Mobile health applications for epilepsy in Indian app stores: A systematic review and content analysis using the mobile app rating scale.

OBJECTIVE: The growing prevalence of smartphones may prompt individuals with epilepsy to pursue unfulfilled healthcare requirements through mobile health (mHealth) apps, but the content and quality of these mHealth apps are rarely analysed. Hence, this study aimed to identify and assess the quality of epilepsy apps for patients with epilepsy (PWE), their caregivers, and healthcare practitioners (HCPs) available in the Play Store and App Store of India. METHODS: We performed a systematic search on the Google Play Store and Apple App Store of India to identify the mHealth apps for epilepsy which were released and updated till May 2023. The identified applications were downloaded and the quality was assessed using a Mobile app rating scale (MARS) for the overall quality, Aesthetics, Engagement, Functionality, and Information by three independent reviewers. The intraclass correlation coefficient (ICC) was calculated to assess the interrater reliability between the reviewers. An unpaired t-test was calculated to analyse the difference in mean scores for Android and iOS applications. RESULTS: The systematic search yielded a total of 2518 apps, out of which 26 were selected for inclusion in the study. Among these, 9 apps were compatible with Android, 11 with iOS, and 6 on both platforms. The mean (SD) MARS score of the apps was 3.5 (0.6) and the ICC for the overall app quality was 0.90 (95% CI: 0.82-0.96). Overall, apps scored highest in functionality (3.9), followed by aesthetics (3.6), information (3.3), and engagement (3.2). Among the included apps, the overall quality score was found to be higher for iOS apps than Android (MD = 0.54; 95% CI: 0.02 - 1.07; p-value: 0.042). CONCLUSION: Our study identified twenty-six mHealth applications for epilepsy that integrated various aspects of epilepsy self-management. The results of this study emphasize the importance of ensuring that current and future applications offer evidence-based information, integrate features that align with patient preferences, and generate evidence regarding the effectiveness of application usage.

Exploring Heading Direction Perception in Cervical Dystonia, Tremor, and Their Coexistence.

OBJECTIVE: Dystonias, characterized by excessive muscle contractions resulting in involuntary postures and movements, impact 3 million people globally, making them the third most common movement disorder. Often accompanied by tremors, dystonias have epidemiological links and non-motor features shared with isolated tremor, such as essential tremor. Both dystonia and tremor present with balance dysfunction and abnormal involuntary movements, potentially linked to abnormal cerebellar function. This study explores the perception of one's own linear movement, heading, particularly discrimination of heading direction, in isolated cervical dystonia, isolated tremor, and their combination. We compare such perception behavior in visual and vestibular domains, predicting that visual heading perception would be superior to vestibular heading perception. METHODS: Following the focus on the perception of heading direction, we used psychophysics techniques, such as two-alternative-forced-choice task, to examine perception of direction of one's own movements as they see isolated visual star-cloud movement (visual heading perception) and en bloc body movement (vestibular heading perception). We fitted a sigmoidal psychometric function curve to determine the threshold for visual or vestibular heading perception in our participants. RESULTS: Nineteen participants underwent a two-alternative forced-choice task in the vestibular and visual domains. Results reveal elevated vestibular heading perception thresholds in cervical dystonia with or without tremor, and isolated tremor compared to healthy controls. Vestibular heading perception threshold was comparable in cervical dystonia with tremor and isolated tremor, but it was even worse in isolated cervical dystonia. Visual heading perception, however, remained less affected all three conditions-isolated cervical dystonia, isolated tremor, and their combination. CONCLUSION: These findings indicate shared deficits and distinctions in the perception of linear translational heading across movement disorders, such as isolated cervical dystonia, tremor, or their combination, offering insights into their pathophysiology, particularly the involvement of cerebellum regions responsible for vestibular processing.

Increased syphilis testing and detection of late latent syphilis among women after switching from risk-based to opt-out testing strategy in an urban Australian sexual health clinic: a retrospective observational study.

Background: The Melbourne Sexual Health Centre (MSHC) implemented an opt-out syphilis test for women in December 2017. We aimed to examine the differences in syphilis testing uptake and confirmed syphilis cases among women after switching from risk-based to opt-out testing strategies. Methods: This was a retrospective study examining all women attending the MSHC for the first time in periods of risk-based testing (2015-2017) and opt-out testing (2018-2020). We calculated the proportion of women who tested for syphilis and the proportion of women with confirmed syphilis in each period. A chi-square test was performed to determine the differences in proportion between the risk-based testing and opt-out periods. Findings: A total of 27,481 women (i.e. 13,059 in the risk-based testing period and 14,422 in the opt-out period) were included in the final analysis, and the mean age was 26.8 years (standard deviation = 6.9). The proportion of women who were tested for syphilis at their first consultation increased from 52.8% (6890/13,059) in the risk-based testing period to 67.4% (9725/14,422) in the opt-out period (p < 0.0001). Syphilis positivity did not differ between the two periods (0.48% [33/6890] vs 0.71% [69/9725], p = 0.061) but late latent causes increased from 36.4% [12/33] to 60.9% [42/69] (p = 0.033). Interpretation: The opt-out testing strategy increased syphilis testing among women with increased detection of asymptomatic late latent syphilis. The opt-out syphilis testing strategy is beneficial in sexual health services. Health education and awareness may be required to improve syphilis testing uptake. Funding: National Health and Medical Research Council.

Objective assessment of eye alignment and disparity-driven vergence in Parkinson's disease.

Background: Self-reported diplopia is described in up to one-third of Parkinson's disease (PD) patients. Objective: The purpose of our study was to expand our understanding of the mechanistic underpinnings of diplopia in PD. We hypothesize that the time-based control of eye alignment and increased eye deviation under binocular viewing will be related to the fusion-initiating and fusion-maintaining component deficits of disparity-driven vergence in PD. Methods: We used high-resolution video-oculography to measure eye alignment under binocular and monocular viewing and disparity-driven vergence in 33 PD and 10 age-matched healthy participants. We computed eye deviation and time-based control of eye alignment, occurrence of conjugate saccadic eye movements, latency and gain of vergence (fusion initiation), and variance of eye position at the end of dynamic vergence (fusion maintenance). Results: We categorized PD subjects into three groups, considering their time-based control of eye alignment as compared to healthy controls in binocular viewing. Group 1 = 45% had good control and spent >80% of the time when the eyes were well-aligned, Group 2 = 26% had intermediate control and spent <80% but greater >5% of the time when the eyes were well-aligned, and Group 3 = 29% had very poor control with increased eye deviation majority of the times (<5% of the time when the eyes were well-aligned). All three groups exhibited greater eye deviation under monocular viewing than controls. PD subjects exhibited fusion-initiating and fusion-maintaining vergence deficits (prolonged latencies, reduced vergence gain, increased variance of fusion-maintaining component) with a greater probability of saccadic movements than controls. Group 2 and Group 3 subjects were more likely to exhibit failure to initiate vergence (>20%) than Group 1 (13%) and controls (0%) trials. No significant difference was found in the Unified Parkinson's Disease Rating Scale (UPDRS-a tool to measure the severity of PD) values between the three PD groups (Group 1 = 33.69 ± 14.22, Group 2 = 38.43 ± 22.61, and Group 3 = 23.44 ± 1, p > 0.05). Conclusion: The majority of PD subjects within our cohort had binocular dysfunction with increased eye deviation under monocular viewing and disparity-driven vergence deficits. PD subjects with intermediate or poor control of eye deviation under binocular viewing had greater fusion-initiating and fusion-maintaining vergence deficits. The study highlights the importance of assessing binocular dysfunction in PD subjects independent of the severity of motor symptoms.

Unraveling the Twist: Spatial Navigational Challenges in Cervical Dystonia.

BACKGROUND: Cervical dystonia (CD) is an intricate neurological condition with motor and nonmotor symptoms. These include disruptions in visual perception, self-orientation, visual working memory, and vestibular functions. However, the specific impact of CD on perceiving self-motion direction, especially with isolated visual or vestibular stimuli, remains largely unexplored. OBJECTIVE: This study aimed to examine the effects of CD on linear motion perception, hypothesizing impaired heading discrimination in both vestibular and visual tasks, and that such deficits correlate with the disease severity. METHODS: We employed a cutting-edge motion platform to precisely control whole-body linear motion. Through repeated two-alternative forced-choice tasks, we assessed vestibular heading direction discrimination. Participants observed dynamic star clouds in immersive virtual reality and indicated their perceived self-motion direction, evaluating visual heading direction discrimination. Sensitivity to direction variations and response accuracy errors were analyzed using robust Gaussian cumulative distribution psychometric functions. RESULTS: Heading perception is impaired in individuals with CD, particularly evident in vestibular heading discrimination. CD severity correlated with elevated thresholds for both vestibular and visual heading discrimination. Surprisingly, lateralized CD did not introduce bias in either system, suggesting widespread disruption over localized effects. CONCLUSIONS: Contrary to previous beliefs, our findings challenge the idea that CD-related heading discrimination issues mainly arise from peripheral vestibular effects. Instead, abnormal proprioceptive input from dystonic neck muscles introduces noise into the central mechanism integrating visual, vestibular, and proprioceptive signals. These insights into spatial navigation deficits have implications for future CD research. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Whole chloroplast genome-specific non-synonymous SNPs reveal the presence of substantial diversity in the pigeonpea mini-core collection.

To unravel the plastid genome diversity among the cultivated groups of the pigeonpea germplasm, we characterized the SNP occurrence and distribution of 142 pigeonpea mini-core collections based on their reference-based assembly of the chloroplast genome. A total of 8921 SNPs were found, which were again filtered and finally 3871 non-synonymous SNPs were detected and used for diversity estimates. These 3871 SNPs were classified into 12 groups and were present in only 44 of the 125 genes, demonstrating the presence of a precise mechanism for maintaining the whole chloroplast genome throughout evolution. The Acetyl-CoA carboxylase D gene possesses the maximum number of SNPs (12.29%), but the Adenosine Tri-Phosphate synthatase cluster genes (atpA, atpB, atpE, atpF, atpH, and atpI) altogether bear 43.34% of the SNPs making them most diverse. Various diversity estimates, such as the number of effective alleles (1.013), Watterson's estimate (0.19), Tajima's D ( - 3.15), Shannon's information index (0.036), suggest the presence of less diversity in the cultivated gene pool of chloroplast genomes. The genetic relatedness estimates based on pairwise correlations were also in congruence with these diversity descriptors and indicate the prevalence of rare alleles in the accessions. Interestingly, no stratification was observed either through STRUCTURE, PCoA, or phylogenetic analysis, indicating the common origin of the chloroplast in all the accessions used, irrespective of their geographical distribution. Further 6194 Cleaved Amplified Polymorphic Sequences (CAPS) markers for 531 SNPs were developed and validated in a selected set of germplasm. Based on these results, we inferred that all of the cultivated gene pools of pigeonpea have a common origin for the chloroplast genome and they possess less diversity in protein-coding regions, indicating a stable and evolved plastid genome. At the same time, all diversity analysis indicates the occurrence of rare alleles, suggesting the suitability of the mini-core collection in future pigeonpea improvement programs. In addition, the development of chloroplast genome-based CAPS markers would have utility in pigeonpea breeding programs. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03785-8.

Genome-wide survey, molecular evolution and expression analysis of Auxin Response Factor (ARF) gene family indicating their key role in seed number per pod in pigeonpea (C. cajan L. Millsp.).

Auxin Response Factors (ARF) are a family of transcription factors that mediate auxin signalling and regulate multiple biological processes. Their crucial role in increasing plant biomass/yield influenced this study, where a systematic analysis of ARF gene family was carried out to identify the key proteins controlling embryo/seed developmental pathways in pigeonpea. A genome-wide scan revealed the presence of 12 ARF genes in pigeonpea, distributed across the chromosomes 1, 3, 4, 8 and 11. Domain analysis of ARF proteins showed the presence of B3 DNA binding, AUX response, and IAA domains. Majority of them are of nuclear origin, and do not exhibit the level of genomic expansion as observed in Glycine max (51 members). The duplication events seem to range from 31.6 to 42.3 million years ago (mya). Promoter analysis revealed the presence of multiple cis-acting elements related to stress responses, hormone signalling and other development processes. The expression atlas data highlighted the expression of CcARF8 in hypocotyl, bud and flower whereas, CcARF7 expression was significantly high in pod. The real-time expression of CcARF2, CcARF3 and CcARF18 was highest in genotypes with high seed number indicating their key role in regulating embryo development and determining seed set in pigeonpea.

Monitoring Eye Movement in Patients with Parkinson's Disease: What Can It Tell Us?

Parkinson's disease (PD) affects approximately 10 million individuals worldwide. Visual impairments are a common feature of PD. Patients report difficulties with visual scanning, impaired depth perception and spatial navigation, and blurry and double vision. Examination of PD patients reveals abnormal fixational saccades, strabismus, impaired convergence, and abnormal visually-guided saccades. This review aims to describe objective features of abnormal eye movements in PD and to discuss the structures and pathways through which these abnormalities may manifest.

Neurosarcoidosis - A diagnostic challenge?

Background: Sarcoidosis is an inflammatory granulomatous multisystem disease with an unknown etiology. Neurosarcoidosis is a cryptogenic neuroinflammatory manifestation of sarcoidosis. Objective: This article aims at better understanding of one of the rarer diseases whose diagnosis may be difficult leading to delay in definitive management of the patient. Method: We describe a case of neurosarcoidosis with initial presentation similar to acute invasive fungal rhinosinusitis, whose diagnosis was challenging and delayed owing to the presenting symptoms. Conclusion: The diagnosis of neurosarcoidosis becomes challenging when it presents as isolated clinical neurological symptoms. We want to highlight the variable nature of neurosarcoidosis and its consideration as diagnosis after excluding other common infectious and inflammatory conditions.

Repeat deep anterior lamellar keratoplasty (DALK) for failed primary DALK.

Purpose: To evaluate the effectiveness of repeat deep anterior lamellar keratoplasty (DALK) in patients of previous failed DALK. Methods: : A retrospective analysis of records of seven patients who had undergone repeat DALK following the failure of the primary DALK was done. The indications for repeat surgery, time elapsed since the first surgery, and pre- & postoperative best-corrected visual acuity (BCVA) were noted for all the patients. Results: The follow-up period ranged between one- to four-year post repeat DALK. The indication of primary DALK was keratoconus with vernal keratoconjunctivitis (VKC) (n = 3), corneal amyloidosis (n = 2), Salzman nodular keratopathy (n = 1), and healed keratitis (n = 1). The need for repeat surgery arose when the BSCVA dropped to less than 20/200. The time interval elapsed since the first surgery ranged from two months to four years. Postoperatively, the BSCVA improved from 20/120 to 20/30 at the end of one-year post repeat DALK in all except one patient. All regrafts were clear at the most recent examination, performed after a mean period of 18 months after the secondary graft. No complication was encountered during the resurgery. The dissection of the host bed was easier in the second surgery owing to weaker adhesions. Conclusion: The prognosis for repeat DALK for failed DALK is excellent, and the outcomes of secondary grafts were comparable to those of primary DALK grafts. Re DALK offers the advantage of an easier dissection and lower chances of graft rejection compared to penetrating keratoplasty.

A meta-analysis on the prevalence of Taenia solium and Taenia saginata infections in India.

Tapeworm infections in humans are considered to be a significant public health menace. Despite its public health importance, the data on tapeworm infection remains fragmented and underutilised. The present study reviews the overall burden and distribution of taeniasis and cysticercosis caused by Taenia solium and Taenia saginata in India by conducting a systematic review of the scientific literature based on Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Data from 19 eligible articles were analysed and the prevalence of T. solium-associated taeniasis/cysticercosis was found to be 11.06% (95% confidence interval [CI] 6.856 to 16.119) and the prevalence of T. saginata-associated taeniasis was found to be 4.7% (95% CI 3.301 to 6.301). This systematic review and meta-analysis provides a comprehensive analysis of the available literature on tapeworm infections and assesses the burden of Taenia infection from India, identifying areas of high prevalence requiring active surveillance and public health interventions.

Corneal aberrations, densitometry on scheimpflug imaging, and visual acuity after deep anterior lamellar keratoplasty.

PURPOSE: To evaluate visual acuity, corneal aberrations, and densitometry post deep anterior lamellar keratoplasty (DALK). METHODS: Twenty-five eyes of 25 patients who underwent DALK for corneal stromal diseases with normal endothelium were enrolled in a prospective interventional study. Evaluation for corneal aberrations and densitometry postoperatively was performed using Scheimpflug imaging at 6 months. Anterior Segment Optical Coherence Tomography (ASOCT) was done for host-graft morphology. Correlation analysis of postoperative best-corrected visual acuity with corneal aberrations and corneal densitometry (CD) was performed. RESULTS: Big bubble deep anterior lamellar keratoplasty (BB-DALK) was successful in 18 patients, while 7 eyes underwent manual dissection due to failed BB (Big Bubble) technique. The mean BSCVA was 1.35 ± 0.46 logMAR units pre-operatively which improved to 0.36 ± 0.19 logMAR units post DALK at 6 months (P < 0.001). The mean Root Mean Square (RMS) (µm) of the magnitude of total corneal aberrations, HOA and LOA from central 6mm zone of cornea were 14.6 ± 9.2, 4.7 ± 2.9, and 13.8 ± 8.8, respectively. The mean anterior (120µm), central and posterior corneal (60µm) densitometry in 0-2mm zone were 25.8 ± 7.7 GSU, 18.7 ± 4.16 GSU and 10.09 ± 3.9 GSU respectively. A statistically significant correlation of postoperative residual stromal bed thickness, total corneal HOA, LOA, total corneal aberrations, HOA front and posterior corneal densitometry (0-2mm zone) with postoperative BSCVA was found. CONCLUSION: Though there is a significant improvement in BSCVA after DALK, the quality of vision in terms of aberrometry and densitometry is suboptimal, especially in cases undergoing manual DALK compared to those undergoing big bubble formation.

Prevalence of Pregnancy Associated Malaria in India.

Malaria in pregnancy is a major public health concern. It results in impaired maternal health and adversely effects fetal and perinatal outcomes. The present systematic review was conducted to assess the prevalence, distribution and adverse pregnancy outcomes in malaria infected females in India. A comprehensive search and review of PubMed and Web of Science based on PRISMA guidelines was carried out to find articles reporting prevalence of malaria in pregnant women from India. Data from 16 studies were analyzed and prevalence of malaria among pregnant women in India was found to be 11.4 % (95 % CI: 7.3, 16.3). Prevalence of malaria among asymptomatic and symptomatic pregnant women was found to be 10.62% (95% CI: 6.05, 16.23) and 13.13% (95% CI: 7.2, 20.52), respectively. P. falciparum and P. vivax were both reported with in the same population. The geospatial distribution of malaria in pregnancy spanned over nine very populous states of India. The review also reported severe maternal and perinatal outcomes. Given the seriousness of malaria in pregnant women and its effects on the fetus and new-born, a stringent district wise guideline for early detection and prophylaxis in regions identified in this review will help in its better control.

Benefits of gamification in medical education.

Medical education is changing at a fast pace. Students attend medical school with a high degree of technological literacy and a desire for a diverse educational experience. As a result, a growing number of medical schools are incorporating technology-enhanced active learning and multimedia education tools into their curriculum. Gamified training platforms include educational games, mobile medical apps, and virtual patient scenarios. We provide a systematic review of what is meant by gamification in this era. Specific educational games, mobile apps, and virtual simulations that may be used for preclinical and clinical training have been discovered and classified. The available data were presented in terms of the recognized platforms for medical education's possible benefits. Virtual patient simulations have been shown to enhance learning results in general. Gamification could improve learning, engagement, and cooperation by allowing for real-world application. They may also help with promoting risk-free healthcare decision-making, remote learning, learning analytics, and quick feedback. We account for Preclinical training which included 5 electronic games and 4 mobile apps, while clinical training included 5 electronic games, 10 mobile applications, and 12 virtual patient simulation tools. There were additionally nine more gamified virtual environment training products that were not commercially accessible. Many of these studies have shown that utilizing gamified media in medical education may confer advantages. This collection of hyperlinked resources may be utilized by medical students, practitioners, and instructors at all levels.

Prevalence of Amoebiasis and Associated Complications in India: A Systematic Review.

PURPOSE: Intestinal protozoan parasites are responsible for diarrheal diseases causing significant morbidity and mortality. Entamoeba histolytica is the principle protozoan parasite associated with diarrheal infections. The infection is often associated with inaccessibility to clean drinking water and poor sanitary conditions in low- and middle-income countries including India. A comprehensive systematic review was performed to evaluate a reliable nationwide estimate for prevalence and geographic distribution of amoebiasis in India and the complications associated with it. METHODS: We used the PRISMA guidelines to perform a systematic review and meta-analysis of articles published between the year 2001-2020. Two English language databases PubMed and Web of Science were searched to achieve relevant studies. RESULTS: Initial searches resulted in 467 studies out of which 64 eligible articles involving data from 289,659 human subjects from 12 states and 4 union territories were included in the final analysis. Prevalence of amoebiasis ranged from 3-23% in asymptomatic population, 0.64-11% in symptomatic patients and 1-17.5% in HIV-infected patients. Highest prevalence was seen in Tamil Nadu, Andaman Nicobar Island and North East India. Extra intestinal invasion of Entamoeba histolytica leading to complications such as amoebic liver abscess, amoebic colitis, colonic perforation and ameboma were also reported. Such complications have the potential to increase healthcare burden and may prove to be fatal. CONCLUSION: Amoebiasis remains a significant public health issue in India responsible for diarrheal diseases causing significant morbidity and mortality. Entamoeba histolytica is the principle protozoan parasite associated with amoebiasis. Public health efforts should be directed towards its control and better diagnostic methods should be employed for distinguishing between pathogenic and non-pathogenic species of Entamoeba.

Effect of Viewing Conditions on Fixation Eye Movements and Eye Alignment in Amblyopia.

Purpose: Patients with amblyopia are known to have fixation instability, which arises from alteration of physiologic fixation eye movements (FEMs) and nystagmus. We assessed the effects of monocular, binocular, and dichoptic viewing on FEMs and eye alignment in patients with and without fusion maldevelopment nystagmus (FMN). Methods: Thirty-four patients with amblyopia and seven healthy controls were recruited for this study. Eye movements were recorded using infrared video-oculography during (1) fellow eye viewing (FEV), (2) amblyopic eye viewing (AEV), (3) both eye viewing (BEV), and (4) dichoptic viewing (DcV) at varying fellow eye (FE) contrasts. The patients were classified per the clinical type of amblyopia and FEM waveforms into those without nystagmus, those with nystagmus with and without FMN. Fixational saccades and intersaccadic drifts, quick and slow phases of nystagmus, and bivariate contour ellipse area were analyzed in the FE and amblyopic eye (AE). Results: We found that FEMs are differentially affected with increased amplitude of quick phases of FMN observed during AEV than BEV and during DcV at lower FE contrasts. Increased fixation instability was seen in anisometropic patients at lower FE contrasts. Incomitance of eye misalignment was seen with the greatest increase during FEV. Strabismic/mixed amblyopia patients without FMN were more likely to demonstrate a fixation switch where the AE attends to the target during DcV than patients with FMN. Conclusions: Our findings suggest that FEM abnormalities modulate with different viewing conditions as used in various amblyopia therapies. Increased FEM abnormalities could affect the visual function deficits and may have treatment implications.

Does visuospatial motion perception correlate with coexisting movement disorders in Parkinson's disease?

Postural instability and balance impairment are common in Parkinson's disease (PD). Multiple factors, such as increased tone, bradykinesia, freezing of gait, posture, axial stiffness, and involuntary appendicular movements, can affect balance. The recent studies found that PD patients have abnormal perception of self-motion in vestibular domain. We asked whether measures of balance function, such as perception of one's motion, correlate with specific movement disorders seen in PD. Moving retinal image or self-motion in space triggers the perception of self-motion. We measured one's linear motion (heading) perception when subjects were moved en bloc using a moving platform (vestibular heading). Similar motion perception was generated in the visual domain (visual heading) by having the subjects view a 3D optical flow with immersive virtual reality goggles. During both tasks, the subjects reported the motion direction in the two-alternative-forced-choice paradigm. The accuracy of perceived motion direction was calculated from the responses fitted to the psychometric function curves to estimate how accurately and precisely the subjects can perceive rightward versus leftward motion (i.e., threshold and slope). Response accuracies and psychometric parameters were correlated with the disease duration, disease severity (total Unified Parkinson's Disease Rating Scale-III, UPDRS-III), and tremor, rigidity, axial, gait/posture components of UPRDS-III. We also correlated heading perception with the number of falls and subjective assessment of balance confidence using the Activities-Specific Balance Component (ABC) Scale. Accuracy, threshold, and sensitivity of vestibular heading perception significantly correlated with the disease duration and severity, particularly the tremor. Correlations were stronger for leftward heading perception in the vestibular domain. The visual heading perception was correlated with ABC Scale, especially with its items concerning optic-flow processing. There was asymmetry in leftward versus rightward vestibular heading perception. The level of asymmetry correlated with the axial component of UPDRS-III. Differences in the clinical parameters that correlate with visual versus vestibular heading perception suggest that two heading perception processes have different mechanistic underpinnings. The correlation of discordance between vestibular and visual heading perception with disease severity and duration suggests that visual function can be utilized for balance rehab in PD patients.

Subthalamic deep brain stimulation affects heading perception in Parkinson's disease.

Parkinson's disease (PD) presents with visuospatial impairment and falls. It is critical to understand how subthalamic deep brain stimulation (STN DBS) modulates visuospatial perception. We hypothesized that DBS has different effects on visual and vestibular perception of linear motion (heading), a critical aspect of visuospatial navigation; and such effects are specific to modulated STN location. Two-alternative forced-choice experiments were performed in 14 PD patients with bilateral STN DBS and 19 age-matched healthy controls (HC) during passive en bloc linear motion and 3D optic-flow in immersive virtual reality measured vestibular and visual heading. Objective measure of perception with Weibull psychometric function revealed that PD has significantly lower accuracy [L: 60.71 (17.86)%, R: 74.82 (17.44)%] and higher thresholds [L: 16.68 (12.83), R: 10.09 (7.35)] during vestibular task in both directions compared to HC (p < 0.05). DBS significantly improved vestibular discrimination accuracy [81.40 (14.36)%] and threshold [4.12 (5.87), p < 0.05] in the rightward direction. There were no DBS effects on the slopes of vestibular psychometric curves. Visual heading perception was better than vestibular and it was comparable to HC. There was no significant effect of DBS on visual heading response accuracy or discrimination threshold (p > 0.05). Patient-specific DBS models revealed an association between change in vestibular heading perception and the modulation of the dorsal STN. In summary, DBS may have different effects on vestibular and visual heading perception in PD. These effects may manifest via dorsal STN putatively by its effects on the cerebellum.

Temporal Patterns of Spontaneous Fixational Eye Movements: The Influence of Basal Ganglia.

BACKGROUND: Spontaneity is a unique feature of the nervous system. One of the fundamentally critical and recognized forms of spontaneous motor activity is witnessed in the visuomotor system. Microsaccades, the miniature spontaneous eye movements, are critical for the visual perception. We hypothesized that microsaccades follow specific temporal patterns that are modulated by the basal ganglia output. METHODS: We used high-resolution video-oculography to capture microsaccades in 48 subjects (31 healthy and 17 with Parkinson's disease) when subjects were asked to hold their gaze on a straight-ahead target projected on white background. We analyzed spontaneous discharge patterns of microsaccades. RESULTS: The first analysis considering coefficient of variation in intersaccadic interval distribution demonstrated that microsaccades in Parkinson's disease are more dispersed than the control group. The second analysis scrutinized microsaccades' temporal variability and revealed 3 distinct occurrence patterns: regular rhythmic, clustered, and randomly occurring following a Poisson-like process. The regular pattern was relatively more common in Parkinson's disease. Subthalamic DBS modulated this temporal pattern. The amount of change in the temporal variability depended on the DBS-induced volume of tissue activation and its overlap with the subthalamic nucleus. The third analysis determined the autocorrelations of microsaccades within 2-second time windows. We found that Parkinson's disease altered local temporal organization in microsaccade generation, and DBS had a modulatory effect. CONCLUSION: The microsaccades occur in 3 temporal patterns. The basal ganglia are one of the modulators of the microsaccade spontaneity.