All Publications

  • Prefrontal reinstatement of contextual task demand is predicted by separable hippocampal patterns. Nature communications Jiang, J., Wang, S., Guo, W., Fernandez, C., Wagner, A. D. 2020; 11 (1): 2053


    Goal-directed behavior requires the representation of a task-set that defines the task-relevance of stimuli and guides stimulus-action mappings. Past experience provides one source of knowledge about likely task demands in the present, with learning enabling future predictions about anticipated demands. We examine whether spatial contexts serve to cue retrieval of associated task demands (e.g., context A and B probabilistically cue retrieval of task demands X and Y, respectively), and the role of the hippocampus and dorsolateral prefrontal cortex (dlPFC) in mediating such retrieval. Using 3D virtual environments, we induce context-task demand probabilistic associations and find that learned associations affect goal-directed behavior. Concurrent fMRI data reveal that, upon entering a context, differences between hippocampal representations of contexts (i.e., neural pattern separability) predict proactive retrieval of the probabilistically dominant associated task demand, which is reinstated in dlPFC. These findings reveal how hippocampal-prefrontal interactions support memory-guided cognitive control and adaptive behavior.

    View details for DOI 10.1038/s41467-020-15928-z

    View details for PubMedID 32345979

  • Blast Exposure, White Matter Integrity, and Cognitive Function in Iraq and Afghanistan Combat Veterans. Frontiers in neurology Ivanov, I., Fernandez, C., Mitsis, E. M., Dickstein, D. L., Wong, E., Tang, C. Y., Simantov, J., Bang, C., Moshier, E., Sano, M., Elder, G. A., Hazlett, E. A. 2017; 8: 127


    The long-term effects of blast exposure are a major health concern for combat veterans returning from the recent conflicts in Iraq and Afghanistan. We used an optimized diffusion tensor imaging tractography algorithm to assess white matter (WM) fractional anisotropy (FA) in blast-exposed Iraq and Afghanistan veterans (n = 40) scanned on average 3.7 years after deployment/trauma exposure. Veterans diagnosed with a blast-related mild traumatic brain injury (mTBI) were compared to combat veterans with blast exposure but no TBI diagnosis. Blast exposure was associated with decreased FA in several WM tracts. However, total blast exposure did not correlate well with neuropsychological testing performance and there were no differences in FA based on mTBI diagnosis. Yet, veterans with mTBI performed worse on every neurocognitive test administered. Multiple linear regression across all blast-exposed veterans using a six-factor prediction model indicated that the amount of blast exposure accounted for 11-15% of the variability in composite FA scores such that as blast exposure increased, FA decreased. Education accounted for 10% of the variability in composite FA scores and 25-32% of FA variability in the right cingulum, such that as level of education increased, FA increased. Total blast exposure, age, and education were significant predictors of FA in the left cingulum. We did not find any effect of post-traumatic stress disorder on cognition or composite FA. In summary, our findings suggest that greater total blast exposure is a contributing factor to poor WM integrity. While FA was not associated with neurocognitive performance, we hypothesize that FA changes in the cingulum in veterans with multiple combat exposures and no head trauma prior to deployment may represent a marker of vulnerability for future deficits. Future work needs to examine this longitudinally.

    View details for DOI 10.3389/fneur.2017.00127

    View details for PubMedID 28484418

    View details for PubMedCentralID PMC5399028

  • Gpr126 Is Critical for Schwann Cell Function during Peripheral Nerve Regeneration. The Journal of neuroscience : the official journal of the Society for Neuroscience Fernandez, C. n., Iyer, M. n., Low, I. n. 2017; 37 (12): 3106–8

    View details for PubMedID 28330980

  • Cerebral [F-18]T807/AV1451 retention pattern in clinically probable CTE resembles pathognomonic distribution of CTE tauopathy TRANSLATIONAL PSYCHIATRY Dickstein, D. L., Pullman, M. Y., Fernandez, C., Short, J. A., Kostakoglu, L., Knesaurek, K., Soleimani, L., Jordan, B. D., Gordon, W. A., Dams-O'Connor, K., Delman, B. N., Wong, E., Tang, C. Y., Dekosky, S. T., Stone, J. R., Cantu, R. C., Sano, M., Hof, P. R., Gandy, S. 2016; 6