Exploring the Role of Theta-Gamma Coupling in Working Memory Tasks: A Study on N-Back, Digit Span, and Corsi Span Performance

Theta-Gamma Coupling (TGC) has been identified over the past decade as a stable biomarker of information ordering during the performance of working memory tasks, such as the N -back task. Previous research also suggests that reducing prefrontal cortical theta phase-gamma amplitude coupling (TGC) is an early indicator of cognitive impairment. This study aimed to reaffirm the relationship between TGC and accuracy during the N-back working memory task and to establish a relationship between TGC and performance in a healthy population during the Digit Span and Corsi Span working memory tasks, which require ordering information in different formats. Thirty-six healthy participants (18 males and 18 females; mean age: 23.64, SD: 3.85) were recruited. The results of this study demonstrate a statistically significant positive correlation between TGC and performance across all three tasks using Spearman's and Pearson's correlation analyses. Results: N-back-Spearman's correlation <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\rho=0.46,p= 0.006)$</tex>, Pearson's correlation (p= 0.37, p = 0.033); Digit Span task-Spearman's correlation <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\rho= 0.56, p = 0.001)$</tex>, Pearson's correlation <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\rho=0.51,p= 0.014)$</tex> and Corsi-Span task-Spearman's correlation <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\rho=0.44, p=0.016)$</tex>, Pearson's correlation <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\rho=0.46,\ \mathrm{p}=0.004)$</tex>. Moreover, no statistically significant differences were found in TGC for all three tasks based on Gender. Conclusion: The results of this study provide direct evidence of a relationship between Theta-Gamma Coupling and performance during working memory tasks that require information ordering, reaffirming its stability as a neurophysiological biomarker for working memory and its potential in detecting cognitive impairment.