Embryonic cells transplanted Create new period of brain "plasticity" Keep Alive
UCSF scientists report they were able to bring a new period of "plasticity" or ability to change in the neural circuitry of the visual cortex of young rats. The approach, they say, could someday be used to create new periods of plasticity in the human brain that allows the repair of neural circuitry after injury or illness.
The strategy - which involved transplanting a specific type of immature neurons from embryonic mice in the visual cortex of young mice - Could be used to treat the altered neural circuitry in abnormal fetal development or postnatal, stroke, traumatic brain injury, psychiatric illness and aging.
Like all regions of the brain, the visual cortex goes through a very plastic during early childhood. The cells respond strongly to visual signals, which relay a quick, directed from one cell for the next in a process known as synaptic transmission. Produced chemical connections en este proceso de producción de circuitos neuronales que es crucial para la función del sistema visual. En los ratones, este período crítico de plasticidad se produce hacia el final de la cuarta semana de vida.
El catalizador de la plasticidad denominado período crítico en la corteza visual es el desarrollo de la señalización sináptica de las neuronas que liberan el neurotransmisor GABA inhibitorio. Estas neuronas reciben señales de otras neuronas excitadoras, contribuyendo así a mantener el equilibrio de la excitación y la inhibición en el sistema visual.
In their study, published in the journal Science, (Vol. 327. No. 5969, 2010), the scientists wanted to determine whether embryonic neurons, once they had become GABA-inhibitory neurons production, may induce plasticity in mice after the normal critical period had closed. The first team
dissected immature neurons from their origin in the median eminence embryonic node (MEG) of embryonic mice. Then transplanted MGE cells in the visual cortex of animals at two different stages minors. The stem cells aimed at the visual cortex were scattered throughout the region, matured into neurons GABAergic inhibition, and made widespread synaptic connections with excitatory neurons.
The scientists then conducted a process known as monocular visual deprivation, which blocked the visual cues for an eye in each animal for four days. When this process takes place during the critical period, the cells in the cortex visual rapidly become less sensitive to the private eye of sensory stimulation, and become more sensitive to non-private eye, creating changes in neural circuits. This phenomenon, known as ocular dominance plasticity, greatly decreases as the brain matures beyond this critical period of postnatal development.
The team wanted to see if the transplanted cells will affect the visual system's response to visual deprivation after the critical period. Researchers The effects of stem cell after allowing them to grow for various lengths of time. When cells were as young as 17 days old or as old as 43 days old, which had little impact on neural circuits in the region. However, when they were 33-39 days old, its impact was significant. During that time, the monocular visual deprivation neuronal responses changed away from private eye to the non-private eye, revealing the status of ocular dominance plasticity.
Naturally occurring, or endogenous, inhibitory neurons are also around 33-39 days of age when the normal period critical for plasticity occurs. Therefore, the impact that the transplanted cells "occurred once they had reached the age cell inhibitory neurons during the normal critical period.
The finding, the team says, suggests that the normal critical period of plasticity in the visual cortex is governed by a developmental program intrinsic inhibitory neurons, and inhibitory neurons may retain embryonic precursors and run this program when transplanted into the cortex after birth, so the creation of a new period of plasticity.
"The findings suggest that ultimately it may be possible using transplantation of inhibitory neurons, or some factor that is produced by inhibitory neurons to create a new period of plasticity DURATION n limited to repair damaged brains, "says the author Sunil P. Gandhi, PhD, a postdoctoral fellow in the laboratory of Michael Stryker, PhD, professor of fisiologíay member of the Centro Integral Keck Neuroscience at UCSF. "It will be important to determine if the transplant is equally effective in older animals."
Similarly, "the findings raise a fundamental question: how these cells, as go through a specific stage of development, creating these windows of plasticity? , The author says Derek G. Southwell, PhD, a student in the laboratory of Arturo Alvarez-Buylla, PhD, Heather and Melanie Muss Professor of Neurological Surgery and a member of the Eli and Edythe Broad Center for Health and Regeneration Research stem cell at UCSF.
The results could be relevant to understanding why learn certain behaviors, such as language, easily occurs in young children but not adults, says Alvarez-Buylla. "Grafted MGE cells may someday provide a way to induce cortical plasticity and learning in the future."
The results also complement two other recent studies using cells from MGE UCSF help ; na modify neural circuits. In a collaborative study between the laboratories of Scott Baraban, PhD, professor of neurological surgery, John Rubinstein, MD, PhD, professor of psychiatry, and Alvarez-Buylla, cells were grafted into the neocortex of rodents juvenile, which reduced the intensity and frequency of epileptic seizures. (Proceedings of the National Academy of Sciences, vol. 106, no. 36, 2009). Other teams are exploring this tactic, too.
In the other study (Cell Stem Cell, vol. 6, Number 3, 2010), the UCSF scientists reported the first use of MGES to treat motor symptoms in mice with a condition designed to mimic Parkinson's disease. The finding was reported by the laboratory of Arnold Kriegstein, MD, PhD, UCSF professor of neurologíay director of the Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research at UCSF, in collaboration with Alvarez-Buylla and Bankiewicz Krys, MD, PhD, UCSF professor of neurological surgery.
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