Researchers Restore Neuron Branching in Model of Mutant NHE6 Gene

Mice with the  NHE6 gene mutation show less dendritic branching. Using Neurolucida, researchers traced a GFP-labeled neuron reconstructed with confocal z stacks in a wild type mouse (left) and a mouse with a mutant NHE6 gene (right).

Mice with the NHE6 gene mutation show less dendritic branching. Using Neurolucida, researchers traced a GFP-labeled neuron reconstructed with confocal z stacks in a wild type mouse (left) and a mouse with a mutant NHE6 gene (right). Image courtesy of first author Qing Ouyang, PhD, Alpert Medical School, Brown University.

Children with the neurogenetic disorder Christianson Syndrome experience delays in language and learning; they may also have seizures, and display symptoms of autism. Scientists say these disorders are a result of stunted brain cell growth, which occurs because of a mutation in the gene that produces the protein NHE6—a protein also mutant in several forms of autism.

Neurons in human brains with the mutant gene don’t branch as robustly or form connections as well as neurons in normal brains. But researchers at Brown University may have found a way to restore the ability of these cells to grow properly.

In their study, published in the journal Neuron, senior author Dr. Eric Morrow and his team describe a signaling pathway for neuronal growth involving NHE6. Using a mouse model with an NHE6 gene mutation, they found that reduced levels of NHE6 combined with increased acidity in a cell’s endosome, results in a depletion of the receptor protein TrkB, a key player in the growth and branching of axons and dendrites.

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MBF customer Dr. Thomas Südhof wins Nobel Prize

The Nobel Prize in Physiology or Medicine was awarded to Drs. Thomas Südhof, James Rothman, and Randy Schekman for discovering the principles of how molecules are transported within cells and in between cells and how they are delivered to the right place at the right time. Disruptions in this precise system are implicated in numerous neurological and immunological disorders.sudoflab

Dr. Sudhof uncovered how neurotransmitters are released into a synaptic cleft precisely when they need to be. His research explained the molecular machinery that responds to an influx of calcium and signals the release of neurotransmitters.

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Researchers Use Stereo Investigator to Identify Abnormalities in Autistic Brains

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A baby makes eye contact with a passing stranger and his social development begins. Unable to resist the infant’s smile, the stranger smiles back and the baby starts to learn about human emotion through facial expression. But some babies, especially those on the autism spectrum, don’t make eye contact. What compels these tiny humans to avoid the eyes of people around them? Scientists specializing in developmental disabilities say the flocculus, a brain region in the cerebellum integral to eye movement control, may play a role in atypical gaze.

In their study of the postmortem brains of 12 autistic subjects and 10 control subjects, the research team, led by Dr. Jerzy Wegiel of the New York State Institute for Basic Research in Developmental Disabilities, in Staten Island, saw abnormally large flocculi in eight autistic subjects. According to the study, published last month in Brain Research, seven of these subjects exhibited “poor, very poor, or no eye contact” during the course of their lives.

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Neurolucida Helps Scientists Map Rett Syndrome’s Brain Dysfunction in Mouse Model

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At first, all appears normal with the infant’s development. But one day, around her first birthday, she stops making eye contact, her babbling comes to an end, she wrings her hands, and holds her breath. The child will likely survive into adulthood, but with Rett syndrome, she will lead a life with severe disabilities.

The symptoms of this autism-related disorder are complex, and treatments are not available. At the Case Western Reserve University School of Medicine, in Cleveland, Dr. David Katz and his team of neuroscientists are researching the rare genetic disorder, which affects one in 10,000 mostly female children. Their recent study, published in the Journal of Neuroscience, describes a map of brain dysfunction in a mouse model of Rett syndrome, as well as a promising treatment with the drug ketamine.

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Science News: Our Weekly Picks From Around the Web

Munich Scientists Reprogram Brain Cells Called Pericytes into Neurons
Brain cells called pericytes can be reprogrammed into neurons with just two proteins, pointing to a novel way to treat neurodegenerative disorders.
www.the-scientist.com (10/04/2012)

Neuroscientists Unravel Vegetative State Mystery
By exploring parts of the brain that trigger during periods of daydreaming, neuroscientists from Western University have made a significant breakthrough in understanding what happens in the brain to cause vegetative state.
communications.uwo.ca (10/14/2012)

Ketamine Can Help Improve Brain Function in Rett Syndrome Mice
A study in the Journal of Neurosciences showed that in a mouse model of Rett syndrome, researchers were able to reverse abnormalities in brain activity and improve neurological function by treating the animals with an FDA-approved anesthesia drug, ketamine.
www.news-medical.net (10/04/2012)
Abstract: www.jneurosci.org

New public brain-scan database opens autism research frontiers
Scientists have a valuable new tool for studying autism: a public database of more than 1,000 brain scans.
scopeblog.stanford.edu (09/28/2012)

Leftover DNA From Sons May Alter Their Mothers’ Brains, Study Says
The Fred Hutchinson Cancer Research Center study also found that women with more male DNA in their brains were less likely to have suffered from Alzheimer’s disease.
www.seattletimes.com (09/27/2012)

McGovern Neuroscientist Constantine-Paton Wins Lifetime Achievement Award
Over the past 30 years, Constantine-Paton has established a reputation as a leading figure in the field of developmental neuroscience. She will be recognized for her achievements during SfN’s annual meeting this month.
web.mit.edu (09/28/2012)

Kamila and Henry Markram say Autism Results from a Supercharged Brain

To a child with autism the world is an intense place. Strangers unnerve. Surprises unsettle. To cope, the autistic child creates his own internal world. It’s placid, secure, and void of extremes.

Though autism is one of the most common childhood developmental disorders in existence, affecting an estimated one in 110 children, we know little about how it works. Most theories suggest a deficiency in the brain caused by some combination of genetics and environmental factors. But Drs. Kamila and Henry Markram of the Ecole Polytechnique Fédérale in Lausanne say it’s not a deficient brain that makes autistic people socially inept, linguistically challenged, and prone to obsession. It’s actually the opposite. The brains of autistic people are so supercharged, they say, that their life experiences overwhelm them.

In their paper “The Intense World Theory — a unifying theory of the neurobiology of autism” (Frontiers in Neuroscience, 2010), the Markrams explain how overly strong reactions make the autistic brain excessively selective. This phenomenon, they say, becomes more extreme with each experience until the autistic eventually disassociates him or herself from “a painfully intense world.”

The Markrams studied the valproic acid rat, an animal model of autism. Their analysis of the rats’ neocortex and amygdala revealed hyper-reactivity and hyper-plasticity of the neural microcircuits in these areas of the brain — an unusual physiology that results in hyper-perception, hyper-attention, hyper-memory and hyper-emotionality.

“Basically, our theory really says that most autistic people or people with Asperger’s are savants,” Kamila Markram told New Scientist. “But this is buried under social withdrawal and fear of new environments. Their resistance to interaction and fear may obscure the hypercapability that they have. It may well turn out that successful treatments could expose truly capable and highly gifted individuals.”

Read “The Intense World Theory — a unifying theory of the neurobiology of autism” at Frontiers in Human Neuroscience.

April is Autism Awareness Month. Learn more about autism and find out how you can help at autism-society.org.

{Markram K and Markram H (2010) The Intense World Theory – a unifying theory of the neurobiology of autism. Front. Hum. Neurosci. 4:224. doi: 10.3389/fnhum.2010.00224}