Schedule of Events | Symposia

Postdoctorial Fellowship Award Winner

Distinct neurophysiological mechanisms of developing medial temporal lobe in human episodic memory

Poster Session B - Sunday, March 30, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Qin Yin¹, Elizabeth L. Johnson², Adam J. O. Dede², Robert T. Knight³, Eishi Asano^4,5, Noa Ofen^1,5; ¹University of Texas at Dallas, Dallas, TX, ²Northwestern University, Chicago, IL, ³University of California, Berkeley, CA, ⁴Children’s Hospital of Michigan, Detroit, MI, ⁵Wayne State University, Detroit, MI

Anterior and posterior regions of the medial temporal lobe (MTL) are posited to support memory differentially yet the neurophysiology of MTL functional heterogeneity in the developing MTL remains largely unknown. We utilized pediatric intracranial EEG from 19 subjects (5.9-20.5 years) who completed a scene recognition memory task to investigate the neurophysiology of memory formation in the anterior (aMTL) and posterior (pMTL) MTL. Analyses focused on high-frequency activity (HFA; 70-150Hz), low-frequency theta oscillations, and HFA-theta phase-amplitude coupling (PAC). HFA timing differed between pMTL and aMTL in that HFA peaked after scene onset in pMTL and around subjects’ encoding responses (indicating indoor/outdoor of a scene) in aMTL. Subsequent memory analysis revealed increased HFA in hit trials after scene onset primarily in pMTL; the increase positively correlated with memory performance. Theta oscillations were detected in both pMTL [hit, 7.59(7.73) Hz; miss, 7.61(2.89) Hz] and aMTL [hit, 7.23(6.10); miss, 7.11(5.78) Hz]. Moreover, theta was associated with memory performance. In pMTL, the frequency and performance association differed by age, such that higher frequency was associated with better performance in children but not in adolescents. In aMTL, higher frequency and lower bandwidth were associated with better performance, suggesting that a fine-tuned aMTL theta mechanism supports better memory, regardless of age. Increased PAC during hit trials was observed before subjects’ responses primarily in aMTL, evincing theta-associated mnemonic representations in aMTL. These findings highlight the respective contributions of pMTL and aMTL to exogenous and endogenous processes and reveal distinct neurophysiological underpinnings of human memory in the developing MTL.

Topic Area: LONG-TERM MEMORY: Development & aging