Neural correlates of cognitive decline in ALS: An fNIRS study of the prefrontal cortex

Abstract

Functional near infrared spectroscopy (fNIRS) is a clinically feasible functional neuroimaging modality for detecting early cortical changes due to neurodegenerative diseases that affect cognition. The objective of this preliminary investigation was to test for reduced prefrontal activity in persons with cognitive impairments due to amyotrophic lateral sclerosis (ALS). Participants were required to complete two N-back working memory tasks of increasing complexity during fNIRS recordings. Five participants with ALS and age- and gender-matched healthy participants comprised the experimental and control groups, respectively. Significant reductions in prefrontal oxygenation levels were observed for the left and right hemispheres in the ALS group compared to the control group. Reduced prefrontal activation despite intact behavioral performance for a working memory task may suggest early neuroanatomical, neurophysiological and/or compensatory mechanisms in affected individuals. The fNIRS-derived oxygenation measure shows promise as a sensitive neural marker to identify early neuropsychological impairments due to ALS.

Keywords:

• ALS
• Cognition
• fNIRS
• Functional near infrared spectroscopy
• N-back

Acknowledgments

This research was funded by the Barkley Trust, an NIH-NIDCD grant R01 DC009890, and a seed grant from the Munroe Meyer Institute of Genetics and Rehabilitation. The authors would like to thank Cynthia Didion, Lori Synhorst, Jun Wang, and Suyash Joshi for their help with data collection and analysis.