Mouse Visual Neocortex Supports Multiple Stereotyped Patterns of Microcircuit Activity

Abstract

Spiking correlations between neocortical neurons provide insight into the underlying synaptic connectivity that defines cortical microcircuitry. Here, using two-photon calcium fluorescence imaging, we observed the simultaneous dynamics of hundreds of neurons in slices of mouse primary visual cortex (V1). Consistent with a balance of excitation and inhibition, V1 dynamics were characterized by a linear scaling between firing rate and circuit size. Using lagged firing correlations between neurons, we generated functional wiring diagrams to evaluate the topological features of V1 microcircuitry. We found that circuit connectivity exhibited both cyclic graph motifs, indicating recurrent wiring, and acyclic graph motifs, indicating feedforward wiring. After overlaying the functional wiring diagrams onto the imaged field of view, we found properties consistent with Rentian scaling: wiring diagrams were topologically efficient because they minimized wiring with a modular architecture. Within single imaged fields of view, V1 contained multiple discrete circuits that were overlapping and highly interdigitated but were still distinct from one another. The majority of neurons that were shared between circuits displayed peri-event spiking activity whose timing was specific to the active circuit, whereas spike times for a smaller percentage of neurons were invariant to circuit identity. These data provide evidence that V1 microcircuitry exhibits balanced dynamics, is efficiently arranged in anatomical space, and is capable of supporting a diversity of multineuron spike firing patterns from overlapping sets of neurons.

Analysis of Graph Invariants in Functional Neocortical Circuitry Reveals Generalized Features Common to Three Areas of Sensory Cortex

“…Such a bias may lead to subsampling errors, exactly parallel to the problems that arise from using small fields of view. Since circuit topologies become highly connected with the inclusion of weak functional connections, weak connections may be necessary to provide a large dynamic range similar to a previous study of mouse V1 [37], [42]. These data and analyses suggest that the generalized features of functional circuitry identified in this study maximize the capacity of this system to represent the sensory environment.…”

Temporal Interval Learning in Cortical Cultures Is Encoded in Intrinsic Network Dynamics

“…Thus indicating that the network activity evoked by the same stimulus differed across groups. Averaging across all the traces in which polysynaptic activity was present, revealed that despite the significant trial-by-trial variability of evoked polysynaptic activity (Buonomano, 2003; Luczak et al, 2007; Sadovsky and MacLean, 2014), there were differences in the averaged traces (Figure 1C). To quantify the differences in the temporal structure of the activity we examined the distribution of times of the polysynaptic events (Figure 1D).…”

Diverse cortical codes for scene segmentation in primate auditory cortex

“…Auditory receptive fields are known to be temporally dynamic: the frequency/intensity response areas of single neurons have been shown to vary for onset, sustained, and offset activity (Bartho et al 2011;Fishman and Steinschneider 2009;Loftus and Sutter 2001;Qin et al 2003Qin et al , 2007Tian et al 2013). As a consequence, correlations in response timing and not merely response tuning may influence cortical organization at the microcircuit level to optimize the representation of important stimulus features (Atencio and Schreiner 2013;Bathellier et al 2012;Hansen et al 2012;Ince et al 2013;Padmanabhan and Urban 2014;Sadovsky and MacLean 2014).…”