The overall objective is to characterize the developmental characteristics of MRI measured neural flexibility, as an index of cognitive flexibility, in Chinese toddlers (32 to 42 months old).

The primary objective of this clinical study is to characterize in Chinese toddlers ages 32 - 42 months old the developmental characteristics of MRI measured neural flexibility, as an index of cognitive flexibility, and to assess a range of executive functions (inhibit, shift, emotional control, working memory, plan/organize) using the Global Executive Composite summary score obtained from the BRIEF-P standardized rating scale.

Inclusion Criteria:

1. Written informed consent has been obtained from the parent/legally acceptable representative.
2. Full-term birth (≥ 37 weeks and ≥ 2.5kg)
3. Typically developing Children aged between 32-34 months (2 years 8 months to 2 years10 month of age) at enrolment
4. Neurotypical development as assessed by interview
5. No major risk factors for learning, neurologic, or psychiatric disorder as assessed by interview [defined as a diagnosed learning neurologic or psychiatric disorder in a first degree relative (e.g. parents, siblings)].
6. Dietary requirement detailed below:

S-26 GOLD or ULTIMA GUM--fed group:

I. Daily consumption of S-26 GOLD or ULTIMA GUM for the last 60 days (2 months) II. Desire of the parent to continue feeding GUM during the course of the study

Cow's milk-fed group:

I. Daily consumption of cow's milk or for the last 60 days (2 months) II. Desire of the parent to continue feeding cow's milk during the course of the study

Exclusion Criteria:

1. Delayed birth ( > 41 weeks gestation) as reported in medical record
2. Birth Weight < 2500 g or small for gestational age (birth weight below the 10th percentile) or large for gestational age (birth weight above the 90th percentile) as reported in medical record
3. History of neurological (e.g., head injury, epilepsy), psychiatric or developmental disorder in the toddler as assessed by interview
4. History of diagnosed neurological (e.g., head injury, epilepsy), psychiatric or developmental disorder in parents or siblings, as assessed by interview
5. In utero exposure to alcohol abuse or illicit substances as defined as diagnosis of current substance use disorder in the biological mother and guidelines set by the American College of Obstetricians and Gynecologists and the Royal College of Physicians
6. Multiple birth as reported in medical record
7. Complicated pregnancy (e.g., preeclampsia, gestational diabetes) as assessed by medical interview/ medical record
8. Abnormal screening laboratory values and studies considered to be clinically significant in the opinion of the Investigator (e.g., metabolic disease screening, neonatal bilirubin)

Healthy normal developing Chinese toddlers; minimum number of subjects with successful MRI scans at enrolment and age 42 months: N=60 (≈ 30 fed on S-26 GOLD/ ULTIMA growing-up milk (GUM) and ≈30 fed on cows' milk) with key inclusion as daily consumption of the S-26 GUM or cow's milk for the last 60 days (2 mo).