Brain-to-brain synchrony predicts long-term memory retention more accurately than individual brain measures

Abstract

Little is known about the brain mechanisms that underpin how humans learn while interacting with one another in ecologically-valid environments (1-3). This is because cognitive neuroscientists typically measure one participant at a time in a highly constrained environment (e.g., inside a brain scanner). In the past few years, researchers have begun comparing brain responses across individuals (4-6) demonstrating that brain-to-brain synchrony can predict subsequent memory retention (7-9). Yet previous research has been constrained to non-interacting individuals. Surprisingly, the one study that was conducted in a group setting found that brain synchrony between students in a classroom predicted how engaged the students were, but not how much information they retained (10). This is unexpected because brain-to-brain synchrony is hypothesized to be driven, at least partially, by shared attention (11, 12), and shared attention has been shown to affect subsequent memory (13). Here we used EEG to simultaneously record brain activity from groups of four students and a teacher in a simulated classroom to investigate whether brain-to-brain synchrony, both between students and between the students and the teacher, can predict learning outcomes (Fig. 1A). We found that brain-to-brain synchrony in the Alpha band (8-12Hz) predicted students delayed memory retention. Further, moment-to-moment variation in alpha-band brain-to-brain synchrony discriminated between content that was retained or forgotten. Whereas student-to-student brain synchrony best predicted delayed memory retention at a zero time lag, student-to-teacher brain synchrony best predicted memory retention when adjusting for a [~]200 millisecond lag in the students brain activity relative to the teachers brain activity. These findings provide key new evidence for the importance of brain data collected simultaneously from groups of individuals in ecologically-valid settings.\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=173 SRC=\"FIGDIR/small/644047v2_fig1.gif\" ALT=\"Figure 1\">\nView larger version (43K):\norg.highwire.dtl.DTLVardef@21b335org.highwire.dtl.DTLVardef@7c9823org.highwire.dtl.DTLVardef@1e84b1dorg.highwire.dtl.DTLVardef@19b6f55_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1.C_FLOATNO Experimental setup and timeline. (A) Four students and a teacher were concurrently measured with EEG during a science lesson; (B) The lesson comprised four mini-lectures, each followed by a post-test. Pre-test and delayed post-tests were administered one week prior to and one week following the EEG recording session.\n\nC_FIG HighlightsO_LIElectroencephalogram (EEG) was concurrently recorded in a simulated classroom from groups of four students and a teacher.\nC_LIO_LIAlpha-band (8-12Hz) brain-to-brain synchrony predicted students performance in a delayed post-test.\nC_LIO_LIMoment-to-moment variation in alpha-band brain-to-brain synchrony indicated what specific information was retained by students.\nC_LIO_LIWhereas student-to-student brain synchrony best predicted learning at a zero time lag, student-to-teacher brain synchrony best predicted learning when adjusting for a [~]200 millisecond lag in the students brain activity relative to the teachers brain activity.\nC_LI