TY - JOUR
T1 - L-Theanine and caffeine improve target-specific attention to visual stimuli by decreasing mind wandering
T2 - a human functional magnetic resonance imaging study
AU - Kahathuduwa, Chanaka N.
AU - Dhanasekara, Chathurika S.
AU - Chin, Shao Hua
AU - Davis, Tyler
AU - Weerasinghe, Vajira S.
AU - Dassanayake, Tharaka L.
AU - Binks, Martin
N1 - Funding Information:
The work was supported by the Neuroimaging Seed Grant of the College of Human Sciences, Texas Tech University , Lubbock, TX, USA. The authors do not have any potential conflicts of interest directly related to the production of this manuscript to declare. Dr Binks wishes to report that he received educational funding from The Coca Cola Company (2015) and research funding from Nestlé Health Science Inc (2016). He also has an ongoing nonfinancial relationship with International Food Information Council (Scientific Advisory Board Volunteer).
Publisher Copyright:
© 2017 Elsevier Inc.
PY - 2018/1
Y1 - 2018/1
N2 - Oral intake of L-theanine and caffeine supplements is known to be associated with faster stimulus discrimination, possibly via improving attention to stimuli. We hypothesized that L-theanine and caffeine may be bringing about this beneficial effect by increasing attention-related neural resource allocation to target stimuli and decreasing deviation of neural resources to distractors. We used functional magnetic resonance imaging (fMRI) to test this hypothesis. Solutions of 200 mg of L-theanine, 160 mg of caffeine, their combination, or the vehicle (distilled water; placebo) were administered in a randomized 4-way crossover design to 9 healthy adult men. Sixty minutes after administration, a 20-minute fMRI scan was performed while the subjects performed a visual color stimulus discrimination task. L-Theanine and L-theanine–caffeine combination resulted in faster responses to targets compared with placebo (∆ = 27.8 milliseconds, P =.018 and ∆ = 26.7 milliseconds, P =.037, respectively). L-Theanine was associated with decreased fMRI responses to distractor stimuli in brain regions that regulate visual attention, suggesting that L-theanine may be decreasing neural resource allocation to process distractors, thus allowing to attend to targets more efficiently. L-Theanine–caffeine combination was associated with decreased fMRI responses to target stimuli as compared with distractors in several brain regions that typically show increased activation during mind wandering. Factorial analysis suggested that L-theanine and caffeine seem to have a synergistic action in decreasing mind wandering. Therefore, our hypothesis is that L-theanine and caffeine may be decreasing deviation of attention to distractors (including mind wandering); thus, enhancing attention to target stimuli was confirmed.
AB - Oral intake of L-theanine and caffeine supplements is known to be associated with faster stimulus discrimination, possibly via improving attention to stimuli. We hypothesized that L-theanine and caffeine may be bringing about this beneficial effect by increasing attention-related neural resource allocation to target stimuli and decreasing deviation of neural resources to distractors. We used functional magnetic resonance imaging (fMRI) to test this hypothesis. Solutions of 200 mg of L-theanine, 160 mg of caffeine, their combination, or the vehicle (distilled water; placebo) were administered in a randomized 4-way crossover design to 9 healthy adult men. Sixty minutes after administration, a 20-minute fMRI scan was performed while the subjects performed a visual color stimulus discrimination task. L-Theanine and L-theanine–caffeine combination resulted in faster responses to targets compared with placebo (∆ = 27.8 milliseconds, P =.018 and ∆ = 26.7 milliseconds, P =.037, respectively). L-Theanine was associated with decreased fMRI responses to distractor stimuli in brain regions that regulate visual attention, suggesting that L-theanine may be decreasing neural resource allocation to process distractors, thus allowing to attend to targets more efficiently. L-Theanine–caffeine combination was associated with decreased fMRI responses to target stimuli as compared with distractors in several brain regions that typically show increased activation during mind wandering. Factorial analysis suggested that L-theanine and caffeine seem to have a synergistic action in decreasing mind wandering. Therefore, our hypothesis is that L-theanine and caffeine may be decreasing deviation of attention to distractors (including mind wandering); thus, enhancing attention to target stimuli was confirmed.
KW - Attention
KW - Caffeine
KW - Clinical trial
KW - Echo planar magnetic resonance imaging
KW - Tea
UR - http://www.scopus.com/inward/record.url?scp=85038380294&partnerID=8YFLogxK
U2 - 10.1016/j.nutres.2017.11.002
DO - 10.1016/j.nutres.2017.11.002
M3 - Article
C2 - 29420994
AN - SCOPUS:85038380294
VL - 49
SP - 67
EP - 78
JO - Nutrition Research
JF - Nutrition Research
SN - 0271-5317
ER -