Objective: Ingestion of the nonproteinic amino acid theanine (5-N-ethylglutamine) has been shown to increase oscillatory brain activity in the so-called alpha band (8-14 Hz) during resting electroencephalographic recordings in humans. Independently, alpha band activity has been shown to be a key component in selective attentional processes. Here, we set out to assess whether theanine would cause modulation of anticipatory alpha activity during selective attentional deployments to stimuli in different sensory modalities, a paradigm in which robust alpha attention effects have previously been established.
Methods: Electrophysiological data from 168 scalp electrode channels were recorded while participants performed a standard intersensory attentional cuing task.
Results: As in previous studies, significantly greater alpha band activity was measured over parieto-occipital scalp for attentional deployments to the auditory modality than to the visual modality. Theanine ingestion resulted in a substantial overall decrease in background alpha levels relative to placebo while subjects were actively performing this demanding attention task. Despite this decrease in background alpha activity, attention-related alpha effects were significantly greater for the theanine condition.
Conclusion: This increase of attention-related anticipatory alpha over the right parieto-occipital scalp suggests that theanine may have a specific effect on the brain's attention circuitry. We conclude that theanine has clear psychoactive properties, and that it represents a potentially interesting, naturally occurring compound for further study, as it relates to the brain's attentional system.
*Program in Cognitive Neuroscience, Department of Psychology, The City College of the City University of New York, New York, NY; †The Cognitive Neurophysiology Laboratory, Nathan S. Kline Institute for Psychiatric Research, Program in Cognitive Neuroscience and Schizophrenia, Orangeburg, NY; ‡Unilever Beverages Global Technology Centre, Colworth House, Unilever R&D Colworth, Sharnbrook, Bedfordshire, UK; and §Ferkauf Graduate School of Psychology, Albert Einstein College of Medicine, Bronx, NY.
Address correspondence and reprint requests to: John J. Foxe, PhD, The Cognitive Neurophysiology Laboratory, Nathan S. Kline Institute for Psychiatric Research, Program in Cognitive Neuroscience and Schizophrenia, 140 Old Orangeburg Road, Orangeburg, NY 10962; E-mail: email@example.com
Supported by a grant from the Unilever Beverages Global Technology Centre