Assessment of brain activity during memory encoding in a narcolepsy patient on and off modafinil using normative fMRI data

Abstract

We present behavioral and functional magnetic resonance imaging (fMRI) findings of a 20-year-old female with narcolepsy who completed a standardized fMRI-adapted face memory task both ‘off’ and ‘on’ modafinil compared to a normative sample (N = 38). The patient showed poor recognition performance off modafinil (z = −2.03) but intact performance on modafinil (z = 0.78). fMRI results showed atypical activation during memory encoding off modafinil, with frontal lobe hypoactivity, but hippocampal hyperactivity, whereas all brain regions showed more normalized activation on modafinil. Results from this limited study suggest hippocampal and frontal alterations in individuals with narcolepsy. Further, the results suggest the hypothesis that modafinil may affect brain activation in some people with narcolepsy.

Keywords:

• Narcolepsy
• Memory encoding
• Modafinil
• Normative data
• fMRI
• Hippocampus

Acknowledgments

The authors wish to thank Dr. Wendell Gibby, M.D., for generous MRI facility support for this study.

Conflict of interest: Dr. Mark D. Allen is co-owner of a company that provides functional MRI products and services for commercial use. No other conflicts of interest or financial incentives are associated with any authors of this study.