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futurity_sci_tech 00850.txt

#There s a thermostat that stops neurons from spazzing out Brandeis University rightoriginal Studyposted by Leah Burrows-Brandeis on October 17 2013for the first time scientists have seen evidence in a living animal of a hermostatthat controls with remarkable precision how often neurons fire. Neurons make new pathways and connections as our brain processes new information. In order to do this individual neurons use an internal gauge to maintain a delicate balance that keeps our brains from becoming too excitable. Scientists have theorized long a larger internal system monitors these individual gauges like a neural thermostat regulating average firing rates across the whole brain. Without this thermostat they reasoned our flexible neurons would fire out of control making bad connections or none at all. A demonstrated neural firing-rate set point opens up a whole new approach to thinking about neurological disorders such as epilepsy in which the brain is excited too and autism in which the brain is excited not enough. f we can figure out how these set points are built we may be able to adjust them and bring the brains of people suffering from such disorders back into balancesays Gina Turrigiano a professor at Brandeis University who led the study. Turrigiano and colleagues observed in vivo that neocortical neurons cells that control higher functions such as sight language and spatial reasoning have a set average firing rate and return to this set point even during prolonged periods of sensory deprivation. The average firing rate is regulated so well by this neural thermostat that the rates do not change between periods of sleep and wakefulness. There is a time in early development across mammalian species when the brain does most of its wiring affected largely by the environment in which the animal is being raised. This study demonstrated that during this period neurons are constantly elf-tuningto adjust for changes in environmental inputs says postdoctoral fellow Keith Hengen the paper s first author. f something is disturbed during that critical period of early childhood development functioning neurons can self-adjust and return to their set-point average firing ratehengen says. In this study published in the journal Neuron researchers studied young rats that temporarily lost vision in one eye. In the first 48 hours the neuronal firing rates dropped significantly from lack of external stimuli. But within the next 48 hours those neurons rebounded back to their set-point rateâ##like a cold house heating up. Soon the neocortical neural firing rates were the same in both hemispheres one with visual data and one without. They studied the animals awake and asleepâ##and found that although the pattern of neural firing changed the rate of firing stayed exactly the same. This homeostatic mechanism keeps neurons on an even keel even as they change in response to learning development and environmental factors. he homeostatic rule can control average activity across periods of sleep and wakefulnesshengen says. he other rules in the brain have to play out in the context of this tightly regulated system of locked-in average firing rates. ource: Brandeis Universityyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license n

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