The Cogni-Action Project: Physical Activity, Brain, and Cognition
Condition: Cognitive Function 1, Social
Study type: Interventional

Summary: 
      Education and health are crucial topics for public policies as both largely determine the
      future wellbeing of the society. Currently, several studies recognize that physical activity
      (PA) benefits brain health in children. However, most of these studies have not been carried
      out in developing countries or lack the transference into the education field.

      The Cogni-Action Project is a crossover-randomized trial. The aim of the study is to
      determinate the acute effects of three different training sessions consisting in (i)
      "Moderate-Intensity Continuous Training" (MICT), (ii) "Cooperative High-Intensity Interval
      Training" (C-HIIT), and (iii) sedentary activity on spontaneous brain activity and
      neuroelectric indices of cognitive performance during a working memory and a reading task, as
      measured by electroencephalography (EEG) and eye-tracker. In an energy expenditure
      counterbalanced fashion, 32 adolescents will randomly undergo each training session , two
      weeks apart.

      The main strength of this project is that, to our knowledge, this is the first study
      analysing the potential influence of PA, sedentarism, and physical fitness on brain structure
      and function, cognitive performance, and academic achievement in Latin-America and,
      specifically, in Chile which has been catalogued with an important sociocultural gap. For
      this purpose, this study will use advanced technologies in neuroimaging (MRI),
      electrophysiology EEG, and eye-tracking , as well as objective and quality measurements of
      several physical and cognitive health outcomes.
    

Detailed description: 
      Regarding the study (i.e., crossover-randomized trial), children will be randomized to each
      protocol session, participating in all of them with two-weeks apart . Thus, they will assist
      to our gym to perform one of the three protocol and subsequently they will be move to a
      laboratory where they will undergo EEG and eye-tracking measurements during resting state
      condition and during two different cognitive tasks More details can be found in following
      sections.

      The design of the project will consist of a counterbalanced cross-over trial where the
      participants will perform, on different days, three different PA training protocols in a
      random order. Each child will visit our laboratory three times, every two weeks to ensure a
      "wash-out" period with the purpose of mitigating the PA effect from each protocol.
      Participants will assist to the three different sessions at the same weekday (e.g., Monday)
      and at the same daytime to avoid differences in preceding school activities or circadian
      rhythms. Participants will undergo a "Sedentary condition" (SC), sitting and watching a
      documentary on TV as has been used previously, and two different PA protocols consisting in
      "Moderate-Intensity Continuous Training" (MICT), i.e., continuous outdoor walking, and
      "Cooperative High-Intensity Interval Training" (C-HIIT), composed of a circuit training with
      a partner (physical education teacher). These three protocols have been chosen in view of
      what corresponds to types of activities usually performed in schools. Thus, SC mimics the
      time spent during any academic lesson (i.e. mathematics or language lessons); MICT represents
      the typical activity in a PE class; and C-HIIT has been selected since it is postulated as an
      exercise protocol that could possibly be implemented in the PE class. The three protocols are
      designed so that energy expenditure is equivalent between them, to eliminate differences in
      the energy expenditure as a possible confounding factor. The energy expenditure calculation
      protocol is detailed on supplementary material.

      After each PA protocol, the participants will undergo EEG and eye-tracking measurements as
      follows: 1st, resting state spontaneous brain activity will be assessed during 3 min with EEG
      only, and subsequently, eye-tracking will be registered in parallel with EEG while
      participants perform the cognitive tasks (a working memory task and a reading task). The
      measurements will start between 20 to 25 minutes after the end of each condition. In this
      way, we will emulate a school recess in the Chilean context, before the start of the next
      subject. All measures will be carried out in the "Laboratorio Lenguaje & Cognición ELV",
      which belongs to the Literature and Language Sciences Institute of the Pontificia Universidad
      Católica de Valparaíso. To avoid subjective influence of evaluator, when the participants go
      to the laboratory, the evaluator will be blinded according to which PA protocol participants
      performed.

      Neuroelectric and eye-tracker measurements EEG measurement: A B-Alert X24 device for EEG
      (Advanced Brain Monitoring, California, United States) will be used, which consists of 24
      active electrodes that minimize the noise of electrical devices outside the biological
      processes of interest, ensuring good signal quality. Two channels will be used to register
      electrooculographic activity, to better discriminate between true electroencephalographic and
      electrooculographic activity associated with eye movement and blinking. Recordings will be
      done at a sampling rate of 256 values per second, with a band-pass filter between 0.1 - 100
      Hz, and a notch filter of 50 Hz to eliminate the noise of the surrounding alternating current
      in the room. It should be noted that this equipment is wireless, which makes it more
      convenient and faster to mount on participants. For this study the investigators will focus
      on the channels Fz, Cz, CPz, Pz, POz, Oz, O1 and O2.

      Eye-tracker: A Tobii Pro TX300 (Tobii, Stockholm, Sweden) will be used to track eye movements
      directly through a light sensitive camera near the infrared spectrum. This equipment studies
      the visuomotor characteristics during the process of reading and the trajectories of the look
      around each word. In addition, it will serve to define the exact moments at which these words
      are read and thus be able to synchronize the EEG record to calculate an average signal (N400)
      that reflects the brain's processing of language. The same device records raw values of pupil
      size (diameter), saving all data with a sampling rate of 300 Hz.

      Cognitive tasks during neuroelectric and eye-tracker measurements Working memory task. A
      N-back task will be run through E-Prime 2.0 software synchronized with the
      electroencephalographic recording system and the eye-tracker, to measure neuroelectric
      activity and pupil size diameter time-locked to the presentation of each stimulus (targets
      and non-targets). The protocol is very similar to the one previously explained for the 0-back
      and 2-back conditions during fMRI assessment. The main difference of the present task with
      respect to the fMRI's N-back task is that children must press in the keyboard the number "1"
      when they detect a target stimulus or the number "2" for non-targets. This type of task
      generates an EEG potential related to cognitive processing, characterized by a positive
      deflection that peaks roughly around 300 ms (P300), which has been widely studied in various
      types of tasks that require conscious attention, in any perceptual modality. In other words,
      it is a potential related to events that are consciously perceived, which does not depend on
      the stimulated perceptual path, but rather on the need to reallocate cognitive resources and
      develop appropriate responses according to the ever-changing context. To isolate the EEG
      patterns of P300 in working memory, the investigators will subtract to the result of a 2-back
      task, the one of a 0-back. The P300 event-related potential is expected to emerge especially
      in the average EEG signal time-locked to the onset of detected targets stimuli. Artifacts
      such as electrooculographic signals will be subtracted from the data with an algorithm
      implemented in EEGLAB, an EEG analysis toolbox running in MATLAB (Mathworks®). Manual
      rejection of single trials will be considered based on visual inspection of artifacts in
      data.

      Reading task. Language processing will be assessed by a reading comprehension task where
      short paragraphs will be presented to be read normally. The eye-tracking technique will be
      employed to record eye position, movement and pupil diameter, simultaneous to the EEG record.
      Participants will seat in front of a monitor, at approximately 60 cm, placing their chin on
      an ergonomic stand piece, which helps to decrease head movements and improves eye-tracker
      signal precision. The reading task will be presented with the latest version of Tobii Pro
      Lab. After calibrating the system, each child is given a brief contextualization of the
      topic, before they start to read, knowing that later they will be asked seven comprehension
      questions with varying degrees of complexity. The participants must indicate the correct
      answer among three alternatives. It should be noted that three literary texts will be used,
      presented in a random fashion (1 per exercise condition). These texts will have the same
      difficulty, the same distribution of areas of interest, similar amount of words, and will be
      previously validated by a panel of experts. The reading of each word is expected to generate
      an EEG negative potential with latency close to 400 ms (N400). The amplitude, topographic
      distribution and latency of this potential are electrophysiological neuromarkers of
      linguistic ability in general, and the ability to construct meaning from words. The
      eye-tracker will be used to study the ocular trajectory during reading and establish the
      moments when words are read. EEG and eye-tracking will be registered simultaneously to record
      eye movements related to reading, giving measures such as reading speed, fixation durations,
      number of fixations, among others), and to measure eye fixation related EEG potentials
      associated with cognitive load while reading words. The reader should note that this
      potential coincides experimentally with the N400, so they may represent different brain
      processes superimposed, or be essentially the reflection of the same mechanism.

      Primary outcomes in crossover acute counterbalanced study Resting state spontaneous brain
      activity. After the exercise protocol and before the cognitive tasks, spontaneous brain
      activity will be measured with EEG while children rest in a seated position, in order to
      measure the peak frequency and reactivity of the alpha wave. The dynamics of the alpha peak
      frequency (between 7 and 13 Hz) during a 3 minutes period will be calculated by means of a
      Hilbert transform. Then, an average value and trend of the alpha peak frequency will be
      calculated. It has been postulated that the higher the alpha peak frequency, the greater
      general cognitive capacity and processing speed are. The investigators focus on alpha waves
      because this brainwave has traditionally associated with different theories of attention and
      conscious perception. The frequency of the alpha wave has been discovered to increase after a
      session of cognitive tasks. Additionally, the power and frequency of alpha brainwaves prior
      to cognitive evaluation have been correlated to performance. If PA exerts a positive effect
      over cognitive performance, a single session of PA should also cause an increase in alpha
      peak frequency. In fact, this was found by Gutmann et al. in two consecutive studies.
      However, a statistical relation between PA-induced increments in alpha peak frequency and
      cognitive performance is missing.

      Working memory performance: Hits, misses, omissions, and accuracy will be calculated for
      targets and non-targets of the n-back task, as well as response latency.

      Reading comprehension: Seven questions with varying degree of comprehension complexity will
      be given after the texts are read. For every question there will be four alternatives to
      choose as the correct answer.

      Cognitive load: The investigators group several measures on this category because all of them
      have been related with the concept of cognitive load. The first two come from the EEG, and
      the other two from the eye-tracker.

      P300: The P300 event-related potential associated with the different type of stimulus in the
      n-back (target and non-target) will be quantified according to amplitude and latency of the
      peak.

      N400: This linguistics-related event-related potential also will be described according to
      latency and amplitude. Because it will be synchronized with the eye fixation on words during
      the reading task, it is conceptually a type of fixation-related potential.

      Rapid pupil size variations: Pupil reacts to cognitive requirements and it has been
      associated with increases in cognitive load during various tasks including working memory and
      reading. The amount of high frequency variations in pupil diameter is estimated by a novel
      Index of Cognitive Activity, which increases with cognitive load. This measure can be
      represented as a continuous variable in time thanks to the high sampling rate of the
      eye-tracker. The Index of Cognitive Activity will be measured during the n-back and reading
      tasks.

      Word Fixation times: The length of visual fixations also has been associated with the
      processing time that the brain dedicates to elaborate a cognitive interpretation of
      perception. Average and standard deviation of fixations around words will be calculated for
      the reading task.
    

Intervention name(s): physical activity
Intervention type(s): Behavioral
Intervention description(s): Participants will assist to the three different sessions at the same weekday (e.g., Monday) and at the same daytime to avoid differences in preceding school activities or circadian rhythms. Participants will undergo a "Sedentary condition" (SC), sitting and watching a documentary on TV as has been used previously, and two different PA protocols consisting in "Moderate-Intensity Continuous Training" (MICT), i.e., continuous outdoor walking, and "Cooperative High-Intensity Interval Training" (C-HIIT), composed of a circuit training with a partner (physical education teacher)
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: The Cogni-Action project presents a two-fold design with a cross-sectional investigation and a crossover-randomized trial. The aim of the first part is to establish the associations of physical activity (PA), sedentarism, and physical fitness with brain structure and function, cognitive performance and academic achievement in 797 Chilean schoolchildren. The aim of the second part is to determinate the acute effects of three different training sessions consisting in (i) "Moderate-Intensity Continuous Training" (MICT), (ii) "Cooperative High-Intensity Interval Training" (C-HIIT), and (iii) sedentary activity on spontaneous brain activity and neuroelectric indices of cognitive performance during a working memory and a reading task, as measured by electroencephalography (EEG) and eye-tracker. In an energy expenditure counterbalanced fashion, 32 adolescents will randomly undergo each training session, two weeks apart.
Masking: Single (Outcomes Assessor)
Primary purpose: Other
Keywords: Sedentary lifestyle; academic performance; aerobic fitness; electroencephalogram