Neuroscience
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Comparative Study
Masking Differentially Affects Envelope-following Responses in Young and Aged Animals.
Age-related hearing decline typically includes threshold shifts as well as reduced wave I auditory brainstem response (ABR) amplitudes due to cochlear synaptopathy/neuropathy, which may compromise precise coding of suprathreshold speech envelopes. This is supported by findings with older listeners, who have difficulties in envelope and speech processing, especially in noise. However, separating the effects of threshold elevation, synaptopathy, and degradation by noise on physiological representations may be difficult. ⋯ High-pass noise may affect EFR amplitudes in young animals more than aged by reducing the contributions of high-frequency-sensitive inputs. EFRs to SAM tones in modulated noise (NAM) suggest that neurons of young animals can synchronize to NAM at lower sound levels and maintain dual AM representations better than older animals. The overall results show that EFR amplitudes are strongly influenced by aging and the presence of a competing sound that likely reduces or shifts the pool of responsive neurons.
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In this study, fused electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) techniques were utilized to examine the relationship between the ERP (event-related potential) component P300 and fNIRS hemodynamic signals for high-accuracy deception detection. During the performance of a modified concealed information test (CIT) task, a series of Chinese names were presented, which served as the target, irrelevant, or the probe stimuli for both the guilty and innocent groups. For participants in the guilty group, the probe stimulus was their individual name, whereas for the innocent group, the probe stimulus was one irrelevant name. ⋯ Interestingly, we discovered that for the guilty group, the probe stimulus elicited significantly higher P300 amplitude at parietal site and also evoked significantly stronger oxyhemoglobin (HbO) concentration changes in the bilateral superior frontal gyrus and bilateral middle frontal gyrus than the irrelevant stimuli. However, this is not the case for the innocent group, in which participants exhibited no significant differences in both ERP and fNIRS measures between the probe and irrelevant stimuli. More importantly, our findings also demonstrated that the combined ERP and fNIRS feature was able to differentiate the guilty and innocent groups with enhanced sensitivity, in which AUC (the area under Receiver Operating Characteristic curve) is 0.94 for deception detection based on the combined indicator, much higher than that based on the ERP component P300 only (0.85) or HbO measure only (0.84).
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Somatosensory inputs affect primary motor cortex (M1) excitability; however, the effect of movement-induced somatosensory inputs on M1 excitability is unknown. This study examined whether M1 excitability is modulated by somatosensory inputs with passive movement in 29 healthy subjects. Motor-evoked potentials (MEPs), elicited by transcranial magnetic stimulation (TMS) were recorded from the first dorsal interosseous (FDI) muscle (Experiment 1). ⋯ Passive movement was performed at two movement velocities (Experiment 3) or joint angles (Experiment 4). MEP facilitation was observed depending on the movement velocities or joint angles. These experiments demonstrated that somatosensory inputs induced by passive movements facilitated M1 excitability depending on the ISIs, passive movement velocity, and joint angle.
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Unlike the behavioral effects planarians display when exposed to cocaine, amphetamines, cathinones, ethanol and sucrose, effects of opioid receptor agonists, especially mu opioid receptor agonists, are poorly defined in these flatworms. Here, we tested the hypothesis that planarians exposed to a selective mu opioid receptor agonist, DAMGO (0.1, 1, 10 µM), would display a triad of opioid-like effects (place conditioning, abstinence-induced withdrawal, and motility changes). DAMGO was selected versus morphine because of its greater mu opioid receptor selectivity. ⋯ Acute DAMGO exposure (1 µM) produced hypermotility that was antagonized by naltrexone (1, 10, 100 µM). In contrast, acute exposure to the kappa opioid receptor agonist U50,488H (0.1, 1, 10 µM) resulted in decreased motility. Our results show that a mu opioid agonist produces mammalian-like behavioral responses in planarians that may be related to addiction and suggest opioid-like behavioral effects are conserved in invertebrates.
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Human spatial manipulation ability is sensitive to high-altitude (HA) environment. The present study aimed to investigate the electrophysiological basis of spatial manipulation ability on adult immigrants with long-term HA exposure using the mental rotation (MR) task and the ERP approach. Toward this end, we explored the MR effect in individuals who immigrated to HA areas for three years compared with individuals who lived in low altitude areas. ⋯ The ERP component analysis further indicated that the rotation-related negativity (RRN) amplitude was highly corresponding to the MR effect in each group, the RRN amplitude was significantly larger in the HA group than the low-altitude group related to each rotation angle condition. The brain topographical map further showed that only the right hemisphere regions instead of the bilateral hemisphere regions involved into the MR effect in the HA group, which was different to the low-altitude group. Together, these findings might collectively suggest that the mental resource was insufficient as a result of HA exposure which can be reflected on the RRN amplitude, which may help understanding the neural basis of spatial ability change from the long-term HA exposure.