Magnetoencephalographic (MEG) response properties associated with capacity-limited sensory gating resources during more/less estimation judgements: Case of the disappearing magnetic dipole in right posterior parietal cortex (rPPC) under the cloak of surround masking.

Abstract

Event Abstract Back to Event Magnetoencephalographic (MEG) response properties associated with capacity-limited sensory gating resources during more/less estimation judgements: Case of the disappearing magnetic dipole in right posterior parietal cortex (rPPC) under the cloak of surround masking. Nicola Jastrzebski1*, David Crewther2* and William Woods1* 1 Swinburne University of Technology, Brain and Psychological Sciences Research Centre, Australia 2 Swinburne University of Technology, Centre for Human Psychopharmacology , Australia The elimination of redundant visual input is influenced by a number of factors including modifications in attentional and sensory load. One way to induce such capacity limits over sensory gating resources is through surround masking, a psycho-physical procedure well documented to have deleterious effects upon discrimination of the physical properties of visual perception, such as brightness intensity and differences in contrast. Previous primate neurophysiology literature suggests that high sensory load induced by surround masking, has a regulatory effect upon the inhibitory segments of receptive fields in lateral geniculate nucleus and V1. This 'swamping' of inhibitory resources reduces the visual systems capacity to filter out irrelevant sensory information, resulting in perceptual ambiguity and signal noisiness. We used the Elekta Neuromag (vector view 306) system to observe the electromagnetic (MEG) signature during more/less discrimination judgements of randomly drifting dots, enveloped by either a high (95%) or low (25%) contrast annulus. Essentially, event related fields (ERFs) in the presence of a low-contrast surround were featured by a focused magnetic dipole in rPPC approximately 285-309ms post-stimulus onset.This putative number estimation judgement dipole in rPPC was significantly attenuated (and almost absent in one observer) within the same time-window in the presence of the high-contrast surround. However, the high-contrast surround only appeared to delay this response by approximately 40-60ms and not completely eliminate it. These findings cast a new light on some prevailing notions on the origins of developmental dyscalculia (DD) - arithmetical learning disorder. These findings suggest that DD may be related to poor sensory-gating or inhibitory resources, influenced at a perceptual level, and not just at the cognitive/high-order level of neural organization. Keywords: Dyscalculia, Magnetoencephalography, inhibition, Estimation judgements, Gating resources, Perceptual-sets, Sensory-load, Surround-masking Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Sensation and Perception Citation: Jastrzebski N, Crewther D and Woods W (2015). Magnetoencephalographic (MEG) response properties associated with capacity-limited sensory gating resources during more/less estimation judgements: Case of the disappearing magnetic dipole in right posterior parietal cortex (rPPC) under the cloak of surround masking.. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00307 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. 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Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Ms. Nicola Jastrzebski, Swinburne University of Technology, Brain and Psychological Sciences Research Centre, Melbourne, Australia, nicolajastrzebski@gmail.com Prof. David Crewther, Swinburne University of Technology, Centre for Human Psychopharmacology, Melbourne, Australia, dcrewther@swin.edu.au Dr. William Woods, Swinburne University of Technology, Brain and Psychological Sciences Research Centre, Melbourne, Australia, wwoods@swin.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Nicola Jastrzebski David Crewther William Woods Google Nicola Jastrzebski David Crewther William Woods Google Scholar Nicola Jastrzebski David Crewther William Woods PubMed Nicola Jastrzebski David Crewther William Woods Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.