stimulation. These results support the notion that primary sensory areas are strongly coupled during spontaneous activity.Artigo Criticality between Cortical States(2019-05-21) Fontenele, Antonio J.; Vasconcelos, Nivaldo A. P. de; Feliciano, Thaís; Aguiar, Leandro A. A.; Soares-Cunha, Carina; Coimbra, Bárbara; Porta, Leonardo Dalla; Ribeiro, Sidarta Tollendal Gomes; Rodrigues, Ana João; Sousa, Nuno; Carelli, Pedro V.; Copelli, MauroSince the first measurements of neuronal avalanches, the critical brain hypothesis has gained traction. However, if the brain is critical, what is the phase transition? For several decades, it has been known that the cerebral cortex operates in a diversity of regimes, ranging from highly synchronous states (with higher spiking variability) to desynchronized states (with lower spiking variability). Here, using both new and publicly available data, we test independent signatures of criticality and show that a phase transition occurs in an intermediate value of spiking variability, in both anesthetized and freely moving animals. The critical exponents point to a universality class different from mean-field directed percolation. Importantly, as the cortex hovers around this critical point, the avalanche exponents follow a linear relation that encompasses previous experimental results from different setups and is reproduced by a model.