In amblyopia, abnormal visual experience during development leads to an enduring loss of visual acuity in adulthood. Physiological studies in animal models suggest that intracortical GABAergic inhibition may mediate visual deficits in amblyopia. To better understand the relationship between visual cortical γ-aminobutyric acid (GABA) and perceptual suppression in persons with amblyopia (PWA), we employed magnetic resonance spectroscopy (MRS) to quantify GABA levels in both PWA and normally-sighted persons (NSP). In the same individuals, we obtained psychophysical measures of perceptual suppression for a variety of ocular configurations. In PWA, we found a robust negative correlation between the depth of amblyopia (the difference in visual acuity between the amblyopic and non-amblyopic eyes) and GABA concentration that was specific to visual cortex and was not observed in a sensorimotor cortical control region. Moreover, lower levels of visual cortical GABA were associated with weaker perceptual suppression of the fellow eye by the amblyopic eye and stronger suppression of the amblyopic eye by the fellow eye. Taken together, our findings provide evidence that intracortical GABAergic inhibition is an important component of the pathology of human amblyopia and suggest possible therapeutic interventions to restore vision in the amblyopic eye through enhancement of visual cortical GABAergic signaling in PWA.

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Cognitive control involves the allocation of cognitive resources in order to successfully navigate and interact with the world. Oftentimes, control involves balancing the demands brought on by performing immediately relevant tasks and those required in order to perform future intended actions. For example, directing attention towards navigating through traffic on a highway while also needing to remember to exit the freeway at a particular street. This ability to delay execution of a goal until the appropriate time in the future is referred to as prospective memory (PM). The dual mechanisms of cognitive control (DMC) framework posits that individuals can use two different strategies to remember an intended action: a proactive control strategy involving working memory maintenance of the goal and monitoring of the environment, or a reactive control strategy relying on timely retrieval of goal information from episodic memory. Previous research on prospective memory has demonstrated that performance improves when individuals engage these control strategies in accordance with the demands of the task environment. However, it is unclear how people select a control strategy, particularly in situations with dynamic task demands. We hypothesized that if people flexibly adapt their strategy in response to changes in the environment, this should facilitate prospective memory. Across two experiments, we asked participants to identify the reappearance of a picture target (a prospective memory intention) while at the same time performing an ongoing visual search task. The attentional demands of the ongoing task were manipulated to monotonically increase or decrease on a moment to moment basis. The selection of control strategies was identified using reaction time costs and neural measures of intention maintenance. Results showed that people fluidly modified control strategies, shifting towards proactive control when the attentional demands decreased, and shifting towards reactive control when attentional demands increased. Critically, these adaptive shifts in control strategy were associated with better prospective memory performance. These results demonstrate that fine-grained control of attention and memory resources serves an adaptive role for remembering to carry out future plans.

Protection of historic monuments and precincts of significant heritage and cultural value is commonly exercised through various legal instruments. However, each heritage monument and precinct also requires a setting to establish its context. The setting should provide an appropriate linkage to the monument and precinct, and needs some form of control mechanism to ensure that future development is sympathetic to the protected site and enhances its appreciation. In India, the 'Ancient Monuments and Archaeological Sites and Remains Act 2010', addresses this issue, to take care of the sensitive dynamics of conservation and development in areas surrounding protected monuments and precincts. This entails making Heritage Bye-laws, regulations and guidelines, with an inbuilt flexibility to cater to the changing needs and aspirations of the surrounding community, yet preserving the inherent character of the setting. This paper discusses some visual simulation methods to support formulation of such instruments, adopted in three particular cases in India. In particular, the methods contribute towards (i) conservation planning for heritage districts, (ii) formulation of site-specific byelaws based on existing scenario, (iii) assessment of visual impact of future construction, and (iv) preparation of enabling design guidelines for infill/new construction. The methodology uses view control study and visual simulation techniques as decision tools, and illustrates how translation of vernacular idioms may be employed in formulating design guidelines to ensure a consonance in built form.