The heatmap shows results derived from partial correlation analyses where any one variable shown is predicted based on the other variables available. The column Brain serotonin, for example, refers to results of partial correlation analyses in the context of which brain serotonin concentrations were predicted based on plasma Trp concentrations, brain Trp concentrations, age, and diet. Numbers in parentheses refer topvalues and numbers not in parentheses to correlation coefficients. Brain serotonin concentrations were not significantly influenced by age and diet when accounting for plasma and brain Trp concentrations, suggesting that plasma and brain Trp concentrations can fully explain age and diet effects on brain serotonin concentrations.
