Stem Cells Identify Spread of Brain Disorders

Human embryonic stem cells. Courtesy, Wikipedia.

Stem cells made from patients have been used to identify the mechanism through which Alzheimer disease (AD) and Parkinson disease (PD) can spread across the brain, suggesting a potential new treatment approach.

This is one of the latest scientific developments about the brain and how it works presented this week at Neuroscience 2014, the annual meeting of the Society for Neuroscience.

Other research advances in neuroscience were reported in the areas of technological breakthroughs, the brain’s integration of various senses, diet and obesity, spinal cord injuries, sleep and memory, early-life experiences and brain development, and the brain and addiction.

Stem cells

New stem cell findings presented at the conference include the following:

• Neural stem cells derived from unfertilized human eggs reduce PD symptoms when they are transplanted into the brains of animal models.

• Scientists have been able to reduce the presence of a defective protein responsible for Huntington disease, without affecting the levels of its normal protein counterpart.

• Stem cells can better promote repair of brain tissue after a stroke when they are injected into the damaged area as part of a precise mix of supporting cells.

Neuroscience breakthroughs

Technological breakthroughs in neuroscience reported at the meeting include the following:

• Nanoparticles derived from a rare earth metal can slow down some of the brain-cell degeneration in a mouse model of PD. They may offer a treatment for the disease.

• Separate groups of cells deep within the brains of mice that play key roles in hunger and eating have been identified with the use of hair-thin visual probes and high-resolution fluorescence microscopes.  This could offer new insights into self-destructive eating disorders, such as anorexia and bulimia.

• Using optogenetics technology, researchers have demonstrated in mice that dopamine plays a crucial role in enabling the body to move, thus helping explain how the motor-system symptoms of PD and other movement disorders develop.

The protein tau

Studies showed the following new evidence about the central role that the protein tau plays in the progression of AD, traumatic brain injury (TBI), and other disorders:

• The symptoms of both AD and TBI are associated in mice with the overproduction of the same toxic form of the tau protein.

• Microglia may help trigger the spread of Alzheimer-associated toxic protein in rodents.

• New mouse models containing both tau tangles and amyloid plaques may offer a more accurate research tool for studying AD.

The brain and the senses

New research illustrates the importance of the brain’s ability to integrate different senses and how the brain can adapt when those sensory inputs change:

• To adapt to deafness, a brain region typically devoted to merging vision and hearing repurposes to strengthening peripheral vision instead.

• A brain region involved in integrating vision and hearing operates differently in persons who have autism spectrum disorders.

• Years after a hand transplant or reattachment, brain centers responsible for movement and sense of touch continue to reorganize and have improved function.

Diet and obesity

New findings about how diet and obesity alter the brain and behavior include the following:

• Being overweight or obese is associated with shrinkage of an area of the brain involved in long-term memory in cognitively healthy older adults.

• Prenatal exposure to a high-fat diet results in altered brain wiring in young monkeys, suggesting that exposure to a high-fat diet in the womb may alter children’s eating habits later in life.

• The “hunger hormone” ghrelin plays a pivotal role in helping a calorie-restrictive diet reduce brain-cell damage associated with PD, a finding that suggests a possible new approach to treating the disease.

Spinal cord injury

Research findings suggesting new approaches to chronic spinal cord injuries include the following:

• More than a year after spinal cord injury, injection of a bacterial enzyme that breaks down scar tissue can improve lung function.

• Long after the initial injury, early-stage nerve cells transplanted into the site of a paralyzing spinal cord injury in rats generate new nerve cells capable of making long-range connections.

• A high-bandwidth brain-machine interface is able to translate brain signals into instructions that allow monkeys to operate a motorized wheelchair.

• Paraplegic patients can operate a supportive “exoskeleton” that allows them to walk through the use of an advanced brain-machine interface.

Sleep and memory

Findings about the relationship between sleep and memory include the following:

• Increasing the production of a naturally occurring protein in mice enables them to retain spatial memory skills after being deprived of sleep.

• Eating during what would normally be the “sleep” phase of the day causes memory problems in mice, even if they get enough sleep at another time of the day. This finding may have implications for shift workers and others who experience disrupted sleep patterns.

• Two drugs restored function and reduced excessive sleepiness in brain-injured mice, perhaps by protecting the brain from inflammation, an after-effect of TBI.

• Neural processing that occurs during sleep enhances the ability of mice to control neuroprosthetics, a finding that may help patients learn how to use such devices more effectively.

Early-lifeexperience and brain development

New and recent findings about how early-life experiences affect brain development into adolescence include the following:

• Early-life stress appears to reduce the number of a key receptor in the brain’s reward center. The receptor is linked to subsequent development of addictive-like behaviors in mice.

• Exposure to abuse or neglect during childhood is associated with differences in the development of circuits in the brain’s decision-making center during adolescence, affecting the regulation of emotions and impulses.

• A caretaker’s presence buffers children against emotional reactivity and influences the function of brain circuits regulating emotion. These circuits mature by adolescence, when they are no longer influenced by a caretaker’s presence.

Addiction

Research offered new information on the mechanisms and brain regions involved in addictions:

• Pairing exposure to the scent of cigarettes with unpleasant smells, or “aversive conditioning,” while persons sleep may curb smoking.

• Activation of a specific brain circuit appears to dampen the drive to drink alcohol in rats.

 • Cannabis use during adolescence alters brain signaling into adulthood. This animal study builds on previous research that sought to explain the link between cannabis abuse and schizophrenia.