Neuroscience
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The Confidence of a decision could be considered as the internal estimate of decision accuracy. This variable has been studied extensively by different types of recording data such as behavioral, electroencephalography (EEG), eye and electrophysiology data. Although the value of the reported confidence is considered as one of the most important parameters in decision making, the confidence reporting phase might be considered as a restrictive element in investigating the decision process. ⋯ As a matter of fact, our proposed EEG and eye data properties are capable of recognizing more than nine distinct levels of confidence. Among our proposed features, the latency of the pupil maximum diameter through the stimulus presentation was established to be the most associated one to the confidence levels. Through the time-dependent analysis of these features, we recognized the time interval of 500-600 ms after the stimulus onset as an important time in correlating features to the confidence levels.
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Repeatedly pairing a brief train of vagus nerve stimulation (VNS) with an auditory stimulus drives reorganization of primary auditory cortex (A1), and the magnitude of this VNS-dependent plasticity is dependent on the stimulation parameters, including intensity and pulse rate. However, there is currently little data to guide the selection of VNS train durations, an easily adjusted parameter that could influence the effect of VNS-based therapies. Here, we tested the effect of varying the duration of the VNS train on the extent of VNS-dependent cortical plasticity. ⋯ Trains lasting 0.125 or 2.0 s failed to alter A1 responses, indicating that both shorter and longer stimulation durations are less effective at enhancing plasticity. A second set of experiments evaluating the effect of delivering 4 or 64 pulses in a fixed 0.5 s VNS train duration paired with tone presentation reveal that both slower and faster stimulation rates are less effective at enhancing plasticity. We incorporated these results with previous findings describing the effect of stimulation parameters on VNS-dependent plasticity and activation of neuromodulatory networks to generate a model of synaptic activation by VNS.
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Theories of emotion suggest a close relation of interoception and emotion. However, knowledge of underlying neuronal networks is still sparse. Repetitive transcranial magnetic stimulation (rTMS) is one neurostimulation method allowing causal conclusions between functions and brain regions via stimulation or inhibition of underlying brain structures. ⋯ Moreover, cardiac and respiratory IAc were positively associated with P3 amplitudes and negatively related to positive valence ratings. Positive associations of decreases of cardiac/respiratory IAc with decreases of arousal ratings and decreases of P3 amplitudes for negative stimuli after inhibition of the frontotemporal insular network and after inhibition of somatosensory cortices allow the conclusion of a causal relationship between reduced activity in interoceptive network structures and blunted emotional processing of visual stimuli. Our results suggest that both arousal, and valence aspects of emotional processing are disturbed after inhibition of interoceptive network structures, confirming core assumptions of peripheral theories of emotions and models of interoceptive predictive coding.
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Cerebral ischemia induces neuroinflammation and microglial activation, in which activated microglia upregulate their proliferative activity and change their metabolic states. In activated microglia, l-arginine is metabolized competitively by inducible nitric oxide synthase (iNOS) and arginase (Arg), which then synthesize NO or polyamines, respectively. Our previous study demonstrated that Sema4D deficiency inhibits iNOS expression and promotes proliferation of ionized calcium-binding adaptor molecule 1 (Iba1)-positive (Iba1+) microglia in the ischemic cortex, although the underlying mechanisms were unclear. ⋯ In addition, urea and polyamine levels in the ischemic cortex of Sema4D-/- mice were higher than those of WT mice; furthermore, the presence of Sema4D inhibited polyamine production in primary microglia obtained from Sema4D-/- mice. Finally, microglia cultured under polyamine putrescine-supplemented conditions demonstrated increased proliferation rates over non-supplemented controls. These findings indicate that Sema4D regulates microglial proliferation at least in part by regulating the competitive balance of l-arginine metabolism.
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Gap junctions mediate electrical coupling between neurons and modulate their firing activity. In mouse neocortical layer 5, the major types of pyramidal neurons organize into cell type-specific microcolumns that exhibit modular neuronal activity. During cortical development, microcolumn neurons are electrically coupled in a cell type-specific manner at the stage of synaptogenesis, forming a dense network of gap junctions. ⋯ This slow synchronization is mediated by electrical transmission that is an order of magnitude slower than that of gap junction-coupled neurons of other types. Theoretical and structural analyses suggested that apical dendrites are a major site of electrical coupling, providing slow electrical transmission. These results suggest that the gap junction network organizes neuronal activity of developing cortical circuit modules with unique slow dynamics.