Internal Consistency of Functional Magnetic Resonance Imaging and Electroencephalography Measures of Reward in Late Childhood and Early Adolescence

Abstract

Background: Abnormal neural response to reward is increasingly thought to function as a biological correlate of emerging psychopathology during adolescence. However, this view assumes such responses have good psychometric properties-especially internal consistency-an assumption that is rarely tested.

Methods: Internal consistency (i.e., spilt-half reliability) was calculated for event-related potentials (ERPs) and Blood Oxygen Level Dependent (BOLD) responses to monetary gain and loss feedback from the same sample of 8-14 year-old females (n=177). Internal consistency for ERPs (i.e. feedback negativity) and BOLD responses within the ventral striatum and medial/lateral prefrontal cortex to gain, loss, difference scores (gain-loss), and residual scores (gain controlling for loss) were compared. Moderation analyses were conducted to investigate whether internal consistency differed by age.

Results: ERP and BOLD responses to gain and loss feedback showed high internal consistency in all regions (Spearman Brown Coefficients (SB) ≥ 0.70). When considering difference and residual scores, however, responses showed lower internal consistency (SBs ≤ 0.50), with particularly low internal consistency for subtraction-based scores (SB ≤ 0.36). Age was not a significant moderator of split-half relationships, indicating similar internal consistency across late childhood to early adolescence.

Conclusions: Within the same subjects, high internal consistency was observed for both ERP and fMRI measures of response to gains and losses, which did not vary as a function of age. Moreover, excellent psychometric properties were evident even within the first half of the experiment. Difference scores were characterized by lower internal consistency, although regression-based approaches outperformed subtraction-based difference scores.

Keywords: Adolescence; Childhood; ERP; Internal consistency; Reward; fMRI.

Figure 1. EEG Split-Half Relationships

A) Head map of the SCOREs (difference in ERP to gain-loss) and wave forms of the ERP to gain, loss, and difference at FCz. Internal consistency was weak for the B) SCOREs, but strong for the ERP to C) gain and D) loss. Split-half reliabilities did not differ with age.

Figure 2. fMRI Split-Half Relationships by Age

For both the A) Medial Prefrontal Cortex (MPFC [6,63,3] black circle) and B) Right Ventral Striatum (R VS [13,7,−8] white circle) high internal consistency was observed for the response to gain feedback (top panels), but not for the difference in responses to gain versus loss feedback (gain-loss, bottom panels). Internal consistency did not differ with age for either region.