Neuropsychologia
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In several previous behavioral studies, we have identified a group of amnestic patients that, behaviorally, appear to exhibit severe deficits in recollection with relative preservation of familiarity-based recognition. However, these studies have relied exclusively on behavioral measures, rather than direct measures of physiology. Event-related potentials (ERPs) have been used to identify putative neural correlates of familiarity- and recollection-based recognition memory, but little work has been done to determine the extent to which these ERP correlates are spared in patients with relatively specific memory disorders. ⋯ The current patients were able to discriminate between old and new items fairly well, but showed nearly chance-level performance at source recognition. Moreover, whereas control subjects exhibited ERP correlates of memory that have been linked to recollection and familiarity, the patients only exhibited the mid-frontal FN400 ERP effect related to familiarity-based recognition. The results show that recollection can be severely impaired in amnesia even when familiarity-related processing is relatively spared, and they also provide further evidence that ERPs can be used to distinguish between neural correlates of familiarity and recollection.
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Facial expressions are one of the most important ways to communicate our emotional state. In popular culture and in the scientific literature on face processing, the eye area is often conceived as a very important - if not the most important - cue for the recognition of facial expressions. In support of this, an underutilization of the eye area is often observed in clinical populations with a deficit in the recognition of facial expressions of emotions. ⋯ However, we found an underutilization of the eye area by human participants in comparison to the ideal observer. We then demonstrated that the mouth area contains the most discriminative motions across expressions. We propose that the greater utilization of the mouth area by the human participants might come from remnants of the strategy the brain has developed with dynamic stimuli, and/or from a strategy whereby the most informative area is prioritized due to the limited capacity of the visuo-cognitive system.
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A short period of prism adaptation (PA) has been shown to reduce spatial neglect symptoms. Recent evidence suggests that the positive effects of PA might be restricted to visually guided actions, with PA having little effect on perception. However, the majority of studies have adopted a concurrent exposure technique that fosters the development of a change in felt arm position (proprioceptive straight ahead, PSA). ⋯ In line with the previous research, concurrent exposure produced a large shift in PSA and a shift on the manual line bisection task. Interestingly, terminal exposure produced a large shift in VSA and a shift in performance on the perceptual line bisection task. Our results shed light on the underlying mechanisms of prism-induced neglect recovery and help to address an apparent discrepancy within the literature.
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In this training study, we aimed to selectively train participants' filtering mechanisms to enhance visual working memory (WM) efficiency. The highly restricted nature of visual WM capacity renders efficient filtering mechanisms crucial for its successful functioning. Filtering efficiency in visual WM can be measured via the lateralized change detection task with distractors. ⋯ However, these improvements did not transfer to improved filtering mechanisms in the change detection task. Instead, we obtained suggestive evidence for an overall improvement in filtering mechanisms in the change detection task for both the training and control group. Apparently, there exist differences in the exact nature of filtering mechanisms that operate in change detection and MOT.
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Whether an agent receives positive task feedback or a monetary reward, neural activity in their striatum increases. In the latter case striatal activity reflects extrinsic reward processing, while in the former, striatal activity reflects the intrinsically rewarding effects of performing well. There can be a "hidden cost of reward", which is a detrimental effect of extrinsic on intrinsic reward value. ⋯ The quality of performance does not significantly influence dorsal striatum activity. In conclusion, our results indicate that the dorsal striatum is primarily sensitive to optional or actually received external rewards, whereas the ventral striatum may be coding intrinsic reward due to positive performance feedback. Thus the ventral striatum is suggested to be involved in the processing of intrinsically motivated behavior.