Scientists sniff out unexpected role for stem cells in the brain

For decades, scientists thought that neurons in the brain were born only during the early development period and could not be replenished. More recently, however, they discovered cells with the ability to divide and turn into new neurons in specific brain regions. The function of these neuroprogenitor cells remains an intense area of research. Scientists at the National Institutes of Health (NIH) report that newly formed brain cells in the mouse olfactory system — the area that processes smells — play a critical role in maintaining proper connections.

New Information about Neurons Could Lead to Advancements in Understanding Brain and Neurological Disorders

Neurons are electrically charged cells in the nervous system that interpret and transmit information using electrical and chemical signals. A neuron’s electrical charge is determined by the flow of ions – charged atoms – in and out of the cell through pores, called ion channels. These pores open, allowing ions to rush in, and then shut. The neuron becomes charged and “sparks” the next neuron in line.

Memory in silent neurons

When we learn, we associate a sensory experience either with other stimuli or with a certain type of behavior. The neurons in the cerebral cortex that transmit the information modify the synaptic connections that they have with the other neurons. According to a generally-accepted model of synaptic plasticity, a neuron that communicates with others of the same kind emits an electrical impulse as well as activating its synapses transiently.

Researchers discover a “switch” in Alzheimer’s and stroke patient brains

A new study by researchers at Sanford-Burnham Medical Research Institute (Sanford-Burnham) has identified a chemical “switch” that controls both the generation of new neurons from neural stem cells and the survival of existing nerve cells in the brain. The switch that shuts off the signals that promote neuron production and survival is in abundance in the brains of Alzheimer’s patients and stroke victims. The studysuggests that chemical switch, MEF2, may be a potential therapeutic target to protect against neuronal loss in a variety of neurodegenerative diseases, such as Alzheimer’s, Parkinson’s and autism.

Noninvasive brain control

Optogenetics, a technology that allows scientists to control brain activity by shining light on neurons, relies on light-sensitive proteins that can suppress or stimulate electrical signals within cells. This technique requires a light source to be implanted in the brain, where it can reach the cells to be controlled. MIT engineers have now developed the first light-sensitive molecule that enables neurons to be silenced noninvasively, using a light source outside the skull. This makes it possible to do long-term studies without an implanted light source. The protein, known as Jaws, also allows a larger volume of tissue to be influenced at once. This noninvasive approach could pave the way to using optogenetics in human patients to treat epilepsy and other neurological disorders, the researchers say, although much more testing and development is needed.

The Brain’s Balancing Act

“Our study shows that the inhibitory neurons are the master regulators that contact hundreds or thousands of cells and make sure that the inhibitory synapses at each of these contacts is matched to the different amounts of excitation that these cells are receiving,” Scanziani explained. If, for example, the level of excitatory stimulation that a nerve cell is receiving is doubled, the inhibitory synapses over a period of a few days will also double their strength. In terms of clinical applications, the scientists said that neurological diseases such as autism, epilepsy and schizophrenia are believed to be a problem, at least in part, of the brain’s ability to maintain an optimal E/I ratio.

UT Southwestern to collect brain tissue for autism research

The medical school is one of four sites nationwide that will collect, store and distribute brain tissue to scientists studying the disease, which affects an estimated one in 68 children. UT Southwestern is an inaugural member of Autism BrainNet, an initiative created last year by The Simons Foundation, Autism Speaks and the Autism Science Foundation. The group also created an outreach program and tissue donation registration site called It Takes Brains. UT Southwestern will collect autistic and normal brain tissue samples in the South Central and Midwest regions of the U.S. to be distributed to researchers around the world.

International study yields important clues to the genetics of epilepsy

An international team of researchers has discovered a significant genetic component of Idiopathic Generalized Epilepsy (IGE), the most common form of epilepsy. Epilepsy is a neurological disorder characterized by sudden, uncontrolled electrical discharges in the brain expressed as a seizure. The new research implicates a mutation in the gene for a protein, known as cotransporter KCC2. KCC2 maintains the correct levels of chloride ions in neurons, playing a major part in regulating excitation and inhibition of neurons. The results indicate that a genetic mutation of KCC2 might be a risk factor for developing IGE.

Following direction -- How neurons can tell top from bottom and front from back

An unexpected finding is that each pathway is redundant in both in A/P and D/V guidance, and in diverse processes that are involved in viability. “This redundancy tends to mask the roles of netrin and Wnt signaling in various biological processes,” says Dr. Levy-Strumpf. “Now that we have identified the redundancy we can get a better insight into the concerted contribution of these two key signalling pathways in normal development as well as in tumor progression and metastasis.” ‘By means of a comprehensive genetic analysis, we found that simultaneous loss of Wnt and netrin signaling components reveals previously unknown and unexpected redundant roles for Wnt and netrin signaling pathways in both D/V and A/P guidance of migrating cells and axons in C. elegans, as well as in processes essential for organ function and viability. Thus, in addition to providing polarity information for migration along the axis of their gradation, Wnts and netrin are each able to guide migrationsorthogonal to the axis of their gradation.’

Sleep After Learning Strengthens Connections Between Brain Cells and Enhances Memory, NYU Langone Scientists Find

Researchers at NYU Langone Medical Center show for the first time that sleep after learning encourages the growth of dendritic spines, the tiny protrusions from brain cells that connect to other brain cells and facilitate the passage of information across synapses, the junctions at which brain cells meet. Moreover, the activity of brain cells during deep sleep, or slow-wave sleep, after learning is critical for such growth.