Community Research and Development Information Service - CORDIS

Final Report Summary - SPACELOAD (Spatial processing under attentional load: from clinical to fMRI evidence)

Everyday life requires to continuously process the surrounding space to extract behaviourally-relevant information. When attention is loaded, however, this processing might become difficult. This happens, for instance, when the environment to be attended is characterized by several stimuli which have to be processed in parallel (e.g., talking while driving). In the present project we studied the effects of attentional load in visual tasks. The aim was to investigate the core cognitive and neural mechanisms subtending normal and pathological (persons who suffered a brain damage) spatial processing.
The cognitive function we use to explore the surrounding environment is called visuospatial processing (VSP). It is almost continuously active because it allows, for instance, to process the location occupied by objects and to move safely in space. It is implemented by an intricate brain network, which maximizes the efficiency in selecting and processing behaviorally relevant information. Under most conditions the limits -and even the presence- of visuospatial processes go unnoticed and we interact with the space very efficiently and in an effortless manner. Under certain conditions, however, VSP becomes difficult and might not succeed in efficiently processing the surrounding space. As previously mentioned, this is clearly the case when another task has to be performed in parallel (dual-tasking). Both before and during the project the fellow has been leading several clinical studies in brain-damaged persons and no explicit VSP disorders according to standard testing. Results consistently showed that monitoring visual space for the appearance of a relevant target while attention was loaded (e.g. because a letter had to be concurrently reported) can lead to the “disappearance” of one side of space from conscious perception. Brain-damaged persons who perform within normal range at standard testing for spatial processing can fail to perceive items on one side of space when facing computer-based tasks loading their VSP. The portion of space which “disappears” under load is invariably the one opposite to the lesioned hemisphere. In the present project we further studied to what extent performing more than one task in parallel and devoting attention towards more than one sensory modality influences the efficiency of VSP and alters spatial awareness through an integrated approach. The behavioral effects of increased task load on VSP were coupled, in healthy participants, with techniques allowing to study which brain signals implement these processes at a neural level and with structural neuroimaging techniques in brain-damaged patients. We maximally capitalized on the sensitivity of the dual-task approach to study the mechanisms behind spatial monitoring performance and spatial awareness deficits in both normal and impaired cognitive architectures. Moreover, we studied the modulation of spatial processing by brain stimulation and by changing the type of stimuli. Finally, the Fellow has also studied the effect of stroke on more abstract levels of spatial processing, like for instance the memorization of temporally-ordered items.
The implementation of WP1 (healthy participants) started by finalising two studies using cognitive neuroscience/neuroimaging methods of spatial attention under load (both already published), done under the technical supervision of colleagues abroad. A first one was done with Event Related Potentials by coupling the method described in the project and the use of a technique which is capable of detecting also fast changes in brain activity. This experiment followed an explicit suggestion of the expert panel which reviewed the project. A second one was done using pupil dilation measure, a technique which in the last years is becoming more and more widely used in cognitive neuroscience. Both studies allowed a smoother transition from neuropsychology/experimental psychology to cognitive neuroscience, a transition which was the main aim of the present fellowship and which is resulting in an important added value to my career. These studies provided very useful information for the brain imaging part as well, because they showed a lack of behavioural asymmetries. We decided to take advantage of this information and, after having explored several alternatives, continued the testing by using a task which maximized the possibility to detect asymmetric attentional networks activation and which can be later used for experiments beyond the project itself. We therefore had to invest more efforts on preparing the task than initially thought. In the meanwhile, however, the fellow gained a good degree of confidence with fMRI experiment design and programming and started to gain confidence with neuroimaging analysis (Milestones 1a & b) also thanks to the intensive use of SPM software for the processing of structural neuroimages within clinical workpackage (WP2).
Content wise, the findings of WP2 went beyond expectations. Just to mention three of the main findings, by means of the load/dual-task approach it was possible to show that VSP deficits under load frequently appear for the side opposite to the lesion also when the damaged hemisphere is the left one. This result is potentially ground-breaking because according to neuropsychological textbooks VSP deficits after left brain damage are not common. Moreover, by using a bottom-up manipulation the fellow managed to detect the presence of spontaneous recovery after several years from stroke -when neural plasticity is thought to be no longer present. Finally, the fellow demonstrated that the manipulation was so effective to induce distortions in the perceived space. These findings would deserve a much longer description because of their potential impact in the field. They have been already published in top neuropsychological journals. We also decided to integrate the structural neuroimaging part with two recent approaches for performing lesion mapping and template-based tractography which are methodologically more robust than the ones presented so far. This has been possible due to a hands-on training abroad. Deliverable 2 about the improving the use of structural neuroimaging as a complementary tool for the fellow’s neuropsychological investigations has therefore been successfully achieved. Preliminary data on the use of dual-tasking in chronic left brain damaged patients have been presented in several congresses.
The quality and novelty of the clinical research performed was very high. It has been a truly multidisciplinary approach because connecting the cognitive with the neural level of explanation. By combining advanced cognitive neuroscience methods in healthy participants with the structural reconstructions of brain damage in patients, the experimental psychology methods were perfectly integrated with behavioral neurology and functional neuroimaging. The neuropsychological study of brain-damaged patients has long been directed to understanding the organization of the intact cognitive system, without an explicit orientation towards clinical relevance. Our approach preferred a bidirectional communication and cross-fertilization whereby cognitive paradigms are translated into clinical research with a focus on understanding the cognitive aspects of the pathological condition. Crucially, the tasks mimicked complex and multitasking every-day life situations. Multitasking contexts are the rule rather than the exception in present-day life, in particular when complex behavior is guided by multiple competing goals that need to be held and updated in parallel. We have characterized the implementation of fast adaptive VSP processes (not dissimilar from those involved, for instance, in navigating the space while speaking) in well-controlled laboratory conditions. Through our approach we have originally addressed, two important -albeit somehow overlooked- aspects of VSP: the neurofunctional correlates of spatial processing under load and whether dual-tasking might become an instrument to diagnose and study how pathological VSP emerges and develops in time and how it is related to different brain damages. Besides the several papers the fellow published in international journals also the network of scientific collaborations (with six different research groups) and the findings of the studies with brain damaged patients went beyond expectations.The clinical task has been made available to about 10 research groups in Europe (Belgium, Italy, France, Switzerland, Sweden). For most of these groups sharing the program meant starting a new collaboration. In the host institution the fellow had the opportunity to be immersed in a very competitive internationally-recognized context of excellence. The project played a causal role in the establishment of an independent research group where the Fellow will be the principal investigator: he has been recently selected for a tenured-track position. The well-esteemed Marie Curie fellowship allowed him to reach additional autonomy and leadership more rapidly.

Reported by

UNIVERSITEIT GENT
Belgium
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