1,721,084 research outputs found
International Society for Magnetic Resonance in Medicine Workshop on Advances in High Field MR
No full textEnergetics and Activation of the Central Nervous System by In Vivo Nuclear Magnetic Resonance
Full text linkStefano Pascarella, Mario Compiani, Staderin
Activity-dependent energy budget for neocortical signaling: Effect of short-term synaptic plasticity on the energy expended by spiking and synaptic activity
No full textThe available estimate of the energy expended for signaling in rat neocortex is refined to examine the separate contribution of spiking and synaptic activity as a function of average neuronal firing rate. By taking into account a phenomenological model of short-term synaptic plasticity, we show that the transition from low to high cortical activity is accompanied by a substantial increase in relative energy consumed by action potentials vs. synaptic potentials. This consideration might be important for a deeper understanding of how information is represented in the cortex and which metabolic pathways are upregulated to sustain cortical activity. (c) 2012 Wiley Periodicals, Inc
Metabolic Pathways and Activity-Dependent Modulation of Glutamate Concentration in the Human Brain
No full textGlutamate is one of the most versatile molecules present in the human brain, involved in protein synthesis, energy production, ammonia detoxification, and transport of reducing equivalents. Aside from these critical metabolic roles, glutamate plays a major part in brain function, being not only the most abundant excitatory neurotransmitter, but also the precursor for gamma-aminobutyric acid, the predominant inhibitory neurotransmitter. Regulation of glutamate levels is pivotal for normal brain function, as abnormal extracellular concentration of glutamate can lead to impaired neurotransmission, neurodegeneration and even neuronal death. Understanding how the neuron-astrocyte functional and metabolic interactions modulate glutamate concentration during different activation status and under physiological and pathological conditions is a challenging task, and can only be tentatively estimated from current literature. In this paper, we focus on describing the various metabolic pathways which potentially affect glutamate concentration in the brain, and emphasize which ones are likely to produce the variations in glutamate concentration observed during enhanced neuronal activity in human studies
Uncoupled couplings: combined fMRI and ^1H--MRS for the study of the neurovascular and neurometabolic coupling
No full textK+ Homeostasis in the Brain: A New Role for Glycogenolysis
No full textThe results of the study of Xu and colleagues in this issue constitute a critical new piece of information on the functional specialization of astrocytes for K+ homeostasis in the brain. The relationship between astrocytes and potassium has been long recognized in half a century of research. Now this relation appears to have found its metabolic correlate in astrocytic glycogen. Xu et al. showed that glycogen is committed to fuel astrocytic K+ uptake, as this process is abolished when glycogenolysis is inhibited even in the presence of glucose. They went further by showing that the cellular mechanisms which selectively mobilize glycogen involve the participation of several intracellular signaling cascades. As with all good science, these findings generate a number of fundamental questions that are open for experimental research
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