The effects of neglect on white matter in the developing brain

photo credit: Angela Catlin public domain. This 13-year-old Romanian child shows the physical neglect that is now seen matched in the brains of even those in better institutions.

photo credit: Angela Catlin public domain. This 13-year-old Romanian child shows the physical neglect that is now seen matched in the brains of even those in better institutions.

Several decades ago, both contraception and abortion were banned in Romania, leading to the institutionalization of hundreds of thousands of abandoned children. Some of the institutions provided adequate food and shelter, but almost none of them were able to provide the human interactions that are so vital to healthy brain development. Is is known that neglect alters the brain, but the Bucharest Early Intervention Project (EAIP) conducted this latest study in order to identify which areas of the brain are most impacted.

The researchers compared 2 year olds who had lived with a family for their entire lives, had lived in an institution up until the start of the study when they were placed in foster care, and those who had and continued to be institutionalized. The diffusion tensor images of these childrens’ brains from ages 2 and 8 were compared between conditions, revealing that institutionalized children had significantly less white matter development than children raised in a household, with the foster care group falling somewhere in the middle at age 8.

More specifically, they found breakdown in the structural integrity of the corpus callosum (involved in communication between both sides of the brain), parts of the limbic circuitry (involved in emotion and fight-or-flight response), and many other areas of the white matter of the brain associated with functions like attention, executive function, and sensory processing. This research provides evidence for which aspects of the brain are affected in institutionalized, neglected children, as well as providing an indication that even after 2 years old, some white matter damage can be remedied if living conditions improve. These results indicate that the first two years do not define the trajectory of white matter development and that toddlers who have been institutionalized or otherwise neglected are byno means lost causes and that they can still experience healthy neuroplasticity in the right environment.

http://www.iflscience.com/brain/neglect-childhood-leaves-marks-brain

Bick, J., Zhu, T., Stamoulis, C., Fox, N. A., Zeanah C., Nelson, C. A., Effect of early institutionalization on long-term white matter development: a randomized clinical trial. JAMA Pediatrics, 2015.

The Neural System That Prevents You From Constantly Falling On Your Ass

Those living in cold climates know what a daily struggle walking and staying upright can be: every icy path is a potential hospital bill. Most of the time, the human body manages to keep us vertical. Other times, gravity betrays us, and we are down for the count. But what exactly is going on in our brain to mediate balance, motor dexterity, and, most importantly, keeping upright to prevent embarrassing falls?

Last month, Martyn Goulding and his team at the Salk Institute of Biological Studies reported discovering the neural system that determines our icy path fate. Specifically, these researchers found a cluster of retinoid-related orphan receptor alpha (RORα) neurons in the spinal cord that “function[s] as a ‘mini-brain’ to integrate sensory information and make the necessary adjustments to our muscles so that we don’t slip and fall.” Tracing the nerve fibers in mice with cutting-edge imaging techniques, the researchers found that RORα neurons incorporate information sent from the somatosensory sensors on the soles of the feet to detect subtle changes in pressure and movement. These signals from the light touch transmission pathway eventually reach the brain for further processing. The RORα cluster is also connected to neurons in the ventral spinal cord, suggesting a role in controlling movement as well. Together, the RORα “mini-brain” cluster works to keep us from falling and slipping on those tricky ice paths.

Goulding and his team hypothesize that much of the balancing process is an unconscious procedure. It is thought that the gauging of pressure and movement changes at the feet, and the subsequent processing and feedback from the spinal cord neurons are all happening on autopilot. The example that Steeve Bourane, a postdoctoral researcher in Goulding’s lab, uses is the stiffening of calf muscles: “If you stand on a slippery surface for a long time, you’ll notice your calf muscles get stiff, but you may not have noticed you were using them.” Bourane claims that, as the body is making subtle adjustments to keep balance, the mind is free to address other higher-level tasks – in other words, the autopilot function of balance is adaptive for multifaceted situations that require more than just the tending to balance to overcome.

The discovery of the “mini-brain” balance circuit leads to a whole new wave of research for the neural processes that contribute to movement control and sensing the environment through touch. The research is envisioned to translate to clinical applications, particularly for diseases that affect motor skills and balance. Spinal cord injury patients and the elderly are two demographics that are predicted to benefit most from this novel line of research. These applications may be many years away, however, given that this research focus is just developing. Hopefully, this research will better equip future generations to face the slippery paths of doom that plague cold climates everywhere.

Works cited:

Bourane, S., Grossmann, K. S., Britz, O., Dalet, A., Del Barrio, M. G., Stam, F. J., … & Goulding, M. (2015). Identification of a Spinal Circuit for Light Touch and Fine Motor Control. Cell, 160(3), 503-515.

http://www.salk.edu/news/pressrelease_details.php?press_id=2070

http://www.sciencedaily.com/releases/2015/01/150129132811.htm

Rethinking Being Like the “Cool Kids”

In the past, the media often portrayed the “cool” skater kids as the kids who perform daredevil tricks, speeding down the ramps, without helmets or pads. (Think Rocket Power.) When I was younger, I was really into rollerblading (I still am) and I was the girl that always tried to race out of the garage before my parents could notice that I wasn’t wearing a helmet. I was already the only girl playing street hockey with the boys on our street, and I didn’t want to look like a sissy with my helmet on… At the time, I didn’t understand why it was so important it was to wear a helmet. I knew about concussions, but they only lasted a week or two, right?

There has been a growing amount of research around the long-term impacts of concussions and other traumatic head injuries, and the physical damage they do to the brain. A recent study conducted by Albaugh, Orr, Nickerson, Zweber, Slauterbeck, Hipko, Gonyea, Andrews, Brackenbury, Watts, and Hudziak (2015) investigated the physical changes in cortical morphology among adolescents who had a history of concussions. Specifically, they targeted boys ages 14 – 23 who played ice hockey. They underwent neuroimaging and took a baseline Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) testing. ImPACT tests are universally used to measure concussion symptoms in cognition. Their concussion history and baseline measures of psychopathology were also recorded.

Cortical thickness is a general term for the thickness of the layers of the brain tissue in the cerebral cortex. In mammals, cortical thickness corresponds to perceived intelligence, and larger cortical volume indicates increased behavior flexibility (Kolb & Whishaw, 2001). Cortical thickness is also correlated with number of neurons. Most mammals show almost exactly the same amount of neurons when the same volumes of cortex are compared (Kolb & Whishaw, 2001)

Results showed that higher scores on the ImPACT test, indicting greater endorsed post-concussion symptoms, were related to less cortical thickness in brain areas. Specific brain areas that indicated this were regions of the left medial prefrontal cortex and left temporal cortex. Albaugh et al. (2015) also found an “Age by Concussion History” interaction for cortical thickness in right ventrolateral prefrontal and right parietal regions. People with history of concussions showed reduced rates of age-related cortical thinning. Cortical thinning is a normative process that happens as we age. Reduced rates of this process are associated with anxious/depressed symptoms and attention problems.

There are different degrees of concussion severity. Typically, the severity is measured through performance on the ImPACT test through various cognitive symptoms. Common symptoms include difficulty concentrating, difficulty remembering, fatigue, and mental fog. In the past, it has been thought that these symptoms are only present when recovering, similar to when you catch a cold. These long-term effects, however, are important when considering safety measures in contact sports such as hockey and football. Sports leagues should use this knowledge to strengthen their regulations and requirements on safety headwear, because ultimately, you only get one brain and you have to take care of it!

Works Cited

Albaugh, M., Orr, C., Nickerson, J., Zweber, C., Slauterbeck, J., Hipko, S., Gonyea, J., Andrews, T., Brackenbury, J., Watts, R., Hudziak, J. (2015). Postconcussion Symptoms Are Associated with Cerebral Cortical Thickness in Healthy Collegiate and Preparatory School Ice Hockey Players. The Journal of Pediatrics, 166(2), 394 – 400.

Kolb, B., & Whishaw, I. Q. (2001). An introduction to brain and behavior. Worth Publishers. Retrieved from http://books.google.com.

New Neurons: Who Needs Em Anyway?

Neuroscientists once contested the idea that new brain cells could be created in the adult brain, but now most agree that it is a normal part of brain development in adulthood. While neurogenesis is associated with improvements in cognitive performance, it is not always easy to create an environment that fosters neurogenesis. I was wondering why it is so difficult to create new cells in the brain and what conditions may exist that prevent neurogenesis from occurring. During my research I came around the hundreds of articles on stress and its inhibitory effects on neurogenesis, but then I came across something a little more interesting.

In a review published earlier this year, Maya Opendak and Elizabeth Gould at Princeton investigated the possibility that the inhibitory effect of stress on new cell growth in the brain has an adaptive function (Opendak & Gould 2015). Opendak and Gould (2015) specifically looked at the effect of stressful environments on neurogenesis, and how it may be beneficial to prevent cognitive improvements in circumstances where survival must be prioritized. They posited that the brain’s stress hormones, like glucocorticoid, work to prevent neurogenesis to keep the subject (human or otherwise) anxious and promote avoidance behavior (Opendak and Gould 2015). This would be beneficial in any scenario where exploration of one’s environment could mean death. Of course, an excess of stress and long-term prevention of cell proliferation could lead to significant cognitive deficits that become maladaptive (Opendak & Gould, 2015).

In support of Opendak & Gould’s (2015) adaptive hypothesis, they also found that conditions other than stress could hinder neurogenesis. For example, they cited studies that established that socially dominant rats produce more neurons than their subordinate counterparts. The dominant rats do not experience less stress, specifically they do not have lower glucocorticoid levels that could impair neuron proliferation (Opendak & Gould, 2015). This implies that the factors hindering neurogenesis are part of a broader range of circumstantial variables that require more basic brain functioning, and less cognitive enhancement. In contrast, when stress is low and humans (or other animals) are operating in a low risk environment, cognitive improvements resulting from neurogenesis will allow them to more effectively and meaningfully interact with their surroundings.

While stress being able to hinder neurogenesis in a state of nature may be beneficial, for humans in modern society it seems like it could be incredibly detrimental. I am specifically thinking of students from a wide variety of socioeconomic backgrounds attempting to learn at similar paces while experiencing starkly different out-of-school environments. This article made me think that maybe tasks that increase neurogenesis, like physical activity, could be critical in leveling the playing field among younger and older students alike. More research on this is likely necessary to investigate the possibilities of increasing neurogenesis as a means of healthy educational practices.

 

Works Cited

Opendak, M., & Gould, E. (2015). Dult eurogenesis: A substrate for experience-dependent           change. Trends in Cognitive Neuroscience, XX, 1-11. Retrieved February 24, 2015.

Exercise and Mental Health

Recently, many researchers have been focusing on the effects of exercise on both physical and mental health.  Unfortunately, much of the developed world is plagued by obesity and many people do not exercise as much as they should.  Many people realize that exercise is crucial for maintaining a healthy BMI, but what most people do not realize is that exercise affects the brain in such a way that memory and even mental health can be improved.

A study recently published in Biology of Sport indicates that exercise can initiate neurogenesis in the subventricular zone of rats.  The function of the subventricular zone has not been studied extensively in humans, but in rats, it is a major source of neural stem cells used in adult neurogenesis.  Rats were divided into a control group and an exercise group (5 days of swimming exercise, for 8 weeks).  Afterwards, the researchers measured neurogenesis in the subventricular zone, and levels of nerve growth factor and synapsin (a protein involved in neurotransmitter release), in the olfactory bulb.  After analyzing the brains of the rats, they found that the swimming exercise group had significantly higher neurogenesis in the SVZ than the control group.

Because neurogenesis is expected to play a role in psychiatric illnesses, including depression, anxiety, and schizophrenia, the results indicate that exercise is more important for mental health than previously believed.  What I am curious about is if the exercise itself is the only factor in increasing neurogenesis.  Stress and disrupted sleep are also known to decrease neurogenesis, and affect not only a person’s happiness but their cognitive functioning as well.  Many people exercise to reduce their stress, so could the increase in neurogenesis due to exercise be due to multiple factors?

A study done by Koehl et al. (2008) found that the endorphins released during exercise can also increase cell proliferation in vitro. This indicates that the endorphins released during exercise either have multiple effects, or that the cell proliferation that they cause is helping to contribute to the elevated mood that exercise is known to cause.  Because neurogenesis is a highly researched topic and is thought to be involved in many neurological and psychological disorders, I expect that there will be much more research on its connection to health in the near future.

References:

Chae, C., Jung, S., An, S., Park, B., Kim, T., Wang, S., … Kim, H. (2014). Swimming exercise stimulates neurogenesis in the subventricular zone via increase in synapsin I and nerve growth factor levels. Biology of Sport, 31(4), 309-314.

Koehl, M., Meerlo, P., Gonzales, D., Rontal, A., Turek, F., & Abrous, D. (2008). Exercise-induced promotion of hippocampal cell proliferation requires beta-endorphin. The Journal of the Federation of American Societies for Experimental Biology, 22(7), 2253-2262.

Dolphins in Captivity: What Do They Think?

In class we recently discussed the harmful effects of orca captivity on these animals’ psychological states. This led me to wonder how captivity may affect dolphins; another popular cetacean in captive settings. It is no secret that dolphins are highly intelligent animals, but what skills do they possess that suggest this intelligence and how might this intelligence indicate they may be emotionally or psychologically suffering in captivity? Lori Marino, a senior lecturer at Emory University, studies these exact issues in dolphins.

Marino conducted a study in 2000, which tested dolphins’ ability to recognize their selves in a mirror. Although this may seem like a simple task, prior to this study only humans and great apes had displayed this behavior. Humans don’t preform this behavior until 18-24 months of age, when other abstract concepts of the self start developing. The study included two captive-born dolphins. Their bodies were marked and then they were given the opportunity to observe themselves in a reflective surface. The dolphins indicated they were aware the mirror was a reflection of themselves by exploring the marked areas of their bodies in the reflections. If the dolphins were left unmarked, they did not show the same immediate interest in looking at themselves as when they had been marked. Although this behavior cannot conclusively determine if dolphins preform other self-awareness processes, such as introspection (analyzing their own thoughts and feelings) or awareness that other dolphins have their own thoughts and feelings, it is a good start. Marino has stated that the more self-aware dolphins are the more vulnerable they may be to captive life. She believes the more aware a dolphin is of his/her present and past circumstances, the more the dolphin can feel the difference between pleasant and unpleasant situations, thus leading to rumination about the negative consequences of the current situation.

Further evidence of dolphins’ capacities for emotion and complex mental processes comes from neurological research. MRI scans reveal that features of the dolphin neocortex are expanded. The neocortex is responsible for higher-level thinking and emotional processing. The dolphin brain is also four to five times larger for their body size compared to another animal of similar size. Taken together, this behavioral and neurological research suggests that dolphins may not be happy as captive animals. Their emotional and mental abilities may enable them to perceive living in such a small, enclosed, and empty area as negatively as you or I would. Efforts to ensure the welfare of dolphins in captive settings are imperative to make these settings enjoyable for them.

 

Works Cited:

“Dolphins: Second-Smartest Animals?” Discovery News. Web. 24 Feb 2015. http://news.discovery.com/animals/whales-dolphins/dolphins-smarter-brain-function.htm

Reiss, D., & Marino. (2000). Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence. Proceedings of the National Academy of Sciences of the United States of America, 98, 5937-5942.

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