Monday, May 4, 2015

Space Radiation Exposure Causes Damaged Neurons and Synapses in Areas Associated with Memory and Decision-Making




Hotz, Robert Lee. (2015, May 1) Study: Deep-Space Radiation Could Damage Astronauts’ Brains Cosmic rays could leave travelers to Mars confused, forgetful and slow to react. The Wall Street Journal, http://www.wsj.com/articles/study-deep-space-radiation-could-damage-astronauts-brains-1430503356

As NASA develops plans for a manned mission to Mars, scientists said Friday that cosmic rays during an interplanetary voyage could cause subtle brain damage, leaving astronauts confused, forgetful and slow to react to the unexpected.

In a NASA-funded study of radiation-exposed mice published Friday in Science Advances, researchers at the University of California, Irvine and the University of Nevada warned that prolonged bombardment by charged particles in deep space could affect the brain cells involved in decision-making and memory, with implications for possible manned forays into deep space.

…In 2013, Dr. Zeitlin reported radiation levels between Earth and Mars detected by the Mars Science Laboratory craft during its cruise to the red planet, and found that the exposure was the equivalent of getting “a whole-body CT scan once every 5 or 6 days.”

Deep-space radiation is a unique mix of gamma rays, high-energy protons and cosmic rays from newborn black holes, and radiation from exploding stars. Earth’s bulk, atmosphere and magnetic field blocks or deflects most deep-space cosmic rays. Shielding on spacecraft also helps.

…The researchers found the mice had damaged neurons and synapses in areas associated with memory and decision-making, such as the hippocampus and prefrontal cortex.



SOURCE

Vipan K. Parihar, Barrett Allen, Katherine K. Tran, Trisha G. Macaraeg, Esther M. Chu, Stephanie F. Kwok, Nicole N. Chmielewski, Brianna M. Craver, Janet E. Baulch, Munjal M. Acharya, Francis A. Cucinotta, Charles L. Limoli. What happens to your brain on the way to Mars. Science Advances 01 May 2015: Vol. 1 no. 4 e1400256. DOI: 10.1126/sciadv.1400256

Abstract

As NASA prepares for the first manned spaceflight to Mars, questions have surfaced concerning the potential for increased risks associated with exposure to the spectrum of highly energetic nuclei that comprise galactic cosmic rays. Animal models have revealed an unexpected sensitivity of mature neurons in the brain to charged particles found in space. 

Astronaut autonomy during long-term space travel is particularly critical as is the need to properly manage planned and unanticipated events, activities that could be compromised by accumulating particle traversals through the brain. 

Using mice subjected to space-relevant fluences of charged particles, we show significant cortical- and hippocampal-based performance decrements 6 weeks after acute exposure. 

Animals manifesting cognitive decrements exhibited marked and persistent radiation-induced reductions in dendritic complexity and spine density along medial prefrontal cortical neurons known to mediate neurotransmission specifically interrogated by our behavioral tasks. 

Significant increases in postsynaptic density protein 95 (PSD-95) revealed major radiation-induced alterations in synaptic integrity. Impaired behavioral performance of individual animals correlated significantly with reduced spine density and trended with increased synaptic puncta, thereby providing quantitative measures of risk for developing cognitive decrements. 

Our data indicate an unexpected and unique susceptibility of the central nervous system to space radiation exposure, and argue that the underlying radiation sensitivity of delicate neuronal structure may well predispose astronauts to unintended mission-critical performance decrements and/or longer-term neurocognitive sequelae.

 
ADDITIONAL SOURCES

Trani, D., Datta, K., Dorion, K., Kallakury, B., & Fornace Jr, A. J. (2010). Enhanced intestinal tumor multiplicity and grade in vivo after HZE exposure: Mouse models for space radiation risk estimates. Radiation and Environmental Biophysics, 49(3), 389-396.


No comments:

Post a Comment