Is short-term memory capacity (7±2) really predicted by theta to gamma cycle length ratio?

• Published in: Behavioural brain research Vol. 414; p. 113465
• Main Authors: Malenínská, Kristýna, Rudolfová, Veronika, Šulcová, Kateřina, Koudelka, Vlastimil, Brunovský, Martin, Horáček, Jiří, Nekovářová, Tereza
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 24.09.2021
• Subjects: Adult; cross-frequency coupling; EEG; Female; gamma; Gamma Rhythm - physiology; Humans; Male; Memory, Short-Term - physiology; Models, Biological; phase-amplitude coupling; Psychomotor Performance - physiology; short-term memory capacity; theta; Theta Rhythm - physiology; Wechsler Scales; Young Adult; phase-amplitude coupling; theta; EEG; short-term memory capacity; gamma; cross-frequency coupling
• ISSN: 0166-4328; 1872-7549; 1872-7549
• DOI: 10.1016/j.bbr.2021.113465

•Gamma EEG waves were stable across two measurements, theta waves were not stable.•Theta/gamma ratio measured during rest is not correlated with performance in digit span task.•Theta/gamma ratio is not stable across two measurements in one individual Several studies suggest that EEG parameters, reflecting top-down processes in the brain, may predict cognitive performance, e.g. short-term memory (STM) capacity. According to Lisman and Idiart’s model, STM capacity is predicted by theta and gamma EEG waves and their ratio. This model suggests that the more periods of gamma band waves fit into one period of theta band waves, the more information can be stored. We replicated the study by Kaminski et al. (2011), which recorded spontaneous EEG activity and measured verbal STM capacity with a modified digit span task from the Wechsler battery. Our study included more subjects and two EEG recording sessions. We discuss the possible limits of EEG correlates of STM capacity as EEG parameters were not stable across the two measurements and no correlation was found between the theta/gamma ratio and performance in the digit span task.