Neuroscience
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Parkinson's disease is one of the most prevalent neurodegenerative motor disorders worldwide with postural instability, bradykinesia, resting tremor and rigidity being the most common symptoms of the disease. Despite the fact that the molecular mechanisms of Parkinson's disease pathogenesis have already been well described, there is still no coherent picture of the etiopathogenesis of this disease. According to modern concepts, neurodegeneration is induced mainly by oxidative stress, neuroinflammation, dysregulation of cerebral proteostasis, apoptotic dysregulation, and impaired autophagy. ⋯ The review also discusses the role of calpains in the development of Parkinson's disease. It is known that α-synuclein is a substrate of calcium-dependent proteases of the calpain family. Truncated forms of α-synuclein are not only involved in the process of formation of the aggregates, but also increase their toxicity.
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Chronic insomnia (CI) is a common sleep disorder in middle-aged and elderly individuals. Long-term sleep deprivation can lead to physical, mental, and cognitive damage. Resting-state networks (RSNs) in the brain are closely linked to cognition and behavior. ⋯ Moreover, FC values in the right middle frontal gyrus within right frontal parietal network of CI-I patients were negatively correlated with the Mini-Mental State Examination scores. These results may explain hyperarousal, attention deficit and motor impairments in CI patients. Furthermore, the aberrant alterations of RSNs in CI-I patients may play a crucial role in the onset and progression of cognitive impairment in CI patients.
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Controversy persists regarding the representation of linguistically negated actions, specifically concerning activation and inhibitory mechanisms in the motor system, and whether negated action sentences evoke an initial motor simulation of the action to be negated. We conducted two experiments probing corticospinal excitability (CSE) and short-interval intracortical inhibition (SICI) in the primary motor cortex at different latencies while reading affirmative and negative action sentences. In experiment one, twenty-six participants read action and non-action sentences in affirmative or negative forms. ⋯ Negated action sentences showed the same motor excitability as affirmed action sentences with no additional inhibition at early latencies. These results lend support for the idea that actions to be negated are initially simulated within the motor system. Neural differences between affirmative and negative action sentences may occur outside the primary motor cortex.
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Empathy deficiencies are prevalent among deaf individuals. It has yet to be determined whether they exhibit deficiencies in both trait empathy and state empathy, along with the effect of top-down attention. ⋯ For state empathy, we found that deaf individuals showed stronger automatic emotional empathy responses and paid more cognitive evaluation resources. Moreover, the differential processing of empathy between deaf individuals and hearing individuals towards others' pain could be regulated by top-down attention, which occurs both in the early and late processing stages of pain empathy.
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This study assessed the neural mechanisms and relative saliency of categorization for speech sounds and comparable graphemes (i.e., visual letters) of the same phonetic label. Given that linguistic experience shapes categorical processing, and letter-speech sound matching plays a crucial role during early reading acquisition, we hypothesized sound phoneme and visual grapheme tokens representing the same linguistic identity might recruit common neural substrates, despite originating from different sensory modalities. Behavioral and neuroelectric brain responses (ERPs) were acquired as participants categorized stimuli from sound (phoneme) and homologous letter (grapheme) continua each spanning a /da/-/ga/ gradient. ⋯ Auditory and visual categorization also recruited common visual association areas in extrastriate cortex but in opposite hemispheres (auditory = left; visual = right). Our findings reveal both auditory and visual sensory cortex supports categorical organization for phonetic labels within their respective modalities. However, a partial overlap in phoneme and grapheme processing among occipital brain areas implies the presence of an isomorphic, domain-general mapping for phonetic categories in dorsal visual system.