Neuroscience letters
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Neuroscience letters · Aug 2016
Regional homogeneity changes in amnestic mild cognitive impairment patients.
Regional Homogeneity (ReHo) measures the local coherence of spontaneous brain activity, and it is sensitive to detect aberrant local functional connectivity of brain region. We tried to explore the activity of brain network by ReHo method in amnestic mild cognitive impairment (aMCI) patients and examine the impact of regional brain atrophy on the functional results. ⋯ Our study indicated that aMCI patients showed significant abnormal local coherence of biological activity in resting state and ReHo could serve as a sensitive biomarker in functional imaging studies of aMCI.
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Neuroscience letters · Aug 2016
Effects of the swimming exercise on the consolidation and persistence of auditory and contextual fear memory.
Exposure to negative environmental events triggers defensive behavior and leads to the formation of aversive associative memory. Cellular and molecular changes in the central nervous system underlie this memory formation, as well as the associated behavioral changes. In general, memory process is established in distinct phases such as acquisition, consolidation, evocation, persistence, and extinction of the acquired information. ⋯ In addition, rats submitted to swimming exercise over six weeks showed an improved performance in the test of auditory-cued fear memory persistence, but not in the test of contextual fear memory persistence. Moreover, no significant effect from swimming exercise was observed on consolidation of both contextual and auditory fear memory. So, our study, revealing the effect of the swimming exercise on different stages of implicit memory of tone/foot shock conditioning, contributes to and complements the current knowledge about the environmental modulation of memory process.
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Neuroscience letters · Aug 2016
L-DOPA treatment in MPTP-mouse model of Parkinson's disease potentiates homocysteine accumulation in substantia nigra.
One of the intermediates of methionine cycle, the homocysteine (Hcy), elevates in plasma of Parkinson's disease (PD) patients undergoing L-DOPA (3,4-dihydroxyphenylalanine) therapy and has been regarded as a risk factor of the disease. Several evidences pointed out that Hcy causes degeneration of dopaminergic neurons. In rodent, elevated level of Hcy in brain or infusion of the same directly into the substantia nigra (SN) potentiates dopaminergic neurodegeneration. ⋯ Interestingly, L-DOPA treatment significantly elevates Hcy level in nigra but not in striatum of parkinsonian mice, when compared with L-DOPA naïve group. However, there is no significant decrease in the number of dopaminergic neurons in SN region in the parkinsonian mice given L-DOPA treatment. Thus, the present study demonstrates that L-DOPA treatment potentiates the level of Hcy in the SN without causing aggravated neurodegeneration in parkinsonian mice model.
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Neuroscience letters · Aug 2016
Propofol anesthesia reduces Lempel-Ziv complexity of spontaneous brain activity in rats.
Consciousness is thought to scale with brain complexity, and it may be diminished in anesthesia. Lempel-Ziv complexity (LZC) of field potentials has been shown to be a promising measure of the level of consciousness in anesthetized human subjects, neurological patients, and across the sleep-wake states in rats. Whether this relationship holds for intrinsic networks obtained by functional brain imaging has not been tested. ⋯ Dynamic brain networks were defined at voxel level by sliding window analysis of regional homogeneity (ReHo) of the BOLD signal. From scans performed at low to high propofol dose, the LZC was significantly reduced by 110%. The results suggest that the difference in LZC between conscious sedated and anesthetized unconscious subjects is conserved in rats and this effect is detectable in large-scale brain network obtained from fMRI.
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Neuroscience letters · Aug 2016
The neural mechanism of biomechanical constraints in the hand laterality judgment task: A near-infrared spectroscopy study.
The mental rotation (MR) task is defined as a discrimination task between mirror-reversed images involving discrepancy in angular orientation. Various studies have shown that the MR task likely causes mental imagery, that is, visual and/or motor imagery, depending on stimulus types. When figures of rotated hands are presented to be identified as a left or right hand, reaction times (RTs) usually show an effect of biomechanical constraints (BC): a hand in a position difficult to reach with a real movement results in longer RTs. ⋯ In the HLJ task, both the RTs and the activity of the left superior parietal lobe (SPL) showed an interaction between Hand (left, right) and Orientation (135°, 225°) i.e., the BC effect, but not in the character judgment task. More specifically, in the analysis of BC-related activity of SPL, although the Hand×Orientation interaction was significant, the left SPL for the left hand significantly increased from 135° to 225°, but the reversed increase (from 225° to 135°) was not found for the right hand. These results suggest that left SPL is involved in the BC effect and NIRS differentiates left hand awkwardness of right-hander in the HLJ task.