Biology subjects

Tse, P. U.

Publications and source records attributed to Tse, P. U..

5 recordsLinked to original sources

bioRxiv2022

DeepAction: A MATLAB toolbox for automated classification of animal behavior in video

The identification of behavior in video is a critical but time-consuming component in many areas of animal behavior research. Here, we introduce DeepAction, a deep learning-based toolbox for automatically annotating animal behavior in video. Our approach uses features extracted from raw video frames by a pretrained convolutional neural network to train a recurrent neural network classifier. We evaluate the classifier on two benchmark rodent datasets and show that it achieves high accuracy, requires little training data, and surpasses both human agreement and similar existing methods. We also create a confidence score for classifier output, and show our method provides an accurate estimate of classifier performance and reduces the time required by human annotators to review and correct automatically-produced annotations. We release our system and accompanying annotation interface as an adaptable, non-technical, and open-source MATLAB toolbox.

neuroscience↗

bioRxiv2021

The perceived position of a moving object is reset by temporal, not spatial limits

When the internal texture of a Gabor patch drifts orthogonally to its physical path, its perceived motion deviates dramatically from its physical path. The local position shifts accumulate to such an extent that a 45{degrees} oblique physical path appears to be vertical. However, at some point, a limit is reached and the path resets back to its veridical location, whereupon a new accumulation starts, making the new perceived path segment appear parallel to the pre-reset segment, but offset horizontally from it. Here, we tested whether spontaneous resets of this motion-induced position shift depend on the time or the distance over which position errors accrue, or both. We introduced a temporal gap in the middle of the path that forced the illusory path to reset back to its veridical physical position. This gap-triggered reset allowed us to measure the magnitude of the illusory offset up to that point. We found that perceived offset was less than expected for the angle of illusory drift, indicating that spontaneous resets had occurred prior to the gap-induced reset. The position offset decreased when the pre-gap duration increased but approximately doubled when the path length doubled. This pattern of perceived offsets is best accounted for by spontaneous resets that occur randomly over time at a constant rate, independently of the distance traveled. Our results suggest a temporal, not spatial, limit for the accumulation of position errors that underlies this illusion.

neuroscience↗

bioRxiv2019

Neural correlates of conscious visual perception lie outside the visual system: evidence from the double-drift illusion

When perception differs from the physical stimulus, as it does for visual illusions and binocular rivalry, the opportunity arises to localize where perception emerges in the visual processing hierarchy. Representations prior to that stage differ from the eventual conscious percept even though they provide input to it. Here we investigate where and how a remarkable misperception of position emerges in the brain. This \"double-drift\" illusion causes a dramatic mismatch between retinal and perceived location, producing a perceived path that can differ from its physical path by 45{degrees} or more [1]. The deviations in the perceived trajectory can accumulate over at least a second [1] whereas other motion-induced position shifts accumulate over only 80 to 100 ms before saturating [2]. Using fMRI and multivariate pattern analysis, we find that the illusory path does not share activity patterns with a matched physical path in any early visual areas. In contrast, a whole-brain searchlight analysis reveals a shared representation in more anterior regions of the brain. These higher-order areas would have the longer time constants required to accumulate the small moment-to-moment position offsets that presumably originate in early visual cortices, and then transform these sensory inputs into a final conscious percept. The dissociation between perception and the activity in early sensory cortex suggests that perceived position does not emerge in what is traditionally regarded as the visual system but emerges instead at a much higher level.

neuroscience↗

bioRxiv2019

Still moving: The double-drift illusion survives smooth pursuit.

If a gabor pattern drifts in one direction while its internal texture drifts in the orthogonal direction, observers see a remarkable shift in its perceived direction when it is viewed in the periphery. The reported direction of the double-drift stimulus (also known as the infinite regress and curveball illusions) is some combination of the actual external motion of the gabor envelope and the internal motion of its texture (Tse & Hsieh, 2006). Here we find that if the observers track a fixation point that moves in tandem with the gabor, the illusion is undiminished. The pursuit of the moving fixation spot keeps the gabor roughly fixed at one location on the retina, cancelling its external motion, leaving only the internal motion. The gabor is seen to move in the world at roughly its actual speed as the motion of the eye is discounted at some point to recover velocities in world coordinates (e.g. Wallach, 1959). Our finding indicates that the combination of internal and external motion that produces the double drift illusion must happen after the eye movement signals have been factored into stimulus motions. We also test the double drift effect at various path lengths, durations, and speeds, with both mid-grey and black backgrounds, all with a static fixation. These results confirm that a simple vector combination of the two speeds alone accounts for virtually all the direction shifts on the grey background. On the black background, the illusion is eliminated. These results place constraints on where perceived spatial coordinates arise in the visual processing hierarchy to locations at or beyond where compensation for pursuit eye movements arise, specifically V3A, V6, MSTd, and VIP (e.g., Nau et al, 2018).

neuroscience↗

bioRxiv2018

Multivariate directed connectivity analysis (MDCA) enables decoding of directed interactions in neural and social networks

Many scientific fields currently face the daunting task of studying the dynamics of complex networks. For example, while we know that the rich mental phenomena of humans and other animals are mediated by complex systems of neural circuits in the brain, the mechanistic links between these biological networks and the functions that they mediate are poorly understood. Here we present a novel class of methods, termed multivariate directed connectivity analysis, to investigate network dynamics via patterns of directed interactions between network nodes. We validate these methods using simulated data and apply them to three real-world datasets, two neuroscientific and one investigating the 2016 US presidential candidates influence on the social media service Twitter. We find that these methods enable novel understanding of how information processing is distributed across networks. The methods are generally applicable to the study of dynamic information networks in biological, computational, and other fields of research.

neuroscience↗