II Semana do Cérebro

Entre os dias de 13 a 16 do mês de março do corrente ano, será realizada a ll Semana do cérebro, “Semeando conhecimento – Natal 2013”, uma iniciativa dos discentes e docentes do Instituto do Instituto do Cérebro da Universidade Federal do Rio Grande do Norte (ICe-UFRN) em parceria com a Sociedade Brasileira de Neurociências e Comportamento (SBNeC), Universidade Potiguar (UnP) e o Centro Universitário Mauricio de Nassau (UniNassau).
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NMDA receptor blockade impairs the muscarinic conversion of sub-threshold transient depression into long-lasting LTD in the hippocampus-prefrontal cortex pathway in vivo.

Synaptic plasticity in the hippocampal inputs (CA1) to the prefrontal cortex (mPFC) is thought to play an important role organizing cognitive, emotional and executive behaviors. In particular, cholinergic fibers from the brainstem and basal forebrain innervate the mPFC and exert a modulatory drive on synaptic responses and neuronal activity during different behavioral states, which can be affected in some pathological conditions. Here, we investigated how the muscarinic and glutamatergic (NMDA) neurotransmission affected synaptic plasticity in the mPFC and the communication between the hippocampus and the mPFC in vivo.
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OLM interneurons differentially modulate CA3 and entorhinal inputs to hippocampal CA1 neurons

The vast diversity of GABAergic interneurons is believed to endow hippocampal microcircuits with the required flexibility for memory encoding and retrieval. However, dissection of the functional roles of defined interneuron types has been hampered by the lack of cell-specific tools. We identified a precise molecular marker for a population of hippocampal GABAergic interneurons known as oriens lacunosum-moleculare (OLM) cells. By combining transgenic mice and optogenetic tools, we found that OLM cells are important for gating the information flow in CA1, facilitating the transmission of intrahippocampal information (from CA3) while reducing the influence of extrahippocampal inputs (from the entorhinal cortex). Furthermore, we found that OLM cells were interconnected by gap junctions, received direct cholinergic inputs from subcortical afferents and accounted for the effect of nicotine on synaptic plasticity of the Schaffer collateral pathway. Our results suggest that acetylcholine acting through OLM cells can control the mnemonic processes executed by the hippocampus.
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Speech Graphs Provide a Quantitative Measure of Thought Disorder in Psychosis

Psychosis has various causes, including mania and schizophrenia. Since the differential diagnosis of psychosis is exclusively based on subjective assessments of oral interviews with patients, an objective quantification of the speech disturbances that characterize mania and schizophrenia is in order. In principle, such quantification could be achieved by the analysis of speech graphs. A graph represents a network with nodes connected by edges; in speech graphs, nodes correspond to words and edges correspond to semantic and grammatical relationships.
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Gamma responses correlate with temporal expectation in monkey primary visual cortex

Attending to an event in time leads to gamma increase and alpha suppression in V1. Anticipatory effects on gamma and alpha are global in V1.
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Multiple phase-amplitude couplings in the hippocampus

The phase of the hippocampal theta rhythm modulates the amplitude of multiple layer-specific oscillations in CA1.
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Adult neural stem cells (NSCs) give rise to neurons of distinct subtype specificity

This work describes an adherent culture preparation, which allows for continuous single-cell tracking of NSC behavior. Time-lapse video microscopy followed by post-imaging immunocytochemistry is used to identify progeny and study NSC's mode of cell division and lineage progression.
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Forming what-where associations

Tort and colleagues describe a mechanism underlying the emergence of hippocampal firing patterns that represent the conjunction of an item (what) and its location (where).
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Cross-modal responses in the primary visual cortex encode complex objects and correlate with tactile discrimination

The primary visual cortex can engage in meaningful tactile processing depending on task demand.
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Attractor networks and memory formation and erasure

A unified computational model based on attractor dynamics that accounts for the processes of memory reconsolidation and extinction
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Revisiting Hebb's postulates

A new analysis framework to address the cell assembly hypothesis at the systems level.
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Motion representation in V1 is mediated by transcortical feedback

Global features of the visual scenery are fed back to lower visual processing units to facilitate the integration of local cues into a global construct.
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Stem cells to neurons: Independent of local niche

Adult neural stem cells (NSCs) could be used to treat nervous system disorders, but does their specification require a local niche? Using adult mouse NSCs, Costa and colleagues show that progression from stem cell to neuron is cell-intrinsic and independent of the local niche.
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Universal dynamics of spike avalanches across sleep-wake cycle

A unique scale-invariant regime of spike avalanches across all major behaviors.
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Neocortex and vocal production in marmosets

Our data provide direct evidence that the ventrolateral prefrontal cortex, a key region for speech control in humans, is also activated during vocal production in a non-human New World primate.
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Detecting brain waves communication

Tort et al present a powerful framework for quantifying the level of coupling among simultaneous brain oscillations, which will help elucidating the importance of brain waves communication in cognitive processes.
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