What does visual snow look like? Quantification by matching a simulation.

The primary symptom of visual snow syndrome (VSS) is the unremitting perception of small, flickering dots covering the visual field. VSS is a serious but poorly understood condition that can interfere with daily tasks. Several studies have provided qualitative data about the appearance of visual snow, but methods to quantify the symptom are lacking. Here, we developed a task in which participants with VSS adjusted parameters of simulated visual snow on a computer monitor until the simulation matched their internal visual snow. On each trial, participants (n = 31 with VSS) modified the size, density, update speed, and contrast of the simulation. Participants' settings were highly reliable across trials (intraclass correlation coefficients > 0.89), and they reported that the task was effective at stimulating their visual snow. On average, visual snow was very small (less than 2 arcmin in diameter), updated quickly (mean temporal frequency = 18.2 Hz), had low density (mean snow elements vs. background = 2.87%), and had low contrast (average root mean square contrast = 2.56%). Our task provided a quantitative assessment of visual snow percepts, which may help individuals with VSS communicate their experience to others, facilitate assessment of treatment efficacy, and further our understanding of the trajectory of symptoms, as well as the neural origins of VSS.

Faster bi-stable visual switching in psychosis.

Bi-stable stimuli evoke two distinct perceptual interpretations that alternate and compete for dominance. Bi-stable perception is thought to be driven at least in part by mutual suppression between distinct neural populations that represent each percept. Abnormal visual perception has been observed among people with psychotic psychopathology (PwPP), and there is evidence to suggest that these visual deficits may depend on impaired neural suppression in the visual cortex. However, it is not yet clear whether bi-stable visual perception is abnormal among PwPP. Here, we examined bi-stable perception in a visual structure-from-motion task using a rotating cylinder illusion in a group of 65 PwPP, 44 first-degree biological relatives, and 43 healthy controls. Data from a 'real switch' task, in which physical depth cues signaled real switches in rotation direction were used to exclude individuals who did not show adequate task performance. In addition, we measured concentrations of neurochemicals, including glutamate, glutamine, and γ-amino butyric acid (GABA), involved in excitatory and inhibitory neurotransmission. These neurochemicals were measured non-invasively in the visual cortex using 7 tesla MR spectroscopy. We found that PwPP and their relatives showed faster bi-stable switch rates than healthy controls. Faster switch rates also correlated with significantly higher psychiatric symptom levels, specifically disorganization, across all participants. However, we did not observe any significant relationships across individuals between neurochemical concentrations and SFM switch rates. Our results are consistent with a reduction in suppressive neural processes during structure-from-motion perception in PwPP, and suggest that genetic liability for psychosis is associated with disrupted bi-stable perception.

Opioid-Free Analgesia is Safe and Effective in Anterior Cervical Spine Surgery: A Randomized Controlled Trial.

STUDY DESIGN: Randomized controlled trial (RCT). OBJECTIVE: Compare the efficacy of a multimodal, opioid-free (OF) pain management pathway with a traditional opioid-containing (OC) pathway in patients undergoing anterior cervical procedures. SUMMARY OF BACKGROUND DATA: Previous studies have compared opioid-based pain regimens to opioid-sparing regimens following cervical spine surgery, but have been limited by high rates of crossover, retrospective designs, reliance on indwelling pain catheters, opioid utilization for early postoperative analgesia, and/or a lack of patient-reported outcome measures. METHODS: This is a RCT in which patients were allocated to either an OF or OC perioperative pain management protocol. Eligible study participants included adult (age up to 18 y) patients who underwent primary, 1-level or 2-level anterior cervical surgery [anterior cervical discectomy and fusion (ACDF), anterior cervical disc arthroplasty (ACDA), or hybrid (ACDF and ACDA at different levels)] for degenerative pathology. The primary outcome variable was subjective pain level at 24 hours postoperative. The final study cohort consisted of 50 patients (22 OF, 28 OC). RESULTS: Patients in the OF group reported lower median postoperative pain levels at 6 hours (4 for OF vs. 7 for OC; P =0.041) and 24 hours (3 for OF vs. 5 for OC; P =0.032). At 2-week and 6-week follow-up, pain levels were similar between groups. Patients in the OF group reported greater comfort at 12 hours (9 for OF vs. 5 for OC; P =0.003) and 24 hours (9 for OF vs. 5 for OC; P =0.011) postoperatively. Notably, there were no significant differences in patients' reported pain satisfaction, overall surgical satisfaction, or overall sense of physical and mental well-being. In addition, there were no significant differences in falls, delirium, or constipation postoperatively. CONCLUSIONS: A multimodal OF pain management pathway following anterior cervical surgery for degenerative disease results in statistically noninferior pain control and equivalent patient-reported outcome measures compared with a traditional OC pathway.

Adapting to Visual Noise Alleviates Visual Snow.

Purpose: Visual snow syndrome-characterized by flickering specks throughout the visual field and accompanied by other symptoms-can disrupt daily life and affects roughly 2% of the population. However, its neural bases remain mysterious, and treatments are lacking. Here, we report the first intervention that can temporarily eliminate the visual snow symptom, allowing many observers to see the world without snow for the first time since symptom onset. Prolonged viewing of a visual stimulus strongly reduces the responsiveness of the visual pathways to subsequent stimuli, and we tested whether such adaptation could affect visual snow. Methods: Participants with visual snow (total n = 27) viewed high-contrast dynamic noise patterns, resembling television static, and then judged the strength of the symptom. Results: Visual snow was temporarily reduced in strength to the point that it was invisible at longer adaptation durations for most observers. The effect followed typical trends of adaptation for physical stimuli in normally sighted observers: Effect duration increased monotonically with duration of exposure to the adapter and was specific to dynamic noise. Conclusions: These results establish that spontaneous neural activity in the visual system is causally related to the visual snow percept. Because they perceive this activity, people with visual snow may provide a unique window into the generation and suppression of noise in the visual system. Adaptation allows reliable experimental control over visual snow, and so is a strong candidate for diagnostic testing and a promising tool for further understanding its neural origins, which could in turn aid the development of treatments.

The psychosis human connectome project: Design and rationale for studies of visual neurophysiology.

Visual perception is abnormal in psychotic disorders such as schizophrenia. In addition to hallucinations, laboratory tests show differences in fundamental visual processes including contrast sensitivity, center-surround interactions, and perceptual organization. A number of hypotheses have been proposed to explain visual dysfunction in psychotic disorders, including an imbalance between excitation and inhibition. However, the precise neural basis of abnormal visual perception in people with psychotic psychopathology (PwPP) remains unknown. Here, we describe the behavioral and 7 tesla MRI methods we used to interrogate visual neurophysiology in PwPP as part of the Psychosis Human Connectome Project (HCP). In addition to PwPP (n = 66) and healthy controls (n = 43), we also recruited first-degree biological relatives (n = 44) in order to examine the role of genetic liability for psychosis in visual perception. Our visual tasks were designed to assess fundamental visual processes in PwPP, whereas MR spectroscopy enabled us to examine neurochemistry, including excitatory and inhibitory markers. We show that it is feasible to collect high-quality data across multiple psychophysical, functional MRI, and MR spectroscopy experiments with a sizable number of participants at a single research site. These data, in addition to those from our previously described 3 tesla experiments, will be made publicly available in order to facilitate further investigations by other research groups. By combining visual neuroscience techniques and HCP brain imaging methods, our experiments offer new opportunities to investigate the neural basis of abnormal visual perception in PwPP.

Faster bi-stable visual switching in psychosis.

Bi-stable stimuli evoke two distinct perceptual interpretations that alternate and compete for dominance. Bi-stable perception is thought to be driven at least in part by mutual suppression between distinct neural populations that represent each percept. Abnormal visual perception is observed among people with psychotic psychopathology (PwPP), and there is evidence to suggest that these visual deficits may depend on impaired neural suppression in visual cortex. However, it is not yet clear whether bi-stable visual perception is abnormal among PwPP. Here, we examined bi-stable perception in a visual structure-from-motion task using a rotating cylinder illusion in a group of 65 PwPP, 44 first-degree biological relatives, and 43 healthy controls. Data from a 'real switch' task, in which physical depth cues signaled real switches in rotation direction were used to exclude individuals who did not show adequate task performance. In addition, we measured concentrations of neurochemicals, including glutamate, glutamine, and γ-amino butyric acid (GABA), involved in excitatory and inhibitory neurotransmission. These neurochemicals were measured non-invasively in visual cortex using 7 tesla MR spectroscopy. We found that PwPP and their relatives showed faster bi-stable switch rates than healthy controls. Faster switch rates also correlated with significantly higher psychiatric symptom levels across all participants. However, we did not observe any significant relationships across individuals between neurochemical concentrations and SFM switch rates. Our results are consistent with a reduction in suppressive neural processes during structure-from-motion perception in PwPP, and suggest that genetic liability for psychosis is associated with disrupted bi-stable perception.

Weakened untuned gain control is associated with schizophrenia while atypical orientation-tuned suppression depends on visual acuity.

Perceptual distortions are core features of psychosis. Weakened contrast surround suppression has been proposed as a neural mechanism underlying atypical perceptual experiences. Although previous work has measured suppression by asking participants to report the perceived contrast of a low-contrast target surrounded by a high-contrast surround, it is possible to modulate perceived contrast solely by manipulating the orientation of a matched-contrast center and surround. Removing the bottom-up segmentation cue of contrast difference and isolating orientation-dependent suppression may clarify the neural processes responsible for atypical surround suppression in psychosis. We examined surround suppression across a spectrum of psychotic psychopathology including people with schizophrenia (PSZ; N = 31) and people with bipolar disorder (PBD; N = 29), first-degree biological relatives of these patient groups (PBDrel, PSZrel; N = 28, N = 21, respectively), and healthy controls (N = 29). PSZ exhibited reduced surround suppression across orientations; although group differences were minimal at the condition that produced the strongest suppression. PBD and PSZrel exhibited intermediate suppression, whereas PBDrel performed most similarly to controls. Intriguingly, group differences in orientation-dependent surround suppression magnitude were moderated by visual acuity. A simulation in which visual acuity and/or focal attention interact with untuned gain control reproduces the observed pattern of results, including the lack of group differences when orientation of center and surround are the same. Our findings further elucidate perceptual mechanisms of impaired center-surround processing in psychosis and provide insights into the effects of visual acuity on orientation-dependent suppression in PSZ.

Biomechanical comparison of Tibial-sided supplemental fixation techniques in Bone-Patellar Tendon-Bone anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this study was to compare the biomechanical properties of a commercially available suture anchor and a screw post for supplemental tibial fixation of a bone-patellar tendon-bone (BTB) graft at time zero. We hypothesized that supplemental fixation using a suture anchor would demonstrate similar biomechanical performance in comparison with a screw post. METHODS: Sixteen fresh frozen, healthy human cadaveric knees underwent BTB autograft harvest, placement, and primary tibial-sided interference screw fixation using a standardized technique performed by a single surgeon. Specimens were randomly assigned to one of two tibial-sided supplemental fixation groups (suture anchor or screw post), yielding eight specimens in each group. Each specimen was affixed to a custom loading apparatus, with the tibial tunnel aligned in a vertical position that allowed for parallel "worst-case scenario" loading and eliminated loading variation due to tibial tunnel angle. Grafts were pretensioned to 30 N and biomechanical performance was compared with respect to cyclical loading between 50-250 N for 500 cycles at 0.5 Hz and pull-to-failure loading at 60 mm/min. RESULTS: The suture anchor and screw post supplemental constructs demonstrated similar performance with respect to all biomechanical parameters assessed, including yield strength (294.0 N [IQR 267.2-304.2 N] versus 332.1 N [IQR 313.8-350.4 N]; P = 0.079) and ultimate strength (330.1 N [IQR 306.9-418.7 N] versus 374.7 N [IQR 362.0-387.3 N]; P = 0.3798). However, of the eight original specimens in each group, one suture anchor specimen (12.5%) and six metallic screw post specimens (75%) failed during cyclical testing and were unable to undergo displacement and load to failure testing. CONCLUSION: This study provides preliminary evidence that supplemental tibial-sided fixation of a BTB ACL graft with a suture anchor has similar loading characteristics or load-to-failure strength when compared to supplemental fixation with a screw post construct. STUDY DESIGN: Laboratory Controlled Study. LEVEL OF EVIDENCE: Basic Science Study.

Comorbidity scores reported in anatomic and reverse total shoulder arthroplasty: a systematic review.

BACKGROUND: Due to the aging population, the number of reverse shoulder arthroplasty (RSA) and anatomic shoulder arthroplasty (TSA) continue to increase annually. Although outcome measures are frequently reported in literature for patients who undergo shoulder arthroplasty, no studies have analyzed reporting of patient comorbidities in this population. The purpose of this study was to evaluate reporting of comorbidity indices in shoulder arthroplasty literature and assess how this reporting may inform management and outcomes. METHODS: A database was compiled systematically using PubMed to identify articles pertaining to shoulder arthroplasty published between 2019 and 2021. The search terms, "reverse shoulder arthroplasty" and "anatomic shoulder arthroplasty," were used to identify clinical studies. Non-clinical (e.g., translational and basic science) and review articles were excluded. Included studies were then analyzed for reporting of comorbidity indices. RESULTS: A total of 199 articles were included in this review and reported comorbidities. Of these, 15.6% (31 of 199) pertained to TSA, while 84.4% (168 of 199) pertained to RSA. Within this review, 57.8% (115 of 199) articles utilized comorbidity scores, while 42.2% (84 of 199) reported only comorbid diagnoses. Among the scores utilized, the American Society of Anesthesiologists (ASA) physical status classification system was the most widely used among both the TSA (52.9%, 9 of 17) and the RSA studies (58.2%, 57 of 98). Additional scores within the RSA literature included the Charlson Comorbidity Index (CCI) (35.3%, 6 of 17), the Charlson Comorbidity Index by Deyo et al. (J Clin Epidemiol. 45(6):613-9, 1992) (CCI-Deyo; 5.9%, 1 of 17), the Modified Charlson Comorbidity Index (modified-CCI) (5.9%, 1 of 17), the Elixhauser et al. (Med Care. 36(1):8-27, 1998) Comorbidity Measure (ECM) (11.8%, 2 of 17), and the Modified Frailty Index (mFI) (5.9%, 1 of 17). With the TSA literature, the additional comorbidity scores included the CCI (30.6%, 30 of 98), the CCI-Deyo (6.1%, 6 of 98), the modified-CCI (1.0%, 1 of 98), the ECM (8.2%, 8 of 98), the Factor-5 modified Frailty Index (mFI-5) (1.0%, 1 of 98), and the mFI (1.0%, 1 of 98). CONCLUSION: The reporting of comorbidity indices is an important factor when considering patient outcomes and complications reported in shoulder arthroplasty literature. Although the reporting of these scores appears to be more prevalent in current literature, there is no standard or consistency in terms of which scores are reported. Given this diversity in comorbidity scores, further research is necessary to develop a single standardized score to properly analyze the effect of comorbidities on shoulder arthroplasty patient outcomes.

Hip Arthroscopic Microfracture Augmented With Platelet-Rich Plasma-Infused Micronized Cartilage Allograft Significantly Improves Functional Outcomes.

PURPOSE: To evaluate functional outcomes and survivorship in patients at 1 year after undergoing arthroscopic microfracture augmented with hyaline allograft for symptomatic chondral defects of the hip. METHODS: Consecutive patients with and without prior hip procedures presenting with Outerbridge grade IV chondral lesion of the acetabulum or femoral head were prospectively followed. Patients underwent hip microfracture augmented with hyaline allograft suspended in autologous platelet-rich plasma between October 2016 and April 2018. Extent of cartilage degeneration was quantified using the chondromalacia severity index (CMI). Patient functional scores, including Tegner, Hip Outcome Score-Activities of Daily Living (HOS-ADL), Sport-Specific Subscale (HOS-SSS), modified Harris Hip Score (mHHS), and Nonarthritic Hip Score (NAHS) were collected preoperatively and at minimum 1-year postoperatively. Minimal clinically important difference (MCID) was analyzed. Statistical significance was established at P < .05. Pearson's coefficient analysis was performed to identify preoperative variables correlated with clinical outcomes. RESULTS: Fifty-seven patients (86.4%) had minimum 1-year follow-up and were included in the final analysis, with a mean age and body mass index (BMI) of 38.3 ± 9.1 years and 27.7 ± 4.9 kg/m2, respectively. Comparison of baseline and postoperative score averages demonstrated significant improvements in Tegner scores (3.7 ± 2.9 vs 5.1 ± 2.6; P = .003), HOS-ADL (63.3 ± 16.4 vs 89.1 ± 14.5; P < .001), HOS-SSS (40.8 ± 20.4 vs 79.5 ± 21.6; P < .001), mHHS (61.5 ± 16.2 vs 87.0 ± 17.7; P < .001), and NAHS (56.6 ± 14.9 vs 78.7 ± 18.3; P < .001). The percentage of patients who achieved MCID for HOS-ADL, HOS-SSS, mHHS, and NAHS were 89.8%, 83.0%, 75.6%, and 81.6%, respectively. Overall, 91.8% of patients met the threshold for achieving MCID in at least one outcome score. Of the 57 patients, 5 (8.8%) failed clinically, with 1 (1.8%) undergoing revision surgery and 4 (6.9%) undergoing conversion to total hip arthroplasty. There was a direct correlation between preoperative alpha angle and postoperative HOS-ADL. Femoral chondral lesion size and CMI inversely correlated with postoperative HOS-ADL. CONCLUSIONS: Treatment of hip chondral defects with microfracture and hyaline allograft augmentation demonstrated excellent survivorship and significantly improved patient report outcomes at 1 year. LEVEL OF EVIDENCE: IV, retrospective case series.

Current Trends in Orthobiologics: An 11-Year Review of the Orthopaedic Literature.

BACKGROUND: The use of "orthobiologics" or regenerative therapies in orthopaedic surgery has grown in recent years. Particular interest has been raised with regard to platelet-rich plasma, bone marrow aspirate, adipose-derived cells, and amniotic cells. Although studies have analyzed outcomes after orthobiologic treatment, no study has analyzed how the literature as a whole has evolved. PURPOSE: To evaluate trends in platelet-rich plasma, bone marrow aspirate, adipose-derived cells, and amniotic cell publications and to assess how these might inform efforts to establish minimum reporting standards and forecast future use. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: A database was compiled systematically using PubMed to identify articles published between 2009 and 2019 within 9 prominent orthopaedic journals and pertaining to the use of platelet-rich plasma, bone marrow aspirate, adipose-derived cells, and amniotic cells in the treatment of musculoskeletal conditions. Included articles were classified as clinical, nonclinical (translational or basic science), or review, and a variety of study parameters were recorded for each. Additional queries were performed to identify articles that utilized minimum reporting standards. RESULTS: A total of 474 articles (132 clinical, 271 nonclinical, 71 review) were included, consisting of 244 (51.5%) platelet-rich plasma, 146 (30.8%) bone marrow aspirate, 72 (15.2%) adipose-derived cells, and 12 (2.5%) amniotic cells. The greatest annual increase in publications for each orthobiologic topic was from 2018 to 2019. The American Journal of Sports Medicine demonstrated the highest number of overall (34.2%) and clinical (50.0%) publications, and accounted for 44.3% of all platelet-rich plasma publications. The Journal of Orthopaedic Research accounted for the second highest overall number of publications (24.9%) and highest nonclinical publications (41.0%). Platelet-rich plasma accounted for 91.5% of all level 1 clinical studies, while much greater than half of bone marrow aspirate, adipose-derived cells, and amniotic cell publications were level 3 or lower. Out of the 207 articles that used some form of reporting protocol, 59 (28.5%) used an established algorithm and 125 (60.4%) used their own. CONCLUSION: Interest in orthobiologics continues to grow, as evidenced by an increasing trend in publications over an 11-year period. However, current reporting on orthobiologic formulations is largely heterogeneous, emphasizing the need for minimum reporting standards and higher-quality studies.

The psychosis human connectome project: An overview.

Investigations within the Human Connectome Project have expanded to include studies focusing on brain disorders. This paper describes one of the investigations focused on psychotic psychopathology: The psychosis Human Connectome Project (P-HCP). The data collected as part of this project were multimodal and derived from clinical assessments of psychopathology, cognitive assessments, instrument-based motor assessments, blood specimens, and magnetic resonance imaging (MRI) data. The dataset will be made publicly available through the NIMH Data Archive. In this report we provide specific information on how the sample of participants was obtained and characterized and describe the experimental tasks and procedures used to probe neural functions involved in psychotic disorders that may also mark genetic liability for psychotic psychopathology. Our goal in this paper is to outline the data acquisition process so that researchers intending to use these publicly available data can plan their analyses. MRI data described in this paper are limited to data acquired at 3 Tesla. A companion paper describes the study's 7 Tesla image acquisition protocol in detail, which is focused on visual perceptual functions in psychotic psychopathology.

Dermatomyositis and polymyositis in total hip arthroplasty.

BACKGROUND: Idiopathic inflammatory myopathies (IIM) are systemic autoimmune disorders such as dermatomyositis (DM), polymyositis (PM), inclusion body myopathy, and autoimmune necrotizing myopathy that, similar to osteoarthritis, affect quality of life and activities of daily living. Moreover, these patients are often burdened with chronic pain and disability; however, the outcomes and risk of total hip arthroplasty (THA) in this patient population remain unclear. AIM: To evaluate 90-d complications and costs in patients with these conditions. METHODS: A retrospective case control study was designed by accessing data from the Medicare dataset available on the PearlDiver server. Patients with IIM, here, those with DM and PM were matched based on possible confounding variables to a cohort without these diseases and with the same 10-year risk of mortality as defined by the Charlson Comorbidity Index Score (CCI). Univariate and multivariate analysis were performed to evaluate complications and t-tests to evaluate 90-d Medicare reimbursements as markers of costs after THA. RESULTS: The total sample was 1090 patients with each cohort comprised of 545. Females were 74.9% of the population. The mean CCI was 5.89 (SD 2.11). Those with IIM had increased rates of pneumonia [odds ratio (OR) 1.45, P < 0.001] and pulmonary embolism (OR 1.46, P = 0.035) and decreased hematoma risks (OR 0.58, P = 0.00). 90-d costs were on average $1411 greater for those with IIM yet not significantly different (P = 0.034). CONCLUSION: Patients with IIM have an increased 90-d rate of pneumonia and pulmonary embolism concomitant with a decreased hematoma rate consistent with their pro-coagulatory state. Further attention to increased resource utilization in these patients is also warranted.

Assessing methods for geometric distortion compensation in 7 T gradient echo functional MRI data.

Echo planar imaging (EPI) is widely used in functional and diffusion-weighted MRI, but suffers from significant geometric distortions in the phase encoding direction caused by inhomogeneities in the static magnetic field (B0 ). This is a particular challenge for EPI at very high field (≥7 T), as distortion increases with higher field strength. A number of techniques for distortion correction exist, including those based on B0 field mapping and acquiring EPI scans with opposite phase encoding directions. However, few quantitative comparisons of distortion compensation methods have been performed using human EPI data, especially at very high field. Here, we compared distortion compensation using B0 field maps and opposite phase encoding scans in two different software packages (FSL and AFNI) applied to 7 T gradient echo (GE) EPI data from 31 human participants. We assessed distortion compensation quality by quantifying alignment to anatomical reference scans using Dice coefficients and mutual information. Performance between FSL and AFNI was equivalent. In our whole-brain analyses, we found superior distortion compensation using GE scans with opposite phase encoding directions, versus B0 field maps or spin echo (SE) opposite phase encoding scans. However, SE performed better when analyses were limited to ventromedial prefrontal cortex, a region with substantial dropout. Matching the type of opposite phase encoding scans to the EPI data being corrected (e.g., SE-to-SE) also yielded better distortion correction. While the ideal distortion compensation approach likely varies depending on methodological differences across experiments, this study provides a framework for quantitative comparison of different distortion compensation methods.

Clinical presentation, imaging findings, and arthroscopic features in skeletally immature and mature adolescent hip patients: a comparative double-cohort retrospective study.

The purpose of this study was to evaluate differences in clinical presentation and extent of surgery required based on skeletal maturity between two cohorts of adolescent hip arthroscopy patients. We hypothesized that skeletal immaturity would be associated with a lower frequency of pincer impingement and a decreased need for surgical acetabuloplasty. A database of 1481 hip arthroscopies performed by a single orthopaedic surgeon between 2008 and 2016 was queried. Patients ≤18 years of age with femoroacetabular impingement were divided into two groups based on Risser score: Risser 1-4 (skeletally immature) or Risser 5 (skeletally mature). Groups were compared with respect to presentation, diagnosis, and arthroscopic procedures performed. Eighty-eight skeletally immature and 49 skeletally mature patients were included. Mixed impingement was more common in skeletally mature patients than immature (67.3% vs. 48.9%, P = 0.037). Skeletal maturity was associated with a significantly increased probability of undergoing acetabuloplasty (odds ratio = 4.6, 95% confidence interval 1.4-15.5; P = 0.014). Extent of chondral degeneration was similar between groups. Our findings support the hypothesis that skeletally immature hips undergo acetabuloplasty less frequently and demonstrate similar chondromalacia compared with a skeletally mature cohort. These results suggest that arthroscopic treatment for impingement-associated hip pain may be a reasonable option to consider for symptomatic skeletally immature patients who have completed a structured course of nonoperative treatment. Additional longitudinal outcomes data are needed to clarify the natural history of impingement-associated hip pain in younger populations and whether hip arthroscopy delays progression of osteoarthritis in these patients.

Reduced influence of perceptual context in schizophrenia: behavioral and neurophysiological evidence.

BACKGROUND: Accurate perception of visual contours is essential for seeing and differentiating objects in the environment. Both the ability to detect visual contours and the influence of perceptual context created by surrounding stimuli are diminished in people with schizophrenia (SCZ). The central aim of the present study was to better understand the biological underpinnings of impaired contour integration and weakened effects of perceptual context. Additionally, we sought to determine whether visual perceptual abnormalities reflect genetic factors in SCZ and are present in other severe mental disorders. METHODS: We examined behavioral data and event-related potentials (ERPs) collected during the perception of simple linear contours embedded in similar background stimuli in 27 patients with SCZ, 23 patients with bipolar disorder (BP), 23 first-degree relatives of SCZ, and 37 controls. RESULTS: SCZ exhibited impaired visual contour detection while BP exhibited intermediate performance. The orientation of neighboring stimuli (i.e. flankers) relative to the contour modulated perception across all groups, but SCZ exhibited weakened suppression by the perceptual context created by flankers. Late visual (occipital P2) and cognitive (centroparietal P3) neural responses showed group differences and flanker orientation effects, unlike earlier ERPs (occipital P1 and N1). Moreover, behavioral effects of flanker context on contour perception were correlated with modulation in P2 & P3 amplitudes. CONCLUSION: In addition to replicating and extending findings of abnormal contour integration and visual context modulation in SCZ, we provide novel evidence that the abnormal use of perceptual context is associated with higher-order sensory and cognitive processes.

Deficits in Auditory and Visual Sensory Discrimination Reflect a Genetic Liability for Psychosis and Predict Disruptions in Global Cognitive Functioning.

Sensory discrimination thresholds (i.e., the briefest stimulus that can be accurately perceived) can be measured using tablet-based auditory and visual sweep paradigms. These basic sensory functions have been found to be diminished in patients with psychosis. However, the extent to which worse sensory discrimination characterizes genetic liability for psychosis, and whether it is related to clinical symptomatology and community functioning remains unknown. In the current study we compared patients with psychosis (PSY; N=76), their first-degree biological relatives (REL; N=44), and groups of healthy controls (CON; N=13 auditory and visual/N=275 auditory/N=267 visual) on measures of auditory and visual sensory discrimination, and examined relationships with a battery of symptom, cognitive, and functioning measures. Sound sweep thresholds differed among the PSY, REL, and CON groups, driven by higher thresholds in the PSY compared to CON group, with the REL group showing intermediate thresholds. Visual thresholds also differed among the three groups, driven by higher thresholds in the REL versus CON group, and no significant differences between the REL and PSY groups. Across groups and among patients, higher thresholds (poorer discrimination) for both sound and visual sweeps strongly correlated with lower global cognitive scores. We conclude that low-level auditory and visual sensory discrimination deficits in psychosis may reflect genetic liability for psychotic illness. Critically, these deficits relate to global cognitive disruptions that are a hallmark of psychotic illnesses such as schizophrenia.

Late fMRI Response Components Are Altered in Autism Spectrum Disorder.

Disrupted cortical neural inhibition has been hypothesized to be a primary contributor to the pathophysiology of autism spectrum disorder (ASD). This hypothesis predicts that ASD will be associated with an increase in neural responses. We tested this prediction by comparing fMRI response magnitudes to simultaneous visual, auditory, and motor stimulation in ASD and neurotypical (NT) individuals. No increases in the initial transient response in any brain region were observed in ASD, suggesting that there is no increase in overall cortical neural excitability. Most notably, there were widespread fMRI magnitude increases in the ASD response following stimulation offset, approximately 6-8 s after the termination of sensory and motor stimulation. In some regions, the higher fMRI offset response in ASD could be attributed to a lack of an "undershoot"-an often observed feature of fMRI responses believed to reflect inhibitory processing. Offset response magnitude was associated with reaction times (RT) in the NT group and may explain an overall reduced RT in the ASD group. Overall, our results suggest that increases in neural responsiveness are present in ASD but are confined to specific components of the neural response, are particularly strong following stimulation offset, and are linked to differences in RT.

Weaker neural suppression in autism.

Abnormal sensory processing has been observed in autism, including superior visual motion discrimination, but the neural basis for these sensory changes remains unknown. Leveraging well-characterized suppressive neural circuits in the visual system, we used behavioral and fMRI tasks to demonstrate a significant reduction in neural suppression in young adults with autism spectrum disorder (ASD) compared to neurotypical controls. MR spectroscopy measurements revealed no group differences in neurotransmitter signals. We show how a computational model that incorporates divisive normalization, as well as narrower top-down gain (that could result, for example, from a narrower window of attention), can explain our observations and divergent previous findings. Thus, weaker neural suppression is reflected in visual task performance and fMRI measures in ASD, and may be attributable to differences in top-down processing.

Concentrations of Cortical GABA and Glutamate in Young Adults With Autism Spectrum Disorder.

The balance of excitation and inhibition in neural circuits is hypothesized to be increased in autism spectrum disorder, possibly mediated by altered signaling of the inhibitory neurotransmitter γ-aminobutyric acid (GABA), yet empirical evidence in humans is inconsistent. We used edited magnetic resonance spectroscopy (MRS) to quantify signals associated with both GABA and the excitatory neurotransmitter glutamate in multiple regions of the sensory and sensorimotor cortex, including primary visual, auditory, and motor areas in adult individuals with autism and in neurotypical controls. Despite the strong a priori hypothesis of reduced GABA in autism spectrum disorder, we found no group differences in neurometabolite concentrations in any of the examined regions and no correlations of MRS measure with psychophysical visual sensitivity or autism symptomatology. We demonstrate high data quality that is comparable across groups, with a relatively large sample of well-characterized participants, and use Bayesian statistics to corroborate the lack of any group differences. We conclude that levels of GABA and Glx (glutamate, glutamine, and glutathione) in the sensory and sensorimotor cortex, as measured with MRS at 3T, are comparable in adults with autism and neurotypical individuals. Autism Res 2020, 13: 1111-1129. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: γ-Aminobutyric acid (GABA) and glutamate are the main inhibitory and excitatory neurotransmitters in the human brain, respectively, and their balanced interaction is necessary for neural function. Previous research suggests that the GABA and glutamate systems might be altered in autism. In this study, we used magnetic resonance spectroscopy to measure concentrations of these neurotransmitters in the sensory areas in the brains of young adults with autism. In contradiction to the common hypothesis of reduced GABA in autism, we demonstrate that concentrations of both GABA and glutamate, in all the brain regions examined, are comparable in individuals with autism and in neurotypical adults. © 2020 International Society for Autism Research, Wiley Periodicals, Inc.