Objective: To study the neurocognitive profile and its relationship to prefrontal dysfunction in non-demented Parkinson's disease (PD) with deficient haptic perception. Methods: Twelve right-handed patients with PD and 12 healthy control subjects underwent thorough neuropsychological testing including Rey complex figure, Rey auditory verbal and figural learning test, figural and verbal fluency,...

Substantial evidence suggests that the phasic activities of dopaminergic neurons in the primate midbrain represent a temporal difference (TD) error in predictions of future reward, with increases above and decreases below baseline consequent on positive and negative prediction errors, respectively. However, dopamine cells have very low baseline activity, which implies that the representation of...

Reversal learning tasks assess behavioral flexibility by requiring subjects to switch from one learned response choice to a different response choice when task contingencies change. This requires both the processing of negative feedback once a learned response is no longer reinforced, and the capacity for flexible response selection. In 2-choice reversal learning tasks, subjects switch between ...

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Background: Dorsolateral prefrontal cortex (DLPFC), posterior parietal cortex, and regions in the occipital cortex have been identified as neural sites for visual working memory (WM). The exact involvement of the DLPFC in verbal and non-verbal working memory processes, and how these processes depend on the time-span for retention, remains disputed. Methods: We used functional MRI to explore the...

Quantum Probability (QP) Theory provides an alternative account of empirical phenomena in decision making that Classical Probability (CP) cannot explain. Cognitive architectures combine probabilistic mechanisms with symbolic knowledgebased representations (e.g., heuristics) to address effects that motivate QP. They provide simple and natural explanations of these phenomena based on general cogn...

Abstract: In line with Dixon, Levine, Reicher & Durrheim's argument, I suggest that prejudice should be understood in broadly political rather than narrowly psychological terms. First, what counts as prejudice is a political judgement. Second, studies of collective action demonstrate that it is in 'political' struggles, where subordinate groups together oppose dominant groups, that prejudice ca...

Background: Numerous previous experiments have used oddball paradigm to study change detection. This paradigm is applied here to study change detection of facial expressions in a context which demands abstraction of the emotional expression-related facial features among other changing facial features. Methods: Event-related potentials (ERPs) were recorded in adult humans engaged in a demanding ...

Background: The genetic and molecular mechanisms of tameness are largely unknown. A line of silver foxes (Vulpes vulpes) selected for non-aggressive behavior has been used in Russia since the 1960's to study the effect of domestication. We have previously compared descendants of these selected (S) animals with a group of non-selected (NS) silver foxes kept under identical conditions, and showed...

Background: If all available acoustic phonetic information of words is used during lexical access and consequently stored in the mental lexicon, then all pseudowords that deviate in a single acoustic feature from a word should hamper word recognition. By contrast, models assuming underspecification of redundant phonological information in the mental lexicon predict a differential disruption of ...