Frontiers in Behavioral Neuroscience最新文献

Synthetic exendin-4 (EX4, exenatide), is a GLP-1 receptor agonist used clinically to treat glycemia in Type-2 diabetes mellitus. EX4 also promotes weight loss and alters food reward-seeking behaviors in part due to activation of GLP-1 receptors in the mesolimbic dopamine system. Evidence suggests that GLP-1 receptor activity can directly attenuate cue-induced reward seeking. Here, we tested the effects of EX4 (0.6, 1.2, and 2.4 μg/kg, i.p.) on incentive cue (IC) responding, using a task where rats emit a nosepoke response during an intermittent reward-predictive IC to obtain a sucrose reward. EX4 dose-dependently attenuated responding to ICs and increased the latencies to respond to the IC and enter the sucrose reward cup. Moreover, EX4 dose-dependently decreased the total number of active port nosepokes for every cue presented. There was no effect of EX4 on the number of reward cup entries per reward earned, a related reward-seeking metric with similar locomotor demand. There was a dose-dependent interaction between the EX4 dose and session time on the responding to ICs and nosepoke response latency. The interaction indicated that effects of EX4 at the beginning and end of the session differed by the dose of EX4, suggesting dose-dependent pharmacokinetic effects. EX4 had no effect on free sucrose consumption behavior (i.e., total volume consumed, bout size, number of bouts) within the range of total sucrose volumes obtainable during the IC task (~3.5 ml). However, when rats were given unrestricted access for 1 h, where rats obtained much larger total volumes of sucrose (~30 ml), we observed some dose-dependent EX4 effects on drinking behavior, including decreases in total volume consumed. Together, these findings suggest that activation of the GLP-1 receptor modulates the incentive properties of cues attributed with motivational significance.

Previous studies suggested that self-focused attention (SFA), implicated in social anxiety disorder (SAD), correlates with heightened activity in the right frontopolar area (rFPA), which is the right prefrontal cortex just behind the forehead. Transcranial static magnetic field stimulation (tSMS) is a non-invasive brain stimulation method capable of temporarily suppressing brain function beneath the magnet. We explored whether tSMS on individuals with tendencies toward SAD elicited (1) suppressing rFPA activation during the resting-state and (2) reducing SFA during a subsequent speech task. Twenty-three university students with social anxiety performed two speech tasks. Between tasks, the tSMS group received neodymium magnet stimulation while the sham group received fake magnet stimulation on the rFPA for 20 min. Resting-state rFPA activities was measured using functional near-infrared spectroscopy (fNIRS), while SFA (body sensations and observer perspective), field perspective, and detached mindfulness (DM) perspective were assessed via questionnaires during both speech tasks. The observer perspective means SFA to self-imagery from others’ viewpoint, while the field and DM perspectives mean appropriately focusing on the external environment. The results indicated that tSMS intervention decreased rFPA activity from pre- to post-intervention rest. Then, tSMS reduced SFA to bodily sensations and increased DM perspective from pre- to post-intervention speech, especially in those with high levels of social anxiety. Furthermore, tSMS enhanced the field perspective regardless of social anxiety tendency. The results suggest that tSMS may suppress overactivity in rFPA, reduce SFA to body sensation, and increase adaptive attention in highly socially anxious individuals. Our study suggests the possibility of the clinical application of tSMS for treating SAD.