Lateral posterior parietal activity during reality monitoring discriminations of memories of high and low perceptual vividness

Abstract

Regions of the lateral posterior parietal cortex (PPC) tend to be more active during recognition of previously studied items compared to correct rejection of unstudied items. Previously, we demonstrated that this effect is sourcespecific. While items that were encoded through visual perception elicited robust successful retrieval activity in the lateral PPC during a subsequent source memory test, items that were visually imagined did not elicit this effect. Memories of perceived events typically contain more perceptually-based contextual details than memories of imagined events. Therefore, source-based differences in lateral parietal activity might be due to a difference in the perceptual vividness of memories of perceived and imagined events. The goal of the present study was to test this hypothesis. Participants perceived and imagined items in both high and low perceptual vividness conditions. Experiment 1 demonstrated that memories for items encoded in the high vividness conditions contained significantly greater visual detail than memories encoded in the low vividness conditions. In Experiment 2, participants were scanned while they made source memory judgments about items that were previously perceived and imagined in high and low vividness conditions. Consistent with previous findings, the left lateral PPC was more active during retrieval of perceived compared to imagined events. However, lateral PPC activity did not vary according to vividness, suggesting that source effects in this region cannot be explained by a difference in the perceptual vividness of memories encoded through perception versus imagination.

Unbalanced Occlusion Modifies the Pattern of Brain Activity During Execution of a Finger to Thumb Motor Task

“…On these basis, it could be proposed that, during a finger to thumb task performed in Bite OFF, subjects have to produce a larger imagery effort in order to perform the movement, leading to a higher activation of structures involved in visual image recognition. According to this hypothesis, significant clusters described in the present study are activated during visual imagery (Nakao et al, 2011), visual memory load (Rahm et al, 2014), but also during visuospatial processing (Grabner et al, 2009; King and Miller, 2014), hand movement (Macaluso et al, 2007), trajectory prediction (Olsson and Lundström, 2013) and discomfort perceptions (Ogino et al, 2007). Finally, on the left side, activity has been observed also during clenching (Wong et al, 2011).…”