1,720,959 research outputs found
Frontal executive function, apathy and behaviour in parkinson's disease
No full textThe pattern of cognitive deficits in Parkinson's disease is variable, but often includes executive impairment similar to that seen in patients with frontal lesions, as well as episodic memory impairment, visuospatial dysfunction and impaired verbal fluency. That could derive from the not irrelevant "new" role of the basal ganglia in determining cognitive process refinement. We discuss a huge number of pathological observations, starting from neuro-anatomical and biochemical networks, from basal ganglia to thalamus and cortical cortex
Non-motor aspects of parkinson's disease
No full textFor many decades, PD was regarded as a unique entity, namely a sporadic neurodegenerative disease with its main lesion in the substantia nigra. The actual pathology was described as pathognomonic Lewy bodies in nigral dopaminergic cells, and the clinical abnormalities were thought to be due to insufficient dopamine release from nigrostriatal terminals, primarily in the putamen. It is now realized that the classical stereotypic description of PD starting with tremor or hypokinesia/rigidity and progressing to postural instability and eventually to cognitive decline is not the only scenario (although it may be the more common one). This latter observation led to a definition of the "Lewy body dementia" concept where motor symptoms may be minimal initially. In many patients, the disease starts with autonomic (particularly gastro-intestinal) or sensory (i.e., olfactory) manifestations. The identification of a-synuclein as a key constituent of Lewy bodies allowed the demonstration of specific changes in other areas such as the olfactory bulb and particularly the brain stem. Changes in the raphe nucleus and the locus coeruleus which antedate the substantia nigra lesions could explain some mental manifestations, particularly the depression which has been described prior to the first motor manifestations. Several behavioral disorders may be observed in people with PD. Hypodopaminergic states linked to the disease itself or associated with low levodopa levels may frequently contribute to symptoms such as anxiety, apathy, fatigue, sleep disruption. About twothirds of PD patients with fluctuations reported significant "on-off" mood swings. The excessive use of dopaminergic treatment may eventually lead to a pervasive behavioral syndrome termed homeostatic hedonistic dysregulation (HHD). We discuss these aspects with a particular interest in clinical practice
Freezing in-on and parkinson's disease: Cognition and behavior
No full textFreezing of gait (FOG) refers to transient episodes, usually lasting seconds, in which a patient is unable to initiate or continue locomotion, occurring on a background of relatively good ability to move and is best described by patients as "feet get glued to the ground." Freezing of gait is common in Parkinson's disease, with increasing prevalence as the disease progresses, but it has been commonly reported in pathologically proven progressive supranuclear palsy and vascular parkinsonism. Two types of freezing of gait have been recognized in patients affected by Parkinson's Disease, taking L-Dopa. The most common is an "off" -freezing of gait, which can be improved with L-Dopa or dopaminergic treatment, such as apomorphine. "Off" -freezing appears during an "off" state, when the patient is generally bradykinetic and rigid. In contrast, "on" -freezing is characterized by a worsening of symptoms as the dose of L-Dopa is increased, and by a general improvement, as the dose is decreased or, better said, modulated. The onfreezing of gait is related to abnormal execution of complex motor tasks such as repetitive, simultaneous, or sequential motor acts. Different Authors suggested that the primary underlying abnormality might be related to the inability to deliver, or hold a pre-programmed, continuous, and complex motor act, in response to an established and correct internal plan of action. Therefore, we hypothesized that PD- on freezing patients might be clinically well differentiated from the other clinical subtypes of PD and might present a specific cognitive impairment, different from that presented by PD patients, without on-FOG. We discuss these hypothesis, based on clinical studies and follow-up
Parkinson's disease as a model of basal ganglia disruption
No full textThe assumption that the PD neurodegenerative process begins in the dopaminergic substantia nigra has been seriously challenged by recent publications. New different studies have provided evidence in support of a lower brainstem origin, predating involvement of the nigra. In addition to the prominent loss of nigro-striatal dopamine neurons, there is also degeneration of nor-epinephrine neurons in the locus coeruleus, cholinergic neurons in the nucleus basalis of Meynert, the dorsal motor nucleus of the vagus, and involvement of the spinal cord and peripheral autonomic system. There is dysfunction of multiple neurotransmitter systems and research is underway to determine if therapeutic restoration of these transmitters can provide benefit in PD. We discuss these biochemical and pathological aspects inside the most classic clinical assumption of PD as a dopaminergic depletion-induced diseas
Danni cerebrali post-attinici
No full textLa radioterapia è curativa, ma, applicata al parenchima cerebrale, crea alterazioni cognitive e comportamentali, senza apparenti correlazioni con la sede del tumore. Il danno encefalico da radioterapia avviene nella sostanza bianca, per necrosi dei vasi arteriolari, con ialinizzazione diffusa della parete, perdita della componente mio-intimale e obliterazione luminale. La conseguenza è l'occlusione delle arterie perforanti profonde, con sofferenza nei territori parenchimali corrispondenti e alterazioni della ri-perfusione in quello di confine. La radioterapia è un'ancora di salvezza; perciò corre l'obbligo di acquisire nuove strategie e nuovi protocolli che ottimizzino l'apporto positivo e proficuo anti-neoplastico. Al pari, si devono prendere in considerazione i rischi associati alla terapia e ponderare le conseguenze di un over-treatment, che può rendere inabile e dipendente il paziente trattato
Apathy and parkinson's disease
No full textApathy is a pathology of voluntary action or goal-directed behavior (GDB) and the underlying mechanism(s) responsible for apathy may be seen as dysfunctions occurring at the level of elaboration, execution and control of GDB. Apathy is often present after direct lesions of the prefrontal cortex (PFC), but it is also a common clinical feature of basal ganglia diseases. It can be observed in neurodegenerative diseases such as Parkinson's disease or as progressive supranuclear palsy and Huntington's disease. Apathy is also frequently encountered after focal lesions of specific structures of the basal ganglia such as the caudate nuclei, the internal pallidum and the medial-dorsal thalamic nuclei. Apathy is therefore one of the clinical consequences of the disruption of the PFC-basal ganglia axis, one of the functional systems involved in the generation and control of self-generated purposeful behaviour. From this perspective, a prefrontal-like syndrome (including apathy as one of its clinical manifestations) can be encountered following diseases that mainly involve the basal ganglia. This suggests that apathy can also be the consequence of a 'prefrontal-like' syndrome due to lesions mostly affecting the basal ganglia. Therefore, we try to define the apathy importance in PD, and even in different clinical phenotype profiles of PD
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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