1,721,013 research outputs found
Pramipexole in Parkinson's disease. A short-term study using the combined levodopa-dopamine agonist test
No full textThe aim of our study was to investigate the efficacy of pramipexole in advanced parkinsonian patients by means of an acute stimulation test. We studied the motor effects of pramipexole in fluctuating parkinsonian patients by comparing the response to acute levodopa with the response to levodopa + pramipexole. The adjunct of pramipexole to levodopa increased the time spent on from 136±22.3 to 186±20.6 minutes (p<0.01), while it did not change the latency to on, the magnitude of the motor improvement, or the duration and severity of dyskinesias. The main effect of pramipexole in fluctuating parkinsonian patients is an increased duration of the on phase
Overt and Covert Effects of Mental Fatigue on Attention Networks: Evidence from Event-Related Potentials during the Attention Network Test
Full text linkMental fatigue is a variation in the psychophysiological state that subjects encounter during or after prolonged cognitive activity periods, affecting top-down attention and cognitive control. The present study aimed to investigate the effects of mental fatigue on attention in the context of the three attention networks according to the Posnerian model (alerting, orienting, and executive networks) by combining the Attentional Network Test (ANT) and event-related potentials technique. Thirty healthy subjects were enrolled in the study. A continuous arithmetic task lasting one hour induced mental fatigue, and EEG recordings were conducted before and after the task while subjects were performing the ANT. The efficiencies of three networks were comparable between groups, while RTs shortened only in the control group and the accuracy related to the alerting and conflict networks declined only after mental effort. Mental fatigue reduced N1 amplitude during alerting network engagement and p3 amplitude during orienting. It also reduced N2 and P3 amplitude during the conflict, particularly the incongruent target-locked response. These findings underscore the covert effects of mental fatigue on attention, suggesting that even in healthy young subjects, compensatory mechanisms may maintain adequate overt performances, but fatigue still has a detrimental effect on top-down attentional mechanisms
The Cerebellum Modulates Attention Network Functioning: Evidence from a Cerebellar Transcranial Direct Current Stimulation and Attention Network Test Study
No full textThe functional domain of the cerebellum extends beyond its traditional role in motor control. In recent years, this structure has increasingly been considered to play a crucial role even in cognitive performance and attentional processes. Attention is defined as the ability to appropriately allocate processing resources to relevant stimuli. According to the Posnerian model, three interacting networks modulate attentive processes: the alerting, orienting, and executive networks. The aim of this study was to investigate the role played by the cerebellum in the functioning of the attentive networks using the Attention Network Test (ANT). We studied the effects of transcranial direct current stimulation (tDCS), delivered over the cerebellum in cathodal, anodal, and sham sessions, on ANT parameters in healthy subjects. After anodal and sham tDCS, the efficiency of the three attention networks remained stable, and a significant reduction in reaction time (RT) following the task repetition was observed for both congruent and incongruent targets, indicating a learning effect. After cathodal stimulation, instead, while the efficiency of the alerting and orienting networks remained stable, the efficiency of the executive network was significantly reduced. Moreover, a significant reduction in RT was observed for the congruent target alone, with no difference being detected for the incongruent target, indicating that cerebellar inhibition caused an attentive executive dysfunction specifically related to the ability to process complex stimuli in which conflict signals or errors are present. These results point to a role of the cerebellum, a subcortical structure that is thought to affect error processing both directly, by making predictions of errors or behaviors related to errors, and indirectly, by managing the functioning of brain cortical areas involved in the perception of conflicting signals, in the functioning of the attentional networks, particularly the executive network
Attentional dysfunctions after hippocampal stroke: evidence from Event-Related Potentials in a case report.
No full textCognitive vulnerability to levodopa therapy in ataxia-telangiectasia patients: a psychophysiological study
No full textAtaxia-telangiectasia (AT) is a human disease caused by mutations in the ATM gene. The neural phenotype of AT includes progressive cerebellar neurodegeneration, which results in ataxia, oculocutaneous teleangiectasias, immunodeficiency, recurrent infections, radiosensitivity and proneness to cancer. No therapies are available for this disease. Experimental studies on mice showed severe degeneration of tyrosine hydroxylase-positive, dopaminergic nigro-striatal neurons, and their terminals in the striatum. The aim of the current study was to investigate the effects of the levodopa therapy on motor and cognitive performance in AT patients using clinical and psychophysiological evaluation. 3 young AT-patients (age: 12 years) underwent a neurological evaluation and a CNV recording in basal condition (T0) and at two times points after levodopa therapy (at 4 weeks – T1 and 8 weeks – T2). MICARS and UPDRS III scales were administered in order to assess clinical performance and disability. CNV amplitude (total and in two different temporal windows – W1, W2) was evaluated. Reaction times were also obtained. Total CNV amplitude (T0 vs T2: Fz p=0,03; T1 vs T2: Fz p=0,05 Cz p=0.07), W1 (T0 vs T2: Fz p=0,06; T1 vs T2: Fz p=0,08) and W2-CNV areas (T0 vs T2: Fz p=0,05, Cz p=0,05, Pz p=0,05; T1 vs T2: Fz p=0,01, Cz p=0,04) were significantly higher after 8 weeks of levodopa therapy than during basal condition and at 4 weeks of levodopa therapy. UPDRSIII values significantly improved after 8 weeks of L-dopa therapy (T0 vs T2: p=0,004). Our data suggest that levodopa treatment led to a significant improvement in motor performance in AT patients. Additionally, the ability to sustain attention during a double choice motor task appears to ameliorate after levodopa therapy. These results induce us to hypothesize the presence of a dopaminergic dysfunction likely related to a possible involvement of the subcortical networks in AT subjects as suggested by experimental studies. Moreover, from a clinical point of view, these evidences support the potential role of levodopa in the treatment of individuals with ataxia telangiectasia
Idiopathic environmental intolerance attributed to electromagnetic fields: neuropsychophysiological approach to decode a new self-reported condition
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