Description:
Olshausen and Field (1996) developed a simple cell receptive field model for natural scene processing in V1, based on unsupervised learning and non-orthogonal basis function optimization of an overcomplete representation of visual space. The model was originally tested with an ensemble of whitened natural scenes, simulating pre-cortical filtering in the retinal ganglia and lateral geniculate nucleus, and the basis functions qualitatively resembled the orientation-specific responses of V1 simple cells in the spatial domain. In this study, the quantitative tuning responses of the basis functions in the spectral domain are estimated using a Gaussian model, to determine their goodness-of-fit to the known bandwidths of simple cells in primate V1. Five simulation experiments which examined key features of the model are reported: changing the size of the basis functions; using a complete versus over-complete representation; changing the sparseness factor; using a variable learning rate; and mapping the basis functions with a whitening spatial function. The key finding of this study is that across all image themes, basis function sizes, number of basis functions, sparseness factors and learning rates, the spatial-frequency tuning did not closely resemble that of primate area 17 — the model results more closely resembled the unclassified cat neurones of area 19 with a single exception, and not area 17 as predicted. [ABSTRACT FROM AUTHOR]
Description:
Orthogonal facial processing models attempt to mimic the local decomposition performed in the visual cortex by simple cell receptive fields. The purpose of this study was to investigate how the neurophysiological validity of orthogonal models of facial processing could be improved by implementing a "whitening" filter, based on current knowledge of similar filtering that occurs in the retina. By using a metric known as the "distributed coding efficiency index" (DCE), this study demonstrates that an orthogonal facial processing model significantly increased coding efficiency when a low-pass, zero-phase whitening filter was applied. The extent to which orthogonal decomposition of filtered data represents a realistic V1 model is discussed. [ABSTRACT FROM AUTHOR]
Description:
Background The study examined the measurement equivalence for teacher ratings across Malaysian Malay, Chinese and Indian children. Methods Malaysian teachers completed ratings of the ODD symptoms for 574 Malay, 247 Chinese and 98 Indian children. Results The results supported the equivalences for the configural, metric, and error variances models, and the equivalences for ODD latent variances and mean scores. Discussion Together, these findings suggest good support for measurement and structural equivalences of the ODD symptoms across these ethnic groups. The theoretical and clinical implications of the findings for cross-cultural equivalence of the ODD symptoms are discussed.
Description:
Background The study examined the measurement equivalence for teacher ratings across Malaysian Malay, Chinese and Indian children. Methods Malaysian teachers completed ratings of the ODD symptoms for 574 Malay, 247 Chinese and 98 Indian children. Results The results supported the equivalences for the configural, metric, and error variances models, and the equivalences for ODD latent variances and mean scores. Discussion Together, these findings suggest good support for measurement and structural equivalences of the ODD symptoms across these ethnic groups. The theoretical and clinical implications of the findings for cross-cultural equivalence of the ODD symptoms are discussed.
Description:
The selection of parameters for phase space reconstruction of empirically observed data has been a source of criticism when estimating the correlation dimension (D2) from observed data rather than from the solution of differential equations, when analyzing noisy and potentially non-stationary signals, such as the electroencephalogram (EEG). The largely arbitrary selection of the time-delay reconstruction (T) of temporal dynamics, and for the embedding (M) of these series, has been widely criticized. This study adopted an analytic and statistical framework within which the scaling behavior of D2 with respect to T and M, could be examined over five data lengths (N = 4096, 8192, 12288, 16384, and 20480) over an 8 × 8 grid of cat EEG. It was found that D2 was invariant over all data lengths only within a very narrow T range (T = 10–16) for M = 4. A statistically significant T by M interaction was found using multiple analysis of variance, with D2 being highly correlated over T as a function of M. Finally, an examination of phase-randomized surrogates indicated that statistically significant differences existed between EEG and phase-randomized surrogates over all data lengths, with time delays (T = 10–16), indicating that the D2 for EEG is phase-dependent when it is invariant with respect to data length. The implications of these findings are discussed with respect to current models of ECoG generation, and their implication with respect to the integration in the brain. [ABSTRACT FROM AUTHOR]
Description:
Objective: The aims of this study were to i) to compare physical impairments in people with chondrolabral pathology identified at hip arthroscopy 12-24 months previously to age-matched healthy people; and ii) to understand whether gendersex has any influence on impairments. Methods: 84 patients (42 female; age=36±10) 12-24 months post hip arthroscopy and 60 controls (41 female; age=36±10) were included. Measurements of active hip ROM and strength were assessed. Two-way analyses of co-variance examined the effect of gendersex and chondrolabral pathology on hip ROM and strength. Results: Patients exhibited less hip internal rotation (IR) ROM (p=0.001) and more extension (p=0.014) ROM; and less hip adduction (p<0.001), extension (p=0.001), flexion (p<0.001), ER (p=0.044) and IR (p<0.001) strength when compared to controls. For abduction strength, a significant interaction was found between the presence of chondrolabral pathology and gendersex (p=0.035). Conclusions: People with hip chondrolabral pathology have differences in hip ROM and strength when compared to controls. Rehabilitation programs should focus on addressing these specific physical impairments in order to enhance outcomes. This information may be of great value to both researchers and clinicians alike in determining interventions to improve outcomes in people with early hip OA.
Description:
Microglia are the immune cells in the central nervous system and can produce cytokines when they are activated by an insult or injury. In the present study, we investigated in detail the time frame of the activation of microglia in the hypothalamic paraventricular nucleus (PVN) following myocardial infarction in rats. Morphological changes and immunohistochemistry to detect CD11b (clone OX-42) were used to identify activated microglia. Compared to rats that had undergone sham surgical procedures, there was a significant increase of between 40 and 50% in the proportion of activated microglia in the PVN 4–16 weeks following myocardial infarction (P < 0.001, One way ANOVA). At 24 h or 1 week post myocardial infarction, however, there was no significant increase in the proportion of activated microglia. Echocardiography and haemodynamic parameters after myocardial infarction indicated significantly reduced left ventricular function. In conclusion, following myocardial infarction, activation of microglia in the PVN does not occur immediately but once manifested, activation is sustained. Thus, activated microglia may contribute to the chronic elevation in cytokine levels observed following myocardial infarction. Since cytokines elicit sympatho-excitatory effects when locally microinjected into the PVN, activated microglia may contribute to the mechanisms mediating the chronic increase in sympathetic nerve activity in animals with reduced left ventricular function induced following myocardial infarction.
Description:
Following a myocardial infarction (MI), inflammatory cytokines are elevated in the brain, as well as in plasma, indicating that inflammation is occurring in the brain in addition to the periphery. Microglia are the immune cells in the central nervous system and can produce cytokines when they are activated by an insult or injury. In the present study, we investigated whether MI in rats induces activation of microglia in the brain. We used immunohistochemistry to detect CD11b (clone OX-42) and morphological changes to identify activated microglia. Compared to control rats that had undergone sham surgical procedures, there was a significant increase in activated microglia in the hypothalamic paraventricular nucleus (PVN) following myocardial infarction. Activated microglia were not observed in the ventral hypothalamus, adjacent to the PVN, nor in the cortex, indicating the response was not the result of a generalized inflammatory reaction in the brain. Echocardiography and haemodynamic parameters after myocardial infarction indicated that reduced left ventricular function but congestive heart failure had not developed. In conclusion, microglia are activated in the PVN but not in the adjacent hypothalamus following myocardial infarction. The activated microglia may contribute to the increased local production of pro-inflammatory cytokines observed in the PVN after myocardial infarction and resulting in reduced left ventricular function.
Description:
Objectives MoodSwings 2.0 is an online self-guided intervention for bipolar disorder that includes educational modules, interactive tools, and discussion forums. The primary aim of the study was to determine if participation in MoodSwings 2.0 would result in decreased symptoms of depression and mania compared to the control condition. Secondary aims were to identify improvements in core depression symptoms, quality of life, medication adherence, functioning, and time to relapse. Methods This was a three-arm randomized controlled trial that compared two intervention arms against a peer support control group (forum). A total of 304 adults aged 21 to 65 years with a diagnosis of bipolar disorder were assigned to a forum-only control group (Group 1; n = 102), a forum plus modules treatment group (Group 2; n = 102), or a forum, modules, and tools treatment group (Group 3; n = 100), in addition to usual care. Results There was a significant intervention impact showing improvement on the primary outcome of depression for Group 2 compared to Group 1 (P = .05) with effect sizes (Cohen's d) ranging from 0.17 to 0.43. There was also a significant intervention impact showing improvement on the secondary outcome of core depression for Group 2 (P = .02) and Group 3 (P = .05), but worse physical functioning for Group 3 (P = .01), compared to Group 1. Conclusions This study provides evidence of the efficacy of internet-based psychoeducation interventions for bipolar disorder in reducing depressive symptoms. Further investigation is needed to assess effectiveness in a public program.
Description:
Subarachnoid hemorrhage secondary to rupture of an intracranial aneurysm is a highly lethal medical condition. Current management strategies for unruptured intracranial aneurysms involve radiological surveillance and neurosurgical or endovascular interventions. There is no pharmacological treatment available to decrease the risk of aneurysm rupture and subsequent subarachnoid hemorrhage. There is growing interest in the pathogenesis of intracranial aneurysm focused on the development of drug therapies to decrease the incidence of aneurysm rupture. The study of rodent models of intracranial aneurysms has the potential to improve our understanding of intracranial aneurysm development and progression. This review summarizes current mouse models of intact and ruptured intracranial aneurysms and discusses the relevance of these models to human intracranial aneurysms. The article also reviews the importance of these models in investigating the molecular mechanisms involved in the disease. Finally, potential pharmaceutical targets for intracranial aneurysm suggested by previous studies are discussed. Examples of potential drug targets include matrix metalloproteinases, stromal cell-derived factor-1, tumor necrosis factor-α, the renin-angiotensin system and the β-estrogen receptor. An agreed clear, precise and reproducible definition of what constitutes an aneurysm in the models would assist in their use to better understand the pathology of intracranial aneurysm and applying findings to patients
Description:
Subarachnoid hemorrhage secondary to rupture of an intracranial aneurysm is a highly lethal medical condition. Current management strategies for unruptured intracranial aneurysms involve radiological surveillance and neurosurgical or endovascular interventions. There is no pharmacological treatment available to decrease the risk of aneurysm rupture and subsequent subarachnoid hemorrhage. There is growing interest in the pathogenesis of intracranial aneurysm focused on the development of drug therapies to decrease the incidence of aneurysm rupture. The study of rodent models of intracranial aneurysms has the potential to improve our understanding of intracranial aneurysm development and progression. This review summarizes current mouse models of intact and ruptured intracranial aneurysms and discusses the relevance of these models to human intracranial aneurysms. The article also reviews the importance of these models in investigating the molecular mechanisms involved in the disease. Finally, potential pharmaceutical targets for intracranial aneurysm suggested by previous studies are discussed. Examples of potential drug targets include matrix metalloproteinases, stromal cell-derived factor-1, tumor necrosis factor-
Description:
BACKGROUND: This study evaluated the measurement invariance and agreement across parent and teacher ratings of the DSM-IV-TR oppositional defiant disorder (ODD) symptoms. METHOD: Malaysian parents and teachers of 934 children (between 6 and 11 years of age) completed rating scales comprising the ODD symptoms. RESULTS: Findings showed support for full measurement invariance (configural, metric and thresholds). Additional results indicated low parent-teacher agreement for all symptoms. DISCUSSION: The theoretical and clinical and implications of these findings are discussed.
Description:
Episodic ataxia type 2(EA-2) is a rare, autosomal dominant disorder characterised by recurrent episodes of ataxia and dysarthria,due to mutations in the CACNA1A gene on chromosome 19 encoding voltage-dependent Ca2+ channels. The aim of the present study was to explore whether axonal membrane properties, assessed using nerve excitability techniques, were abnormal in patients with EA-2 . Nerve excitability techniques were applied to the median nerve of three individuals from three generations of a single family, all of whom had typical features of EA-2. This family was found to have a novel mutation at codon 1451 of the Ca2+ channel alpha 1A subunit. Nerve excitability testing demonstrated significant abnormalities,with all patients outside the normal 95 % confidence limits in having a high rheobase and reduced early hyperpolarizing threshold electrotonus. On average there were also significant reductions in refractoriness,late sub excitability and early depolarizing threshold electrotonus. Mathematical modelling indicated that a similar pattern of abnormalities may result from a reduced voltage dependence of slow K+ channels (KCNQ channels). There are significant and distinctive changes in peripheral nerve excitability in EA-2 patients,which are presumably induced indirectly. These findings raise the possibility that excitability testing may prove a convenient screening test for patients with this suspected channelopathy.
Description:
Emerging evidence suggests that disordered eating, particularly binge-eating symptomatology, is overrepresented within Polycystic Ovary Syndrome (PCOS) populations. This comorbidity presents a clinical dilemma as current treatment approaches for PCOS emphasize the importance of weight management, diet, exercise, and the potential for harm of such treatment approaches in PCOS patients with comorbid disordered eating. However, limited research has assessed the occurrence of binge eating and disordered eating in PCOS patients. Consequently, little is known about the prevalence of binge eating in PCOS, and the possible etiological processes to explain this comorbidity remain poorly understood. Given the paucity of research on this topic, the aims of this narrative review are fourfold: 1) to outline the main symptoms of PCOS and binge eating; 2) to provide an overview of the prevalence of binge eating in PCOS; 3) to outline possible etiological factors for the comorbidity between PCOS and binge eating; and 4) to provide an overview of management strategies of binge eating in PCOS.
Description:
Emerging evidence suggests that disordered eating, particularly binge-eating symptomatology, is overrepresented within Polycystic Ovary Syndrome (PCOS) populations. This comorbidity presents a clinical dilemma as current treatment approaches for PCOS emphasize the importance of weight management, diet, exercise, and the potential for harm of such treatment approaches in PCOS patients with comorbid disordered eating. However, limited research has assessed the occurrence of binge eating and disordered eating in PCOS patients. Consequently, little is known about the prevalence of binge eating in PCOS, and the possible etiological processes to explain this comorbidity remain poorly understood. Given the paucity of research on this topic, the aims of this narrative review are fourfold: 1) to outline the main symptoms of PCOS and binge eating; 2) to provide an overview of the prevalence of binge eating in PCOS; 3) to outline possible etiological factors for the comorbidity between PCOS and binge eating; and 4) to provide an overview of management strategies of binge eating in PCOS.
Description:
OBJECTIVES: It can be difficult to distinguish vestibular migraine (VM) from Meniere's disease (MD) in its early stages. Using vestibular-evoked myogenic potentials (VEMPs), we sought to identify test parameters that would help discriminate between these two vestibular disorders. METHODS: We first recorded ocular and cervical VEMPs (oVEMP/cVEMP) to air-conducted clicks and bone-conducted vibration in 30 control participants, 30 participants with clinically definite VM and 30 participants with clinically probable VM. Results were compared with a group of 60 MD patients from a previous study. oVEMPs and cVEMPs were then recorded at octave frequencies of 250 Hz to 2000 Hz in 20 controls and 20 participants each with clinically definite VM and MD. Inter-aural amplitude asymmetry ratios and amplitude frequency ratios were compared between groups. RESULTS: For click, tendon-hammer-tap and minishaker-tap VEMPs, there were no significant differences in reflex amplitudes or symmetry between controls, definite VM and probable VM. Compared with MD patients, participants with VM had significantly fewer reflex abnormalities for click-cVEMP, click-oVEMPs and minitap-cVEMPs. The ratio of cVEMP amplitude generated by tone bursts at a frequency of 0.5 kHz to that generated by 1 kHz was significantly lower for MD affected ears than for VM or controls ears. cVEMP asymmetry ratios for 0.5 kHz tone bursts were significantly higher for MD than VM. CONCLUSIONS: The 0.5/1 kHz frequency ratio, 0.5 kHz asymmetry ratio and caloric test combined, separated MD from VM with a sensitivity of 90.0% and specificity of 70.0%.
Description:
Study design: Cross-sectional study. Objectives: To identify socio-demographic and injury-related factors that contribute to activity limitations and participation restrictions in people with spinal cord injury (SCI) in Bangladesh. Setting: Centre for the Rehabilitation of the Paralysed (CRP), Savar, Dhaka, Bangladesh. Methods: This study involved 120 (83% men) participants with SCI; their median (interquartile range) age and injury duration were 34 (25-43) years and 5 (2-10) years, respectively. Data were collected from the follow-up records kept by the Community Based Rehabilitation (CBR) unit of CRP and a subsequent home visit that included interview-Administered questions, questionnaires, and a neurological examination. The dependent variables were activity limitations and participation restrictions, assessed with the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0, scored 0-100; a high score indicates greater activity limitations and participation restrictions). Independent variables included socio-demographic factors (i.e., age, sex, marital status, educational level, monthly household income, employment status, and place of residence) and injury-related factors (i.e., injury duration, cause of injury, injury severity, and type of paralysis). Multivariable linear regression analyses were performed to identify the factors that independently contributed to activity limitations and participation restrictions. Results: Three significant independent variables explained 20.7% of the variance in activity limitations and participation restrictions (WHODAS 2.0 score), in which tetraplegia was the strongest significant contributing factor, followed by rural residence and complete injury. Conclusions: This study would indicate that tetraplegia, complete injury, and residing in a rural area are the major contributions in limiting the activity and participation following SCI in Bangladesh.