Table of Contents Author Guidelines Submit a Manuscript
Neural Plasticity
Volume 2016 (2016), Article ID 6353845, 12 pages
http://dx.doi.org/10.1155/2016/6353845
Research Article

Altered Effective Connectivity of Hippocampus-Dependent Episodic Memory Network in mTBI Survivors

1Neuroimaging Laboratory, School of Biomedical Engineering, Shenzhen University Health Science Center, Shenzhen 518060, China
2Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
3Departments of Linguistics and Psychology, Xidian University, Xi’an 710071, China
4School of Foreign Languages, Northwestern Polytechnical University, Xi’an 710029, China

Received 14 September 2016; Accepted 14 November 2016

Academic Editor: Kevin K. W. Wang

Copyright © 2016 Hao Yan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Linked References

  1. M. Ariza, J. M. Serra-Grabulosa, C. Junqué et al., “Hippocampal head atrophy after traumatic brain injury,” Neuropsychologia, vol. 44, no. 10, pp. 1956–1961, 2006. View at Publisher · View at Google Scholar · View at Scopus
  2. E. D. Bigler, “Anterior and middle cranial fossa in traumatic brain injury: relevant neuroanatomy and neuropathology in the study of neuropsychological outcome,” Neuropsychology, vol. 21, no. 5, pp. 515–531, 2007. View at Publisher · View at Google Scholar · View at Scopus
  3. B. Levine, N. Kovacevic, E. I. Nica et al., “The Toronto traumatic brain injury study: injury severity and quantified MRI,” Neurology, vol. 70, no. 10, pp. 771–778, 2008. View at Publisher · View at Google Scholar · View at Scopus
  4. P. M. Vespa, D. L. McArthur, Y. Xu et al., “Nonconvulsive seizures after traumatic brain injury are associated with hippocampal atrophy,” Neurology, vol. 75, no. 9, pp. 792–798, 2010. View at Publisher · View at Google Scholar · View at Scopus
  5. W. L. Maxwell, K. Dhillon, L. Harper et al., “There is differential loss of pyramidal cells from the human hippocampus with survival after blunt head injury,” Journal of Neuropathology and Experimental Neurology, vol. 62, no. 3, pp. 272–279, 2003. View at Publisher · View at Google Scholar · View at Scopus
  6. W. S. Carbonell and M. S. Grady, “Regional and temporal characterization of neuronal, glial, and axonal response after traumatic brain injury in the mouse,” Acta Neuropathologica, vol. 98, no. 4, pp. 396–406, 1999. View at Publisher · View at Google Scholar · View at Scopus
  7. D. M. Geddes, M. C. LaPlaca, and R. S. Cargill II, “Susceptibility of hippocampal neurons to mechanically induced injury,” Experimental Neurology, vol. 184, no. 1, pp. 420–427, 2003. View at Publisher · View at Google Scholar · View at Scopus
  8. J. E. S. Pierce, D. H. Smith, J. Q. Trojanowski, and T. K. McIntosh, “Enduring cognitive, neurobehavioral and histopathological changes persist for up to one year following severe experimental brain injury in rats,” Neuroscience, vol. 87, no. 2, pp. 359–369, 1998. View at Publisher · View at Google Scholar · View at Scopus
  9. M. A. Warner, T. S. Youn, T. Davis et al., “Regionally selective atrophy after traumatic axonal injury,” Archives of Neurology, vol. 67, no. 11, pp. 1336–1344, 2010. View at Publisher · View at Google Scholar · View at Scopus
  10. K. Ng, D. J. Mikulis, J. Glazer et al., “Magnetic resonance imaging evidence of progression of subacute brain atrophy in moderate to severe traumatic brain injury,” Archives of Physical Medicine and Rehabilitation, vol. 89, no. 12, pp. S35–S44, 2008. View at Publisher · View at Google Scholar · View at Scopus
  11. H. Eichenbaum, A. P. Yonelinas, and C. Ranganath, “The medial temporal lobe and recognition memory,” Annual Review of Neuroscience, vol. 30, pp. 123–152, 2007. View at Publisher · View at Google Scholar · View at Scopus
  12. L. R. Squire, C. E. L. Stark, and R. E. Clark, “The medial temporal lobe,” Annual Review of Neuroscience, vol. 27, pp. 279–306, 2004. View at Publisher · View at Google Scholar · View at Scopus
  13. E. Tulving, D. L. Schacter, D. R. McLachlan, and M. Moscovitch, “Priming of semantic autobiographical knowledge: a case study of retrograde amnesia,” Brain and Cognition, vol. 8, no. 1, pp. 3–20, 1988. View at Publisher · View at Google Scholar · View at Scopus
  14. D. Hassabis and E. A. Maguire, “Deconstructing episodic memory with construction,” Trends in Cognitive Sciences, vol. 11, no. 7, pp. 299–306, 2007. View at Publisher · View at Google Scholar · View at Scopus
  15. D. Hassabis, D. Kumaran, S. D. Vann, and E. A. Maguire, “Patients with hippocampal amnesia cannot imagine new experiences,” Proceedings of the National Academy of Sciences of the United States of America, vol. 104, no. 5, pp. 1726–1731, 2007. View at Publisher · View at Google Scholar · View at Scopus
  16. E. Race, M. M. Keane, and M. Verfaellie, “Medial temporal lobe damage causes deficits in episodic memory and episodic future thinking not attributable to deficits in narrative construction,” The Journal of Neuroscience, vol. 31, no. 28, pp. 10262–10269, 2011. View at Publisher · View at Google Scholar · View at Scopus
  17. C. Coste, B. Navarro, C. Vallat-Azouvi, M. Brami, P. Azouvi, and P. Piolino, “Disruption of temporally extended self-memory system following traumatic brain injury,” Neuropsychologia, vol. 71, pp. 133–145, 2015. View at Publisher · View at Google Scholar
  18. R. G. Knight and K. O'Hagan, “Autobiographical memory in long-term survivors of severe traumatic brain injury,” Journal of Clinical and Experimental Neuropsychology, vol. 31, no. 5, pp. 575–583, 2009. View at Publisher · View at Google Scholar · View at Scopus
  19. P. Piolino, B. Desgranges, L. Manning, P. North, C. Jokic, and F. Eustache, “Autobiographical memory, the sense of recollection and executive functions after severe traumatic brain injury,” Cortex, vol. 43, no. 2, pp. 176–195, 2007. View at Publisher · View at Google Scholar · View at Scopus
  20. E. Tulving, “Episodic memory: from mind to brain,” Annual Review of Psychology, vol. 53, pp. 1–25, 2002. View at Publisher · View at Google Scholar · View at Scopus
  21. R. S. Rosenbaum, A. Gilboa, and M. Moscovitch, “Case studies continue to illuminate the cognitive neuroscience of memory,” Annals of the New York Academy of Sciences, vol. 1316, no. 1, pp. 105–133, 2014. View at Publisher · View at Google Scholar · View at Scopus
  22. K. Friston, “Causal modelling and brain connectivity in functional magnetic resonance imaging,” PLoS Biology, vol. 7, no. 2, article no. e33, 2009. View at Google Scholar · View at Scopus
  23. S. M. Smith, K. L. Miller, G. Salimi-Khorshidi et al., “Network modelling methods for FMRI,” NeuroImage, vol. 54, no. 2, pp. 875–891, 2011. View at Publisher · View at Google Scholar · View at Scopus
  24. O. Sporns, “Contributions and challenges for network models in cognitive neuroscience,” Nature Neuroscience, vol. 17, no. 5, pp. 652–660, 2014. View at Publisher · View at Google Scholar · View at Scopus
  25. B. B. Biswal, M. Mennes, X. N. Zuo et al., “Toward discovery science of human brain function,” Proceedings of the National Academy of Sciences of the United States of America, vol. 107, pp. 4734–4739, 2010. View at Google Scholar
  26. H.-J. Park and K. Friston, “Structural and functional brain networks: from connections to cognition,” Science, vol. 342, no. 6158, Article ID 1238411, 2013. View at Publisher · View at Google Scholar · View at Scopus
  27. K. J. Friston, “Functional and effective connectivity: a review,” Brain Connectivity, vol. 1, no. 1, pp. 13–36, 2011. View at Google Scholar
  28. G. Chen, J. P. Hamilton, M. E. Thomason, I. H. Gotlib, Z. S. Saad, and R. W. Cox, “Granger causality via vector auto-regression tuned for FMRI data analysis,” in Proceedings of the 17th Annual Scientific Meeting and Exhibition (ISMRM '09), vol. 17, p. 1718, International Society for Magnetic Resonance in Medicine, Honolulu, Hawaii, USA, April 2009.
  29. V. L. Morgan, B. P. Rogers, H. H. Sonmezturk, J. C. Gore, and B. Abou-Khalil, “Cross hippocampal influence in mesial temporal lobe epilepsy measured with high temporal resolution functional magnetic resonance imaging,” Epilepsia, vol. 52, no. 9, pp. 1741–1749, 2011. View at Publisher · View at Google Scholar · View at Scopus
  30. F. Tagliaferri, C. Compagnone, M. Korsic, F. Servadei, and J. Kraus, “A systematic review of brain injury epidemiology in Europe,” Acta Neurochirurgica, vol. 148, no. 3, pp. 255–268, 2006. View at Publisher · View at Google Scholar · View at Scopus
  31. J. D. Cassidy, L. J. Carroll, P. M. Peloso et al., “Incidence, risk factors and prevention of mild traumatic brain injury: results of the WHO Collaborating Centre Task Force on Mild Traumatic Brain Injury,” Journal of Rehabilitation Medicine, vol. 36, no. 43, pp. 28–60, 2004. View at Publisher · View at Google Scholar · View at Scopus
  32. P. Dischinger, K. Read, T. Kerns et al., “Causes and outcomes of mild traumatic brain injury: an analysis of CIREN data,” Annual Proceedings—Association for the Advancement of Automotive Medicine, vol. 47, pp. 577–589, 2003. View at Google Scholar
  33. J. D. Corrigan, M. Wolfe, W. J. Mysiw, R. D. Jackson, and J. A. Bogner, “Early identification of mild traumatic brain injury in female victims of domestic violence,” Clinical Journal of Women's Health, vol. 1, no. 4, pp. 184–190, 2001. View at Publisher · View at Google Scholar · View at Scopus
  34. E. J. O'Shaughnessy, R. S. Fowler Jr., and V. Reid, “Sequelae of mild closed head injuries,” Journal of Family Practice, vol. 18, no. 3, pp. 391–394, 1984. View at Google Scholar · View at Scopus
  35. L. J. Carroll, J. D. Cassidy, L. Holm, J. Kraus, and V. G. Coronado, “Methodological issues and research recommendations for mild traumatic brain injury: the who collaborating centre task force on mild traumatic brain injury,” Journal of Rehabilitation Medicine, no. 43, pp. 113–125, 2004. View at Google Scholar · View at Scopus
  36. V. A. Anderson, S. A. Morse, G. Klug et al., “Predicting recovery from head injury in young children: a prospective analysis,” Journal of the International Neuropsychological Society, vol. 3, no. 6, pp. 568–580, 1997. View at Google Scholar · View at Scopus
  37. A. Roebroeck, E. Formisano, and R. Goebel, “Mapping directed influence over the brain using Granger causality and fMRI,” NeuroImage, vol. 25, no. 1, pp. 230–242, 2005. View at Publisher · View at Google Scholar · View at Scopus
  38. X.-W. Song, Z.-Y. Dong, X.-Y. Long et al., “REST: a toolkit for resting-state functional magnetic resonance imaging data processing,” PLoS ONE, vol. 6, no. 9, Article ID e25031, 2011. View at Publisher · View at Google Scholar · View at Scopus
  39. M. Jenkinson, P. Bannister, M. Brady, and S. Smith, “Improved optimization for the robust and accurate linear registration and motion correction of brain images,” NeuroImage, vol. 17, no. 2, pp. 825–841, 2002. View at Publisher · View at Google Scholar · View at Scopus
  40. R.-P. Behrendt, “Conscious experience and episodic memory: hippocampus at the crossroads,” Frontiers in Psychology, vol. 4, article 304, 2013. View at Publisher · View at Google Scholar · View at Scopus
  41. A. Talati and J. Hirsch, “Functional specialization within the medial frontal gyrus for perceptual go/no-go decisions based on ‘what,’ ‘when,’ and ‘where’ related information: an fMRI study,” Journal of Cognitive Neuroscience, vol. 17, no. 7, pp. 981–993, 2005. View at Publisher · View at Google Scholar · View at Scopus
  42. O. Demirci, M. C. Stevens, N. C. Andreasen et al., “Investigation of relationships between fMRI brain networks in the spectral domain using ICA and Granger causality reveals distinct differences between schizophrenia patients and healthy controls,” NeuroImage, vol. 46, no. 2, pp. 419–431, 2009. View at Publisher · View at Google Scholar · View at Scopus
  43. R. Stilla, G. Deshpande, S. LaConte, X. Hu, and K. Sathian, “Posteromedial parietal cortical activity and inputs predict tactile spatial acuity,” Journal of Neuroscience, vol. 27, no. 41, pp. 11091–11102, 2007. View at Publisher · View at Google Scholar · View at Scopus
  44. G. Deshpande, K. Sathian, and X. Hu, “Effect of hemodynamic variability on Granger causality analysis of fMRI,” NeuroImage, vol. 52, no. 3, pp. 884–896, 2010. View at Publisher · View at Google Scholar · View at Scopus
  45. E. Bullmore and O. Sporns, “Complex brain networks: graph theoretical analysis of structural and functional systems,” Nature Reviews Neuroscience, vol. 10, no. 3, pp. 186–198, 2009. View at Publisher · View at Google Scholar · View at Scopus
  46. D. Sridharan, D. J. Levitin, and V. Menon, “A critical role for the right fronto-insular cortex in switching between central-executive and default-mode networks,” Proceedings of the National Academy of Sciences of the United States of America, vol. 105, no. 34, pp. 12569–12574, 2008. View at Publisher · View at Google Scholar · View at Scopus
  47. M. C. Stevens, G. D. Pearlson, and V. D. Calhoun, “Changes in the interaction of resting-state neural networks from adolescence to adulthood,” Human Brain Mapping, vol. 30, no. 8, pp. 2356–2366, 2009. View at Publisher · View at Google Scholar · View at Scopus
  48. W. Liao, J. Ding, D. Marinazzo et al., “Small-world directed networks in the human brain: multivariate Granger causality analysis of resting-state fMRI,” NeuroImage, vol. 54, no. 4, pp. 2683–2694, 2011. View at Publisher · View at Google Scholar · View at Scopus
  49. Z. Liu, Y. Zhang, L. Bai et al., “Investigation of the effective connectivity of resting state networks in Alzheimer's disease: a functional MRI study combining independent components analysis and multivariate Granger causality analysis,” NMR in Biomedicine, vol. 25, no. 12, pp. 1311–1320, 2012. View at Publisher · View at Google Scholar · View at Scopus
  50. A. P. Holmes, R. C. Blair, J. D. G. Watson, and I. Ford, “Nonparametric analysis of statistic images from functional mapping experiments,” Journal of Cerebral Blood Flow and Metabolism, vol. 16, no. 1, pp. 7–22, 1996. View at Google Scholar · View at Scopus
  51. T. E. Nichols and A. P. Holmes, “Nonparametric permutation tests for functional neuroimaging: a primer with examples,” Human Brain Mapping, vol. 15, no. 1, pp. 1–25, 2002. View at Publisher · View at Google Scholar · View at Scopus
  52. J. L. Vincent, A. Z. Snyder, M. D. Fox et al., “Coherent spontaneous activity identifies a hippocampal-parietal memory network,” Journal of Neurophysiology, vol. 96, no. 6, pp. 3517–3531, 2006. View at Publisher · View at Google Scholar · View at Scopus
  53. M. D. Greicius, B. Krasnow, A. L. Reiss, and V. Menon, “Functional connectivity in the resting brain: a network analysis of the default mode hypothesis,” Proceedings of the National Academy of Sciences of the United States of America, vol. 100, no. 1, pp. 253–258, 2003. View at Publisher · View at Google Scholar · View at Scopus
  54. A. R. Laird, S. B. Eickhoff, K. Li, D. A. Robin, D. C. Glahn, and P. T. Fox, “Investigating the functional heterogeneity of the default mode network using coordinate-based meta-analytic modeling,” Journal of Neuroscience, vol. 29, no. 46, pp. 14496–14505, 2009. View at Publisher · View at Google Scholar · View at Scopus
  55. D. L. Schacter, D. R. Addis, and R. L. Buckner, “Remembering the past to imagine the future: the prospective brain,” Nature Reviews Neuroscience, vol. 8, no. 9, pp. 657–661, 2007. View at Publisher · View at Google Scholar · View at Scopus
  56. I. Shapira-Lichter, N. Oren, Y. Jacob, M. Gruberger, and T. Hendler, “Portraying the unique contribution of the default mode network to internally driven mnemonic processes,” Proceedings of the National Academy of Sciences of the United States of America, vol. 110, no. 13, pp. 4950–4955, 2013. View at Publisher · View at Google Scholar · View at Scopus
  57. A. Anticevic, M. W. Cole, J. D. Murray, P. R. Corlett, X.-J. Wang, and J. H. Krystal, “The role of default network deactivation in cognition and disease,” Trends in Cognitive Sciences, vol. 16, no. 12, pp. 584–592, 2012. View at Publisher · View at Google Scholar · View at Scopus
  58. E. D. Leshikar, A. H. Gutchess, A. C. Hebrank, B. P. Sutton, and D. C. Park, “The impact of increased relational encoding demands on frontal and hippocampal function in older adults,” Cortex, vol. 46, no. 4, pp. 507–521, 2010. View at Publisher · View at Google Scholar · View at Scopus
  59. F. Eustache, A. Viard, and B. Desgranges, “The MNESIS model: memory systems and processes, identity and future thinking,” Neuropsychologia, vol. 87, pp. 96–109, 2016. View at Publisher · View at Google Scholar
  60. E. Tulving, “Episodic memory and common sense: how far apart?” Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 356, no. 1413, pp. 1505–1515, 2001. View at Publisher · View at Google Scholar · View at Scopus
  61. E. Tulving, Elements of Episodic Memory, Oxford University Press, London, UK, 1983.
  62. A. P. Yonelinas, “The hippocampus supports high-resolution binding in the service of perception, working memory and long-term memory,” Behavioural Brain Research, vol. 254, pp. 34–44, 2013. View at Publisher · View at Google Scholar · View at Scopus
  63. E. A. Maguire and S. L. Mullally, “The hippocampus: a manifesto for change,” Journal of Experimental Psychology: General, vol. 142, no. 4, pp. 1180–1189, 2013. View at Publisher · View at Google Scholar · View at Scopus
  64. D. C. Rubin and S. Umanath, “Event memory: a theory of memory for laboratory, autobiographical, and fictional events,” Psychological Review, vol. 122, no. 1, pp. 1–23, 2015. View at Publisher · View at Google Scholar · View at Scopus
  65. T. T. Rogers, M. A. Lambon Ralph, P. Garrard et al., “Structure and deterioration of semantic memory: a neuropsychological and computational investigation,” Psychological Review, vol. 111, no. 1, pp. 205–235, 2004. View at Publisher · View at Google Scholar · View at Scopus
  66. K. Patterson, P. J. Nestor, and T. T. Rogers, “Where do you know what you know? The representation of semantic knowledge in the human brain,” Nature Reviews Neuroscience, vol. 8, no. 12, pp. 976–987, 2007. View at Publisher · View at Google Scholar · View at Scopus
  67. M. A. Lambon Ralph, “Neurocognitive insights on conceptual knowledge and its breakdown,” Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 369, no. 1634, Article ID 20120392, 2014. View at Publisher · View at Google Scholar · View at Scopus
  68. G. Winocur, M. Moscovitch, and B. Bontempi, “Memory formation and long-term retention in humans and animals: convergence towards a transformation account of hippocampal-neocortical interactions,” Neuropsychologia, vol. 48, no. 8, pp. 2339–2356, 2010. View at Publisher · View at Google Scholar · View at Scopus
  69. R. A. Diana, A. P. Yonelinas, and C. Ranganath, “Imaging recollection and familiarity in the medial temporal lobe: a three-component model,” Trends in Cognitive Sciences, vol. 11, no. 9, pp. 379–386, 2007. View at Publisher · View at Google Scholar · View at Scopus
  70. L. J. Gottlieb, J. Wong, M. De Chastelaine, and M. D. Rugg, “Neural correlates of the encoding of multimodal contextual features,” Learning and Memory, vol. 19, no. 12, pp. 605–614, 2012. View at Publisher · View at Google Scholar · View at Scopus
  71. L. R. Squire, A. S. Van Der Horst, S. G. R. McDuff, J. C. Frascino, R. O. Hopkins, and K. N. Mauldin, “Role of the hippocampus in remembering the past and imagining the future,” Proceedings of the National Academy of Sciences of the United States of America, vol. 107, no. 44, pp. 19044–19048, 2010. View at Publisher · View at Google Scholar · View at Scopus
  72. R. P. C. Kessels, D. Hobbel, and A. Postma, “Aging, context memory and binding: a comparison of ‘what, where and when’ in young and older adults,” International Journal of Neuroscience, vol. 117, no. 6, pp. 795–810, 2007. View at Publisher · View at Google Scholar · View at Scopus
  73. F. Lekeu, P. Marczewski, M. Van Der Linden et al., “Effects of incidental and intentional feature binding on recognition: a behavioural and PET activation study,” Neuropsychologia, vol. 40, no. 2, pp. 131–144, 2002. View at Publisher · View at Google Scholar · View at Scopus
  74. E. M. Aminoff, K. Kveraga, and M. Bar, “The role of the parahippocampal cortex in cognition,” Trends in Cognitive Sciences, vol. 17, no. 8, pp. 379–390, 2013. View at Publisher · View at Google Scholar · View at Scopus
  75. M. St-Laurent, M. Moscovitch, and M. P. McAndrews, “The retrieval of perceptual memory details depends on right hippocampal integrity and activation,” Cortex, vol. 84, pp. 15–33, 2016. View at Publisher · View at Google Scholar
  76. D. C. Park and P. Reuter-Lorenz, “The adaptive brain: aging and neurocognitive scaffolding,” Annual Review of Psychology, vol. 60, pp. 173–196, 2009. View at Publisher · View at Google Scholar · View at Scopus
  77. A. H. Gutchess, R. C. Welsh, T. Hedden et al., “Aging and the neural correlates of successful picture encoding: frontal activations compensate for decreased medial-temporal activity,” Journal of Cognitive Neuroscience, vol. 17, no. 1, pp. 84–96, 2005. View at Publisher · View at Google Scholar · View at Scopus
  78. C. Grady, “The cognitive neuroscience of ageing,” Nature Reviews Neuroscience, vol. 13, no. 7, pp. 491–505, 2012. View at Publisher · View at Google Scholar · View at Scopus
  79. A. Gilboa, C. Alain, D. T. Stuss, B. Melo, S. Miller, and M. Moscovitch, “Mechanisms of spontaneous confabulations: a strategic retrieval account,” Brain, vol. 129, no. 6, pp. 1399–1414, 2006. View at Publisher · View at Google Scholar · View at Scopus
  80. R. Cabeza, N. D. Anderson, J. K. Locantore, and A. R. McIntosh, “Aging gracefully: compensatory brain activity in high-performing older adults,” NeuroImage, vol. 17, no. 3, pp. 1394–1402, 2002. View at Publisher · View at Google Scholar · View at Scopus
  81. P. A. Reuter-Lorenz and K. A. Cappell, “Neurocognitive aging and the compensation hypothesis,” Current Directions in Psychological Science, vol. 17, no. 3, pp. 177–182, 2008. View at Publisher · View at Google Scholar · View at Scopus
  82. S. Carlomagno, S. Giannotti, L. Vorano, and A. Marini, “Discourse information content in non-aphasic adults with brain injury: a pilot study,” Brain Injury, vol. 25, no. 10, pp. 1010–1018, 2011. View at Publisher · View at Google Scholar · View at Scopus
  83. A. Marini, V. Galetto, E. Zampieri, L. Vorano, M. Zettin, and S. Carlomagno, “Narrative language in traumatic brain injury,” Neuropsychologia, vol. 49, no. 10, pp. 2904–2910, 2011. View at Publisher · View at Google Scholar · View at Scopus
  84. D. Tromp, A. Dufour, S. Lithfous, T. Pebayle, and O. Després, “Episodic memory in normal aging and Alzheimer disease: insights from imaging and behavioral studies,” Ageing Research Reviews, vol. 24, pp. 232–262, 2015. View at Publisher · View at Google Scholar