The neural mechanism for the dyadic process of teaching is poorly understood. Although theories about teaching have proposed that before any teaching takes place, the teacher will predict the knowledge state of the student(s) to enhance the teaching outcome, this theoretical Prediction-Transmission hypothesis has not been tested with any neuroimaging studies. Using functional near-infrared spectroscopy-based hyperscanning, this study measured brain activities of the teacher-student pairs simultaneously. Results showed that better teaching outcome was associated with higher time-lagged interpersonal neural synchronization (INS) between right temporal-parietal junction (TPJ) of the teacher and anterior superior temporal cortex (aSTC) of the student, when the teacher's brain activity preceded that of the student. Moreover, time course analyses suggested that such INS could mark the quality of the teaching outcome at an early stage of the teaching process. These results provided key neural evidence for the Prediction-Transmission hypothesis about teaching, and suggested that the INS plays an important role in the successful teaching.

The neural mechanism for selectively tuning in to a target speaker while tuning out the others in a multi-speaker situation (i.e., the cocktail-party effect) remains elusive. Here we addressed this issue by measuring brain activity simultaneously from a listener and from multiple speakers while they were involved in naturalistic conversations. Results consistently show selectively enhanced interpersonal neural synchronization (INS) between the listener and the attended speaker at left temporal–parietal junction, compared with that between the listener and the unattended speaker across different multi-speaker situations. Moreover, INS increases significantly prior to the occurrence of verbal responses, and even when the listener’s brain activity precedes that of the speaker. The INS increase is independent of brain-to-speech synchronization in both the anatomical location and frequency range. These findings suggest that INS underlies the selective process in a multi-speaker situation through neural predictions at the content level but not the sensory level of speech.

Human beings organise socially. Theories have posited that interpersonal neural synchronisation might underlie the creation of affiliative bonds. Previous studies tested this hypothesis mainly during a social interaction, making it difficult to determine whether the identified synchronisation is associated with affiliative bonding or with social interaction. This study addressed this issue by focusing on the teacher–student relationship in the resting state both before and after a teaching period. Brain activity was simultaneously measured in both individuals using functional near-infrared spectroscopy. The results showed a significant increase in brain synchronisation at the right sensorimotor cortex between the teacher and student in the resting state after, but not before, the teaching period. Moreover, the synchronisation increased only after a turn-taking mode of teaching but not after a lecturing or video mode of teaching. A chain mediation analysis showed that brain synchronisation during teaching partially mediated the relationship between the brain synchronisation increase in the resting state and strength of the affiliative bond. Finally, both role assignment and social interaction were found to be required for affiliative bonding. Together, these results support the hypothesis that interpersonal synchronisation in brain activity underlies affiliative bonding and that social interaction mechanically mediates the bonding process.

Tanshinone I (Tan I), a diterpene quinone extracted from herbal medicine Salvia miltiorrhiza Bunge, has recently been reported to have antitumor effects. As the mechanism of its proapoptotic effects on human myeloid leukemia cells has not been extensively studied, we performed an in-depth evaluation of the effects of Tan I on apoptosis in human K562 and HL-60 cells. The results revealed that Tan I could inhibit the growth of leukemia cells and cause apoptosis in a time- and dose-dependent manner. Apoptosis was observed clearly by flow cytometry and Hoechst 33258 staining, as well as DNA fragmentation analysis. After treatment by Tan I for 48 h, the percentage of disruption of mitochondrial membrane potential (Δψm) was increased in a dose-dependent manner. Western blotting analysis demonstrated the cleavage of caspase-3 zymogen protein and a dose-dependent cleavage of poly-(ADP-ribose) polymerase. Tan I-induced apoptosis was accompanied by a significant decrease in survivin and an increase in Bax. Moreover, Tan I treatment remarkably downregulated the phosphorylation of both P85/PI3K and Akt in a time-dependent manner, and the PI3K/AKT-specific inhibitor (LY294002) mimicked the apoptosis-inducing effects of Tan I. We therefore conclude that the induction of apoptosis by Tan I in these leukemia cells is mainly related to the disruption of Δψm, the upregulation of Bax expression, and the activation of caspase-3. This process is highly correlated with the inactivation of PI3K/Akt/survivin signaling pathways. The results indicate that Tan I may serve as an effective adjunctive reagent in the treatment of leukemia.