Poster Session A, Saturday, March 23, 1:30 pm - 3:30 pm, Pacific Concourse
Scene complexity visual alpha modulations facilitate memory development
Qin Yin1, Elizabeth L. Johnson1,2, Lingfei Tang1, Eishi Asano1, Noa Ofen1,3; 1Wayne State University, 2University of California, Berkeley, 3Weizmann Institute of Science, Rehovot, Israel
Maturation of high-level visual regions is associated with developmental gains in the encoding of complex visual stimuli such as scenes. However, it is unknown whether low-level visual processing in the occipital cortex supports the development of memory for visual stimuli. Alpha rhythms are the most prominent feature in occipital regions and have been shown to support visual processing. We provide rare intracranial evidence from 21 subjects (6.2-20.5 years) undergoing direct cortical monitoring (ECoG) for seizure management, which reveals that occipital alpha activity during visual processing supports memory formation in children. Subjects studied pictures of scenes classified as high- or low-complexity defined by the number of unique object categories, in preparation for a recognition test. Recognition accuracy for high-complexity, but not low-complexity, scenes increased with age. Peak alpha frequencies (9.6 ± 2.0, mean ± SD) were calculated per-subject across all occipital electrodes (n = 99) using fast Fourier transform, and task-induced alpha power time-series were analyzed using Hilbert-bandpass for each 3-s scene encoding trial, z-scored on a 300-ms pre-stimulus baseline via statistical bootstrapping. Outputs were tested on the group level using linear mixed-effects models and ANCOVA. Task-induced alpha increases were lower for high-complexity than for low-complexity scenes. Critically, complexity effects in select epochs were sensitive to individual differences in age and recognition accuracy. Subsequent memory effects were observed for high-complexity but not low-complexity scenes. A complementary analysis of 6-20-Hz time-frequency representations revealed consistent results of complexity and subsequent memory effects. These results suggest that visual alpha supports memory formation in children.
Topic Area: LONG-TERM MEMORY: Development & aging