Visual Processing Functions Research Articles

Individualized identification of first-episode bipolar disorder using machine learning and cognitive tests

Identifying cognitive dysfunction in the early stages of Bipolar Disorder (BD) can allow for early intervention. Previous studies have shown a strong correlation between cognitive dysfunction and number of manic episodes. The objective of this study was to apply machine learning (ML) techniques on a battery of cognitive tests to identify first-episode BD patients (FE-BD). Two cohorts of participants were used for this study. Cohort #1 included 74 chronic BD patients (CHR-BD) and 53 healthy controls (HC), while the Cohort #2 included 37 FE-BD and 18 age- and sex-matched HC. Cognitive functioning was assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB). The tests examined domains of visual processing, spatial memory, attention and executive function. We trained an ML model to distinguish between chronic BD patients (CHR-BD) and HC at the individual level. We used linear Support Vector Machines (SVM) and were able to identify individual CHR-BD patients at 77% accuracy. We then applied the model to Cohort #2 (FE-BD patients) and achieved an accuracy of 76% (AUC=0.77). These results reveal that cognitive impairments may appear in early stages of BD and persist into later stages. This suggests that the same deficits may exist for both CHR-BD and FE-BD. These cognitive deficits may serve as markers for early BD. Our study provides a tool that these early markers can be used for detection of BD.

Structural correlates of atypical visual and motor cortical oscillations in pediatric-onset multiple sclerosis.

We have previously demonstrated that pediatric‐onset multiple sclerosis (POMS) negatively impacts the visual pathway as well as motor processing speed. Relationships between MS‐related diffuse structural damage of gray and white matter (WM) tissue and cortical responses to visual and motor stimuli remain poorly understood. We used magnetoencephalography in 14 POMS patients and 15 age‐ and sex‐matched healthy controls to assess visual gamma (30–80 Hz), motor gamma (60–90 Hz), and motor beta (15–30 Hz) cortical oscillatory responses to a visual‐motor task. Then, 3T MRI was used to: (a) calculate fractional anisotropy (FA) of the posterior visual and corticospinal motor WM pathways and (b) quantify volume and thickness of the cuneus and primary motor cortex. Visual gamma band power was reduced in POMS and was associated with reduced FA of the optic radiations but not with loss of cuneus volume or thickness. Activity in the primary motor cortex, as measured by postmovement beta rebound amplitude associated with peak latency, was decreased in POMS, although this reduction was not predicted by structural metrics. Our findings implicate loss of WM integrity as a contributor to reduced electrical responses in the visual cortex in POMS. Future work in larger cohorts will inform on the cognitive implications of this finding in terms of visual processing function and will determine whether the progressive loss of brain volume known to occur in POMS ultimately contributes to both progressive dysfunction in such tasks as well as progressive reduction in cortical electrical responses in the visual cortex.

Changes in functional connectivity in people with HIV switching antiretroviral therapy

We assessed changes in functional connectivity by fMRI (functional magnetic resonance imaging) and cognitive measures in otherwise neurologically asymptomatic people with HIV (PWH) switching combination antiretroviral therapy (cART). In a prospective study (baseline and follow-up after at least 4 months), virologically suppressed PWH switched non-nuclease reverse-transcriptase inhibitors (NNRTI; tenofovir-DF/emtricitabine with efavirenz to rilpivirine) and integrase-strand-transfer inhibitors (INSTI; tenofovir-DF/emtricitabine with raltegravir to dolutegravir). PWH were assessed by resting-state fMRI and stop-signal reaction time (SSRT) task fMRI as well as with a cognitive battery (CogState™) at baseline and follow-up. Switching from efavirenz to rilpivirine (n = 10) was associated with increased functional connectivity in the dorsal attention network (DAN) and a reduction in SSRTs (p = 0.025) that positively correlated with the time previously on efavirenz (mean = 4.8 years, p = 0.02). Switching from raltegravir to dolutegravir (n = 12) was associated with increased connectivity in the left DAN and bilateral sensory-motor and associative visual networks. In the NNRTI study, significant improvements in the cognitive domains of executive function, working memory and speed of visual processing were observed, whereas no significant changes in cognitive function were observed in the INSTI study. Changes in fMRI are evident in PWH without perceived neuropsychiatric complaints switching cART. fMRI may be a useful tool in assisting to elucidate the underlying pathogenic mechanisms of cART-related neuropsychiatric effects.

Towards machine to brain interfaces: sensory stimulation enhances sensorimotor dynamic functional connectivity in upper limb amputees

Objective. Recent development of sensory stimulation techniques demonstrates the ability to elicit touch-like phantom sensations in upper limb amputees. The cortical processing of this phantom sensation and the corresponding influences on sensorimotor functional connectivity have not been studied. We hypothesize that sensory stimulation has a profound impact on the sensorimotor cortical functional interactions, which will be uncovered by dynamic functional connectivity (dFC) analysis of amputees’ electroencephalogram (EEG) recordings. Approach. We investigated dFC between cortical areas associated with somatosensory, motor, visual, and multisensory processing functions using EEG signals. We applied dFC to the EEG of two amputees performing hand movements with and without sensory stimulation and compared the results with those from three able-bodied subjects. We quantified the changes due to sensory stimulation using dFC metrics, namely temporal distance, number of connection paths, temporal global and local efficiencies, and clustering coefficient. Main results. We show a significant effect of sensory stimulation on functional connectivity in the amputee brains, with notable facilitation on multisensory processing among the cortical systems involved in sensorimotor processing. The dFC metrics reveal that sensory stimulation enhances the speed of information transfer (shown by decreases in temporal distance) and the number of connection paths between the brain systems involved in sensorimotor processing, including primary somatosensory and motor, and higher order processing regions. Significance. This is the first work to reveal dynamic communication between somatosensory, motor, and higher order processing regions in the cortex of amputees in response to sensory stimulation. We believe that our work provides crucial insights into the cortical impact of sensory stimulation in amputees, which may lead to the design of personalized brain-informed sensory feedback paradigms. This in turn may lead to building novel Machine to Brain Interfaces involving sensory feedback and the resultant enhanced motor performance.

Examining the influence of decorated sidewaall in road tunnels using fMRI technology

In long tunnels where the driving environment is boring and monotonous, the speed perception of drivers is usually compromised. Although researchers have conducted a host of studies on driving safety in tunnels and found out that the sidewall environment was a significant factor that affected driver behavior inside tunnels, little is known regarding the mechanism of how the tunnel sidewall impacts the drivers, especially which regions of neural system are related to the impact of the sidewall. To fill this gap, the current study aims at examining the influence of the decorated tunnel sidewall on drivers’ brain activity using fMRI. To this end, an experiment was conducted where thirty-five subjects are recruited. The experiment was conducted using fMRI under two tunnel scenarios: empty sidewall and decorated sidewall. The video of the driving scene was taken in the real driving environment of a tunnel and presented by a projector outside the operating room. The results showed that the fusiform gyrus and precuneus were more activated in tunnels with the decorated sidewall than that with an empty sidewall. These regions are known to be responsible for visual recognition, visual processing and visual spatial functions. Therefore, it indicates that the presence of decorated sidewall provides drivers with a better spatial and speed perception and could help reduce accidents associated with speed judgment. The differences between driver groups were also explored and the finding revealed that the activation level of superior frontal gyrus is different between male and female drivers, which indicated that the same sidewall decoration has different effect between driver groups.

Neuropsychological profile of children and adolescents with psychosis risk syndrome: the CAPRIS study.

Neuropsychological underperformance is well described in young adults at clinical high risk for psychosis, but the literature is scarce on the cognitive profile of at-risk children and adolescents. The aim of this study is to describe the neuropsychological profile of a child and adolescent sample of patients with psychosis risk syndrome (PRS) compared to healthy controls and to analyze associations between attenuated psychotic symptoms and cognitive impairment. Cross-sectional baseline data analysis from a longitudinal, naturalistic, case-control, two-site study is presented. Eighty-one help-seeking subjects with PRS and 39 healthy controls (HC) aged between 10 and 17years of age were recruited. PRS was defined by: positive or negative attenuated symptoms, Brief Limited Intermittent Psychotic Symptoms (BLIPS), genetic risk (first- or second-degree relative), or schizotypal personality disorder plus impairment in functioning. A neuropsychological battery was administered to assess general intelligence, verbal and visual memory, visuospatial abilities, speed processing, attention, and executive functions. The PRS group showed lower general neuropsychological performance scores at a multivariate level and lower scores than controls in general intelligence and executive functions. Lower scores on executive function and poorer attention were associated with high scores of positive attenuated psychotic symptoms. No association with attenuated negative symptoms was found. This study provides evidence of cognitive impairment in PRS children and adolescents and shows a relationship between greater cognitive impairment in executive functions and attention tasks and severe attenuated positive symptoms. However, longitudinal studies are needed to clarify the nature of cognitive impairment as a possible vulnerability marker.

Children Use Regions in the Visual Processing and Executive Function Networks during a Subsequent Memory Reading Task.

Memory encoding is a critical process for memory function, which is foundational for cognitive functioning including reading, and has been extensively studied using subsequent memory tasks. Research in adults using such tasks indicates the participation of visual and cognitive-control systems in remembered versus forgotten words. However, given the known developmental trajectories of these systems, the functional neuroanatomy of memory encoding in children may be different than in adults. We examined brain activation for silent word reading and checkerboard viewing during an event-related reading task in 8-12 year-old children. Results indicate greater activation for checkerboard viewing than lexical processing in early visual regions, as well as for lexical processing versus checkerboard viewing in regions in left sensorimotor mouth, cingulo-opercular and dorsal-attention networks. Greater activation for remembered than forgotten words was observed in bilateral visual system and left lateralized regions within the ventral- and dorsal-attention, cingulo-opercular and fronto-parietal networks. These findings suggest a relatively mature reliance on the cognitive-control system, but greater reliance on the visual system in children when viewing words subsequently remembered. The location of regions with greater activity for remembered words reinforces the involvement of the attention and cognitive-control systems in subsequent memory in reading.

Hemisphere and Gender Differences in the Rich-Club Organization of Structural Networks.

Structural and functional differences in brain hemispheric asymmetry have been well documented between female and male adults. However, potential differences in the connectivity patterns of the rich-club organization of hemispheric structural networks in females and males remain to be determined. In this study, diffusion tensor imaging was used to construct hemispheric structural networks in healthy subjects, and graph theoretical analysis approaches were applied to quantify hemisphere and gender differences in rich-club organization. The results showed that rich-club organization was consistently observed in both hemispheres of female and male adults. Moreover, a reduced level of connectivity was found in the left hemisphere. Notably, rightward asymmetries were mainly observed in feeder and local connections among one hub region and peripheral regions, many of which are implicated in visual processing and spatial attention functions. Additionally, significant gender differences were revealed in the rich-club, feeder, and local connections in rich-club organization. These gender-related hub and peripheral regions are involved in emotional, sensory, and cognitive control functions. The topological changes in rich-club organization provide novel insight into the hemisphere and gender effects on white matter connections and underlie a potential network mechanism of hemisphere- and gender-based differences in visual processing, spatial attention and cognitive control.

Children With Dyslexia and Typical Readers: Sex-Based Choline Differences Revealed Using Proton Magnetic Resonance Spectroscopy Acquired Within Anterior Cingulate Cortex.

Children with dyslexia exhibit slow and inaccurate reading, as well as problems in executive functions. Decreased signal activation in brain regions related to visual processing and executive functions has been observed with functional magnetic resonance imaging with reports of sex differences in brain patterns for visual processing regions. However, the underlying neurochemistry associated with deficits in executive functions for children with dyslexia has not been thoroughly evaluated. Reading ability and executive functions were assessed in fifty-three children [ages 8–12 years old, dyslexia (n = 24), and typical readers (n = 30)]. We employed short echo, single voxel, proton magnetic resonance spectroscopy to evaluate the perigenual anterior cingulate cortex (ACC). Pearson correlations were calculated between metabolite concentrations and measures of reading, processing speed, and executive function. Logistic regression models were used to determine the effects of brain metabolite concentrations, processing speed, and reading scores on dyslexia status. Differences by child’s sex were also examined. Compared to typical readers, higher global executive composite t-score is associated with greater odds for dyslexia (OR 1.14; 95% CI 1.05, 1.23); increased processing speed appears to be protective for dyslexia (OR 0.95; 95% 0.89–1.00). After adjustment for multiple comparisons, females with dyslexia showed strong and significant negative correlations between processing speed and myo-inositol (r = -0.55, p = 0.005) and choline (r = -0.54, p = 0.005) concentrations; effect modification by sex was confirmed in linear regression models (psex∗Cho = 0.0006) and (psex∗mI = 0.01). These associations were not observed for males or the group as a whole. These findings suggest that children with dyslexia share difficulty in one or more areas of executive function, specifically those related to response time. Also, metabolite changes in the ACC may be present in children with dyslexia, especially for females, and may hold value as possible markers for dyslexia.

Diffusely Abnormal White Matter, T2 Burden of Disease, and Brain Volume in Relapsing-Remitting Multiple Sclerosis.

Multiple sclerosis (MS) diffusely abnormal white matter (DAWM) is a mildly hyperintense magnetic resonance imaging abnormality distinct from typical lesions. Our goal was to investigate the prevalence and natural history of DAWM in a large cohort (n = 348) of relapsing-remitting MS (RRMS) patients. The presence of DAWM and relationship to changes in T2 burden of disease (BOD), brain volume (brain fractional ratio, BFR), and disability (Expanded Disability Status Scale, EDSS) were investigated at baseline and year 7-8 (long-term follow-up, LTF). DAWM was present in 25.3% (88 of 348) of patients at baseline. At LTF, DAWM was unchanged in 69.3% (61 of 88), decreased in 28.4% (25 of 88), and increased in 2.3% (2 of 88) of patients. Baseline BOD and change in BOD did not significantly differ between patients with and without DAWM. DAWM was associated with greater reduction in BFR at LTF (P = .038). DAWM and DAWM change did not predict EDSS or EDSS progression. DAWM is present in a quarter of RRMS patients, and rarely increases or develops de novo. DAWM predicts brain atrophy but does not predict physical disability. Because of its posterior periventricular location, further investigation is warranted to evaluate its relationship to other measures of disability, including visual spatial processing and cognitive function.

Structural and functional brain abnormalities in drug-naive, first-episode, and chronic patients with schizophrenia: a multimodal MRI study.

BackgroundStructural and functional brain abnormalities in schizophrenia (SZ) have been widely reported. However, a few studies have investigated both structural and functional characteristics in SZ patients at different stages to understand the neuropathology of SZ.MethodsIn this study, we recruited 44 first-episode drug-naive SZ (FESZ) patients, 44 medicated chronic SZ (CSZ) patients, and 56 normal controls (NCs) and acquired their structural and resting-state functional magnetic resonance imaging (MRI). We then made group comparisons on structural and functional characteristics, including regional gray matter volume (GMV), regional homogeneity, amplitude of low-frequency fluctuation, and degree centrality. A linear support vector machine (SVM) combined with a recursive feature elimination (RFE) algorithm was implemented to discriminate three groups.ResultsOur results indicated that the regional GMV was significantly decreased in patients compared with that in NCs; CSZ patients have more diffused GMV decreases primarily involved in the frontal and temporal lobes when compared with FESZ patients. Both FESZ and CSZ patients showed significant functional alterations compared with NCs; when compared with FESZ patients, CSZ patients showed significant reductions in functional characteristics in several brain regions associated with auditory, visual processing, and sensorimotor functions. Moreover, a linear SVM combined with a RFE algorithm was implemented to discriminate three groups. The accuracies of the three classifiers were 79.80%, 83.16%, and 81.71%, respectively. The performance of classifiers in this study with multimodal MRI was better than that of previous discriminative analyses of SZ patients with single-modal MRI.ConclusionOur findings bring new insights into the understanding of the neuropathology of SZ and contribute to stage-specific biomarkers in diagnosis and interventions of SZ.

Application of chaos in a recurrent neural network to control in ill-posed problems: a novel autonomous robot arm.

Inspired by a viewpoint that complex/chaotic dynamics would play an important role in biological systems including the brain, chaotic dynamics introduced in a recurrent neural network was applied to robot control in ill-posed situations. By computer experiments we show that a model robot arm without an advanced visual processing function can catch a target object and bring it to a set position under ill-posed situations (e.g., in the presence of unknown obstacles). The key idea in these works is adaptive switching of a system parameter (connectivity) between a chaos regime and attractor regime in a neural network model, which generates, depending on environmental circumstances, either chaotic motions or definite motions corresponding to embedded attractors. The adaptive switching results in useful functional motions of the robot arm. These successful experiments indicate that chaotic dynamics is potentially useful for practical engineering control applications. In addition, this novel autonomous arm system is implemented in a hardware robot arm that can avoid obstacles and reach for a target in a situation where the robot can get only rough target information, including uncertainty, by means of a few sensors, as indicated in the appendix, A1 and A2.

15-Sensory and cognitive processing of visual stimuli in adolescents with type 1 diabetes mellitus: Electrophysiological study

To quantify objectively visual processing and executive functions in adolescents with type 1 diabetes mellitus (T1D) we evaluated electrophysiological markers of brain response in the oddball task (P3b component) and to the pattern-reversal stimulation (P100 wave). While P100 wave indicates, with a millisecond accuracy, visual sensory processing, the P3b reflects key elements of the executive control like an attention, a short-term visual working memory, and a decision-making. The peak time of the P100 wave in adolescents with T1D and without diabetic retinopathy (10 males, 12 females, 12–18 years) was significantly prolonged compared to a group of controls (8 males, 11 females, 10–21 years) p 0.066). In spite that peak time and amplitude of the P3b component did not diverge significantly, we found an enlarged area under curve of the P3b for patients (p = 0.035). There were no differences for the visual acuity, reaction time or task accuracy. Our study did show differences between groups in electrophysiological responses, in spite of no differences in their behavioral performance. Supported by MH CZ - DRO (UHHK). J. K. was supported by the Charles University project POGRES Q40/07.

Different neural substrates for precision stepping and fast online step adjustments in youth

Humans can navigate through challenging environments (e.g., cluttered or uneven terrains) by modifying their preferred gait pattern (e.g., step length, step width, or speed). Growing behavioral and neuroimaging evidence suggests that the ability to modify preferred step patterns requires the recruitment of cognitive resources. In children, it is argued that prolonged development of complex gait is related to the ongoing development of involved brain regions, but this has not been directly investigated yet. Here, we aimed to elucidate the relationship between structural brain properties and complex gait in youth aged 9–18 years. We used volumetric analyses of cortical grey matter (GM) and whole-brain voxelwise statistical analyses of white matter (WM), and utilized a treadmill-based precision stepping task to investigate complex gait. Moreover, precision stepping was performed on step targets which were either unperturbed or perturbed (i.e., unexpectedly shifting to a new location). Our main findings revealed that larger unperturbed precision step error was associated with decreased WM microstructural organization of tracts that are particularly associated with attentional and visual processing functions. These results strengthen the hypothesis that precision stepping on unperturbed step targets is driven by cortical processes. In contrast, no significant correlations were found between perturbed precision stepping and cortical structures, indicating that other (neural) mechanisms may be more important for this type of stepping.

The edge of awareness: Mask spatial density, but not color, determines optimal temporal frequency for continuous flash suppression.

The study of how visual processing functions in the absence of visual awareness has become a major research interest in the vision-science community. One of the main sources of evidence that stimuli that do not reach conscious awareness-and are thus "invisible"-are still processed to some degree by the visual system comes from studies using continuous flash suppression (CFS). Why and how CFS works may provide more general insight into how stimuli access awareness. As spatial and temporal properties of stimuli are major determinants of visual perception, we hypothesized that these properties of the CFS masks would be of significant importance to the achieved suppression depth. In previous studies however, the spatial and temporal properties of the masks themselves have received little study, and masking parameters vary widely across studies, making a metacomparison difficult. To investigate the factors that determine the effectiveness of CFS, we varied both the temporal frequency and the spatial density of Mondrian-style masks. We consistently found the longest suppression duration for a mask temporal frequency of around 6 Hz. In trials using masks with reduced spatial density, suppression was weaker and frequency tuning was less precise. In contrast, removing color reduced mask effectiveness but did not change the pattern of suppression strength as a function of frequency. Overall, this pattern of results stresses the importance of CFS mask parameters and is consistent with the idea that CFS works by disrupting the spatiotemporal mechanisms that underlie conscious access to visual input.

CAN EYETRACKING METRICS RELATE TO PERFORMANCE ON VISUAL COGNITIVE TESTS OF INDIVIDUALS WITH YOUNG-ONSET ALZHEIMER’S DISEASE?

Eyetracking has been used to determine oculomotor impairments in individuals with Alzheimer's disease (AD) and other neurodegenerative conditions (Crawford et al., 2005; Boxer et al., 2012; Yang et al., 2013; Shakespeare et al., 2015). Phenotypic differences in eyetracking metrics have also been reported between typical AD and the clinicoradiological syndrome posterior cortical atrophy (PCA; Shakespeare et al., 2015). In this study, we explored the relationship between eyetracking metrics and standard visual cognitive tests in a phenotypically diverse cohort of patients with young onset dementia AD (YOAD), all with symptom onset before the age of 65 years. Fifty-seven participants were included: 36 individuals with YOAD (10 of whom also met criteria for PCA) and 21 age-matched healthy controls. Participants completed three eyetracking experiments: fixation, pro-saccade and smooth pursuit tasks (see Figure 1). Frequentist summary metrics were used as outcome measures and their relationship with aspects of cognitive function explored by looking at correlations with basic visual (shape discrimination), visuoperceptual (fragmented letters, object decision), visuospatial (dot counting, letter cancellation) and measures of single word recognition included in the cognitive tests. Consistent with previous findings, the small PCA subgroup showed more abnormalities in oculomotor characteristics compared to the remainder of the cohort for 4/7 eyetracking metrics (see Table 1). Across the whole YOAD cohort, the pro-saccade and smooth pursuit tasks showed moderate correlations with visuoperceptual and visuospatial test scores. Conversely, the measure for the fixation task showed no significant relationship to any visual cognitive task. Basic visual shape discrimination performance was only related to pro-saccade performance, whilst the spatial dot counting test alone associated with pro-saccade accuracy. The relatively simple and specific nature of eyetracking opens routes to sensitive, quantitative, repeatable evaluations not only of basic oculomotor function but also visuoperceptual and visuospatial processes and other domains of higher cognitive function in individuals with neurodegenerative disease. The current findings provide further insights into the complex relationship between aspects of visual processing and oculomotor function. Performance of a control and a patient with YOAD (PCA) in the different eyetracking tasks: light blue circles show fixations, orange arrows indicate saccades and red dots/crosses represent target position. Orange circles in the pro- saccade task outline the interest area (an area within two degrees of visual angle from the target position).

Analysis of the Relationship Between Training Experience and Visual Sensory Functions in Athletes from Different Sports

Abstract Introduction. Gaining insight into the mechanisms and scope of possible adaptations of visual functions to the conditions determined by the demands imposed by sports training seems to be very interesting not only from a cognitive point of view, but also with respect to the practical applications of the findings of such investigations in the training process. The aim of the study was to assess the function of early visual processing in athletes representing different sports disciplines with varying training experience. Material and methods. The study involved 95 athletes practising football (n = 24), volleyball (n = 22), boxing (n = 26), and rowing (n = 23). The bioelectric function of the visual pathway was assessed based on recordings of visual evoked potentials (VEPs). The regions which were stimulated were the peripheral and central areas of the retina. During the test, we recorded the amplitude (μV) and latency (ms) of the P100 component of the VEP waveform for both monocular stimulation (for the dominant and non-dominant eye) and binocular stimulation. Results. Lower VEP P100 amplitude values were found for the peripheral and central locations for monocular and binocular viewing in more experienced volleyball players and rowers (p < 0.05). In the case of boxers with greater training experience, a significantly lower (p < 0.05) amplitude of the VEP P100 wave was observed in the central location in the dominant eye. However, we did not find significant differences (p > 0.05) in intragroup variability in VEP P100 latency in relation to training experience in any of the sports disciplines examined. Conclusions. Training experience has an influence on the early stage of sensory processing with respect to neural activity. Training experience has been found to differentiate athletes in terms of the temporal parameters of the visual evoked potentials recorded in the current study only to a limited extent.

Event-related potentials in schizotypal personality disorder and schizophrenia

The article presents an analysis of event-related potentials in Go/NoGo test from patients with schizophrenia and schizotypal personality disorder relative to healthy subjects. Identified differences in the group of patients with schizophrenia are consistent with previous studies and indicate a violation of the processes associated with different stages of visual information processing and executive functions. Special features of the brain activity from patients with schizotypal personality disorder were significantly less pronounced, and, presumably, pointed on the changes in the processes of attention redistribution and action monitoring. The results agree well with the clinical symptoms of schizophrenia and schizotypal personality disorder that allows us to consider this technique as a possible additional diagnostic criterion of these disorders.

Psychosis in Parkinson’s Disease: Epidemiology, Pathophysiology, and Management

Psychotic symptoms are common in Parkinson's disease (PD) and are associated with poorer quality of life and increased caregiver burden. PD psychosis is correlated with several factors, such as more advanced disease, cognitive impairment, depression, and sleep disorders. The underlying causes of psychosis in PD thus involve a complex interplay between exogenous (e.g., drugs, intercurrent illnesses) and endogenous (e.g., PD disease pathology) factors. Current theories of the pathophysiology of PD psychosis have come from several neuropathological and neuroimaging studies that implicate pathways involving visual processing and executive function, including temporo-limbic structures and neocortical gray matter with altered neurotransmitter functioning (e.g., dopamine, serotonin, and acetylcholine). Treatment of PD psychosis requires a step-wise process, including initial careful investigation of treatable triggering conditions and a comprehensive evaluation with adjustment of PD medications and/or initiation of specific antipsychotic therapies. Clozapine remains the only recommended drug for the treatment of PD psychosis; however, because of regular blood monitoring, quetiapine is usually first-line therapy, although less efficacious. Emerging studies have focused on agents involving other neurotransmitters, including the serotonin 5-HT2A receptor inverse agonist pimavanserin, cholinesterase inhibitors, and antidepressants and anxiolytics.

The Effects of Perceptual Learning on Visual Processing Functions in Professional Baseball Players

The Effects of Perceptual Learning on Visual Processing Functions in Professional Baseball Players