Neural substrates on the judgment of sequential benefits and losses.

People need to adapt to situations where they experience sequential benefits (or losses) to ensure survival. This study investigated the neural substrates involved in judgments of sequential benefits and losses. A total of 29 healthy volunteers participated in this study, in which they were asked to participate in a game of purchasing stocks while a magnetic resonance imaging scan was performed. This game had two main types of trials: (1) participants received four sequential financial benefits (or losses), and (2) participants received an equal amount of benefits (or losses) immediately. The results showed greater activation of the orbitofrontal cortex (OFC) when four benefits were received sequentially than when an equal amount of benefits was received immediately. This indicates that the OFC plays a crucial role in the process of mental integration of sequential benefits and interpretation of their valuations. It also showed greater activation of the dorsal striatum when four sequental losses were received than when an equal amount of losses was received immediately. However, it cannot be concluded that activation of the dorsal striatum reflects the differences between sequential and immediate losses, because previous studies have not confirmed this perspective. Therefore, it is necessary to clarify the function of the striatum in processing these losses.

The Role of the Left Inferior Frontal Gyrus in Introspection during Verbal Communication.

Conversation enables the sharing of our subjective experiences through verbalizing introspected thoughts and feelings. The mentalizing network represents introspection, and successful conversation is characterized by alignment through imitation mediated by the mirror neuron system (MNS). Therefore, we hypothesized that the interaction between the mentalizing network and MNS mediates the conversational exchange of introspection. To test this, we performed hyperscanning functional magnetic resonance imaging during structured real-time conversations between 19 pairs of healthy participants. The participants first evaluated their preference for and familiarity with a presented object and then disclosed it. The control was the object feature identification task. When contrasted with the control, the preference/familiarity evaluation phase activated the dorso-medial prefrontal cortex, anterior cingulate cortex, precuneus, left hippocampus, right cerebellum, and orbital portion of the left inferior frontal gyrus (IFG), which represents introspection. The left IFG was activated when the two participants' statements of introspection were mismatched during the disclosure. Disclosing introspection enhanced the functional connectivity of the left IFG with the bilateral superior temporal gyrus and primary motor cortex, representing the auditory MNS. Thus, the mentalizing system and MNS are hierarchically linked in the left IFG during a conversation, allowing for the sharing of introspection of the self and others.

Neural substrates of shared visual experiences: a hyperscanning fMRI study.

Sharing experience is a fundamental human social cognition. Since visual experience is a mental state directed toward the world, we hypothesized that sharing visual experience is mediated by joint attention (JA) for sharing directedness and mentalizing for mental state inferences. We conducted a hyperscanning functional magnetic resonance imaging with 44 healthy adult volunteers to test this hypothesis. We employed spoken-language-cued spatial and feature-based JA tasks. The initiator attracts the partner's attention by a verbal command to a spatial location or an object feature to which the responder directs their attention. Pair-specific inter-individual neural synchronization of task-specific activities was found in the right anterior insular cortex (AIC)-inferior frontal gyrus (IFG) complex, the core node of JA and salience network, and the right posterior superior temporal sulcus, which represents the shared categories of the target. The right AIC-IFG also showed inter-individual synchronization of the residual time-series data, along with the right temporoparietal junction and dorsomedial prefrontal cortex-the core components for mentalization and the default mode network (DMN). This background synchronization represents sharing the belief of sharing the situation. Thus, shared visual experiences are represented by coherent coordination between the DMN and salience network linked through the right AIC-IFG.