Final Report Summary - STANIB (Space, Time and Number In the Brain)
The title of the project “Space, Time and Number in the Brain” describes well the scope of the research. We have made major advances in all three broad areas. While the achievements are far too numerous to detail we highlight three examples here:
Constructing a stable representation of the world: A long-standing problem in neuroscience is how the visual system constructs a neural representation – or map – of the external world, that remains stable as we actively explore the world body, head and eye movements. We have conducted several studies during this project that have made major in-roads on this problem: fMRI evidence clearly shows that spatiotopic maps exist in the dorsal visual stream, and this result has been strongly reinforced by psychophysical studies on “saccadic adaptation” and adaptation to motion. However, we also show that the construction of these maps is not immediate, but takes up to 500 ms to complete. As these maps are being created, neural units bridge the saccade with exhibit a “transient spatiotopy”. Classical psychophysical studies describe quantitatively these mechanisms, results confirmed by a novel technique, “classification images”. All these results have been reported is the highest-quality journals (Current Biology, J. Neuroscience etc), and presented as an invited plenary lecture at the European Conference for Visual Perception (Alghero, 2012), published in Perception.
Perception of Number. An important novel aspect of the project was to consider the estimation of the numerosity of objects to comprise a primary sensory attribute, like the perception of colour or motion. We have provided much evidence that this is the case, provided the density of the items is not so great they are no longer segregated into separate entities. Clear evidence of two separate systems – for numerosity and for texture – has helped clear up much recently generated confusion in the area.
Another major innovation has been to explain the “logarithmic” nature of the mapping of number to space (the numberline), thought to reflect an intrinsic logarithmic encoding of number in humans. We have been able to show that the logarithmic-like distortions arise from dynamic serial-dependencies in number mapping, rather than static no-linearities. This is important, not only because performance on the numberline correlates strongly with mathematical performance, but because it reveals a general perceptual principle of serial dependency, or hysteresis, opening new and interesting lines of research. Again this work has been published well, including publications in Cognition, Psychological Sciences and PNAS.
Neuroplasticity of the human visual system. Neuroplasticity is a fundamental property of the developing nervous system, but the brain is thought to be relatively hard-wired after closure of the critical period. We have devised a new technique using binocular rivalry – a sensitive probe of neural competition – to show that adult human visual cortex retains a surprisingly high degree of neural plasticity, with important perceptual consequences, calling for a revaluation of adult visual cortical plasticity, fundamental to understanding how the adult visual system reacts to sensory loss, and for developing new therapeutic strategies that exploit the intrinsic plasticity of the visual cortex.
Structure for continued excellence. The more general objective of this project was to found a centre of excellence for human perceptual research in Tuscany, to produce a major European nucleus for research and training in perceptual science. We have clearly achieved this goal, even going beyond expectations. We have established a true “centre of excellence”, distributed over three neighbouring Tuscan laboratories with complementary expertise. All units have collaborated well on the research questions originally proposed in Annex 1, and have expanded the research to new horizons. Importantly, the atmosphere of this international group has remained friendly, collaborative and mutually supportive.
The full extent of the achievement of the grant can be ascertained by considering the scientific output: over 70 publications in excellent scientific journals, including nine in Current Biology, nine in the Journal of Neuroscience, and many others in PNAS, Brain, Psychological Science and Proceedings of the Royal Society.
Constructing a stable representation of the world: A long-standing problem in neuroscience is how the visual system constructs a neural representation – or map – of the external world, that remains stable as we actively explore the world body, head and eye movements. We have conducted several studies during this project that have made major in-roads on this problem: fMRI evidence clearly shows that spatiotopic maps exist in the dorsal visual stream, and this result has been strongly reinforced by psychophysical studies on “saccadic adaptation” and adaptation to motion. However, we also show that the construction of these maps is not immediate, but takes up to 500 ms to complete. As these maps are being created, neural units bridge the saccade with exhibit a “transient spatiotopy”. Classical psychophysical studies describe quantitatively these mechanisms, results confirmed by a novel technique, “classification images”. All these results have been reported is the highest-quality journals (Current Biology, J. Neuroscience etc), and presented as an invited plenary lecture at the European Conference for Visual Perception (Alghero, 2012), published in Perception.
Perception of Number. An important novel aspect of the project was to consider the estimation of the numerosity of objects to comprise a primary sensory attribute, like the perception of colour or motion. We have provided much evidence that this is the case, provided the density of the items is not so great they are no longer segregated into separate entities. Clear evidence of two separate systems – for numerosity and for texture – has helped clear up much recently generated confusion in the area.
Another major innovation has been to explain the “logarithmic” nature of the mapping of number to space (the numberline), thought to reflect an intrinsic logarithmic encoding of number in humans. We have been able to show that the logarithmic-like distortions arise from dynamic serial-dependencies in number mapping, rather than static no-linearities. This is important, not only because performance on the numberline correlates strongly with mathematical performance, but because it reveals a general perceptual principle of serial dependency, or hysteresis, opening new and interesting lines of research. Again this work has been published well, including publications in Cognition, Psychological Sciences and PNAS.
Neuroplasticity of the human visual system. Neuroplasticity is a fundamental property of the developing nervous system, but the brain is thought to be relatively hard-wired after closure of the critical period. We have devised a new technique using binocular rivalry – a sensitive probe of neural competition – to show that adult human visual cortex retains a surprisingly high degree of neural plasticity, with important perceptual consequences, calling for a revaluation of adult visual cortical plasticity, fundamental to understanding how the adult visual system reacts to sensory loss, and for developing new therapeutic strategies that exploit the intrinsic plasticity of the visual cortex.
Structure for continued excellence. The more general objective of this project was to found a centre of excellence for human perceptual research in Tuscany, to produce a major European nucleus for research and training in perceptual science. We have clearly achieved this goal, even going beyond expectations. We have established a true “centre of excellence”, distributed over three neighbouring Tuscan laboratories with complementary expertise. All units have collaborated well on the research questions originally proposed in Annex 1, and have expanded the research to new horizons. Importantly, the atmosphere of this international group has remained friendly, collaborative and mutually supportive.
The full extent of the achievement of the grant can be ascertained by considering the scientific output: over 70 publications in excellent scientific journals, including nine in Current Biology, nine in the Journal of Neuroscience, and many others in PNAS, Brain, Psychological Science and Proceedings of the Royal Society.