Neuroscience
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The association between a fit body and a fit brain in children has led to a rise of behavioral and neuroscientific research. Yet, the relation of cardiorespiratory fitness on premotor neurocognitive preparation with early visual processing has received little attention. Here, 41 healthy, lower and higher fit preadolescent children were administered a modified version of the Eriksen flanker task while electroencephalography (EEG) and behavioral measures were recorded. ⋯ Fitness-related differences selectively emerged at prefrontal brain regions during response preparation, with larger pN amplitude for higher than lower fit children, and at early perceptual stages after stimulus onset, with larger P1 and N1 amplitudes in higher relative to lower fit children. Collectively, the results suggest that the benefits of being aerobically fit appear at the stage of cognitive preparation prior to stimulus presentation and the behavioral response during the performance of a task that challenges cognitive control. Further, it is likely that enhanced activity in prefrontal brain areas may improve cognitive control of visuo-motor tasks, allowing for stronger proactive inhibition and larger early allocation of selective attention resources on relevant external stimuli.
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This study used the framework of the referent configuration hypothesis and slow changes in the external conditions during vertical oscillation of a hand-held object to infer the characteristics of hypothetical control variables. The study had two main objectives: (1) to show that hypothetical control variables, namely, referent coordinates and apparent stiffness of vertical hand position and grip force can be measured in an experiment; and (2) to establish relation(s) between these control variables that yield the classic grip-force-load-force coupling. Healthy subjects gripped a handle and performed vertical oscillations between visual targets at one of five metronome-prescribed frequencies. ⋯ To validate the method, these values were used to predict the vertical force and the grip force applied to the handle for movement cycles that were not utilized in the reconstruction process. Analysis of the coupling between the four variables, two referent coordinates and two apparent stiffness values, revealed a single strong constraint reflecting the coupling between the grip force and vertical force. We view these data as providing experimental support for the idea of controlling natural, multi-muscle actions with shifts in a low-dimensional set of referent coordinates.
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The role of the cerebral cortex in maintaining human standing balance remains unclear. Beta corticomuscular coherence (CMC) provides a measure of communication between the sensory-motor cortex and muscle, but past literature has not demonstrated significant beta CMC during human stance. This study evaluated the effects of stance width, vision, and surface compliance on beta CMC during human stance using methods to enhance sensitivity to CMC. ⋯ No significant differences were detected when comparing eyes-open to eyes-closed conditions or when comparing firm- to foam-surface conditions. Correlations between CMC magnitude and COP sway elicited some significant relationships, but there was no consistent direction or pattern of correlation based on muscle or stance condition. Results demonstrate that significant beta CMC is evident during human standing balance, and that beta CMC is responsive to changes in mechanical, but not visual or surface, conditions.
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GABA (γ-amino-butyric acid) -mediated signaling is normally associated with synaptic inhibition due to ionotropic GABA receptors that gate an inward Cl(-) current, hyperpolarizing the membrane potential. However, there are also situations where ionotropic GABA receptors trigger a Cl(-) efflux that results in depolarization. The well-characterized central nervous system of the medicinal leech was used to study the functional significance of opposing effects of GABA at the synaptic circuit level. ⋯ BUM treatment depressed N cell synapses, again similar to what is observed following BIC treatment and suggests that GABA has an excitatory effect on these synapses. The opposing effects of GABA could also be observed at the behavioral level with BIC and VU increasing responsiveness to non-nociceptive stimulation while BIC and BUM decreased responsiveness to nociceptive stimulation. These findings demonstrate that distinct synaptic inputs within a shared neural circuit can be differentially modulated by GABA in a functionally relevant manner.
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Growing numbers of evidence indicate that cognitive impairments are part of clinical profile of childhood absence epilepsy. Little is known on neuropathological changes accompanied by cognitive deficits in absence epilepsy. The aim of the present study was to investigate age-dependent neuropathological changes accompanied by learning and memory impairments in Wistar Albino Glaxo from Rijswijk (WAG/Rij) rat model of absence epilepsy. ⋯ In addition, a higher number of apoptotic cells as well as a higher expression of caspase-3 was observed in the hippocampal CA1 and CA3 regions, the laterodorsal thalamic nucleus, and the somatosensory cortex of 6-month-old WAG/Rij rats compared to other animal groups. These results indicate significant enhancement of neuronal damage and cell death accompanied by memory deficits after seizure attacks in a rat model of absence epilepsy. Seizure-induced neuronal injury and death may underlie cognitive impairments in absence epilepsy.