[Diagnostic value of neuropsychological tests in mild cognitive impairment comorbid with Parkinson's disease]. / Diagnostyczna wartosc testów neuropsychologicznych w lagodnych zaburzeniach poznawczych towarzyszacych chorobie Parkinsona.

Mild cognitive impairment (MCI) is present in on average one-fourth of Parkinson's disease (PD) patients with no dementia diagnosis. Only recently has PD-MCI been treated as a new diagnostic entity. In 2012, unified criteria were adopted which allow both diagnosing MCI in Parkinson's disease (PD-MCI) and further classification taking into account the profile of cognitive dysfunctions and the probability of evolution towards dementia. The diagnostic criteria were presented in the form of stipulations and guidelines assuming that diagnostic process is based on the neuropsychological assessment of the patient. The notion of MCI had been borrowed and for a couple of years had been relying on definitions developed in relation to Alzheimer's disease. For the first time, in the proposed criteria memory dysfunction is not the basis of classification. Only two categories of dysfunctions have been retained, single-domain and multiple-domain. Whether the adopted criteria will contribute to an accurate diagnosis of cognitive dysfunctions and PD-specific dementing processes remains an open question. In spite of some limitations, the presented criteria can certainly improve the efficacy of monitoring the patient's state at the same time allowing the hope for an appropriate therapy and a higher quality of life. Moreover, the unification of diagnostic criteria will be crucial in assessing usefulness ofneuropsychological test instruments as a basic method of investigating neurodegenerative processes not only in PD.

Tet system in the brain: transgenic rats and lentiviral vectors approach.

Local and regulated expression of exogenous genes in the central nervous system is one of the major challenges of modern neuroscience. We have approached this issue by applying the inducible tetracycline system to regulate the expression of EGFP reporter gene in double transgenic rats. We have obtained a strong induction of EGFP only in male testes, which correlated with a high level of rtTA expression only in this organ. To overcome the problem of lack of rtTA protein in the transgenic rat brain, we have delivered this Tet system activator with lentiviral vectors into the dentate gyrus of hippocampus of transgenic EGFP rats. As a result, after systemic application of doxycycline we have obtained inducible, stable and restricted to the desired brain region expression of EGFP. An advantage of this strategy is that the transgene is located in the same genetic milieu in every cell of the transgenic organism. This is crucial to obtain uniform expression of the regulated gene within the target brain structure. Combination of rat transgenesis and lentiviral vectors is a novel approach enabling precise spatiotemporal regulation of genes of interest strictly in the brain structure of choice or in other tissues.

Nonverbal deficits in explicit and implicit memory of Parkinson's disease patients.

This study examined verbal and nonverbal aspects of explicit and implicit memory in a sample of 19 Parkinson's disease (PD) patients and 21 control subjects. For implicit memory evaluation, we used a Mirror Reading (MR) task employing verbal material as well as a nonverbal Serial Reaction Time (SRT) task. For explicit memory measurement we applied a word pairs task (verbal) and pairs of a Japanese ideograms task (nonverbal). The PD patients displayed impairments in the nonverbal tasks only, namely, in the SRT task and the pairs of Japanese ideograms task. No correlation between Wisconsin Card Sorting Test (WCST) scores and the results of tasks in which PD patients displayed deficits (SRT and pairs of Japanese ideograms) were discovered. Interestingly, such a correlation was found in the case of MR and words pairs tasks, which did not distinguish PD patients from control group.

Emotional processing in Parkinson's disease and schizophrenia: evidence for response bias deficits in PD.

Deficits in facial emotion recognition in Parkinson's disease (PD) patients has been well documented. Nevertheless, it is still not clear whether facial emotion recognition deficits are secondary to other cognitive impairments. The aim of this study was to answer the question of whether deficits in facial emotion recognition in PD result from impaired sensory processes, or from impaired decision processes. To address this question, we tested the ability to recognize a mixture of basic and complex emotions in 38 non-demented PD patients and 38 healthy controls matched on demographic characteristics. By using a task with an increased level of ambiguity, in conjunction with the signal detection theory, we were able to differentiate between sensitivity and response bias in facial emotion recognition. Sensitivity and response bias for facial emotion recognition were calculated using a d-prime value and a c index respectively. Our study is the first to employ the EIS-F scale for assessing facial emotion recognition among PD patients; to test its validity as an assessment tool, a group comprising schizophrenia patients and healthy controls were also tested. Patients with PD recognized emotions with less accuracy than healthy individuals (d-prime) and used a more liberal response criterion (c index). By contrast, patients with schizophrenia merely showed diminished sensitivity (d-prime). Our results suggest that an impaired ability to recognize facial emotions in PD patients may result from both decreased sensitivity and a significantly more liberal response criteria, whereas facial emotion recognition in schizophrenia may stem from a generalized sensory impairment only.

The neural correlates of specific executive dysfunctions in Parkinson's disease.

Several functional neuroimaging studies in patients with Parkinson's disease (PD) have suggested that changes in the fronto-parietal-striatal networks are associated with deficits in executive functioning. However, executive functions (EF) are multifaceted and include three dissociable components: working memory, response inhibition, and task-switching. This study investigated which component of executive functioning is most strongly associated with fronto-parietal-striatal efficiency in PD. PD patients (with and without executive dysfunction), and age-matched healthy subjects, completed a battery of cognitive tests previously shown to discriminate among the three EF components. Principal component analysis conducted on the selected cognitive test variables yielded three expected EF components. The component scores were used in regression analysis to assess the relationship between the EF efficiency and blood oxygenation level-dependent (BOLD) signal related to performing the n-back, an experimental task that draws upon multiple components of executive functioning: working memory, response inhibition, and task-switching. We found distinct neural correlates of specific executive dysfunctions in patients with PD. However, all of them seem to be associated with fronto-parietal-striatal efficiency.