•Action observation therapy can be used for rehabilitation of Parkinson's disease.•Motor imagery practice can be used for rehabilitation of Parkinson's disease.•Rehabilitation for Parkinson's disease ...might combine action observation and motor imagery.•Action observation and motor imagery involve both cortical and sub-cortical processes.
This article discusses recent evidence supporting the use of action observation therapy and motor imagery practice for rehabilitation of Parkinson's disease. A main question that emerges from the review regards the different effectiveness of these approaches and the possibility of integrating them into a single method to enhance motor behaviour in subjects with Parkinson’s disease. In particular, the reviewed studies suggest that action observation therapy can have a positive effect on motor facilitation of patients and that a long-term rehabilitation program based on action observation therapy or motor imagery practice can bring some benefit on their motor recovery. Moreover, the paper discusses how the research on the combined use of action observation and motor imagery for motor improvements in healthy subjects may encourage the combined use of action observation therapy and motor imagery practice for therapeutic aims in Parkinson's disease. To date, this hypothesis has never been experimented.
The potential role of white matter (WM) abnormalities in the pathophysiology of obsessive compulsive disorder (OCD) is substantially unexplored. Apart from alterations in the WM tracts within ...cortico-striato-thalamo-cortical circuitry, recent theorizations predict the existence of more widespread WM abnormalities. In this paper we systematically reviewed the current diffusion tensor imaging literature in OCD and purposely evaluated the prevalence and functional significance of specific WM tissue changes in the disorder. The relationship between clinical variables (medication status, symptom severity) and WM microstructural changes was also assessed. The reviewed studies are consistent with the existence of microstructural alterations in the fronto-basal pathways targeting the orbitofrontal cortex and the anterior cingulate cortex. Moreover, altered anatomical connectivity between lateral frontal and parietal regions and microstructural abnormalities in intra-hemispheric bundles linking distinctive areas of the prefrontal cortex to posterior parietal and occipital association cortices, are consistently reported. Finally, microstructural abnormalities in the corpus callosum, characterized by decreased connectivity in the rostrum and hyperconnectivity in the genu, are substantiated by a large body of evidence.
Poststroke Depression: A Review Robinson, Robert G; Spalletta, Gianfranco
Canadian journal of psychiatry,
06/2010, Letnik:
55, Številka:
6
Book Review, Journal Article
Recenzirano
Odprti dostop
Objective:
To review the world's (English-language) publications related to depression following stroke.
Method:
The databases from MEDLINE and PubMed were reviewed for articles related to poststroke ...depression (PSD), depression and cerebral vascular accident, depression and cerebral vascular disease, and depression and cerebral infarction.
Results:
Most studies examined prevalence rates of depression and the clinical correlates of depression. Based on pooled data, the overall prevalence of major depression was 21.7% and minor depression was 19.5%. The strongest single correlate of depression was severity of impairment in activities of daily living. However, the existence of depression at baseline was found to be associated with greater impairment at follow-up, ranging from 6 weeks to 2 years in 83% of studies. Further, depression following acute stroke was also associated with greater cognitive impairment and increased mortality. PSD has been shown in 6 double-blind controlled studies to be effectively treated with antidepressants, and 1 study has recently shown that PSD can be effectively prevented.
Conclusions:
During the past 20 years, significant progress has been made in the identification and treatment of depression following stroke. In the future, antidepressant treatment will likely play an increasing role in the management of patients with acute stroke. Further research is needed to identify the mechanisms of depression and why antidepressants lead to improved physical and cognitive recovery and decreased mortality.
The most widely accepted model of obsessive–compulsive disorder (OCD) assumes brain abnormalities in the “affective circuit”, mainly consisting of volume reduction in the medial orbitofrontal, ...anterior cingulate and temporolimbic cortices, and tissue expansion in the striatum and thalamus. The advent of whole-brain, voxel-based morphometry (VBM) has provided increasing evidence that regions outside the “affective” orbitofronto-striatal circuit are involved in OCD. Nevertheless, potential confounds from the different image analysis methods, as well as other factors, such as patients' medication and comorbidity status, may limit generalization of results.
In the present paper, we systematically reviewed the whole-brain VBM literature on OCD by focussing specifically on degree of consistency between studies, extent to which findings have been replicated and interrelation between clinical variables and OCD anatomy, a potentially crucial factor that has been systematically examined only in a limited number of studies. The PubMed database was searched through February 2012. A total of 156 studies were identified; 18 of them fulfilled the inclusion/exclusion criteria and included 511 patients and 504 controls. Results support the notion that the brain alterations responsible for OCD are represented at the network level, and that widespread structural abnormalities may contribute to neurobiological vulnerability to OCD. Apart from defects in regions within the classic “affective” circuit, volume reduction of the cortical source of the dorsolateral (DL) prefronto-striatal “executive” circuit (dorsomedial, DL, ventrolateral and frontopolar prefrontal cortices), and of reciprocally connected regions (temporo-parieto-occipital associative areas) is consistently described in OCD patients. Moreover, increased volume of the internal capsule and reduced frontal and parietal white matter volumes may account for altered anatomical connectivity in fronto-subcortical circuitry. Morphometric changes in both “affective” and “executive” parallel the disease clinical course, being at the same time responsible for variation in symptom severity. Thus, OCD mechanisms involve a more widespread network of cerebral dysfunctions than previously thought, which may explain the heterogeneity in clinical manifestations and symptom severity.
Transcranial direct current stimulation (tDCS) has been implemented in neuropsychiatric disorders characterized by cognitive impairment. However, methodological heterogeneity challenges conclusive ...remarks. Through a critical analysis of previous conflicting findings and in the light of current neurobiological models of pathophysiology, we qualitatively assessed the effects of tDCS in neuropsychiatric disorders that share neurobiological underpinnings, as to evaluate whether stimulation can improve cognitive deficits in patients’ cohorts. We performed a systematic review of tDCS studies targeting cognitive functions in mental disorders and pathological cognitive aging. Data from 41 studies, comprising patients with diagnosis of mood disorders, schizophrenia-spectrum disorders, Alzheimer’s disease (AD), and mild cognitive impairment (MCI), were included. Results indicate that tDCS has the capacity to enhance processing speed, working memory, and executive functions in patients with mood and schizophrenia-spectrum disorders. The evidence of a positive effect on general cognitive functioning and memory is either inconclusive in AD, or weak in MCI. Future directions are discussed for developing standardized stimulation protocols and for translating the technique therapeutic potential into effective clinical practice.
Abstract
Network neuroscience shed some light on the functional and structural modifications occurring to the brain associated with the phenomenology of schizophrenia. In particular, resting-state ...functional networks have helped our understanding of the illness by highlighting the global and local alterations within the cerebral organization. We investigated the robustness of the brain functional architecture in 44 medicated schizophrenic patients and 40 healthy comparators through an advanced network analysis of resting-state functional magnetic resonance imaging data. The networks in patients showed more resistance to disconnection than in healthy controls, with an evident discrepancy between the two groups in the node degree distribution computed along a percolation process. Despite a substantial similarity of the basal functional organization between the two groups, the expected hierarchy of healthy brains' modular organization is crumbled in schizophrenia, showing a peculiar arrangement of the functional connections, characterized by several topologically equivalent backbones. Thus, the manifold nature of the functional organization’s basal scheme, together with its altered hierarchical modularity, may be crucial in the pathogenesis of schizophrenia. This result fits the disconnection hypothesis that describes schizophrenia as a brain disorder characterized by an abnormal functional integration among brain regions.
Few investigations have analyzed the neuroanatomical substrate of empathic capacities in healthy subjects, and most of them have neglected the potential involvement of cerebellar structures. The main ...aim of the present study was to investigate the associations between bilateral cerebellar macro- and micro-structural measures and levels of cognitive and affective trait empathy (measured by Interpersonal Reactivity Index, IRI) in a sample of 70 healthy subjects of both sexes. We also estimated morphometric variations of cerebral Gray Matter structures, to ascertain whether the potential empathy-related peculiarities in cerebellar areas were accompanied by structural differences in other cerebral regions. At macro-structural level, the volumetric differences were analyzed by Voxel-Based Morphometry (VBM)- and Region of Interest (ROI)-based approaches, and at a micro-structural level, we analyzed Diffusion Tensor Imaging (DTI) data, focusing in particular on Mean Diffusivity and Fractional Anisotropy. Fantasy IRI-subscale was found to be positively associated with volumes in right cerebellar Crus 2 and pars triangularis of inferior frontal gyrus. The here described morphological variations of cerebellar Crus 2 and pars triangularis allow to extend the traditional cortico-centric view of cognitive empathy to the cerebellar regions and indicate that in empathizing with fictional characters the cerebellar and frontal areas are co-recruited.
Brain imaging is a non-invasive and in vivo direct estimation of detailed brain structure, regional brain functioning and estimation of molecular processes in the brain. The main objective of this ...review was to analyze functional and structural neuroimaging studies of individuals at risk for suicide. We reviewed articles published between 2005 and 2018, indexed in PubMed and Medline, assessing structural and functional alterations of the brain of individuals at high risk for suicide and at low risk for suicide. We reviewed functional and structural neuroimaging studies which included individuals with a history of suicidal ideation or attempt in major depressive disorder (MDD), bipolar disorder (BD), psychosis, and borderline personality disorder (BPD). We selected 45 papers that focused on suicidality in MDD, 17 papers on BD, 11 papers on psychosis, and 5 papers on BPD. The suicidal brain across psychiatric diagnoses seems to heavily involve dysfunction of the fronto-temporal network, primarily involving reductions of gray and white matter volumes in the pre-frontal cortex (PFC), anterior cingulate, and superior temporal gyrus. Nonetheless, there are several ways to define suicidal behaviour and ideation. Therefore, it still remains difficult to combine the evidence from imaging studies that used different definitions of suicidality.
Objective
We previously reported an unexpectedly high seroprevalence (∼10%) of N‐methyl‐D‐aspartate‐receptor subunit‐NR1 (NMDAR1) autoantibodies (AB) in healthy and neuropsychiatrically ill subjects ...(N = 2,817). This finding challenges an unambiguous causal relationship of serum AB with brain disease. To test whether similar results would be obtained for other brain antigen‐directed AB previously connected with pathological conditions, we systematically screened serum samples of 4,236 individuals.
Methods
Serum samples of healthy (n = 1,703) versus neuropsychiatrically ill subjects (schizophrenia, affective disorders, stroke, Parkinson disease, amyotrophic lateral sclerosis, personality disorder; total n = 2,533) were tested. For analysis based on indirect immunofluorescence, we used biochip mosaics of frozen brain sections (rat, monkey) and transfected HEK293 cells expressing respective recombinant target antigens.
Results
Seroprevalence of all screened AB was comparable in healthy and ill individuals. None of them, however, reached the abundance of NMDAR1 AB (again ∼10%; immunoglobulin Ig G ∼1%). Appreciable frequency was noted for AB against amphiphysin (2.0%), ARHGAP26 (1.3%), CASPR2 (0.9%), MOG (0.8%), GAD65 (0.5%), Ma2 (0.5%), Yo (0.4%), and Ma1 (0.4%), with titers and Ig class distribution similar among groups. All other AB were found in ≤0.1% of individuals (anti–AMPAR‐1/2, AQP4, CV2, Tr/DNER, DPPX‐IF1, GABAR‐B1/B2, GAD67, GLRA1b, GRM1, GRM5, Hu, LGl1, recoverin, Ri, ZIC4). The predominant Ig class depended on antigen location, with intracellular epitopes predisposing to IgG (chi‐square = 218.91, p = 2.8 × 10−48).
Interpretation
To conclude, the brain antigen‐directed AB tested here are comparably detectable in healthy subjects and the disease groups studied here, thus questioning an upfront pathological role of these serum AB. Ann Neurol 2014;76:82–94
The corpus callosum (CC), which connects the two cerebral hemispheres, is the largest white matter fiber bundle in the human brain. This structure presents a peculiar myelination pattern: it has ...small diameter fibers, located in the genu, which myelinate much later in normal development, and large diameter fibers of the splenium, which myelinate early in development. Although the pathology of AD mainly involves the cerebral gray matter structure, there is evidence that white matter may also be involved. To illustrate callosal white matter changes in AD pathology, in this review we summarize in vivo imaging studies in humans, focusing on region of interest, voxel-based morphometry, diffusion-weighted imaging, and diffusion tensor imaging techniques. Our aims were to identify where in the CC, when in the different stages of AD, and how callosal changes can be detected with different MRI techniques. Results showed that changes in the anterior (genu and anterior body) as well as in the posterior (isthmus and splenum) portions of the CC might already be present in the early stages of AD. These findings support the hypothesis that two mechanisms, Wallerian degeneration and myelin breakdown, might be responsible for the region-specific changes detected in AD patients. Wallerian degeneration affects the posterior CC subregion, which receives axons directly from those brain areas (temporo-parietal lobe regions) primarily affected by the AD pathology. Instead, the myelin breakdown process affects the later-myelinating CC subregion and explains the earlier involvement of the genu in CC atrophy.
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