For VC to show a differential adaptation response means that the subjective scene representations, including the extended aspects of scenes, must be made available to this region before the onset

of the second scene via some top–down influence. In order to investigate this, and given the hippocampal results noted above, we applied a DCM analysis to the neural dynamics of the HC and early VC during the presentation of the first scene. If the HC was actively involved in updating the visual representations including the extended scenes in line with subjective UK-371804 perception, then we would expect to find evidence for modulation of VC activity by the HC on those trials where BE occurred. This model was compared to two alternative models (modulation of HC activity by VC, and bidirectional modulation). Backward modulation of VC by the HC was the winning model (exceedance probability of 97%), with robust results across both hemispheres ( Fig. 7). These findings therefore confirm that activity in early VC was modulated by the HC when the BE effect occurred, and that this happened during or shortly after the initial stage of scene extrapolation. BE is an intriguing scene-specific phenomenon whereby people reliably remember

seeing more of a scene than was present in the physical input, because they KU-60019 solubility dmso extrapolate beyond the borders of the original stimulus (Intraub and Richardson, 1989). By embedding the scene that is currently being viewed into a wider context, this supports the experience of a continuous and coherent world, and is therefore highly adaptive. Here we found that this extrapolation of scenes occurred rapidly around the time a scene was first viewed, and was associated with engagement of the HC and PHC. Notably, we found that the HC in particular seemed to drive the BE effect, exerting top–down influence on PHC and indeed as far back down the processing stream Histamine H2 receptor as VC. Subsequently, these cortical regions

displayed activity profiles that tracked trial-by-trial subjective perception of the scenes, rather than physical reality, thereby reflecting the BE error. BE is well-characterised cognitively (Intraub, 2012; Hubbard et al., 2010), but surprisingly little is known about its neural substrates. The only two previous neuroscientific studies of BE implicated different brain areas, the PHC and RSC in Park et al. (2007), and the HC in Mullally et al. (2012). Our results reconcile and extend these studies. By focussing specifically, and for the first time, on the initial stage of BE (the BE effect) the point of the extrapolation of scenes, we found that the HC was central to this process, in line with the results of Mullally et al. (2012) where focal bilateral hippocampal damage resulted in attenuated BE. The hippocampal response we observed was manifested rapidly during or just after the initial exposure to a scene and, importantly, before the second presentation of the scene.