The influence of spatial and temporal noise on the detection of first-order and second-order orientation and motion direction

Thresholds for identifying the direction of second-order motion (contrast-modulated dynamic noise) are consistently higher than those for identifying spatial orientation, unlike first-order gratings for which the two thresholds are typically the same. Two explanations of this phenomenon have been proposed: either first-order and second-order patterns are encoded by separate mechanisms with different properties, or dynamic noise selectively impairs ("masks") sensitivity to second-order motion direction but not orientation. The former predicts the two thresholds should remain distinct for second-order patterns, irrespective of the temporal structure (static vs. dynamic) of the noise carrier. The latter predicts direction thresholds should be higher than orientation thresholds, for both second-order and first-order motion patterns, when dynamic (but not static) noise is present. To resolve this issue we measured direction and orientation thresholds for first-order (luminance) and second-order (contrast or polarity) modulations of static or dynamic noise. Results were decisive: The two thresholds were invariably the same for first-order stimuli but markedly different (direction thresholds approximately 50% higher) for second-order stimuli, regardless of the temporal properties (static or dynamic) and the overall contrast of the noise, or the drift temporal frequency of the envelope. This suggests that first-order and second-order motion are encoded separately and that the mechanisms encoding second-order stimuli cannot determine direction at the absolute threshold for spatial form.     

Spontaneous cries can alter the physiological well-being and cerebral oxygenation of very preterm infants

Introduction

Infant crying is a major expression of distress and can occur without any exogenous stimulation. Little is known, however, about the effects of crying on physiological homeostasis in very preterm infants (VPIs).

Methods

Environmental, behavioral (video and audio recording) and physiologic (heart rate [HR], respiratory rate [RR], and systemic [SaO₂] and regional cerebral oxygenation [rSO₂]) parameters were prospectively evaluated over 10 h in 18 VPIs (median gestational age, 28 [27–31] weeks). Only episodes of “spontaneous” and isolated cries were analyzed. Changes in parameters were compared over 5-second periods between baselines and 40 s following the onset of crying. Two periods were distinguished: 0–20 s (a) and 20–40 s (b). Minimal and/or maximal values in these periods were also compared to the baseline.

Results

Of the 18 VPIs initially studied, 13 (72%) presented crying episodes (CE). They experienced 210 “spontaneous” and isolated CE, with a median of 9 [range, 1–63] CEs per child. Physiological values varied significantly from the baseline with mainly a mean decrease in HR of − 4.8 ± 5.3 beats/min (b) after an initial mean increase of + 2.6 ± 2.0 beats/min (a); a mean decrease in RR of − 3.8 ± 4.8 cycles/min (a), followed by a mean increase of + 5.6 ± 7.3 cycles/min (b) and mean unidirectional decreases in SaO₂ and rSO₂ (minimal values) of − 1.8 ± 2.3% and − 2.5 ± 3.0%, respectively.

Conclusion

Spontaneous cries can alter the homeostasis of VPIs. Their possible adverse consequences and high occurrence emphasize the need for better prevention and response to them.     

Fetal and neonatal exposure to the mycotoxin zearalenone induces phenotypic alterations in adult rat mammary gland

Zearalenone is a mycotoxin that is widespread in cereal food. We questioned whether this mycotoxin, administered during known critical exposure periods such as the fetal period and the first days of life, at doses compatible with mean daily intake in humans, could have an effect on mammary gland development in rodents. Wistar female rats were exposed to zearalenone (0.2 μg/kg to 5 mg/kg) during the last 14 days of fetal life and the first 5 post-natal days (PND). The mammary tissue was examined for development and maturation by morphologic analyses and immunochemistry. At PND 30, the mean length of terminal buds was significantly enhanced in all of the zearalenone-exposed females (p < 0.05). The mammary tissue, as evaluated by scoring of tissue slides, was significantly more differentiated in the 1 mg/kg treated group than in controls (p < 0.05). At PND 180, mammary tissue was more differentiated in all of the zearalenone treated groups (p < 0.05). At six months, 4 of 18 females exposed to 5 mg/kg of zearalenone presented mammary hyperplasia lesions. The induction of phenotypic alterations by zearalenone administered in utero and in the neonatal period at doses as low as 0.2 μg/kg suggests that zearalenone could contribute to the induction of breast endocrine disorders.     

Retinal photography for diabetic retinopathy screening in Indigenous primary health care: the Inala experience

Objective: We aimed to determine the impact of clinic based retinal photography on access to appropriate screening for diabetic retinopathy (DR). Design, setting and participants: We opportunistically recruited patients undergoing their annual diabetic cycle of care over a two year period in the urban Indigenous primary health care clinic. Data were collected on retinal outcomes, health variables and referral patterns. Main outcome measures: Access to appropriate screening and ophthalmic follow up, prevalence of DR, acceptability and feasibility of clinic‐based retinal photography were the main outcome measures of this study. Results: One hundred and thirty‐two of a possible 147 patients consented to participate. 30% of participants had DR. Appropriate screening and ophthalmic follow up increased six fold, from 20 to 124 participants, following the introduction of the retinal camera. Most participants felt very positive about DR screening. Conclusions: Primary care DR screening using retinal photography can improve access to DR screening for indigenous patients, reduce the burden on busy outpatient departments and should reduce visual loss. Policy‐makers could contribute to screening sustainability by funding a medicare item‐number for primary care based DR screening associated with the annual diabetic cycle of care. An upfront Practice Incentive Program (PIP) payment could offset set up costs.     

The inhibitory effects on adult male reproductive functions of crude garlic (Allium sativum) feeding.

AIM: to investigate the effects of crude garlic on adult male rat reproductive functions. METHODS: Thirty male rats were divided into five groups: group 1 (untreated) and groups 2, 3, 4 and 5 were fed for 30 days with 5%, 10%, 15% and 30% crude garlic, respectively. Testes and accessory organs were weighed and some markers were assessed. Light and electron microscopy observations were also performed. RESULTS: A significant decrease was observed in the body weight of groups 4 (14%; P < 0.01) and 5 (20%; P < 0.01); of the prostate weight in group 5 (29.1%; P < 0.05) and of seminal vesicle weight in groups 3 (14.4%; P < 0.01), 4 (18.3%; P < 0.01) and 5 (27.3%; P < 0.01). In contrast, testis and epididymis weights were unchanged. In epididymis tissue, the alpha glucosidase activity and the spermatozoa density were unchanged. The treatment resulted in a significant decrease in testosterone serum levels in groups 3 (77.3%; P < 0.01), 4 (77.3%; P < 0.01) and 5 (90.9%; P < 0.01), associated with a significant increase in LH serum levels (P < 0.01). Testicular histology showed a dose-dependent increase in the percentage of empty seminiferous tubules. Moreover, testicular function was affected; a significant decrease in phosphatase acid activity (P < 0.01) and testosterone (P < 0.05) contents were observed. CONCLUSION: Crude garlic consumption during 1 month reduced testosterone secretion and altered spermatogenesis at 10%, 15% and 30% doses.