Neurophysiological Correlates of L-theanine, Caffeine and Their Combination on Improving Selective Attention in a Visual Reaction Time Task: A Functional Magnetic Resonance Imaging (fMRI) Study
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 9
- 试验地点
- 2
- 主要终点
- Differences between fMRI blood oxygen level dependent (BOLD) responses of the brain recorded following administration of each substance and the placebo
研究概览
简要总结
L-theanine and caffeine are nutritional compounds that are naturally found in tea. Our recent findings using an EEG paradigm are consistent with the findings of others, indicating that intake of L-theanine and caffeine reduce the time needed for a person to differentiate between two visual stimuli and react to only one stimulus. In order to understand how these compounds give rise to these improvements, the investigators need to study how these compounds are related to various areas of the brain. To achieve this, the investigators plan to scan the brains of nine participants after they take either 1) L-theanine alone, 2) caffeine alone 3) the combination of both L-theanine and caffeine as compared with a placebo (distilled water), to see which has the greatest impact on attention and on regions in the brain that bring about attention.
详细描述
Recruitment: Participants will be recruited through advertisements in social media, electronic and hardcopy noticeboards at Texas Tech University (e.g. Tech Announce, campus bulletin boards), local media (e.g. newspapers), web-based media (e.g. Craig's list) and flyers placed on bulletin boards off campus. Nine participants will be recruited after screening for the following inclusion and exclusion criteria.
Pre-Screening (Telephone): Individuals who express an interest in participating will be contacted by a graduate or an undergraduate research assistant who will administer a structured telephone interview to: 1) provide information related to the requirements of the study, along with potential risks and benefits 2) Screen for eligibility based on specific inclusion and exclusion criteria. All potential subjects will be informed that their responses will remain confidential and that taking part in the screening interview in no way obligates them to participate.
The first 9 participants who meet eligibility criteria will be scheduled for their appointments (at Texas Tech Neuroimaging Institute; TTNI) immediately or within 48 hours of the telephone conversation depending on the discretion of each potential participant. Each participant will be required to complete 5 visits to TTNI, scheduled at least 5 days apart, in order to complete their participation in the study. The first visit will be 45 minutes in length and each of the 4 subsequent visits will be 90 minutes in length. The participants will be given the right to withdraw from the study at any point. In the event that a screened and included participant should discontinue the study prematurely, additional subjects will be recruited to maintain study total at 9 completers. Since the study is a cross-over design, all participants will be exposed to all experimental conditions (i.e. theanine, caffeine, TC and distilled water) in a random order.
Measurements:
- Recognition Visual Reaction Time (RVRT) Task: Participants will be instructed on the importance of accuracy in performing the RVRT task in advance. A blue-colored background will be presented. Participants will be requested to press a button on a computer keyboard (during practice sessions) and on a fiber optic hand-held device during active testing sessions (in the fMRI scanner) using the index finger of the dominant hand in response to a white flash lasting for 30ms (target stimulus) as quickly as possible, while ignoring a red colored flash lasting for 30ms (distractor stimulus). During each run, 20±2 stimuli of each category of stimuli will be presented and the inter-stimulus interval will be jittered to 5000ms±3000ms. Time taken to respond to target stimuli will be recorded as RVRT. Omissions and responses to distractor stimuli (errors) will also be recorded.
- Scanning paradigm: Each scanning session will be scheduled for 20 minutes, comprised of 3 runs of fMRI scans while the participants are performing the RVRT tasks displayed on an LCD screen and projected via a mirror attached to the head coil of the fMRI machine (each run lasting for 4 minutes) followed by a structural (T1-weighted) scan lasting for 5 minutes.
研究设计
- 研究类型
- Interventional
- 干预模型
- Crossover
- 盲法
- Single (Participant)
入排标准
- 年龄范围
- 18 Years 至 60 Years（Adult）
- 性别
- Male
- 接受健康志愿者
- 是
入选标准
- •Healthy males*
- •Age 18-60 years
排除标准
- •Gross impairment of vision or hearing that would prevent the participants from recognizing visual stimuli
- •Physical, psychiatric or neurological impairment that could affect cognitive or motor functions
- •Exposure to toxins or substances that are known to affect visual, auditory, cognitive or motor functions
- •Regular intake of medication that could alter visual, auditory, cognitive or motor functions
- •History of and / or current alcohol and / or drug abuse
- •Disease or condition known to be precipitated or aggravated by tea or coffee
- •Intake of drugs containing caffeine, other phosphodiesterase inhibitors or adenosine receptor blockers
- •Intake of medications which are known to have pharmacological interactions with caffeine
- •Participants with contra-indications to undergo fMRI scanning
- •Unwilling or unable to discontinue the use of cell phones, smart phones or other electronic devices during the entire study visit.
结局指标
主要结局
Differences between fMRI blood oxygen level dependent (BOLD) responses of the brain recorded following administration of each substance and the placebo
时间窗: Sixty minutes after administration of each of theanine, caffeine, theanine-caffeine combination and placebo
Theanine, caffeine, theanine-caffeine combination and distilled water (placebo) will be administered on 4 separate days (at least 5 days apart) in a random order. Functional MRI scans will be performed 60 minutes after each administration. Primary outcome measure will be the difference in fMRI BOLD responses obtained for each substance and the placebo.
次要结局
- Differences between proportion of errors caused while performing the recognition visual reaction time task following administration of each substance and the placebo(Sixty minutes after administration of each of theanine, caffeine, theanine-caffeine combination and placebo)
- Differences between proportion of omissions caused while performing the recognition visual reaction time task following administration of each substance and the placebo(Sixty minutes after administration of each of theanine, caffeine, theanine-caffeine combination and placebo)
- Differences between mean recognition visual reaction times recorded following administration of each substance and the placebo(Sixty minutes after administration of each of theanine, caffeine, theanine-caffeine combination and placebo)