Neuropsychologia
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Comparative Study
Better or worse than expected? Aging, learning, and the ERN.
This study examined age differences in error processing and reinforcement learning. We were interested in whether the electrophysiological correlates of error processing, the error-related negativity (ERN) and the feedback-related negativity (FRN), reflect learning-related changes in younger and older adults. To do so, we applied a probabilistic learning task in which we manipulated the validity of feedback. ⋯ Importantly, we did not find evidence for an age-related reduction of the ERN, when controlling for performance differences between age groups, which questions the view that older adults are generally impaired in error processing. Finally, we observed a substantial reduction of the FRN in the elderly, which indicates that older adults are less affected by negative feedback and rely more on positive feedback during learning. This finding points to an age-related asymmetry in the processing of feedback valence.
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Clinical Trial Controlled Clinical Trial
Enhancing language performance with non-invasive brain stimulation--a transcranial direct current stimulation study in healthy humans.
In humans, transcranial direct current stimulation (tDCS) can be used to induce, depending on polarity, increases or decreases of cortical excitability by polarization of the underlying brain tissue. Cognitive enhancement as a result of tDCS has been reported. The purpose of this study was to test whether weak tDCS (current density, 57 microA/cm(2)) can be used to modify language processing. ⋯ No decreases in performance were detected. Our finding of a transient improvement in a language task following the application of tDCS together with previous studies which investigated the modulation of picture naming latency by transcranial magnetic stimulation (TMS) and repetitive TMS (rTMS) suggest that tDCS applied to the left PPR (including Wernicke's area [BA 22]) can be used to enhance language processing in healthy subjects. Whether this safe, low cost, and easy to use brain stimulation technique can be used to ameliorate deficits of picture naming in aphasic patients needs further investigations.
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Emotional stimuli can have beneficial effects on memory in healthy aged subjects and partly on patients with dementia. So far, no experimental study has explored the effects of memory for emotional stimuli in patients with mild cognitive impairment (MCI), a concept that describes a transitional state between normal aging and dementia. The present fMRI study explored working memory for emotional stimuli in 16 patients with amnestic MCI (aMCI) and 16 healthy aged participants. ⋯ The precuneus deactivation in healthy aged participants may indicate a disengagement of self-referential processes towards task-related processes. Patients with aMCI revealed a signal increase in the right precuneus for negative compared to neutral targets. This increase in precuneus activity, combined with a behavioural facilitation effect, may indicate a mechanism to compensate disease related processes in aMCI.
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Previous neuroimaging studies have identified a neural circuit that is involved in empathy for pain. However, the temporal dynamics of neural activities underlying empathic processes remains poorly understood. This was investigated in the current study by recording event-related brain potentials (ERPs) from healthy adults who were presented with pictures or cartoons of hands that were in painful or neutral situations. ⋯ The early and late empathic responses were, respectively, modulated by contextual reality of stimuli and by top-down attention to the pain cues. Moreover, the mean ERP amplitudes at 140-180 ms were correlated with subjective reports of the degree of perceived pain of others and of self-unpleasantness. The ERP results support a model of empathy for pain consisting of early emotional sharing and late cognitive evaluation.
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Case Reports Comparative Study
Phonological short-term store impairment after cerebellar lesion: a single case study.
The cerebellum is a recent addition to the growing list of cerebral areas involved in the multifaceted structural system that sustains verbal working memory (vWM), but its contribution is still a matter of debate. Here, we present a patient with a selective deficit of vWM resulting from a bilateral cerebellar ischemic lesion. After this acute event, the patient had impaired immediate and delayed word-serial recall and auditory-verbal delayed recognition. ⋯ The patient showed noticeably reduced scores in the tasks that primarily or exclusively engaged activity of the ph-STS, namely those of Experiment 3, and good performance in the tests that investigated the recirculation of verbal information. This pattern of results implicates the ph-STS as the cognitive locus of the patient's deficit. This report demonstrates a cerebellar role in encoding and/or strengthening the phonological traces in vWM.