Recurrent excitation

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

Neuronal responses to sensory stimuli are strongly modulated by an animal’s brain state. Three distinct subtypes of inhibitory interneurons, parvalbumin (PV), somatostatin (SOM), and vasoactive intestinal peptide (VIP) expressing cells, have been identified as key players in flexibly modulating sensory responses [1]. The three interneuron populations have specialized local microcircuit motifs and are targeted differentially by neuromodulators and top-down inputs from higher-order cortical areas. However, the distinct contribution of each interneuron subtype to modulating a cortical network’s d

Burst-suppression (BS) is a highly structured electroencephalogram (EEG) pattern characterized by alternating periods of high-voltage activity (bursts) and low or flatline activity (suppression). In non-anesthetized adults, BS indicates severe brain pathology, e.g. due to oxygen and glucose deprivation [1]. There are two types of BS: one with identical bursts that are highly periodic and uniform in shape, often signaling a poor prognosis, and one without identical bursts [2]. The neuronal mechanisms behind BS and these variations remain largely unknown. Some studies suggest the involvement of

Two-photon Computer Generated Holography (CGH) based optogenetics allows activation of arbitrarily selected neurons simultaneously in 3D with cellular precision. We integrate two-photon CGH with a single-photon, dual channel light sheet microscope to record whole-brain Ca2+ activity at up to 400 frames per second, for concurrent activation and imaging. We use transgenic zebrafish larvae (5-8 days post fertilization) pan-neuronally expressing an excitatory opsin (HuC:ReaChR) and a Ca2+ indicator (HuC:GCaMP8s). This opsin-indicator combination enables flexible, simultaneous read/write access to

…fast) receive 10-fold stronger recurrent excitation than their early-firing (putative slow) counterparts. This finding raises the question of whether connections between motoneurons are dominantly between fast motoneurons or whether slow motoneurons preferentially connect to fast ones. We performed paired recordings from motoneurons labelled from either gastrocnemius (ankle extensor) or tibialis anterior (ankle flexor

The connectivity structure of many biological systems, including neural circuits, is highly non-uniform. Recent technologies allow detailed mapping of these irregularities, but our understanding of their effect on the overall circuit dynamics is still lacking. By developing complex system analytical tools that perform reduction of the network, I determine the impact of connectivity features on network dynamics. I will demonstrate the use of these tools on neural assemblies (clusters), a ubiquitous non-uniform structure in our brains. I will show how neural assemblies of different sizes natural

Although most synapses within the neocortex are recurrent, the functional impact of this recurrence remains unclear. Prior experimental and theoretical work in the primary visual cortex (V1) suggests that recurrent excitation amplifies responses when signals are weak in order to optimize detection, while recurrent inhibition suppresses responses when signals are strong to optimize discrimination. Deepening our understanding of the logic for when recurrent activity facilitates cooperation among cortical ensembles and when it mediates competition beyond these initial results is fundamental to un