Visual development is thought to be completed at an early age. We suggest that the maturation of the visual brain is not homogeneous: functions with greater need for early availability, such as visuomotor control, mature earlier, and the development of other visual functions may extend well into childhood. We found significant improvement in children between 5 and 14 years in visual spatial integration by using a contour-detection task. The data show that long-range spatial interactions-subserving the integration of orientational information across the visual field-span a shorter spatial range in children than in adults. Performance in the task improves in a cue-specific manner with practice, which indicates the participation of fairly low-level perceptual mechanisms. We interpret our findings in terms of a protracted development of ventral visual-stream function in humans. Human visual development has been considered to be relatively fast and to give way to cognitive development after the basic visual functions are established in infancy, e.g., a very early preference for moving stimuli (1); the ability to process complex motion information at 4 months (2); color (3) and depth (4) discrimination also at around 4 months; and rapidly increasing acuity during the first year (5). However, human anatomical data indicate that, although the gross anatomical structure is constructed before birth, the maturation of neuronal circuits of the visual cortex may extend well into childhood (6, 7). More recent studies even raise the possibility of a significant increase in the number of cortical cells between birth and 6 years of age (8), implying a strikingly extended structural maturation of the human cortex, including the early visual areas (9). In light of these results, the question arises as to whether the maturation of human vision really comes to an end by the first or second year of life.Although behavioral studies of human visual development beyond the second year of age are rare, there is indication that children may encounter problems in tasks involving integration of information across the visual field for object representation: visual segmentation and form identification based on contrasts in texture (10, 11), motion (12), or color (13) and recognition of incomplete objects (14). Here, we directly test the development of visual spatial integration in a contour-detection task. We find that children (aged 5-14 years) perform poorly in the task compared with adults. Our control results clearly show that perceptual immaturity lies behind the poor performance. The results also suggest that there is immaturity at the level of long-range spatial interactions that might span a shorter spatial range in children than in adults. Experiment 1: Human Development of Spatial IntegrationTo segment the visual image and to form object boundaries in the course of perceptual organization, local orientational information extracted by selectively tuned neurons has to be integrated across the visual field. The efficiency of the integra...

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Amblyopia is characterized by losses in a variety of aspects of spatial vision, such as acuity and contrast sensitivity. Our goal was to learn whether those basic spatial deficits lead to impaired global perceptual processing in strabismic and anisometropic amblyopia. This question is unresolved by the current human psychophysical literature. We studied contour integration and contrast sensitivity in amblyopic monkeys. We found deficient contour integration in anisometropic as well as strabismic amblyopic monkeys. Some animals showed poor contour integration in the fellow eye as well as in the amblyopic eye. Orientation jitter of the elements in the contour systematically decreased contour-detection ability for control and fellow eyes, but had less effect on amblyopic eyes. The deficits were not clearly related to basic losses in contrast sensitivity and acuity for either type of amblyopia. We conclude that abnormal contour integration in amblyopes reflects disruption of mechanisms that are different from those that determine acuity and contrast sensitivity, and are likely to be central to V1.

Background: Postoperative cognitive dysfunction (POCD) is an adverse outcome that impacts patients' quality of life. Its diagnosis relies on formal cognitive testing performed before and after surgery. The substantial heterogeneity in methodology limits comparability and meta-analysis of studies. This systematic review critically appraises the methodology of studies on POCD published since the 1995 Consensus Statement and aims to provide guidance to future authors by providing recommendations that may improve comparability between future studies. Methods: This systematic review of literature published between 1995 and 2019 included studies that used baseline cognitive testing and a structured cognitive test battery, and had a minimal follow-up of 1 month. For cohorts with multiple publications, data from the primary publication were supplemented with available data from later follow-up studies. Results: A total of 274 unique studies were included in the analysis. In the included studies, 259 different cognitive tests were used. Studies varied considerably in timing of assessment, follow-up duration, definition of POCD, and use of control groups. Of the 274 included studies, 70 reported POCD as a dichotomous outcome at 1 to <3 months, with a pooled incidence of 2998/10 335 patients (29.0%). Conclusions: We found an overwhelming heterogeneity in methodology used to study POCD since the publication of the 1995 Consensus Statement. Future authors could improve study quality and comparability through optimal timing of assessment, the use of commonly used cognitive tests including the Consensus Statement 'core battery', application of appropriate cut-offs and diagnostic rules, and detailed reporting of the methods used. PROSPERO registry number: CRD42016039293.