Learn More
The dentate gyrus (DG) of the mammalian hippocampus is hypothesized to mediate pattern separation-the formation of distinct and orthogonal representations of mnemonic information-and also undergoes neurogenesis throughout life. How neurogenesis contributes to hippocampal function is largely unknown. Using adult mice in which hippocampal neurogenesis was(More)
We investigated how dopamine (DA) systems contribute to cognitive performance in the domain of learning and attentional flexibility by examining effects of withdrawing DA-ergic medication in patients with Parkinson's disease (PD). Medication remediated impairments in switching between two tasks, thought to depend on circuitry connecting the dorsolateral(More)
Mild cognitive impairment is common in nondemented Parkinson's disease (PD) patients and may be a harbinger of dementia. In view of its importance, the Movement Disorder Society commissioned a task force to delineate diagnostic criteria for mild cognitive impairment in PD. The proposed diagnostic criteria are based on a literature review and expert(More)
We have previously performed detailed clinical and neuropsychological assessments in a community-based cohort of patients with newly diagnosed parkinsonism, and through analysis of a subcohort with idiopathic Parkinson's disease (PD), we have demonstrated that cognitive dysfunction occurs even at the time of PD diagnosis and is heterogeneous. Longitudinal(More)
Freezing of gait (FOG) is a common phenomenon in Parkinson's disease (PD) affecting over half of those in the advanced stages of the disease and often does not respond to standard drug therapies. This article proposes a possible mechanism by which this disorder of movement comes about. Co-ordinated neural activities are dependent on a series of parallel(More)
Dynamic causal modelling (DCM) of functional magnetic resonance imaging (fMRI) data offers new insights into the pathophysiology of neurological disease and mechanisms of effective therapies. Current applications can be used both to identify the most likely functional brain network underlying observed data and estimate the networks' connectivity parameters.(More)
This study examined the effects of L-dopa medication in patients with Parkinson's disease on cortical and subcortical blood flow changes during two tasks known to involve frontostriatal circuitry. Eleven patients with Parkinson's disease were scanned on two occasions, one ON L-dopa medication and one OFF L-dopa medication, during performance of the Tower of(More)
Cognitive abnormalities are common in Parkinson's disease, with important social and economic implications. Factors influencing their evolution remain unclear but are crucial to the development of targeted therapeutic strategies. We have investigated the development of cognitive impairment and dementia in Parkinson's disease using a longitudinal approach in(More)
We have used multiple sources to identify a population-representative cohort of newly diagnosed patients with parkinsonism and Parkinson's disease in the UK over a 2-year period. All patients have been invited to participate in a detailed clinical assessment either at home or in an outpatient clinic. These assessments have been used to refine clinical(More)
Studies in patients with Parkinson's disease (PD) suggest that the characteristic motor symptoms of the disorder are frequently accompanied by impairments in cognition that are most profound in tasks of executive function. Neuropsychological deficits are not an inevitable consequence of the disease, yet the reasons underlying cognitive heterogeneity in PD(More)