Response Inhibition to High Calorie Food Cues Among Adolescents Following Active and Sedentary Video Game Play

Design. A randomized crossover design with counterbalanced treatment conditions will be used to compare the amount of neural inhibition to high and low calorie food cues among adolescents between two conditions. These two conditions will include a 60-minute session of active video game play and a 60-minute session of sedentary video game play. The order of treatment conditions will be randomly assigned using a validated simple randomization technique. During each laboratory session EEG data will be recorded and then later analyzed to assess the individual event related potential (ERP) components following each of the two conditions. Participants will complete a go/no-go response inhibition viewing task with pictures of high calorie and low calorie foods displayed on a computer monitor. The response inhibition task will be administered immediately following the cessation of each video game condition.

Video gaming conditions. The sedentary video game play condition will require participants to play in a seated position for 60 minutes. The active video game play condition will require participants to complete 60 minutes of active video gaming at moderate intense levels (3.0-5.9 metabolic equivalents (METs)) using a popular dance simulation game called 'Dance Dance Revolution' (DDR by Konami Digital Entertainment, Redwood City, CA). DDR elicits moderate intense (3.0-5.9 METs) levels of physical activity. Sixty minutes of active video game play has been shown to produce moderate intense levels of physical activity. Current guidelines recommend adolescents engage daily in 60 minutes or more of moderate-to vigorous-intense physical activity.

Participants. Sixty two healthy adolescents (31 female and 31 male) will be recruited through advertisements and fliers in the local community. Participants will be adolescents between the ages of 12 and 15 years old.

Procedures Screening. Candidates for the study and their guardians will be sent an email containing a link to an online survey. The online survey will be a 'yes or no' questionnaire to ensure participants meet inclusion criteria. Candidates must answer each question properly in order to qualify for the study. As part of the online survey, participants will be asked to report any food allergies and complete a food preference questionnaire. The food preference questionnaire will be used to prepare the standardized meals for each participant. Qualifying candidates will be invited to participate in the study.

Orientation. Participants for the study will be asked to complete the assent and consent forms prior to the first lab session. Participants and their guardians will come to the Clinical Neuroscience lab at least one day prior to their first lab session to pick up their standardized meals. Each participant will be informed of the main purpose of the study and familiarized with the testing procedures. Participants will be instructed to avoid consuming caffeine and other stimulants on the testing day as well as avoiding vigorous-intense physical activity for the 24-hour period prior to testing. Participants will be given a copy of these testing instructions.

Standardized Meals. Participants will be given a standardized breakfast and lunch for each of the testing days. The energy needs for each participant will be estimated using the World Health Organization equations for predicting basal metabolic rates. This equation uses height (cm), weight (kg) and age (years) to predict basal metabolic rates and has been validated for accuracy and reliability. An activity factor of 1.6 for boys and 1.5 for girls will be used to estimate total daily energy requirements.

Meals will be standardized based on macronutrient content (60% carbohydrate, 20% fat, 20% protein), age, gender and physical activity level (light, moderate or high activity). Participants will be given 25% of their daily caloric requirements for breakfast and 25% for lunch. The same foods will be given on both test days and participants will be instructed to consume all the food for both meals. Meal adherence will be assessed at the beginning of each session. Any non-compliance (not eating all food and/or eating other foods) will require participants to redo that particular lab session on a different day when they have followed food protocols.

Meals are designed to represent a reasonable amount of food to provide participants with adequate food intake. Participants will be given both of their standardized meals prior to the first testing day along with instructions to consume only standardized meals on testing days, avoid caffeine consumption and vigorous-intense physical activity 24-hours prior to testing. Participants will be instructed to consume their breakfast and lunch at the same time of day and at least two hours before arriving for each testing day.

Video Gaming Sessions. Each participant will complete two separate lab sessions. Demographic and anthropometric information will be collected at the beginning of the first lab session. Participants will be asked to rate their hunger at the beginning of each lab session. Hoffman et al compared P3 and N2 components between fed (1 hour postprandial) and fasted (17 hour fast) states and found no significant differences in P3 or N2 component amplitude or latency among young adults. Testing procedures and protocols will be reviewed with each participant prior to initiation of each video gaming session. Participants will then be taken to the video game lab to complete a 60-minute video gaming session. At the beginning of the video game session, participants will be fitted with the K4b2 (Cosmed, Rome, Italy) metabolic system, Polar heart rate monitor (Polar, Helsinki, Finland) and GT3X activity monitor (Pensicola, FL) to measure energy expenditure. Metabolic information for each participant will be measured and recorded for analysis.

Immediately following each video gaming condition, participants will be brought into an adjacent room containing the EEG equipment where they will complete the response inhibition tasks. After the second video gaming session participants will be asked to classify each food image as either high- or low-calorie to ensure the participants were correctly identifying food images during the response inhibition tasks. Upon completion of the response inhibition task, participants will be led to a separate room to complete the Stroop-Color Word test.

Response Inhibition Task. Immediately following both the active and passive video game conditions, participants will complete two go/no-go active viewing tasks. The go/no-go task will include pictures of high-calorie and low-calorie foods. Pictures for the viewing tasks will be selected based on findings from Blechert et al who recently reported normative ratings of 568 high- and low-calorie food images. The first viewing task will use a total of 150 pictures, 100 of these will include high-calorie pictures and 50 low-calorie pictures; the low-calorie images will be the target stimuli. The second viewing task will include 100 low-calorie pictures and 50 high-calorie pictures; the high-calorie images will be the target stimuli. Each of the viewing tasks will be shown in a different random order for each participant. Images will be shown for 500 milliseconds (ms) with an inter-trial interval of 1300 ms between images. Following the second response inhibition task, participants will be asked to subjectively rate the pictures according to pleasantness and arousal by using a picture rating scale from 1-9 (with 1 being the lowest and 9 the highest). To determine participant understanding of low vs high calorie foods, participants will be asked to complete a short task in which they will categorize each food picture as either low calorie or high calorie.

Go/No-Go Paradigm. For the high-calorie portion of the go/no-go task, participants will be instructed to press a button with their right index finger when they see images of low-calorie foods, which will be the target stimuli. The low calorie foods will be the target stimulus and the participants must commit their response by pressing the appropriate button. This portion of the task will be called "go". The "no-go" portion of the task will require the participants to withhold pressing the button when images of high-calorie foods are presented. The second go/no-go task will use the opposite instructions of the first task. Participants will be instructed to "go" or press a button when pictures of high-calorie foods are presented and to withhold, or "no-go", when the images of the low-calorie foods are presented, the high-calorie foods will be the target stimuli. Images for both tasks will be presented random order using 150 pictures displayed for 500 ms with an inter-trial interval of 1300 ms. Participants will be instructed to remain as still as possible and to minimize their eye blinks to reduce the amount of artifacts (disruptions or noise) while EEG data is recorded.

To further examine the effects of moderate intense physical activity on response inhibition, participants will be given several food choices while completing an auditory verbal learning test, the Rey auditory verbal learning test (AVLT). The Rey AVLT will be administered according to the protocol validated by Vakil et al which is described previously. After the 6th trial of the Rey AVLT, participants will be given 30 minutes before the final portions of the learning test to consume high and low energy dense foods ad-libitum. During the 30 minute delay period, foods which have been pre-measured and weighed to the nearest 0.1 gram beforehand will be given to each participant as they wait for the delay period of the Rey AVLT. High calorie foods will include high energy dense food items. Low calorie foods will include low energy dense food items, such as fruit slices and vegetables. The test will include 8 trials and allow appropriate time for participants to consume pre-measured foods. Completion of the Rey AVTL test will conclude the entire session.

After completion of the first video gaming session, participants will return after 7 days to complete the second video gaming session. Participants will be contacted 24 hours before their second video gaming session to remind participants of the upcoming testing session. Participants who complete both video gaming sessions and the accompanying tests will receive $40 dollars for completing the study.

Power Analysis. The number of participants was estimated based on a meaningful shift in N2 amplitudes. Since exercise has been shown to have a moderate effect on neural responses to food cues among adults, an estimated mean difference of 0.50 microvolts was used. A mean standard error of 0.63 microvolts was also used in this analysis based on previous research which helped establish a test-retest reliability of N2 amplitudes using EEG techniques.197 Thus, based on a mean N2 difference of 0.5 microvolts, a mean standard error of 0.63 microvolts and an alpha of 0.05, a sample of 55 participants is needed to have 90% power. In addition, based on previous experience measuring ERPs we expect to lose 10% of the EEG measurements due to poor or incomplete data. To account for this loss we will recruit an extra 7 participants, for a total of 62 total participants.

Statistical Analysis. Analysis will be completed using SAS statistical software (version 9.4; SAS Institute, Inc. Cary NC). Participant data will be reported as means and standard deviations. To evaluate the main and interaction effects within each subject, a 2-condition (active and passive) x 2-neural inhibition (Go and No/Go) x 2-calorie (high calorie and low calorie) repeated measures ANOVA will be used. An alpha level of 0.05 will be used for this analysis. Post hoc t-tests will be performed if significant effects are observed to identify significant differences. Bonferroni adjustments will be conducted for multiple comparisons.