Prenatal Alcohol Exposure Alters Error Detection During Simple Arithmetic Processing: An Electroencephalography Study

Abstract

Background: Arithmetic is the domain of academic achievement most consistently related to prenatal alcohol exposure (PAE). Error detection, an important aspect of arithmetic processing, can be examined in a mathematical verification task. Electroencephalographic (EEG) studies using such tasks have shown bursts of synchronized theta-band activity in response to errors. We assessed this activity for error detection in adolescents with PAE and typically developing (TD) matched controls. We predicted that the PAE group would show smaller theta bursts during error detection and weaker responses depending on the size of the error discrepancy.

Methods: Participants' mothers were recruited during pregnancy and interviewed about their alcohol consumption using a timeline follow-back interview. Participants were followed from infancy and diagnosed for fetal alcohol syndrome (FAS) or partial FAS (PFAS) by expert dysmorphologists. EEGs were recorded for 48 adolescents during a verification task, which required differentiation between correct/incorrect solutions to simple equations; incorrect solutions had small or large deviations from correct solutions.

Results: Performance was good-excellent. The PAE group showed lower accuracy than the TD group: Accuracy was inversely related to diagnosis severity. The TD and heavily exposed (HE) nonsyndromal groups showed the expected differentiation in theta-burst activity between correct/incorrect equations, but the FAS/PFAS groups did not. Degree of impairment in brain response to errors reflected severity of diagnosis: The HE group showed the same differentiation between correct/incorrect solutions as TD but failed to differentiate between levels of discrepancy; PFAS showed theta reactions only in response to large error discrepancies; and FAS did not respond to small or large discrepancies.

Conclusions: Arithmetical error-related theta activity is altered by PAE and can be used to distinguish between exposed and nonexposed individuals and within diagnostic groups, supporting the use of numerical and quantitative processing patterns to derive a neurocognitive profile that could facilitate diagnosis and treatment of fetal alcohol spectrum disorders.

Keywords: Electroencephalography; Error Detection; Fetal Alcohol Spectrum Disorders; Fetal Alcohol Syndrome; Numerical Processing; Prenatal Alcohol Exposure.

Figure 1.

Sample trial from the computerized equation verification task. In each trial, participants were presented with a simple equation (see above “1 + 2 =”) followed by a delayed possible solution. The solution could be correct (e.g., “3”), incorrect by a deviation of 1 (L1; e.g., “4”) or by a deviation of 5 (L5; e.g., “8”). The delay between the onset of the equation and solution was designed to allow participants sufficient time to solve the equation before the solution appeared. EEG segmentation was locked to the solution presentation onset, and participants withheld their responses until prompted by the appearance of a question mark.

Figure 2.

ERSP (event related spectral perturbations) power for all groups (rows) and conditions (columns). (A) Topographical maps of low theta (4–5Hz) ERSP power in the 160–410ms post-stimulus time-window. The small circle indicates the group of 8 channels from which mean ERSP was measured. (B) Time-by-frequency plot, as measured from a group of 8 frontal channels. The white vertical line marks the stimulus onset, and the white box indicates the 160–410ms post stimulus time-window and the Low Theta (4–5Hz) frequency band in which mean power was measured.

Figure 3.

Mean ERSP (event related spectral perturbations) Power at low theta (4–5Hz) for each group and condition, controlling for mothers’ education. Error bars denote standard errors.