scholarly journals A unifying framework for synaptic organization on cortical dendrites

2019 ◽  
Author(s):  
Jan H. Kirchner ◽  
Julijana Gjorgjieva
Keyword(s):  
Visual Space ◽  
Plasticity Model ◽  
Synaptic Organization ◽  
Early Postnatal Development ◽  
Synaptic Inputs ◽  
Local Clustering ◽  
Cortical Magnification ◽  
Stimulus Features ◽  
Mouse Visual Cortex ◽  
Synaptic Clustering

AbstractDendritic synaptic inputs are organized into functional clusters with remarkable subcellular precision at the micron level. This organization emerges during early postnatal development through patterned spontaneous activity and manifests both locally where nearby synapses are significantly correlated, and globally with distance to the soma. We propose a biophysically motivated synaptic plasticity model to dissect the mechanistic origins of this organization during development, and elucidate synaptic clustering of different stimulus features in the adult. Our model captures local clustering of orientation in ferret vs. receptive field overlap in mouse visual cortex based on the cortical magnification of visual space. Including a back-propagating action potential explains branch clustering heterogeneity in the ferret, and produces a global retinotopy gradient from soma to dendrite in the mouse. Therefore, our framework suggests that sub-cellular precision in connectivity can already be established in development, and unifies different aspects of synaptic organization across species and scales.

scholarly journals Emergence of local and global synaptic organization on cortical dendrites

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jan H. Kirchner ◽  
Julijana Gjorgjieva
Keyword(s):  
Receptive Field ◽  
Spatial Scales ◽  
Back Propagation ◽  
Receptive Fields ◽  
Visual Space ◽  
Synaptic Organization ◽  
Early Postnatal Development ◽  
Cortical Magnification ◽  
Stimulus Features ◽  
Species Specific

AbstractSynaptic inputs on cortical dendrites are organized with remarkable subcellular precision at the micron level. This organization emerges during early postnatal development through patterned spontaneous activity and manifests both locally where nearby synapses are significantly correlated, and globally with distance to the soma. We propose a biophysically motivated synaptic plasticity model to dissect the mechanistic origins of this organization during development and elucidate synaptic clustering of different stimulus features in the adult. Our model captures local clustering of orientation in ferret and receptive field overlap in mouse visual cortex based on the receptive field diameter and the cortical magnification of visual space. Including action potential back-propagation explains branch clustering heterogeneity in the ferret and produces a global retinotopy gradient from soma to dendrite in the mouse. Therefore, by combining activity-dependent synaptic competition and species-specific receptive fields, our framework explains different aspects of synaptic organization regarding stimulus features and spatial scales.

scholarly journals Visual numerosity estimation is based on anisotropic representations of visual space

2021 ◽  
Author(s):  
Miao Li ◽  
Bert Reynvoet ◽  
Bilge Sayim
Keyword(s):  
Visual Field ◽  
Convex Hull ◽  
Visual Fields ◽  
Spatial Vision ◽  
Visual Space ◽  
Stimulus Features ◽  
Numerosity Estimation ◽  
Numerosity Perception ◽  
Average Eccentricity ◽  
Shed Light

Humans can estimate the number of visually displayed items without counting. This capacity of numerosity perception has often been attributed to a dedicated system to estimate numerosity, or alternatively to the exploitation of various stimulus features, such as density, convex hull, the size of items and occupancy area. The distribution of the presented items is usually not varied with eccentricity in the visual field. However, our visual fields are highly asymmetric, and to date, it is unclear how inhomogeneities of the visual field impact numerosity perception. Besides eccentricity, a pronounced asymmetry is the radial-tangential anisotropy. For example, in crowding, radially placed flankers interfere more strongly with target perception than tangentially placed flankers. Similarly, in redundancy masking, the number of perceived items in repeating patterns is reduced when the items are arranged radially but not when they are arranged tangentially. Here, we investigated whether numerosity perception is subject to the radial-tangential anisotropy of spatial vision to shed light on the underlying topology of numerosity perception. Observers were presented with varying numbers of discs and asked to report the perceived number. There were two conditions. Discs were predominantly arranged radially in the “radial” condition and tangentially in the “tangential” condition. Additionally, the spacing between discs was scaled with eccentricity. Physical properties, such as average eccentricity, average spacing, convex hull, and density were kept as similar as possible in the two conditions. Radial arrangements were expected to yield underestimation compared to tangential arrangements. Consistent with the hypothesis, numerosity estimates in the radial condition were lower compared to the tangential condition. Magnitudes of radial alignment (as well as predicted crowding strength) correlated with the observed numerosity estimates. Our results demonstrate a robust radial-tangential anisotropy, suggesting that the topology of spatial vision determines numerosity estimation. We suggest that asymmetries of spatial vision should be taken into account when investigating numerosity estimation.

scholarly journals Parallel processing of visual space by neighboring neurons in mouse visual cortex

2010 ◽  
Vol 13 (9) ◽  
pp. 1144-1149 ◽  
Author(s):  
Spencer L Smith ◽  
Michael Häusser
Keyword(s):  
Visual Cortex ◽  
Parallel Processing ◽  
Visual Space ◽  
Mouse Visual Cortex

scholarly journals An offset ON-OFF receptive field is created by gap junctions between distinct types of retinal ganglion cells

2020 ◽  
Author(s):  
Sam Cooler ◽  
Gregory W. Schwartz
Keyword(s):  
Retinal Ganglion Cells ◽  
Ganglion Cells ◽  
Cell Model ◽  
Receptive Fields ◽  
Visual Space ◽  
Retinal Ganglion ◽  
Precise Location ◽  
Synaptic Inputs ◽  
Retinotopic Maps ◽  
Edge Location

SummaryReceptive fields (RFs) are a foundational concept in sensory neuroscience. The RF of a sensory neuron is shaped by the properties of its synaptic inputs from connected neurons. In the early visual system, retinotopic maps define a strict relationship between the location of a cell’s dendrites and its RF location in visual space1–3. Retinal ganglion cells (RGCs), the output cells of the retina, form dendritic mosaics that tile retinal space and have corresponding RF mosaics that tile visual space1,2. The precise location of dendrites in some RGCs has been shown to predict their RF shape4. Previously described ON-OFF RGCs have aligned dendrites in ON and OFF synaptic layers, so the cells respond to increments and decrements of light at the same locations in visual space5–8. Here we report a systematic offset between the ON and OFF RFs of an RGC type. Surprisingly, this property does not come from offset ON and OFF dendrites but instead arises from electrical synapses with RGCs of a different type. This circuit represents a new channel for direct communication between ON and OFF RGCs. Using a multi-cell model, we find that offset ON-OFF RFs could improve the precision with which edge location is represented in an RGC population.

scholarly journals Synaptic organization of visual space in primary visual cortex

Nature ◽  
2017 ◽  
Vol 547 (7664) ◽  
pp. 449-452 ◽  
Author(s):  
M. Florencia Iacaruso ◽  
Ioana T. Gasler ◽  
Sonja B. Hofer
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Visual Space ◽  
Synaptic Organization

Early NMDA Receptor Ablation in Interneurons Causes an Activity-Dependent E/I Imbalance in vivo in Prefrontal Cortex Pyramidal Neurons of a Mouse Model Useful for the Study of Schizophrenia

2021 ◽  
Author(s):  
Diego E Pafundo ◽  
Carlos A Pretell Annan ◽  
Nicolas M Fulginiti ◽  
Juan E Belforte
Keyword(s):  
Prefrontal Cortex ◽  
Mouse Model ◽  
Pyramidal Neurons ◽  
Gamma Oscillations ◽  
Dependent Manner ◽  
Early Postnatal Development ◽  
Synaptic Inputs ◽  
Selective Ablation ◽  
Activity Dependent

Abstract Altered Excitatory/Inhibitory (E/I) balance of cortical synaptic inputs has been proposed as a central pathophysiological factor for psychiatric neurodevelopmental disorders, including schizophrenia (SZ). However, direct measurement of E/I synaptic balance have not been assessed in vivo for any validated SZ animal model. Using a mouse model useful for the study of SZ we show that a selective ablation of NMDA receptors (NMDAr) in cortical and hippocampal interneurons during early postnatal development results in an E/I imbalance in vivo, with synaptic inputs to pyramidal neurons shifted towards excitation in the adult mutant medial prefrontal cortex (mPFC). Remarkably, this imbalance depends on the cortical state, only emerging when theta and gamma oscillations are predominant in the network. Additional brain slice recordings and subsequent 3D morphological reconstruction showed that E/I imbalance emerges after adolescence concomitantly with significant dendritic retraction and dendritic spine re-localization in pyramidal neurons. Therefore, early postnatal ablation of NMDAr in cortical and hippocampal interneurons developmentally impacts on E/I imbalance in vivo in an activity-dependent manner.

scholarly journals Author response: Clusters of synaptic inputs on dendrites of layer 5 pyramidal cells in mouse visual cortex

2016 ◽  
Author(s):  
Onur Gökçe ◽  
Tobias Bonhoeffer ◽  
Volker Scheuss
Keyword(s):  
Visual Cortex ◽  
Pyramidal Cells ◽  
Author Response ◽  
Synaptic Inputs ◽  
Mouse Visual Cortex
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