Fig. 5: Fos plume and mapping of DAMGO microinjection in the OT anteromedial hotspot.

A Representative photomicrograph showing local Fos plumes surrounding the cannula tip within the OTam hotspot. B Average size of Fos plumes. DAMGO, n = 6 rats; vehicle, n = 6 rats. D dorsal, M medial, V ventral, L lateral. C Remapping of hedonic function localization (from Fig. 2A) within the OTam revealed by DAMGO microinjections, with symbol size reflecting the average radius of Fos plumes. Each symbol represents the putative cannula tip location for an individual rat plotted on a coronal brain atlas [30]. Symbol color indicates within-subject behavioral changes in hedonic reactions induced by DAMGO, expressed as percent change from vehicle (ACSF) control levels in the same rat (‘liking’ enhancement: red–yellow). D Distant Fos recruitment following DAMGO microinjection into the OTam hotspot. Brain map illustrates increased Fos cell density in mesocorticolimbic structures recruited for hedonic enhancement. Colors denote significant percent Fos elevation relative to vehicle control rats. Significant Fos increases were observed in other hedonic hotspots, including the caudal VP and rostromedial OFC. Fos elevation was also recruited in other limbic regions, such as rostral VTA, arcuate nucleus of the hypothalamus, and medial amygdala. DAMGO, n = 6 rats; vehicle, n = 6 rats. Bar graphs show mean ± SEM of percent Fos enhancement in each structure relative to vehicle controls. p values are calculated using Weltch’s t test. Corresponding FDR-adjusted q values are provided in Table S1.