Introduction: Functional neuroimaging typically relies on the blood-oxygen-level–dependent (BOLD) contrast, which is sensitive to the influx of oxygenated blood following neuronal activity. A new method, functional T1 relaxation in the rotating frame (fT1ρ) is thought to reflect changes in local brain metabolism, likely pH, and may more directly measure neuronal activity. These two methods were applied to study activation of the visual cortex in participants with bipolar disorder as compared to controls. Methods: Thirty-nine participants with bipolar disorder and 32 healthy controls underwent functional neuroimaging during a flashing checkerboard paradigm. Functional images were acquired in alternating blocks of BOLD and fT1ρ. Linear mixed-effect models were used to examine the relationship between these two functional imaging modalities and to test whether that relationship was altered in bipolar disorder. Results: BOLD and fT1ρ signal were strongly related in visual and cerebellar areas during the task in controls. The relationship between these two measures was reduced in bipolar disorder within the visual areas, cerebellum, striatum, and thalamus. Conclusions: These results support a distinct mechanisms underlying BOLD and fT1ρ signals. The weakened relationship between these imaging modalities may provide a novel tool for measuring pathology in bipolar disorder and other psychiatric illnesses.
Bibliographical noteFunding Information:
This study was supported by a generous donation by Roger Koch to the University of Iowa Foundation. Archive and storage of imaging data was supported by the University of Iowa Institute for Clinical and Translational Science (U54TR001013). J.A.W. was supported by the Department of Veterans Affairs (Merit Award), NIMH (5R01MH085724), NHLBI (R01HL113863), and a NARSAD Independent Investigator Award. J.G.F. was supported by the NIMH (K23MH083695) and NHLBI (P01HL014388). C.P.J. was supported in part by a NARSAD Young Investigator Award. V.A.M. was supported in part by a NARSAD Independent Investigator Award
© 2017 The Authors. Brain and Behavior published by Wiley Periodicals, Inc.
- bipolar disorder