Reconstructing Visual Experiences from Brain Activity Evoked by Natural Movies

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Reconstructing Visual Experiences from Brain Activity Evoked by Natural Movies

per CURRENT BIOLOGY 11.9.21

Shinji Nishimoto, An T. Vu, Thomas Naselaris, Yuval Benjamini, Bin Yu, Jack L. Gallant. Quantitative modeling of human brain activity can provide crucial insights about cortical representations [1, 2] and can form the basis for brain decoding devices [3–5]. Recent functional magnetic....

 

 

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Neuroimaging reveals how brain uses objects to recognize scenes

 

 

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Neuroimaging reveals how brain uses objects to recognize scenes

via ScienceDaily: Mind & Brain News on 9/13/11

A new study by psychologists helps to explain how people quickly and accurately recognize complicated scenes such as playgrounds, kitchens and traffic intersections.

 

 

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Associative Learning Increases Trial-by-Trial Similarity of BOLD-MRI Patterns

http://www.jneurosci.org/content/31/33/12021.full.pdf+html

 

Associative Learning Increases Trial-by-Trial Similarity of BOLD-MRI Patterns

 

Rene´e M. Visser,

1,2

H. Steven Scholte,

2,3

and Merel Kindt

1,2

1

Department of Clinical Psychology,

2

Priority Program Brain and Cognition, and

3

Department of Brain and Cognition, University of Amsterdam,

1018 WB Amsterdam, The Netherlands

Associative learning is a dynamic process that allows us to incorporate new knowledge within existing semantic networks. Even after

years, a seemingly stable association can be altered by a single significant experience. Here, we investigate whether the acquisition of new

associations affects the neural representation of stimuli and how the brain categorizes stimuli according to preexisting and emerging

associations. Functional MRI data were collected during a differential fear conditioning procedure and at test (4 –5 weeks later). Two

pictures of faces and two pictures of houses served as stimuli. One of each pair coterminated with a shock in half of the trials (partial

reinforcement). Applying Multivoxel Pattern Analysis (MVPA) in a trial-by-trial manner, we quantified changes in the similarity of

neural representations of stimuli over the course of conditioning. Our findings show an increase in similarity of neural patterns throughout the cortex on consecutive trials of the reinforced stimuli. Furthermore, neural pattern similarity reveals a shift from original categories (faces/houses) toward new categories (reinforced/unreinforced) over the course of conditioning. This effect was differentially

represented in the cortex, with visual areas primarily reflecting similarity of low-level stimulus properties (original categories) and

frontal areas reflecting similarity of stimulus significance (new categories). Effects were not dependent on overall response amplitude

and were still presentduring follow-up. We conclude thattrial-by-trial MVPA is a useful tool for examining how the human brain encodes

relevant associations and forms new associative networks.

 

-----------------------------------------------------------

Lee de-Wit (PhD), Post-Doctoral Researcher

Gestalt ReVision Project, University of Leuven.

https://sites.google.com/site/leehdewit/

http://ppw.kuleuven.be/labexppsy/gestaltrevision/

lee.dewit@psy.kuleuven.be, ++32 16 326 143

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Decoding of coherent but not incoherent motion signals in early dorsal visual cortex

http://www.sciencedirect.com/science/article/pii/S1053811910004052#bb0190

 

NeuroImage
Volume 56, Issue 2, 15 May 2011, Pages 688-698
Multivariate Decoding and Brain Reading

---

doi:10.1016/j.neuroimage.2010.04.011 | How to Cite or Link Using DOI

Permissions & Reprints

 

Decoding of coherent but not incoherent motion signals in early dorsal visual cortex

Sponsored Article

Dietrich Samuel Schwarzkopf^a, b, , , Philipp Sterzer^c, 3 and Geraint Rees^{a, b, 1, 2}

^a UCL Institute of Cognitive Neuroscience, 17 Queen Square, London WC1N 3AR, UK

^b Wellcome Trust Centre for Neuroimaging at UCL, 12 Queen Square, London WC1N 3BG, UK

^c Department of Psychiatry, Charité Campus Mitte, Charitéplatz 1, D-10117 Berlin, Germany

Available online 10 April 2010. 

 

Abstract

When several scattered grating elements are arranged in such a way that their directions of motion are consistent with a common path, observers perceive them as belonging to a globally coherent moving object. Here we investigated how this coherence changes the representation of motion signals in human visual cortex using functional magnetic resonance imaging (fMRI) and multivariate voxel pattern decoding, which have the potential to reveal how well a stimulus is encoded in different contexts. Only during globally coherent motion was it possible to reliably distinguish fMRI signals evoked by different directions of motion in early visual cortex. This effect was specific to the retinotopic representation of the visual field quadrant in V1 traversed by the coherent element path and could not simply be attributed to a general increase in signal strength. Decoding was more reliable for cortical areas corresponding to the lower visual field. Because some previous studies observed poorer speed discrimination when motion was grouped, we also conducted behavioural experiments to investigate this with our stimuli, but did not reveal a consistent relationship between coherence and perceived speed. Taken together, these data show that neuronal populations in early visual cortex represent information that could be used for interpreting motion signals as unified objects.

 

 

 

Inter-area correlations in the ventral visual pathway reflect feature integr...

 

 

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Inter-area correlations in the ventral visual pathway reflect feature integration

via Journal of Vision recent issues door Freeman, J., Donner, T. H., Heeger, D. J. op 26-4-11

During object perception, the brain integrates simple features into representations of complex objects. A perceptual phenomenon known as visual crowding selectively interferes with this process. Here, we use crowding to characterize a neural correlate of feature integration. Cortical activity was measured with functional magnetic resonance imaging, simultaneously in multiple areas of the ventral visual pathway (V1–V4 and the visual word form area, VWFA, which responds preferentially to familiar letters), while human subjects viewed crowded and uncrowded letters. Temporal correlations between cortical areas were lower for crowded letters than for uncrowded letters, especially between V1 and VWFA. These differences in correlation were retinotopically specific, and persisted when attention was diverted from the letters. But correlation differences were not evident when we substituted the letters with grating patches that were not crowded under our stimulus conditions. We conclude that inter-area correlations reflect feature integration and are disrupted by crowding. We propose that crowding may perturb the transformations between neural representations along the ventral pathway that underlie the integration of features into objects.

 

 

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The surface area of human V1 predicts the subjective experience of object size.

The bigger your V1, the less illusions you see...

 

 

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The surface area of human V1 predicts the subjective experience of object size.

per pubmed: top authors autorius Schwarzkopf DS, Song C, Rees G 10.12.7

Related Articles

The surface area of human V1 predicts the subjective experience of object size.

Nat Neurosci. 2010 Dec 5;

Authors: Schwarzkopf DS, Song C, Rees G

The surface area of human primary visual cortex (V1) varies substantially between individuals for unknown reasons. We found that this variability was strongly and negatively correlated with the magnitude of two common visual illusions, where two physically identical objects appear different in size as a result of their context. Because such illusions dissociate conscious perception from physical stimulation, our findings indicate that the surface area of V1 predicts variability in conscious experience.

PMID: 21131954 [PubMed - as supplied by publisher]

 

 

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Cognitive neuroscience 2.0: building a cumulative science of human brain function

 

http://www.cell.com/trends/cognitive-sciences/abstract/S1364-6613(10)00201-9