Lars Muckli

University of Glasgow, Psychology, Faculty Member

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Papers by Lars Muckli

Investigating the effect of stimulus type and task on top-down influences to V1 using fMRI

F1000posters, Jul 18, 2014

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Contextual and Predictive Coding in V1

i-Perception, 2011

Primary visual cortex (V1) is often characterized by the receptive field properties of its feed-f... more

What are we missing here? Brain imaging evidence for higher cognitive functions in primary visual cortex V1

International Journal of Imaging Systems and Technology, May 31, 2010

... ACKNOWLEDGMENTS The author thanks Lucy S. Petro and Petra Vetter for comments on the manuscri... more

Emergence of visual content in the human brain: investigations of amblyopia, blindsight and high-level motion perception with fMRI

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Contextual Feedback to Superficial Layers of V1

Current Biology, 2015

Neuronal cortical circuitry comprises feedforward, lateral, and feedback projections, each of whi... more Neuronal cortical circuitry comprises feedforward, lateral, and feedback projections, each of which terminates in distinct cortical layers [1-3]. In sensory systems, feedforward processing transmits signals from the external world into the cortex, whereas feedback pathways signal the brain&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s inference of the world [4-11]. However, the integration of feedforward, lateral, and feedback inputs within each cortical area impedes the investigation of feedback, and to date, no technique has isolated the feedback of visual scene information in distinct layers of healthy human cortex. We masked feedforward input to a region of V1 cortex and studied the remaining internal processing. Using high-resolution functional brain imaging (0.8 mm(3)) and multivoxel pattern information techniques, we demonstrate that during normal visual stimulation scene information peaks in mid-layers. Conversely, we found that contextual feedback information peaks in outer, superficial layers. Further, we found that shifting the position of the visual scene surrounding the mask parametrically modulates feedback in superficial layers of V1. Our results reveal the layered cortical organization of external versus internal visual processing streams during perception in healthy human subjects. We provide empirical support for theoretical feedback models such as predictive coding [10, 12] and coherent infomax [13] and reveal the potential of high-resolution fMRI to access internal processing in sub-millimeter human cortex.

Measuring the precision of feedback fields in V1 using 3T and 7T fMRI

Journal of Vision, 2015

The receptive fields of V1 neurons are driven by sensory input. V1 neurons are also modulated by ... more The receptive fields of V1 neurons are driven by sensory input. V1 neurons are also modulated by cortical feedback, and this can be conceptualised as neuronal &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;feedback fields&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;. Feedback fields can be investigated in human V1 by performing multivoxel pattern analyses on voxels that respond to an occluded portion of a visual scene. We investigated the spatial precision of feedback to V1 using 3T and 7T functional magnetic resonance imaging. Images were presented to 27 (3T) and 4 (7T) subjects with the lower right quadrant occluded (Smith &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Muckli 2010) and at three different spatially-shifted versions (selected from 2, 3, 4, 6, 7, 8 degrees). Multivoxel patterns were extracted from the non-stimulated cortex (i.e. receiving feedback) and entered into a classifier analysis. We tested the precision of feedback by training the classifier on images presented at 0 degrees and testing on the same two scenes but shifted by e.g. 2 degrees. The 3T data revealed that the non-stimulated portion of V1 was able to discriminate the surrounding visual context even when shifted by 4 degrees. The 7T data corroborated that we are measuring the precision of feedback, as cross-classification was only possible in layers of V1 that receive feedback, i.e. supragrangular layers. To conclude, cross-classification across spatially-shifted images was significant only in outer layers of cortex, where feedback enters V1. Furthermore, classifier performance decreased to chance level as the spatial shift increased above 4 degrees. This result is suggestive of contextual feedback to V1 from a mid-level visual area such as V4, which has receptive fields large enough to capture similar image features despite their shifting location in the visual field. Meeting abstract presented at VSS 2015.

The brain's predictive prowess revealed in primary visual cortex

Proceedings of the National Academy of Sciences of the United States of America, Jan 2, 2016

Cortical predictions interact with post-saccadic input to primary visual cortex

Journal of Vision, 2015

Retinotopically occluded subsections of early visual cortex contain contextual information about individual scenes, category and depth

Journal of vision, 2015

Introduction Activity in early visual cortex contains information about context, even in the abse... more Introduction Activity in early visual cortex contains information about context, even in the absence of meaningful feedforward input (Smith & Muckli, 2010; Vetter, et al. 2014). To explain these contextual effects, previous work suggests that other brain areas predict sensory input, and that predictions are transmitted to early visual areas via dynamic and diffuse feedback. Here, we aimed to enhance our knowledge regarding the level of detail in feedback representations, which may depict scene-specific features (Naselaris, et al. 2014), or conversely, may be categorical, which has been observed when context was provided by auditory stimulation (Vetter, et al. 2014). To adjudicate these possibilities, we examined whether activity patterns in occluded portions of early visual cortex are sufficient for discriminating individual scenes, or if the absence of feedforward input reveals categorical scene groupings. Methods We blocked feedforward input to subsections of retinotopic visual co...

Three-dimensional structure-from-motion activates shape-specific areas in the ventral visual processing stream

by Marcus Naumer, Lars Muckli, and W. Singer

NeuroImage, 2000

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Decoding the spatial scale of information in visual cortex

Journal of Vision, 2014

Dissociation of prediction from conscious perception

Perception, 2014

The framework of predictive coding offers a parsimonious explanation for many perceptual phenomen... more The framework of predictive coding offers a parsimonious explanation for many perceptual phenomena. According to this framework, perception of the outer world is created by the comparison of incoming sensory information with an internal predictive model based on previous experience and context. However, it is unclear whether the predicted percept needs to enter conscious awareness for the internal predictive model to be effective. Here we used an apparent motion paradigm to show that while prediction and conscious awareness of a predicted percept may coincide, a dissociation can be observed. When sensory information provides reliable input for the internal predictive model, the predicted percept does not have to be consciously perceived for successful prediction. However, when sensory input is ambiguous, conscious awareness helps the prediction to take effect.

Contributions of cortical feedback to sensory processing in primary visual cortex

Frontiers in psychology, 2014

Closing the structure-function divide is more challenging in the brain than in any other organ (L... more Closing the structure-function divide is more challenging in the brain than in any other organ (Lichtman and Denk, 2011). For example, in early visual cortex, feedback projections to V1 can be quantified (e.g., Budd, 1998) but the understanding of feedback function is comparatively rudimentary (Muckli and Petro, 2013). Focusing on the function of feedback, we discuss how textbook descriptions mask the complexity of V1 responses, and how feedback and local activity reflects not only sensory processing but internal brain states.

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Methods for Dichoptic Stimulus Presentation in Functional Magnetic Resonance Imaging - A Review

The Open Neuroimaging Journal, 2009

Dichoptic stimuli (different stimuli displayed to each eye) are increasingly being used in functi... more Dichoptic stimuli (different stimuli displayed to each eye) are increasingly being used in functional brain imaging experiments using visual stimulation. These studies include investigation into binocular rivalry, interocular information transfer, three-dimensional depth perception as well as impairments of the visual system like amblyopia and stereodeficiency. In this paper, we review various approaches of displaying dichoptic stimulus used in functional magnetic resonance imaging experiments. These include traditional approaches of using filters (red-green, red-blue, polarizing) with optical assemblies as well as newer approaches of using bi-screen goggles.

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Apparent Rotation: fMRI-Adaptation of the Illusory Rotation Path

Audio-visual integration of artificial and natural object features in the human brain

Imagined Motion: investigating effective connectivity between early visual areas, hMT/V5 and parietal cortex

by Lars Muckli and Elia Formisano

Imagined motion: interactions between parietal cortex, human MT and early visual areas

Imagery of a moving object affects activation patterns and directed influences of hMT/V5+, posterior parietal and early visual regions

by Lars Muckli and Elia Formisano

Heading computations in the human brain-insights from psychophysics and functional neuroimaging

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