Neuroscience
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Evidence of abnormal functional connectivity (FC) has been implicated in patients with somatization disorder (SD). Although the importance of damage to the functional asymmetry has been established, it remains unclear as to whether abnormal intra- and inter-hemispheric FCs are related to patients with SD. We applied resting-state functional magnetic resonance imaging to first-episode, medication-naive patients with SD (n = 25) and matched healthy controls (HCs) (n = 28). ⋯ Moreover, the increased PAS values in the right insula could distinguish patients with SD from HCs with acceptable accuracy (77.36%). First-episode, treatment-naive patients with SD show disrupted asymmetry of inter- and intra-hemispheric FCs. The pattern of disrupted functional asymmetry occurs early in the course of the disease and is independent of medication status, which suggests that disrupted functional asymmetry of salience and auditory networks may be applied as early biological markers for SD.
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The ability to sense occasionally occurring sounds in an environment is critical for animals. To understand this ability, we studied responses to acoustic oddball paradigms in the rat's midbrain auditory neurons. An oddball paradigm is a random sequence of stimuli created using two tone bursts, with one presented at a high probability (standard stimulus) and the other at a low probability (oddball stimulus). ⋯ The increase was particularly large in neurons that displayed transient firing under contralateral stimulation but no firing under ipsilateral stimulation. These neurons likely play a particularly important role in using spatial cues to detect occasionally occurring sounds. Results suggest that effects of spatial separation between two sounds of an oddball paradigm on responses to the sounds were dependent on changes in the level of adaptation and binaural inhibition.
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In the visual decoding domain, the most difficult task is the visual reconstruction aimed at reconstructing the presented visual stimuli given the corresponding human brain activity monitored by functional magnetic resonance imaging (fMRI), especially when reconstructing viewed natural images. Recent research regarded the visual reconstruction as the conditional image generation on fMRI voxels and started to use the generative adversarial networks (GANs) to design computational models for this task. Despite the great improvement in previous GAN-based methods, the fidelity and naturalness of the reconstructed images are still unsatisfactory, the reasons include the small number of fMRI data samples and the instability of GAN training. ⋯ Composed of neural networks, GAN-BVRM is fully differentiable and can directly generate the reconstructed images by iteratively updating the noise input vector through backpropagation to fit the fMRI voxels. In this process, the decoded categories and encoding models are responsible for the semantic and detailed contents of the reconstructed images, respectively. Experimental results revealed that GAN-BVRM improved the fidelity and naturalness, which validated the advantage of the combining of GANs and Bayesian manner for visual reconstruction.
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Histaminergic neurons of the tuberomammillary nucleus (TMN) are important regulators of behavioral and homeostatic processes. Previous work suggested that histaminergic neurons exhibit a characteristic electrophysiological signature, allowing for their identification in brain slice preparations. However, these previous investigations focused on neurons in the ventral subregion of the TMN of rats. ⋯ Moreover, we found no obvious sex differences in the electrical excitability of HDC neurons. However, our data reveal a diversity in the electrophysiological properties of genetically identified histaminergic neurons from mice not previously appreciated from rat studies. Thus, these data highlight the utility of mouse genetics to target the widespread histaminergic neuronal population within the TMN and support the idea that histaminergic neurons are a heterogeneous neuronal population.
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Neurons in the lateral habenula (LHb) are activated by reward omission and inhibited by reward delivery-reward processing functions opposite those of midbrain dopaminergic neurons. To further explore this, we examined the role of the LHb in associating a conditioned stimulus (CS) with the absence of an unconditioned stimulus (US) in an appetitive Pavlovian-conditioning paradigm. Rats underwent training in which a CS (light) was either paired (100% CS-US contingency) or unpaired (0% CS-US contiguity and negative contingency) with an US (food). ⋯ The number of c-Fos-positive signals in LHb neurons projecting to dopaminergic midbrain neurons was higher in the unpaired group than in the paired group. Excitotoxic LHb lesions did not affect the acquisition of conditioned behaviors in the association of a CS with the presence or absence of an US. Significant increases in the numbers of c-Fos-positive neurons in the unpaired group suggest that LHb neurons engage in the process that associates a CS with the absence of an US.