Long-term acclimatization to high-altitude hypoxia modifies interhemispheric functional and structural connectivity in the adult brain.
Structural and functional networks can be reorganized to adjust to environmental pressures and physiologic changes in the adult brain, but such processes remain unclear in prolonged adaptation to high-altitude (HA) hypoxia. This study aimed to characterize the interhemispheric functionally and structurally coupled modifications in the brains of adult HA immigrants.



We performed resting-state functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) in 16 adults who had immigrated to the Qinghai-Tibet Plateau (2300-4400 m) for 2 years and in 16 age-matched sea-level (SL) controls. A recently validated approach of voxel-mirrored homotopic connectivity (VMHC) was employed to examine the interhemispheric resting-state functional connectivity. Areas showing changed VMHC in HA immigrants were selected as regions of interest for follow-up DTI tractography analysis. The fiber parameters of fractional anisotropy and fiber length were obtained. Cognitive and physiological assessments were made and correlated with the resulting image metrics.



Compared with SL controls, VMHC in the bilateral visual cortex was significantly increased in HA immigrants. The mean VMHC value extracted within the visual cortex was positively correlated with hemoglobin concentration. Moreover, the path length of the commissural fibers connecting homotopic visual areas was increased in HA immigrants, covarying positively with VMHC.



These observations are the first to demonstrate interhemispheric functional and structural connectivity resilience in the adult brain after prolonged HA acclimatization independent of inherited and developmental effects, and the coupled modifications in the bilateral visual cortex indicate important neural compensatory mechanisms underlying visual dysfunction in physiologically well-acclimatized HA immigrants. The study of human central adaptation to extreme environments promotes the understanding of our brain's capacity for survival.
Department of Medical Imaging Fuzhou Dongfang Hospital Xiamen University Fuzhou Fujian China; Department of Physiology and Neurobiology Medical College of Xiamen University Xiamen Fujian China.
Ji
J
Chen
Department of Clinical Psychology Gulangyu Sanatorium of PLA Xiamen Fujian China.
Jinqiang
J
Li
Department of Clinical Psychology Gulangyu Sanatorium of PLA Xiamen Fujian China.
Qiaoqing
Q
Han
Magnetic Resonance Center The Affiliated Zhongshan Hospital of Xiamen University Xiamen Fujian China.
Jianzhong
J
Lin
Magnetic Resonance Center The Affiliated Zhongshan Hospital of Xiamen University Xiamen Fujian China.
Tianhe
T
Yang
Department of Medical Imaging Fuzhou Dongfang Hospital Xiamen University Fuzhou Fujian China.
Ziqian
Z
Chen
Department of Physiology and Neurobiology Medical College of Xiamen University Xiamen Fujian China.
Jiaxing
J
Zhang
Adult neuroplasticity; DTI tractography; ICA‐based denoising; high altitude; interhemispheric; resting‐state fMRI
PLoS One. 2013 Jul 16;8(7):e68621
23874692
J Neurosci. 2008 Dec 17;28(51):13754-64
19091966
IEEE Trans Med Imaging. 2004 Feb;23(2):137-52
14964560
J Neurosci. 2010 Nov 10;30(45):15034-43
21068309
J Comput Assist Tomogr. 2007 Sep-Oct;31(5):662-5
17895773
J Cogn Neurosci. 2010 Aug;22(8):1662-9
19583478
J Mol Neurosci. 2009 Jul;38(3):250-6
19424874
Proc Natl Acad Sci U S A. 2009 Feb 10;106(6):2035-40
19188601
Hum Brain Mapp. 2009 Oct;30(10):3127-41
19235882
Brain. 2011 Oct;134(Pt 10):2912-28
21975588
Med Image Anal. 2013 Oct;17(7):844-57
23706753
Radiology. 2014 Jun;271(3):839-47
24588676
J Physiol Pharmacol. 2007 Nov;58 Suppl 5(Pt 2):811-8
18204195
Brain Res. 2005 Sep 7;1055(1-2):1-6
16098951
Cereb Cortex. 2007 Oct;17(10):2420-32
17190967
Neuroimage. 2007 Oct 1;37(4):1286-300
17689982
Exp Brain Res. 2011 Feb;208(3):437-45
21107542
Cortex. 2014 Jul;56:1-13
23489777
Radiographics. 2008 Mar-Apr;28(2):417-39; quiz 617
18349449
Brain Imaging Behav. 2016 Jun;10(2):464-76
25986304
PLoS Comput Biol. 2006 Jul 21;2(7):e95
16848638
Front Neurosci. 2015 Jan 20;8:452
25653582
Clin Neurophysiol. 2011 Sep;122(9):1726-34
21377415
Nature. 2006 Jun 29;441(7097):1087-93
16810244
J Cereb Blood Flow Metab. 2013 Mar;33(3):372-80
23211961
High Alt Med Biol. 2016 Mar;17(1):16-24
26906285
Neuron. 2012 Jul 26;75(2):250-64
22841310
Annu Rev Neurosci. 2005;28:377-401
16022601
Nat Neurosci. 2012 Mar 18;15(4):528-36
22426254
Psychophysiology. 2012 Sep;49(9):1298-306
22803634
PLoS One. 2015 Mar 26;10(3):e0118892
25812124
Neuroimage. 2007 Nov 1;38(2):306-20
17869543
Proc Natl Acad Sci U S A. 2005 Jul 5;102(27):9673-8
15976020
Brain Res. 2010 Aug 12;1348:21-9
20599837
J Appl Physiol (1985). 2013 Aug 1;115(3):365-72
23722709
J Magn Reson. 2011 Dec;213(2):560-70
22152371
Lancet Neurol. 2009 Feb;8(2):175-91
19161909
Neuroimage. 2005 Nov 15;28(3):635-62
16172003
Cortex. 2011 Jul-Aug;47(7):863-73
20832784
Neuroimage. 2008 Jan 1;39(1):279-89
17919927
Cereb Cortex. 2011 May;21(5):1134-46
20943668
Magn Reson Med. 2009 Jun;61(6):1336-49
19319973
Proc Natl Acad Sci U S A. 2014 May 27;111(21):7843-8
24821757
Neuroimage. 2013 Oct 15;80:339-48
23644003
Neuroimage. 2002 Oct;17(2):825-41
12377157
J Cereb Blood Flow Metab. 1994 Jul;14(4):671-9
8014215
Cereb Cortex. 2005 Sep;15(9):1384-92
15635059
Magn Reson Med. 2000 Dec;44(6):925-32
11108630
Neuroimage. 1998 Feb;7(2):119-32
9558644
Brain Behav. 2016 Jun 27;6(9):e00512
27688941
Neuroimage. 2013 Oct 15;80:349-59
23571418
Neuroimage. 2014 Jul 15;95:232-47
24657355
J Magn Reson Imaging. 2006 Jun;23(6):827-39
16649196
PLoS One. 2010 Jul 06;5(7):e11449
20625426
Neuroimage. 2014 Apr 15;90:449-68
24389422
Curr Biol. 2007 Feb 20;17(4):R141-4
17307051
Brain Cogn. 2011 Oct;77(1):53-9
21767899
Neuropsychol Rev. 2004 Dec;14(4):197-224
15796116
High Alt Med Biol. 2012 Jun;13(2):118-25
22724615
Proc Natl Acad Sci U S A. 1996 Sep 3;93(18):9493-8
8790358
J Neurosci. 2005 Nov 2;25(44):10167-79
16267224