What happens to your brain on the way to Mars

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Science Advances  01 May 2015:
Vol. 1, no. 4, e1400256
DOI: 10.1126/sciadv.1400256
  • Fig. 1 Behavioral deficits measured 6 weeks after charged particle exposure.

    (A) Performance on a NOR task reveals significant decrements in recognition memory indicated by the reduced discrimination of novelty. (B) Performance on an OiP task shows significant decrements in spatial memory retention, again indicated by a markedly reduced preference to explore novelty. *P = 0.05, **P = 0.01, ***P = 0.001, analysis of variance (ANOVA).

  • Fig. 2 Reduced dendritic complexity of neurons in the prelimbic layer of the mPFC 8 weeks after HZE particle irradiation.

    Digitally reconstructed images of EGFP-positive mPFC neurons before (0 cGy) and after (30 cGy) irradiation showing dendrites (green) and spines (red). Quantification of dendritic parameters (bar charts) shows that dendritic branching and length are significantly reduced after low-dose (5 and 30 cGy) exposure to oxygen (16O) or titanium (48Ti) particles. *P = 0.05, **P = 0.01, ANOVA.

  • Fig. 3 Reductions in dendritic spine density in the mPFC after HZE particle exposure.

    Representative digital images of 3D reconstructed dendritic segments (green) containing spines (red) in unirradiated (top left panel) and irradiated (bottom panels) brains. Dendritic spine number (left bar chart) and density (right bar chart) are quantified in charged particle–exposed animals 8 weeks after exposure. *P = 0.05, **P = 0.01, ANOVA.

  • Fig. 4 Correlation of spine density with DI.

    Dendritic spine density (per 1.3 mm2) is plotted against the corresponding performance of each animal on the OiP task. (A and B) Reduction in spine number after irradiation is correlated with reduced DI for novelty after exposure to 5 or 30 cGy of 16O (A) or 48Ti (B) charged particles. The correlation between spine density and DI is significant for the 30 cGy 48Ti data (green circles; P = 0.016).

  • Fig. 5 Changes in PSD-95 synaptic puncta in the mPFC 6 weeks after exposure to 5 or 30 cGy of 16O or 48Ti charged particles.

    Fluorescence micrographs show that irradiation leads to increased expression of PSD-95 puncta (bottom) in mPFC neurons after irradiation compared to controls (top left). Quantified PSD-95 puncta (bar chart) in the mPFC. *P = 0.05, **P = 0.01, ANOVA.

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