4.1 Limitations
Our sample consisted of a relatively small sample size of children with cancer and results may reflect the unique neurobiology of this population. We used a within-subjects design and multi-echo fMRI imaging techniques to increase study power. Sampling limitations are attributed to the low base rate of childhood cancer, which precluded our ability to examine sex differences in neural or behavioral measures. However, the sample size in the present study (n = 12) is consistent with previously published neuroimaging studies in pediatric cancer survivors (e.g., n = 8, 15).55,56 We focused on children with cancer because this pediatric population is exposed to disease- and treatment-related stress, is at increased risk of emotion dysregulation,35 and because martial arts-based meditation programs have shown to be effective for reducing pain and emotional distress in this population.21,36 In addition, the relatively wide age span (5-17 years) is a limitation due to differences in functional connectivity in young children compared to older teenagers. Another limitation is that we examined two forms of meditation (i.e., focused attention, mindful acceptance) and one cognitive emotion regulation strategy (distraction), which may not be representative of all available emotion regulation techniques. In addition, we did not have a non-distressing (e.g., positively-valenced) condition to compare our activation patterns to, so it is unclear if the resulting neural activation patterns are specific to regulation of negative stimuli. Additionally, all participants had at least four hours of meditation instruction. Findings may differ based on meditation experience,17 as these techniques become more automatized. Therefore, future studies should examine different forms of meditation and the impact of meditation experience.