Motion opponency at the middle temporal cortex: Preserved motion information and the effect of perceptual learning

Motion opponency, first observed within the primate middle temporal cortex (MT), refers to the suppressing effect of opposite motion directions on neuronal activity. Namely, when opposing motion directional signals stimulate an MT neuron's receptive field, this neuron's response is comparable with that induced by flicker noise. Under such suppression, it is unknown whether any directional information is still represented at MT. In this study, we applied support vector machine (SVM) learning to human functional magnetic resonance imaging data to investigate if any motion defined orientation information was still available from suppressed MT. We found that, at least at the level of ±45° discrimination, such orientation information was still available. Interestingly, after behavioural perceptual learning that improved human discrimination of fine orientation discrimination (e.g. 42° vs. 48°) using the MT-suppressive motion stimuli, the SVM discrimination of ±45° worsened when functional magnetic resonance imaging (fMRI) signals at post-learning MT were used. This result is consistent with findings in Thompson et al. (2013) that, post-perceptual learning, MT suppression was not released, suggesting that motion opponency was perhaps functionally too important for perceptual learning to overcome.

Effects of visual span on Chinese reading performance in normal peripheral vision

The current study examined the relationships among temporal processing speed, spatial visual span and Chinese character reading speed in normal central and peripheral vision. Maximum reading speed (MRS) and critical print size (CPS) of 26 native Chinese readers (13 young and 13 older adults) were determined at three visual field locations: central vision, 10° left and 10° below fixation using a rapid serial visual presentation (RSVP) task. Temporal processing speed was measured using trigrams of randomly selected Chinese characters presented at a range of exposure durations, while spatial visual span was measured using trigrams presented at different spatial positions. It was found that shorter temporal processing speed and larger spatial visual span were associated with faster MRS at the central and inferior visual field locations, but not at the left of fixation location. As expected, reading and visual span metrics were better in central vision compared to both peripheral locations. In addition, reading, temporal processing, and spatial visual span metrics were better in the young than older subjects (except for similar temporal processing speed at two peripheral locations). The results for central and inferior presentation locations support the hypothesis that temporal processing speed and spatial visual span were associated with Chinese character reading speed. Surprisingly, no correlation was observed for the 10° left of the fixation location, suggesting that the factors affecting reading speed might differ for inferior and lateral peripheral viewing locations.

Factors predicting regression of visual acuity following successful treatment of anisometropic amblyopia

Objective

To identify factors associated with visual acuity regression following successful treatment of anisometropic amblyopia.

Design and method

This was a retrospective cohort study. Database records for 100 and 61 children with anisometropic amblyopia who met at least one criterion for successful treatment proposed by the Pediatric Eye Disease Investigator Group (PEDIG) and had at least 1 year of follow-up data available after the criterion was met were analyzed. The study sample was split into two groups, those who regressed within 1 year of successful treatment (no longer met any of the PEDIG criteria for successful treatment) and those who did not. A two-step analysis involving a least absolute shrinkage and selection operator (LASSO) regression and a logistic regression were used to identify predictor variables for increased risk of regression. A broad range of clinical, perceptual, and demographic variables were included in the analyses.

Results

Sixty-eight (42.5%) children regressed within 1 year of successful treatment. Among the 27 predictor variables considered within the statistical modeling process, the three most important for predicting treatment regression were the extent of amblyopic eye visual acuity improvement, age at first hospital visit and sex. Specifically, lower risk of regression was associated with larger amblyopic eye visual acuity improvement with treatment, younger age at initiation of treatment and female sex.

Conclusion

Patients who received treatment at a younger age and responded well to treatment had a lower risk of treatment regression. This pattern of results suggests that early detection of amblyopia and strategies that enhance treatment adherence may reduce the risk of treatment regression. The higher risk of regression in boys than girls that we observed may reflect known sex differences in brain development and /or sex differences in environment within our sample of children from South China.

Neurocognitive Outcomes at Age 2 Years After Neonatal Hypoglycemia in a Cohort of Participants From the hPOD Randomized Trial

IMPORTANCE

Neonatal hypoglycemia is common, but its association with later neurodevelopment is uncertain.

OBJECTIVE

To examine associations between neonatal hypoglycemia and neurocognitive outcomes at corrected age 2 years.

DESIGN, SETTING, AND PARTICIPANTS

Exploratory cohort analysis of the Hypoglycaemia Prevention With Oral Dextrose (hPOD) randomized clinical trial was conducted. The trial recruited participants from January 9, 2015, to May 5, 2019, with follow-up between January 26, 2017, and July 31, 2021. Infants were recruited from 9 maternity hospitals in New Zealand and assessed at home or in a research clinic. Children born late preterm and at term at risk of neonatal hypoglycemia but without evidence of acute or imminent illness in the first hour after birth were screened and treated to maintain blood glucose concentrations greater than or equal to 47 mg/dL.

EXPOSURES

Hypoglycemia was defined as any blood glucose concentration less than 47 mg/dL, recurrent as 3 or more episodes, and severe as less than 36 mg/dL.

MAIN OUTCOMES AND MEASURES

Neurologic examination and tests of development (Bayley III) and executive function. The primary outcome was neurosensory impairment (any of the following: blindness, deafness, cerebral palsy, developmental delay, or executive function total score worse than 1.5 SD below the mean).

RESULTS

A total of 1197 of 1321 (91%) eligible children were assessed at a mean of corrected age 24 months; 616 (52%) were male. Compared with the normoglycemia group, children who experienced hypoglycemia were more likely to have neurosensory impairment (111 [23%] vs 125 [18%]; adjusted risk ratio [aRR], 1.28; 95% CI, 1.01-1.60), particularly if they experienced severe episodes (30 [28%] vs 125 [18%]; aRR, 1.68; 95% CI, 1.20-2.36), but not recurrent episodes (12 [19%] vs 125 [18%]; aRR, 1.06; 95% CI, 0.63-1.80). The risk of cognitive, language, or motor delay was similar between groups, but children who experienced hypoglycemia had lower Bayley-III composite cognitive (adjusted mean difference [aMD], -1.48; 95% CI, -2.79 to -0.18) and motor scores (aMD, -2.05; 95% CI, -3.30 to -0.79).

CONCLUSIONS AND RELEVANCE

In children born at risk of hypoglycemia but otherwise well, those who experienced neonatal hypoglycemia were more likely to have neurosensory impairment at corrected age 2 years, with higher risks after severe episodes. Further research is required to determine causality.

Amblyopia is associated with impaired balance in 3–6-year-old children in China

Purpose

School-age children in China have more advanced motor development than their North American counterparts. This is likely due to cultural differences in children’s regular motor activities. It is unknown whether the motor function impairments associated with binocular visual disorders (BVDs) such as amblyopia in children raised in North America exist for children raised in China.

Design

Prospective case-control study.

Methods

A major tertiary eye hospital in China tested children aged 3 to <7 (n = 63) belonging to three groups: anisometropic or strabismic amblyopia (n = 22), anisometropia or strabismus without amblyopia (n = 20), or controls (n = 21). The main outcome measure was motor function scores (Movement Assessment Battery for Children 2nd edition).

Results

Balance scores varied significantly across groups (F_2,61 = 4.2, p = 0.02) with the amblyopia group (mean ± SD: 12.5 ± 3.0) exhibiting significantly poorer scores than controls (14.8 ± 2.3). The no-amblyopia BVD group (12.8 ± 3.1) did not differ significantly from the other groups. Manual dexterity, catching and throwing and total scores did not vary significantly across the three groups. A separate pre-planned comparison of only the amblyopia and control groups revealed significantly poorer total motor scores in the amblyopia group (10.1 ± 3.2) vs. controls (12 ± 2.4). A linear regression model was unable to significantly predict associations between total motor score and binocular function score (standardized β = −0.09, 95%, p = 0.7), amblyopia etiology (standardized β = 0.14, 95%, p = 0.4), or inter-ocular acuity difference (standardized β = −0.18, 95%, p = 0.4), in the amblyopia group.

Conclusion

Amblyopia is associated with motor function impairment in children raised in China. Motor deficits that may impact everyday activities have been observed in patients with amblyopia across multiple cultures.

Measurement properties of the WHO Disability Assessment Schedule 2.0 for evaluating functional status after inpatient surgery

BACKGROUND

Expert recommendations propose the WHO Disability Assessment Schedule (WHODAS) 2.0 as a core outcome measure in surgical studies, yet data on its long-term measurement properties remain limited. These were evaluated in a secondary analysis of the Measurement of Exercise Tolerance before Surgery (METS) prospective cohort.

METHODS

Participants were adults (40 years of age or older) who underwent inpatient non-cardiac surgery. The 12-item WHODAS and EQ-5DTM-3L questionnaires were administered preoperatively (in person) and 1 year postoperatively (by telephone). Responsiveness was characterized using standardized response means (SRMs) and correlation coefficients between change scores. Construct validity was evaluated using correlation coefficients between 1-year scores and comparisons of WHODAS scores across clinically relevant subgroups.

RESULTS

The analysis included 546 patients. There was moderate correlation between changes in WHODAS and various EQ-5DTM subscales. The strongest correlation was between changes in WHODAS and changes in the functional domains of the EQ-5D-3L-for example, mobility (Spearman's rho 0.40, 95 per cent confidence interval [c.i.] 0.32 to 0.48) and usual activities (rho 0.45, 95 per cent c.i. 0.30 to 0.52). When compared across quartiles of EQ-5D index change, median WHODAS scores followed expected patterns of change. In subgroups with expected functional status changes, the WHODAS SRMs ranged from 'small' to 'large' in the expected directions of change. At 1 year, the WHODAS demonstrated convergence with the EQ-5D-3L functional domains, and good discrimination between patients with expected differences in functional status.

CONCLUSION

The WHODAS questionnaire has construct validity and responsiveness as a measure of functional status at 1 year after major surgery.

Severe disseminated primary varicella in a patient on long term inhaled corticosteroids

Disseminated primary varicella infection can carry risks of significant morbidity and mortality particularly in immunocompromised populations. Routine, funded childhood vaccination against varicella has significantly reduced associated hospitalization and deaths, however, uptake and efficacy among adults is unknown. We present a case of disseminated primary varicella infection (including rash, pneumonitis, hepatitis and thrombocytopenia) in an immunocompetent patient on long term inhaled corticosteroids for asthma. This case highlights potential risk factors for severe varicella which require further study in adults and raises the need to discuss vaccination in at risk groups including appropriate counselling in those who may be at higher risk.