Orientation selectivity

Orientation is one of the most salient features in visual scenes. Neurons at multiple levels of the visual system detect orientation, but in many cases the underlying biophysical mechanisms remain unresolved. Here, we study the mechanism for orientation detection at the earliest stage in the visual system, in B/K wide-field amacrine cells (B/K WACs), a novel group of giant, non-spiking interneurons in the mouse retina. B/K WACs exhibit orientation-selective calcium signals along their long, straight, unbranching dendrites, which contain both synaptic inputs and outputs. In this study, we ident

At eye-opening, layer 2/3 (L2/3) of ferret primary visual cortex (V1) exhibits orientation-selective responses, modular (~periodic) patterns of visually-evoked and spontaneous activity, and spatially periodic orientation maps. L4 activity has weaker orientation selectivity (OS) than, and is spatially uncorrelated with, L2/3 responses at eye-opening, suggesting L2/3 may generate modular activity patterns independently of L4 map or activity organization. Here we characterize L4 and L2/3 receptive fields (RFs) and the L4 orientation map at eye-opening. We then model the connectivity by which L4 i

…By measuring feature selectivity in more than 90 cell types in the fly visual system and leveraging a pair of recently annotated optic lobe connectomes[2][3], we evalu

A fundamental property of neurons in the primary visual cortex is their preference for orientation of edges. It was shown that this orientation tuning is mostly invariant under contrast changes [1], a property that is not explained by a simple feed-forward scheme [2, 3]. We designed a synthetic hybrid neural circuit to study the emergence of orientation selectivity under different thalamo-cortical connections. To this end, a computational model of the retino-thalamic pathway was combined with an in-vitro model of cortical input layer 4. The latter was either a primary culture of cortical neur

A fundamental property of neurons in the primary visual cortex is their preference for orientation of edges that is invariant under contrast changes. We designed a synthetic hybrid neural circuit to study the emergence of orientation selectivity under different thalamo-cortical connection schemes. To this end, a computational model of the retino-thalamic pathway was combined with an in-vitro model of cortical input layer 4. The latter was either a primary culture of cortical neurons or an acute horizontal brain slice of primary visual cortex. The two stages were interfaced optogenetically by e

How the brain processes a stimulus depends not only on its physical properties but also on contextual factors, such as whether it is predictable, expected, or surprising. Though well characterized using non-invasive means, the microcircuit mechanisms responsible for comparing sensory input and expectations remain poorly understood. We recorded single units and local field potential (LFP) activity from primary visual cortex in awake mice engaged in a visual oddball task. Relative to stimulus onset, we distinguish early (50-200ms) and late (200-400ms) neural response windows, a choice compatible

Orientation selectivity is a prominent feature of neurons in the mammalian primary visual cortex, but there is a dichotomy in the spatial arrangement of these neurons across species. Primates, carnivores and marsupials have orientation-selective neurons organized into structured columns forming two-dimensional maps around pinwheel centers. In contrast, rodents display a seemingly random "salt-and-pepper" organization. The evolutionary versus the environmental basis of this distinction remains unclear. Using intrinsic imaging and massed single-cell recordings, we investigated the organization o

…that predict aspects of future orientation selectivity. Previous modelling works have shown that the long-range correlations observed in these networks can arise from locally connected neurons through multi-synaptic interactions. Here we seek to map the structure of cortical lateral interactions through localised perturbations in vivo.We first constructed a rectified recurrent neural netwo

Complex spatio-temporal neural population dynamics such as traveling waves are known to exist across multiple brain regions (Lubenov & Siapas, 2009; Muller et al., 2014), and have been hypothesized to play diverse roles from information transfer (Sato et al., 2012) to long-term memory consolidation (Muller et al., 2016). To-date, however, the empirical validation of these computational hypotheses has been hindered by the lack of a flexible and efficiently trainable model of such behavior. In this work, we introduce the Locally Coupled Oscillatory Recurrent Neural Network (LocoRNN), and sho

…that predict aspects of future orientation selectivity [1]. Previous modelling works have shown that the long-range correlations observed in these networks can arise from purely locally connected neurons through multi-synaptic interactions [1][2]. Here we seek to explicitly map the structure of cortical lateral interactions through localized perturbations in vivo. We first con

Neurons in the primary visual cortex (V1) of rodents are selective to the orientation of the stimulus, as in other mammals such as cats and monkeys. However, in contrast with those species, their neurons display a very different type of spatial organization. Instead of orientation maps they are organized in a “salt and pepper” pattern, where adjacent neurons have completely different preferred orientations. This structure has motivated both experimental and theoretical research with the objective of determining which aspects of the connectivity patterns and intrinsic neuronal responses can exp

Orientation selectivity is a key feature of primary visual cortex (V1). Orientation specific receptive fields (OSRFs) appear to arise from specific feedforward connectivity from lateral geniculate nucleus (LGN) to V1 cells. OSRF development has been hypothesized to arise from a competition between ON- and OFF-center LGN cells, if the difference between same-type and opposite-type correlation functions is a non-monotonic, "Mexican hat" function of cell-cell separation. However experiments found this difference decays monotonically. Many models have assumed "Mexican hat" recurrent connectivity (

Neurons in the primary visual cortex (V1) encode the orientation and contrast of visual stimuli through changes in firing rate (Hubel and Wiesel, 1962). Their activity typically peaks at a preferred orientation and decays to zero at the orientations that are orthogonal to the preferred. This activity pattern is re-scaled by contrast but its shape is preserved, a phenomenon known as contrast invariance. Contrast-invariant selectivity is also observed at the population level in V1 (Carandini and Sengpiel, 2004). The mechanisms supporting the emergence of contrast-invariance at the population lev