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Neurology AND Movement disorders [keywords]
- Which Way Is Down? Positional Distortion in the Tilt Illusion. [JOURNAL ARTICLE]
- PLoS One 2014; 9(10):e110729.
Contextual information can have a huge impact on our sensory experience. The tilt illusion is a classic example of contextual influence exerted by an oriented surround on a target's perceived orientation. Traditionally, the tilt illusion has been described as the outcome of inhibition between cortical neurons with adjacent receptive fields and a similar preference for orientation. An alternative explanation is that tilted contexts could produce a re-calibration of the subjective frame of reference. Although the distinction is subtle, only the latter model makes clear predictions for unoriented stimuli. In the present study, we tested one such prediction by asking four naive subjects to estimate three positions (4, 6, and 8 o'clock) on an imaginary clock face within a tilted surround. To indicate their estimates, they used either an unoriented dot or a line segment, with one endpoint at fixation in the middle of the surround. The surround's tilt was randomly chosen from a set of orientations (±75°, ±65°, ±55°, ±45°, ±35°, ±25°, ±15°, ±5° with respect to vertical) across trials. Our results showed systematic biases consistent with the tilt illusion in both conditions. Biases were largest when observers attempted to estimate the 4 and 8 o'clock positions, but there was no significant difference between data gathered with the dot and data gathered with the line segment. A control experiment confirmed that biases were better accounted for by a local coordinate shift than to torsional eye movements induced by the tilted context. This finding supports the idea that tilted contexts distort perceived positions as well as perceived orientations and cannot be readily explained by lateral interactions between orientation selective cells in V1.
- Episodic and Electrical Nervous System Disorders Caused by Nonchannel Genes. [JOURNAL ARTICLE]
- Annu Rev Physiol 2014 Oct 17.
As noted in the separate introduction to this special topic section, episodic and electrical disorders can appear quite different clinically and yet share many overlapping features, including attack precipitants, therapeutic responses, natural history, and the types of genes that cause many of the genetic forms (i.e., ion channel genes). Thus, as we mapped and attempted to clone genes causing other episodic disorders, ion channels were always outstanding candidates when they mapped to the critical region of linkage in such a family. However, some of these disorders do not result from mutations in channels. This realization has opened up large and exciting new areas for the pathogenesis of these disorders. In some cases, the mutations occur in genes of unknown function or without understanding of molecular pathogenesis. Recently, emerging insights into a fascinating group of episodic movement disorders, the paroxysmal dyskinesias, and study of the causative genes and proteins are leading to the emerging concept of episodic electric disorders resulting from synaptic dysfunction. Much work remains to be done, but the field is evolving rapidly. As it does, we have come to realize that the molecular pathogenesis of electrical and episodic disorders is more complex than a scenario in which such disorders are simply due to mutations in the primary determinants of membrane excitability (channels). Expected final online publication date for the Annual Review of Physiology Volume 77 is February 10, 2015. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
- Neuropsychiatry and Neural Cubism. [JOURNAL ARTICLE]
- Acad Med 2014 Oct 21.
The art movement known as Cubism did not represent a failure of perspective but, rather, was a movement aimed at advancing art by juxtaposing different perspectives. In this issue, Taylor and colleagues describe the current approach by neurologists and psychiatrists to patients with brain disorders as "Neural Cubism" because of the competing angles of these specialists' perspectives about these disorders. They advocate both integrated training for all residents in the two fields and a system of "nested hierarchies" to reclassify brain disorders according to their effect on levels of brain function. The unspoken premise of their article is that it is time for psychiatry and neurology to reunite.This Commentary takes the view that reuniting the long-separated specialties of neurology and psychiatry would not necessarily create better care for all patients with brain disorders but that trainees in both fields would benefit from increased training in the complementary specialty. The new Accreditation Council for Graduate Medical Education clinical neuroscience milestones for psychiatry training and psychiatry milestones for neurology training are steps in the right direction. Increasing opportunities for combined neurology-psychiatry training will help create a cadre of specialists equipped to efficiently care for complex patients within emerging accountable care organizations. Drawing from two fields in the service of understanding brain-behavior interactions increases the potential for innovation at their interface. The author concludes that the time has come to increase the neurological and neuroscience content of psychiatry training but not to unite the two fields.
- Beyond Neural Cubism: Promoting a Multidimensional View of Brain Disorders by Enhancing the Integration of Neurology and Psychiatry in Education. [JOURNAL ARTICLE]
- Acad Med 2014 Oct 21.
Cubism was an influential early-20th-century art movement characterized by angular, disjointed imagery. The two-dimensional appearance of Cubist figures and objects is created through juxtaposition of angles. The authors posit that the constrained perspectives found in Cubism may also be found in the clinical classification of brain disorders. Neurological disorders are often separated from psychiatric disorders as if they stemmed from different organ systems. Maintaining two isolated clinical disciplines fractionalizes the brain in the same way that Pablo Picasso fractionalized figures and objects in his Cubist art. This Neural Cubism perpetuates a clinical divide that does not reflect the scope and depth of neuroscience. All brain disorders are complex and multidimensional, with aberrant circuitry and resultant psychopharmacology manifesting as altered behavior, affect, mood, or cognition. Trainees should receive a multidimensional education based on modern neuroscience, not a partial education based on clinical precedent. The authors briefly outline the rationale for increasing the integration of neurology and psychiatry and discuss a nested model with which clinical neuroscientists (neurologists and psychiatrists) can approach and treat brain disorders.
- Psychogenic nonepileptic seizures and psychogenic movement disorders: two sides of the same coin? [JOURNAL ARTICLE]
- Arq Neuropsiquiatr 2014 Oct; 72(10):793-802.
Psychogenic nonepileptic seizures (PNES) and psychogenic movement disorders (PMD) are commonly seen in Neurology practice and are categorized in the DSM-5 as functional neurological disorders/conversion disorders. This review encompasses historical and epidemiological data, clinical aspects, diagnostic criteria, treatment and prognosis of these rather challenging and often neglected patients. As a group they have puzzled generations of neurologists and psychiatrists and in some ways continue to do so, perhaps embodying and justifying the ultimate and necessary link between these specialties.
- Nonmotor Symptoms in LRRK2 G2019S Associated Parkinson's Disease. [JOURNAL ARTICLE]
- PLoS One 2014; 9(10):e108982.
Idiopathic Parkinson's disease (IPD) and LRRK2-associated PD (LRRK2-PD) might be expected to differ clinically since the neuropathological substrate of LRRK2-PD is heterogeneous. The range and severity of extra-nigral nonmotor features associated with LRRK2 mutations is also not well-defined.To evaluate the prevalence and time of onset of nonmotor symptoms (NMS) in LRRK2-PD patients.The presence of hyposmia and of neuropsychiatric, dysautonomic and sleep disturbances was assessed in 33 LRRK2-G2019S-PD patients by standardized questionnaires and validated scales. Thirty-three IPD patients, matched for age, gender, duration of parkinsonism and disease severity and 33 healthy subjects were also evaluated.University of Pennsylvania Smell Identification Test (UPSIT) scores in LRRK2-G2019S-PD were higher than those in IPD (23.5±6.8 vs 18.4±6.0; p = 0.002), and hyposmia was less frequent in G2019S carriers than in IPD (39.4% vs 75.8%; p = 0.01). UPSIT scores were significantly higher in females than in males in LRRK2-PD patients (26.9±4.7 vs 19.4±6.8; p<0.01). The frequency of sleep and neuropsychiatric disturbances and of dysautonomic symptoms in LRRK2-G2019S-PD was not significantly different from that in IPD. Hyposmia, depression, constipation and excessive daytime sleepiness, were reported to occur before the onset of classical motor symptoms in more than 40% of LRRK2-PD patients in whom these symptoms were present at the time of examination.Neuropsychiatric, dysautonomic and sleep disturbances occur as frequently in patients with LRRK2-G2019S-PD as in IPD but smell loss was less frequent in LRRK2-PD. Like in IPD, disturbances such as hyposmia, depression, constipation and excessive daytime sleepiness may antedate the onset of classical motor symptoms in LRRK2-G2019S-PD.
- Spontaneous locomotor activity and L-DOPA-induced dyskinesia are not linked in 6-OHDA parkinsonian rats. [Journal Article]
- Front Behav Neurosci 2014.:331.
Bradykinesia (slowness of movement) and other characteristic motor manifestations of Parkinson's disease (PD) are alleviated by treatment with L-dihydroxyphenylalanine (L-DOPA). Long-term L-DOPA treatment, however, is associated with complications such as motor fluctuations and dyskinesia that severely impair the quality of life. It is unclear whether the effect of L-DOPA on spontaneous motor activity and its dyskinesia-inducing effect share a common mechanism. To investigate the possible connection between these two effects, we analyzed the spontaneous locomotor activity of parkinsonian rats before surgery (unilateral injection of 6-OHDA in the right medial forebrain bundle), before treatment with L-DOPA, during L-DOPA treatment (the "ON" phase), and after the end of L-DOPA treatment (the "OFF" phase). We correlated the severity of dyskinesia (AIM scores) with locomotor responses in the ON/OFF phases of chronic L-DOPA treatment at two different doses. We treated three groups of parkinsonian animals with chronic injections of 8 mg/kg L-DOPA, 6 mg/kg L-DOPA, and saline solution and one group of non-lesioned animals with 8 mg/kg L-DOPA. At the end of the experiment, tyrosine hydroxylase (TH) immunoreactivity was analyzed in the striatum of all parkinsonian rats. We found no correlation between the severity of dyskinesia and spontaneous locomotor activity in the ON or OFF phase of L-DOPA treatment. The only observed correlation was between the pathological rotation induced by L-DOPA at the highest dose and locomotor activity in the ON phase of L-DOPA treatment. In addition, a L-DOPA withdrawal effect was observed, with worse motor performance in the OFF phase than before the start of L-DOPA treatment. These findings suggest that different neural mechanisms underlie the effect of L-DOPA on spontaneous motor activity and its dyskinesia-inducing effect, with a different dose-response relationship for each of these two effects.
- Neuronal Ceroid Lipofuscinosis: The Increasing Spectrum of an Old Disease. [JOURNAL ARTICLE]
- Curr Mol Med 2014 Oct 10.
Neuronal Ceroid Lipofuscinoses (NCL) are genetically heterogeneous heritable neurodegenerative disorders with worldwide distribution. They are considered as childhood diseases; however rare adult onset forms are known. NCL have a progressive course, affecting visual, motor and cognitive functions, and are associated with myoclonic epilepsy; behavioural problems can be observed at the onset. The outcome is invariably fatal, mostly during the second or third decade. The denomination is based on pathological criteria, i.e. the presence of intralysosomal storage of autofluorescent lipopigment of glycoprotein origin with characteristic ultrastructural features. The NCL are autosomal recessive diseases (but a rare autosomal dominant form of adult onset). Thirteen NCL associated genes have been identified so far, which allow a definite diagnosis to be reached and provide genetic counselling to the families. Still unidentified NCL genes are foreseen. Allelic heterogeneity is observed in some mutated genes; likewise phenotypic heterogeneity is seen in several NCL. The gene products are either soluble proteins (such as lysosomal enzymes) or membrane proteins related to lysosomes, endoplasmic reticulum, synaptic vesicles. Little is known about pathogenetic mechanisms, leading to storage formation and cell death. Current research is focusing on intracellular trafficking, neurotransmission and storage removal. No cure is available for any form. Innovative treatments led to some results in mouse models related to lysosome hydrolase defects. Evidences that autophagy, oxidative stress, excitotoxicity paly roles in NCL cell pathology raise the possibility that selected steps of these processes might become target of treatments, and therefore modify the disease course.
- Movement Disorders in Spinocerebellar Ataxias in a Cohort of Brazilian Patients. [JOURNAL ARTICLE]
- Eur Neurol 2014 Oct 14; 72(5-6):360-362.
Background: Movement disorders (MDs) are well recognized in all subtypes of spinocerebellar ataxias (SCA), but phenomenology and frequency vary widely. Methods: Three hundred seventy-eight patients, from 169 Brazilian families, with SCAs were assessed with neurological examination and molecular genetic testing. Results: Dystonia was the most common movement disorder, found in 5.5% of all patients, particularly in SCA3. We observed Parkinsonian features in 6.6% of SCA3 patients, and myoclonus in two patients of our cohort. Conclusions: Our study demonstrated that MDs are major extracerebellar manifestations of SCA. The observed phenotypes in addition to ataxia may provide significant clues for a particular SCA genotype. © 2014 S. Karger AG, Basel.
- Review of neuropsychiatry and cognitive changes in Parkinson's disease and related movement disorders. [Journal Article]
- JAMA Neurol 2014 Oct 1; 71(10):1329.