Periodic Reporting for period 1 - MappingSpatialVision (Linking the perceptual and neural mechanisms of human spatial perception using behavioral and ultra-high field fMRI signals)
Berichtszeitraum: 2019-06-01 bis 2021-05-31
Humans rely heavily on their sense of vision to interact with the world. Understanding how cognitive functions and clinical disorders affect the way the brain represents visual information across the visual field requires to link human perception with changes in human neuronal populations. To do so, cognitive neuroscientists possess a variety of visual mapping techniques able to link visual perception with changes in the underlying neural circuitry. Modern neuroimaging techniques, such as high-resolution functional magnetic resonance imaging (fMRI), have opened the door to study the organisation of the brain and its ability to adapt its function and structure in response to a wide range of cognitive functions, as well as in patients with diverse ophthalmological and neurological disorders. Yet, the balance between brain plasticity and stability of visual processing remains intensely debated among scientists and clinicians. The controversy relates to the fact that brain functions are highly dynamic, and can yield different properties simply due to differences in experimental factors.
The present project aimed to improve the way we map visual functions across the visual field, at both behavioural and neural levels, and further our understanding of the link between human perception and cortical organisation. Overall, our results show how behavioural and neuroimaging approaches can be combined to link changes in perception with changes in neural activity in both healthy and clinical populations. Our findings provide novel and vital insights regarding the mechanistic underpinnings of neural dynamics associated with cognitive functions (e.g. attention, perceptual learning) and visual disorders (e.g. retinal lesions, stroke-induced brain damage). Moreover, we show that fMRI can be used to predict recovery of conscious vision following visual training in patients with stroke-induced brain damage.
To conclude, the action shows how modern neuroimaging can be used to map visual functions and link neural dynamics to their perceptual consequences in patients with ophthalmological and neurological diseases. Aside from improving our scientific understanding of the plasticity and stability of visual functions, our findings are of vital importance for the development of more principled, customised, clinical rehabilitation therapies.
The present project aimed to improve the way we map visual functions across the visual field, at both behavioural and neural levels, and further our understanding of the link between human perception and cortical organisation. Overall, our results show how behavioural and neuroimaging approaches can be combined to link changes in perception with changes in neural activity in both healthy and clinical populations. Our findings provide novel and vital insights regarding the mechanistic underpinnings of neural dynamics associated with cognitive functions (e.g. attention, perceptual learning) and visual disorders (e.g. retinal lesions, stroke-induced brain damage). Moreover, we show that fMRI can be used to predict recovery of conscious vision following visual training in patients with stroke-induced brain damage.
To conclude, the action shows how modern neuroimaging can be used to map visual functions and link neural dynamics to their perceptual consequences in patients with ophthalmological and neurological diseases. Aside from improving our scientific understanding of the plasticity and stability of visual functions, our findings are of vital importance for the development of more principled, customised, clinical rehabilitation therapies.
In a series of studies, we combined advanced behavioural methods with state-of-the-art fMRI techniques to assess changes in the underlying neural circuitry in healthy human adults as well as in patients with a wide range of ophthalmological and neurological disorders. We used high-resolution neuroimaging and biologically-inspired computational models to assess the properties of the visual cortex. Specifically, we used functional MRI to estimate the portion of the visual field to which a group of neighbouring neurons in the visual cortex responds to, which is known as its population receptive field (pRF). Despite the exceptional challenges we had to face during most of the action’s period due to the ongoing Covid-19 pandemic, we were able to successfully achieve the main objectives of the action.
In one of the projects, we used fMRI to map visual representations in patients with retinitis pigmentosa (RP)–a rare genetic disorder that involves the loss of peripheral retinal cells. We tested the impact of task-related attentional feedback on the dynamic of the underlying neural circuitry (pRFs) in the primary visual cortex (V1) of these patients. Our results show that while the visual system of patients with retinal lesions is intact and largely unresponsive in cortical regions that do not receive retinal inputs, attentional feedback results in brain activity in the lesion projection zone (LPZ) of these patients. Specifically, we show that the attention-related activation of the LPZ in these patients is (1) not spatially-specific and affects both hemispheres of the brain; and (2) associated with atypically large visual pRFs in the V1-LPZ. We propose that these results reflect the influence of top-down signals from extrastriate areas in V1, which are typically regulated by the presence of retinal inputs. We are working on the manuscript related to this project that will be submitted to a peer-reviewed journal in the next few months.
Then, in another project, we examined the neural substrates of training-induced recovery of conscious vision in patients with stroke-induced cortical blindness. Specifically, we linked the changes in visual sensitivity to changes in the underlying neural circuitry measured using fMRI. Overall, our results reveal that visual recovery relies on spared, perilesional V1 cortex that is functionally impaired, but can be brought back “online” using intensive training. Moreover, we show that training increased the coverage of the blind field, which was mediated by the enlargement of V1 pRFs covering the blind field. These findings indicate that a certain level of baseline V1 responsiveness is required for training to effectively induce recovery of conscious vision. The results of this project provide novel and vital insights regarding the neural mechanisms by which visual rehabilitation training restores perceptual functions in the blind field of patients with cortical damage. This project was recently accepted for publication in Nature Communications (currently in press).
Moreover, the beneficiary collaborated on another project, in which he helped design fast and efficient testing protocols to optimise the time required for the behavioural assessment of visual functions in patient populations. The beneficiary was also responsible of the design and set-up of a fully-equipped testing room at the Spinoza Centre for Neuroimaging.
Although the dissemination and exploitation of the results was considerably limited due to the COVID-19 crisis, we were able to disseminate some of our results at several scientific conferences and workshops (4 international; 2 national). The beneficiary was invited to present the results of his research to group of scientists twice, and co-organised a public outreach event–the Weekend of Science–in Amsterdam. The results of the project can be exploited by scientists, to help develop biologically-inspired computational models of visual dynamics, as well as clinicians, to improve current visual rehabilitation therapies.
In one of the projects, we used fMRI to map visual representations in patients with retinitis pigmentosa (RP)–a rare genetic disorder that involves the loss of peripheral retinal cells. We tested the impact of task-related attentional feedback on the dynamic of the underlying neural circuitry (pRFs) in the primary visual cortex (V1) of these patients. Our results show that while the visual system of patients with retinal lesions is intact and largely unresponsive in cortical regions that do not receive retinal inputs, attentional feedback results in brain activity in the lesion projection zone (LPZ) of these patients. Specifically, we show that the attention-related activation of the LPZ in these patients is (1) not spatially-specific and affects both hemispheres of the brain; and (2) associated with atypically large visual pRFs in the V1-LPZ. We propose that these results reflect the influence of top-down signals from extrastriate areas in V1, which are typically regulated by the presence of retinal inputs. We are working on the manuscript related to this project that will be submitted to a peer-reviewed journal in the next few months.
Then, in another project, we examined the neural substrates of training-induced recovery of conscious vision in patients with stroke-induced cortical blindness. Specifically, we linked the changes in visual sensitivity to changes in the underlying neural circuitry measured using fMRI. Overall, our results reveal that visual recovery relies on spared, perilesional V1 cortex that is functionally impaired, but can be brought back “online” using intensive training. Moreover, we show that training increased the coverage of the blind field, which was mediated by the enlargement of V1 pRFs covering the blind field. These findings indicate that a certain level of baseline V1 responsiveness is required for training to effectively induce recovery of conscious vision. The results of this project provide novel and vital insights regarding the neural mechanisms by which visual rehabilitation training restores perceptual functions in the blind field of patients with cortical damage. This project was recently accepted for publication in Nature Communications (currently in press).
Moreover, the beneficiary collaborated on another project, in which he helped design fast and efficient testing protocols to optimise the time required for the behavioural assessment of visual functions in patient populations. The beneficiary was also responsible of the design and set-up of a fully-equipped testing room at the Spinoza Centre for Neuroimaging.
Although the dissemination and exploitation of the results was considerably limited due to the COVID-19 crisis, we were able to disseminate some of our results at several scientific conferences and workshops (4 international; 2 national). The beneficiary was invited to present the results of his research to group of scientists twice, and co-organised a public outreach event–the Weekend of Science–in Amsterdam. The results of the project can be exploited by scientists, to help develop biologically-inspired computational models of visual dynamics, as well as clinicians, to improve current visual rehabilitation therapies.
The novel and key findings of the project impact our understanding of the plasticity and stability of brain functions. The project has both scientific and clinical relevance, having the potential to pave the way to the development of better experimental approaches as well as more efficient clinical rehabilitation therapies. The high incidence of visual diseases in the general population and the dramatic impact of vision loss on everyday functions in our society are testament to the urgency of developing more personalised approaches that take advantage of the diversity of recovery mechanisms potentially available to each individual patient. The results of the project directly relate to these socio-economical health issues and demonstrate that modern neuroimaging is a powerful tool that can be used to identify vital biomarkers of a patient’s potential for recovery that could be harnessed through visual rehabilitation.