scholarly journals Neural Sampling Strategies for Visual Stimulus Reconstruction fromTwo-photon Imaging of Mouse Primary Visual Cortex

2018 ◽  
Author(s):  
Stef Garasto ◽  
Wilten Nicola ◽  
Anil A. Bharath ◽  
Simon R. Schultz

AbstractDeciphering the neural code involves interpreting the responses of sensory neurons from the perspective of a downstream population. Performing such a read-out is an important step towards understanding how the brain processes sensory information and has implications for Brain-Machine Interfaces. While previous work has focused on classification algorithms to identify a stimulus in a predefined set of categories, few studies have approached a full-stimulus reconstruction task, especially from calcium imaging recordings. Here, we attempt a pixel-by-pixel reconstruction of complex natural stimuli from two-photon calcium imaging of mouse primary visual cortex. We decoded the activity of 103 neurons from layer 2/3 using an optimal linear estimator and investigated which factors drive the reconstruction performance at the pixel level. We find the density of receptive fields to be the most influential feature. Finally, we use the receptive field data and simulations from a linear-nonlinear Poisson model to extrapolate decoding accuracy as a function of network size. We find that, on this dataset, reconstruction performance can increase by more than 50%, provided that the receptive fields are sampled more uniformly in the full visual field. These results provide practical experimental guidelines to boost the accuracy of full-stimulus reconstruction.


2009 ◽  
Vol 65 ◽  
pp. S172
Author(s):  
Yoshiya Mori ◽  
Koji Ikezoe ◽  
Junichi Furutaka ◽  
Kazuo Kitamura ◽  
Hiroshi Tamura ◽  
...  


2018 ◽  
Author(s):  
Stef Garasto ◽  
Anil A. Bharath ◽  
Simon R. Schultz

AbstractDeciphering the neural code, that is interpreting the responses of sensory neurons from the perspective of a downstream population, is an important step towards understanding how the brain processes sensory stimulation. While previous work has focused on classification algorithms to identify the most likely stimulus label in a predefined set of categories, fewer studies have approached a full stimulus reconstruction task. Outstanding questions revolve around the type of algorithm that is most suited to decoding (i.e. full reconstruction, in the context of this study), especially in the presence of strong encoding non-linearities, and the possible role of pairwise correlations. We present, here, the first pixel-by-pixel reconstruction of a complex natural stimulus from 2-photon calcium imaging responses of mouse primary visual cortex (V1). We decoded the activity of approximately 100 neurons from layer 2/3 using an optimal linear estimator and an artificial neural network. We also investigated how much accuracy is lost in this decoding operation when ignoring pairwise neural correlations. We found that a simple linear estimator is sufficient to extract relevant stimulus features from the neural responses, and that it was not significantly outperformed by a non-linear decoding algorithm. The importance of pairwise correlations for reconstruction accuracy was also limited. The results of this study suggest that, conditional on the spatial and temporal limits of the recording technique, V1 neurons display linear readout properties, with low information content in the joint distribution of their activity.





2018 ◽  
Author(s):  
J.J. Pattadkal ◽  
G. Mato ◽  
C. van Vreeswijk ◽  
N. J. Priebe ◽  
D. Hansel

SummaryWe study the connectivity principles underlying the emergence of orientation selectivity in primary visual cortex (V1) of mammals lacking an orientation map. We present a computational model in which random connectivity gives rise to orientation selectivity that matches experimental observations. It predicts that mouse V1 neurons should exhibit intricate receptive fields in the two-dimensional frequency domain, causing shift in orientation preferences with spatial frequency. We find evidence for these features in mouse V1 using calcium imaging and intracellular whole cell recordings.



2000 ◽  
Vol 84 (4) ◽  
pp. 2048-2062 ◽  
Author(s):  
Mitesh K. Kapadia ◽  
Gerald Westheimer ◽  
Charles D. Gilbert

To examine the role of primary visual cortex in visuospatial integration, we studied the spatial arrangement of contextual interactions in the response properties of neurons in primary visual cortex of alert monkeys and in human perception. We found a spatial segregation of opposing contextual interactions. At the level of cortical neurons, excitatory interactions were located along the ends of receptive fields, while inhibitory interactions were strongest along the orthogonal axis. Parallel psychophysical studies in human observers showed opposing contextual interactions surrounding a target line with a similar spatial distribution. The results suggest that V1 neurons can participate in multiple perceptual processes via spatially segregated and functionally distinct components of their receptive fields.



2015 ◽  
Vol 28 (3-4) ◽  
pp. 331-349 ◽  
Author(s):  
Frederico A. C. Azevedo ◽  
Frederico A. C. Azevedo ◽  
Michael Ortiz-Rios ◽  
Frederico A. C. Azevedo ◽  
Michael Ortiz-Rios ◽  
...  

A biologically relevant event is normally the source of multiple, typically correlated, sensory inputs. To optimize perception of the outer world, our brain combines the independent sensory measurements into a coherent estimate. However, if sensory information is not readily available for every pertinent sense, the brain tries to acquire additional information via covert/overt orienting behaviors or uses internal knowledge to modulate sensory sensitivity based on prior expectations. Cross-modal functional modulation of low-level auditory areas due to visual input has been often described; however, less is known about auditory modulations of primary visual cortex. Here, based on some recent evidence, we propose that an unexpected auditory signal could trigger a reflexive overt orienting response towards its source and concomitantly increase the primary visual cortex sensitivity at the locations where the object is expected to enter the visual field. To this end, we propose that three major functionally specific pathways are employed in parallel. A stream orchestrated by the superior colliculus is responsible for the overt orienting behavior, while direct and indirect (via higher-level areas) projections from A1 to V1 respectively enhance spatiotemporal sensitivity and facilitate object detectability.



1997 ◽  
Vol 9 (5) ◽  
pp. 959-970 ◽  
Author(s):  
Christian Piepenbrock ◽  
Helge Ritter ◽  
Klaus Obermayer

Correlation-based learning (CBL) has been suggested as the mechanism that underlies the development of simple-cell receptive fields in the primary visual cortex of cats, including orientation preference (OR) and ocular dominance (OD) (Linsker, 1986; Miller, Keller, & Stryker, 1989). CBL has been applied successfully to the development of OR and OD individually (Miller, Keller, & Stryker, 1989; Miller, 1994; Miyashita & Tanaka, 1991; Erwin, Obermayer, & Schulten, 1995), but the conditions for their joint development have not been studied (but see Erwin & Miller, 1995, for independent work on the same question) in contrast to competitive Hebbian models (Obermayer, Blasdel, & Schulten, 1992). In this article, we provide insight into why this has been the case: OR and OD decouple in symmetric CBL models, and a joint development of OR and OD is possible only in a parameter regime that depends on nonlinear mechanisms.



2005 ◽  
Vol 94 (1) ◽  
pp. 788-798 ◽  
Author(s):  
Valerio Mante ◽  
Matteo Carandini

A recent optical imaging study of primary visual cortex (V1) by Basole, White, and Fitzpatrick demonstrated that maps of preferred orientation depend on the choice of stimuli used to measure them. These authors measured population responses expressed as a function of the optimal orientation of long drifting bars. They then varied bar length, direction, and speed and found that stimuli of a same orientation can elicit different population responses and stimuli with different orientation can elicit similar population responses. We asked whether these results can be explained from known properties of V1 receptive fields. We implemented an “energy model” where a receptive field integrates stimulus energy over a region of three-dimensional frequency space. The population of receptive fields defines a volume of visibility, which covers all orientations and a plausible range of spatial and temporal frequencies. This energy model correctly predicts the population response to bars of different length, direction, and speed and explains the observations made with optical imaging. The model also readily explains a related phenomenon, the appearance of motion streaks for fast-moving dots. We conclude that the energy model can be applied to activation maps of V1 and predicts phenomena that may otherwise appear to be surprising. These results indicate that maps obtained with optical imaging reflect the layout of neurons selective for stimulus energy, not for isolated stimulus features such as orientation, direction, and speed.



2018 ◽  
Author(s):  
Adam P. Morris ◽  
Bart Krekelberg

SummaryHumans and other primates rely on eye movements to explore visual scenes and to track moving objects. As a result, the image that is projected onto the retina – and propagated throughout the visual cortical hierarchy – is almost constantly changing and makes little sense without taking into account the momentary direction of gaze. How is this achieved in the visual system? Here we show that in primary visual cortex (V1), the earliest stage of cortical vision, neural representations carry an embedded “eye tracker” that signals the direction of gaze associated with each image. Using chronically implanted multi-electrode arrays, we recorded the activity of neurons in V1 during tasks requiring fast (exploratory) and slow (pursuit) eye movements. Neurons were stimulated with flickering, full-field luminance noise at all times. As in previous studies 1-4, we observed neurons that were sensitive to gaze direction during fixation, despite comparable stimulation of their receptive fields. We trained a decoder to translate neural activity into metric estimates of (stationary) gaze direction. This decoded signal not only tracked the eye accurately during fixation, but also during fast and slow eye movements, even though the decoder had not been exposed to data from these behavioural states. Moreover, this signal lagged the real eye by approximately the time it took for new visual information to travel from the retina to cortex. Using simulations, we show that this V1 eye position signal could be used to take into account the sensory consequences of eye movements and map the fleeting positions of objects on the retina onto their stable position in the world.



2016 ◽  
Author(s):  
Inbal Ayzenshtat ◽  
Jesse Jackson ◽  
Rafael Yuste

AbstractThe response properties of neurons to sensory stimuli have been used to identify their receptive fields and functionally map sensory systems. In primary visual cortex, most neurons are selective to a particular orientation and spatial frequency of the visual stimulus. Using two-photon calcium imaging of neuronal populations from the primary visual cortex of mice, we have characterized the response properties of neurons to various orientations and spatial frequencies. Surprisingly, we found that the orientation selectivity of neurons actually depends on the spatial frequency of the stimulus. This dependence can be easily explained if one assumed spatially asymmetric Gabor-type receptive fields. We propose that receptive fields of neurons in layer 2/3 of visual cortex are indeed spatially asymmetric, and that this asymmetry could be used effectively by the visual system to encode natural scenes.Significance StatementIn this manuscript we demonstrate that the orientation selectivity of neurons in primary visual cortex of mouse is highly dependent on the stimulus SF. This dependence is realized quantitatively in a decrease in the selectivity strength of cells in non-optimum SF, and more importantly, it is also evident qualitatively in a shift in the preferred orientation of cells in non-optimum SF. We show that a receptive-field model of a 2D asymmetric Gabor, rather than a symmetric one, can explain this surprising observation. Therefore, we propose that the receptive fields of neurons in layer 2/3 of mouse visual cortex are spatially asymmetric and this asymmetry could be used effectively by the visual system to encode natural scenes.Highlights–Orientation selectivity is dependent on spatial frequency.–Asymmetric Gabor model can explain this dependence.



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