Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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A synthetic neurobiology approach to orientation selectivity

One of the most prominent features of primary visual cortical neurons is their orientation preference [12]. Many competing models for the emergence of orientation preference have been proposed, from cortical self-organization [1] and retinally imposed tuning [23] to pinning by disorder [4] and randomness of neuronal circuits [5]. In the brain, feedforward and cortical circuits, which are contributing to selectivity, cannot be selectively manipulated. Having developed methods for optogenetic stimulation [6] and structuring [7] of cultured neurons, we established a synthetic biology approach for reconstituting this emergent property in a surrogate visual cortex.

 

PIC

Figure 1: a) The retinothalamic pathway of the cat provides input into V1. Here, we simulate the retinothalamic pathway to provide input for a cell culture. b) A schematic drawing of the holographic photostimulation setup [8]. c) Fluorescence image of rat cortical neurons expressing YFP on a MEA. Overlays show polar plots of tuning curves for two example electrodes (left). Right: their receptive fields and tuning curves (blue: single trials, red: average + 95% C.I.). d) Polarplots for the tuning curves of four example neurons. e) Histogram and cumulative distribution function (CDF) of observed orientation selectivities (blue) together with the shuffled control (green) for neurons with intact (left) and pharmacologically severed synaptic connections (right).

 

We constructed a model of the early visual pathway in-silico (a) that controls a holographic photostimulation setup providing retinothalamic input to a culture of optogenetically-modified neurons (b). We monitor neural responses with a multielectrode array (MEA) [67]. Stimulating the cell culture with moving gratings revealed a substantial degree of orientation tuning even in the absence of orientation tuned afferent input (c,d). We probe this orientation tuning and its origin pharmacologically and by various stimulation conditions (e). Our approach can open up a new way to experimentally dissect the influence of recurrent connections and their connectomic parameters in-vitro.


Contact:  Fred Wolf 

Members working within this Project:

 Manuel Schottdorf 
 Andreas Neef 
 Fred Wolf