Higher Spatial Representations Research Articles

Comparison of large-scale citizen science data and long-term study data for phenology modeling.

Large‐scale observational data from citizen science efforts are becoming increasingly common in ecology, and researchers often choose between these and data from intensive local‐scale studies for their analyses. This choice has potential trade‐offs related to spatial scale, observer variance, and interannual variability. Here we explored this issue with phenology by comparing models built using data from the large‐scale, citizen science USA National Phenology Network (USA‐NPN) effort with models built using data from more intensive studies at Long Term Ecological Research (LTER) sites. We built statistical and process based phenology models for species common to each data set. From these models, we compared parameter estimates, estimates of phenological events, and out‐of‐sample errors between models derived from both USA‐NPN and LTER data. We found that model parameter estimates for the same species were most similar between the two data sets when using simple models, but parameter estimates varied widely as model complexity increased. Despite this, estimates for the date of phenological events and out‐of‐sample errors were similar, regardless of the model chosen. Predictions for USA‐NPN data had the lowest error when using models built from the USA‐NPN data, while LTER predictions were best made using LTER‐derived models, confirming that models perform best when applied at the same scale they were built. This difference in the cross‐scale model comparison is likely due to variation in phenological requirements within species. Models using the USA‐NPN data set can integrate parameters over a large spatial scale while those using an LTER data set can only estimate parameters for a single location. Accordingly, the choice of data set depends on the research question. Inferences about species‐specific phenological requirements are best made with LTER data, and if USA‐NPN or similar data are all that is available, then analyses should be limited to simple models. Large‐scale predictive modeling is best done with the larger‐scale USA‐NPN data, which has high spatial representation and a large regional species pool. LTER data sets, on the other hand, have high site fidelity and thus characterize inter‐annual variability extremely well. Future research aimed at forecasting phenology events for particular species over larger scales should develop models that integrate the strengths of both data sets.

Divisions within the posterior parietal cortex help touch meet vision

AbstractThe parietal cortex is divided into two major functional regions: the anterior parietal cortex that includes primary somatosensory cortex, and the posterior parietal cortex (PPC) that includes the rest of the parietal lobe. The PPC contains multiple representations of space. In Dijkerman & de Haan's (D&dH's) model, higher spatial representations are separate from PPC functions. This model should be developed further so that the functions of the somatosensory system are integrated with specific functions within the PPC and higher spatial representations. Through this further specification of the model, one can make better predictions regarding functional interactions between somatosensory and visual systems.

Prism adaptation improves spatial dysgraphia following right brain damage

Visuo-manual adaptation to prisms produces a long-lasting improvement of visuo-spatial neglect. Improvement is also observed in tasks that do not involve visuo-manual component and that can all be consider to rely on a rightward (ipsilesional) orienting bias. Here, we report positive effects of prism adaptation on spatial dysgraphia, in a neglect patient following right brain damage. A long-lasting improvement concerned the right-page preference reflecting the ipsilesional bias but also the sloping lines and the broken lines reflecting visuo-constructive disorders in handwriting. Moreover, a transient improvement was also evidenced for the graphic errors. These results reinforce the idea that the process of prism adaptation may activate brain functions related to multisensory integration and higher spatial representations and show a generalization at a functional level. Prism adaptation therefore appears as useful tool in the theoretical attempt to identify the underlying ‘core’ mechanisms of the neglect syndrome.

Neglect and prism adaptation: A new therapeutic tool for spatial cognition disorders

Purpose: A large proportion of right-hemisphere stroke patients show unilateral neglect, a neurological deficit of perception, attention, representation, and/or performing actions within their left-sided space, inducing many functional debilitating effects on everyday life, and responsible for poor functional recovery and ability to benefit from treatment. This spatial cognition disorder affects the orientation of behaviour with a shift of proprioceptive representations toward the lesion side. Methods: This shift can be reduced after a prism adaptation period to a right lateral displacement of visual field (induced by a simple target-pointing task with base-left wedge prisms). The modification of visuo-motor or sensory-motor correspondences induced by prism adaptation involves improvement of different symptoms of neglect. Results: Classical visuo-motor tests could be improved for at least 2h after adaptation, but also non-motor and non-visual tasks. In addition, cross-modal effects have been described (tactile extinction and dichotic listening), mental imagery tasks (geographic map, number bisection) and even visuo-constructive disorders. These cognitive effects are shown to result from indirect bottom-up effects of the deeper, adaptive realignment component of the reaction to prisms. Lesion studies and functional imaging data evoke a cerebello-cortical network in which each structure plays a specific role and not all structures are crucial for adaptation ability. Conclusions: These cognitive effects of prism adaptation suggest that prism adaptation does not act specifically on the ipsilesional bias characteristic of unilateral neglect but rehabilitates more generally the visuo-spatial functions attributed to the right cortical hemisphere. These results reinforce the idea that the process of prism adaptation may activate brain functions related to multisensory integration and higher spatial representations and show a generalization at a functional level. Prism adaptation therefore appears as a new powerful therapeutic tool for spatial cognition disorders.