Neuroscience
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Case Reports
Damage to the Intraparietal Sulcus Impairs Magnitude Representations of Results of Complex Arithmetic Problems.
Past research investigating the role of the intraparietal sulcus (IPS) in numerical processes focused mainly on quantity and numerical comparisons as well on single digit arithmetic. The present study investigates the involvement of the IPS in estimating the results of multi-digit multiplication problems. For this purpose, the performance a 24-year-old female (JD) with brain damage in the left IPS was compared to an age-matched control group in the computation estimation task. ⋯ Most control participants used both the approximated calculation strategy that involves rounding and calculation procedures and the sense of magnitude strategy that relies on an intuitive approximated magnitude representation of the results. In contrast, JD used only the former but not the latter strategy. Together, these findings suggest that the damage to the IPS impaired JD's representations of magnitude that play an important role in this computation estimation task.
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Mutations in γ-aminobutyric acid A receptor (GABAA) subunits and sodium channel genes, especially GABRG2 and SCN1A, have been reported to be associated with febrile seizures (FS) and genetic epilepsy with febrile seizures plus (GEFS+). GEFS+ is a well-known family of epileptic syndrome with autosomal dominant inheritance in children. Its most common phenotypes are febrile seizures often with accessory afebrile generalized tonic-clonic seizures, febrile seizures plus (FS+), severe epileptic encephalopathy, as well as other types of generalized or localization-related seizures. ⋯ In summary, mutations in the GABAA receptor can lead to a decrease in numbers of receptors, which may cause the impairment of GABAergic pathway signaling. This data has been the first time to reveal that GABRG2 mutations would affect the function of other genes, and based on this finding we hope this work would also provide a new direction for the research of GABRG2 in GEFS+. It also may provide a molecular basis for the severity of epilepsy, and guide the clinical medication for the treatment of the epilepsy focused on the function on GABAA receptors, which, might be a new strategy for genetic diagnosis and targeted treatment of epilepsy.
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Accumulation of amyloid-β (Aβ) in brain tissue contributes to the pathophysiology of Alzheimer's disease (AD). We recently reported that intrahippocampal transplantation of mouse bone marrow-derived microglia-like (BMDML) cells suppresses brain amyloid pathology and cognitive impairment in a mouse model of AD. How these transplanted cells interact with resident microglia remains unknown. ⋯ Brain TGF-β1 levels and resident microglial TGF-β1R expression were increased by intrahippocampal injection of BMDML cells in a mouse model of AD. Cotreatment with the TGF-βR1 inhibitor suppressed the ability of transplanted BMDML cells to increase microglial TGF-β1R expression and decrease hippocampal Aβ levels. Taken together, these findings suggested that transplanted BMDML cells secreted TGF-β1 to stimulate Aβ phagocytosis by resident microglia and decrease brain Aβ pathology.
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Human visual function degrades with age. Previous studies of visual perception have shown that aged people have worse performance in the coding of orientation information. However, the neuronal mechanism still remains elusive. ⋯ Further investigation of neuronal correlation showed higher noise and signal correlations in aging monkeys than that in young monkeys. These correlation changes predicted a detrimental effect on the efficiency of population coding of orientation information. Taken together, our results suggest that the information coding efficiency of orientation information is impaired during aging and might account for the degradation of performance in human fine orientation discrimination task.
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Fear of falling can have a profound influence on anticipatory postural control during dynamic balance tasks (e.g., rise-to-toes and leg-raise tasks), with fearful individuals typically exhibiting postural adjustments of smaller magnitudes prior to movement onset. However, very little is known about how fear of falling influences the generation of anticipatory postural adjustments (APAs) during gait initiation; a task in which producing smaller APAs may compromise stability. Sixteen young adults initiated gait as fast as possible following an auditory cue during two conditions: Baseline (ground level), and Threat (fear of falling induced via a platform raised 1.1 m). ⋯ We suggest that such failure to scale the APA to the magnitude of the motor output represents a fear-related 'overcompensation', whereby fearful participants sought to ensure that the APA was sufficient for ensuring that their centre of mass was positioned above the support leg prior to gait initiation. During conditions of threat, participants also exhibited greater postural sway prior to initiating gait (i.e., following the auditory cue) and took longer to generate the APA (i.e., impaired reaction). As greater reaction times during voluntary stepping is consistently associated with increased fall-risk, we suggest this as one mechanism through which fear of falling may reduce balance safety.