Julia Veit

University of Freiburg | Albert-Ludwigs-Universität Freiburg · Institute for Physiology

Gamma band synchronization can facilitate local and long-range neural communication. In the primary visual cortex, visual stimulus properties within a specific location determine local synchronization strength, while the match of stimulus properties between distant locations controls long-range synchronization. The neural basis for the differential...

Neural synchronization on fast timescales has been linked to critical aspects of sensation, cognition and action, and impairments in synchronization are associated with neurological disease. Although the strength and spatial scale of neural synchronization varies dramatically with sensory and behavioral context, the circuit mechanisms that regulate...

The cortical microcircuit can dynamically adjust to dramatic changes in the strength, scale, and complexity of its input. In the primary visual cortex (V1), pyramidal cells (PCs) integrate widely across space when signals are weak, but integrate narrowly when signals are strong, a phenomenon known as contrast-dependent surround suppression. Theoret...

The neocortex is functionally organized into layers. Layer four receives the densest bottom up sensory inputs, while layers 2/3 and 5 receive top down inputs that may convey predictive information. A subset of cortical somatostatin (SST) neurons, the Martinotti cells, gate top down input by inhibiting the apical dendrites of pyramidal cells in laye...

Inherited and age-related retinal degenerative diseases cause progressive loss of rod and cone photoreceptors, leading to blindness, but spare downstream retinal neurons, which can be targeted for optogenetic therapy. However, optogenetic approaches have been limited by either low light sensitivity or slow kinetics, and lack adaptation to changes i...

Brain state has profound effects on neural processing and stimulus encoding in sensory cortices. While the synchronized state is dominated by low-frequency local field potential (LFP) activity, low-frequency LFP power is suppressed in the desynchronized state, where a concurrent enhancement in gamma power is observed. Recently, it has been shown th...

Gamma band rhythms may synchronize distributed cell assemblies to facilitate information transfer within and across brain areas, yet their underlying mechanisms remain hotly debated. Most circuit models postulate that soma-targeting parvalbumin-positive GABAergic neurons are the essential inhibitory neuron subtype necessary for gamma rhythms. Using...

Exogenously expressed opsins are valuable tools for optogenetic control of neurons in circuits. A deeper understanding of neural function can be gained by bringing control to endogenous neurotransmitter receptors that mediate synaptic transmission. Here we introduce a comprehensive optogenetic toolkit for controlling GABAA receptor-mediated inhibit...

Anatomical and physiological experiments have outlined a blueprint for the feedforward flow of activity in cortical circuits: signals are thought to propagate primarily from the middle cortical layer (layer 4, L4) up to L2/3 and down to the major cortical output layer (L5). Pharmacological manipulations, however, have contested this model and have...

There are notable differences in functional properties of primary visual cortex (V1) neurons among mammalian species, particularly those concerning the occurrence of simple and complex cells and the generation of orientation selectivity. Here, we present quantitative data on receptive field (RF) structure, response modulation, and orientation tunin...

Background The basal forebrain (BF) regulates cortical activity by the action of cholinergic projections to the cortex. At the same time, it also sends substantial GABAergic projections to both cortex and thalamus, whose functional role has received far less attention. We used deep brain stimulation (DBS) in the BF, which is thought to activate bot...

Neuropeptides are critical signaling molecules, involved in the regulation of diverse physiological processes including energy metabolism, pain perception and brain cognitive state. Prolonged general anesthesia has an impact on many of these processes, but the regulation of peptides by general anesthetics is poorly understood. In this study, we pre...

Acetylcholine is an important neuromodulator involved in cognitive function. The impact of cholinergic neuromodulation on computations within the cortical microcircuit is not well understood. Here we investigate the effects of layer-specific cholinergic drug application in the tree shrew primary visual cortex during visual stimulation with drifting...

Entrainment of neural activity to luminance impulses during the refresh of cathode ray tube monitor displays has been observed in the primary visual cortex (V1) of humans and macaque monkeys. This entrainment is of interest because it tends to temporally align and thus synchronize neural responses at the millisecond timescale. Here we show that, in...

In humans, myocardial infarction is characterized by irreversible loss of heart tissue, which becomes replaced with a fibrous scar. By contrast, teleost fish and urodele amphibians are capable of heart regeneration after a partial amputation. However, due to the lack of a suitable infarct model, it is not known how these animals respond to myocardi...

Fibroblasts with contractile filaments constitute the wall of the post-infarct. (A) Heart section immunostained for a cardiac marker Tropomyosin (red), a myofibroblast marker alpha smooth muscle actin (green) and DAPI (blue). The outer rim of the post-infarct is surrounded by myofibroblasts. (A') Higher magnification of the framed area in (A) revea...

Three-dimensional-reconstruction of the zebrafish heart from a consecutive series of AFOG-stained sections at 7 dpci. Several anatomical structures can be seen: the atrium (spongy appearance, light orange), the ventricle (dense muscle tissue, intense orange), the bulbus arteriosus with abundent collagen (dark blue), the atrioventricular valve (gree...

H&E histological analysis of the scar and of the inflammatory response. (A-C) Heart cross-sections stained with Hematoxylin (dark purple) to visualize nuclei and Eosin (pink) to detect proteins. (A', B' and C') Higher magnifications of framed area shown in left panels. (A-A') At 4 dps, the intact ventricle is surrounded by the compact myocardium. T...

Sham surgery triggers a cell-cycle entry of the cardiomyocytes in the vicinity the epicardium. (A-B) The nuclei of cardiomyocytes express DsRed2-Nuc protein under the control of cmlc-2 promoter. Tropomyosin (blue) labels the myocardium, MCM5 (green) is expressed in the mitotic cells, DAPI marks all the nuclei. Proliferating cardiomyocytes are ident...

A new myocardium surrounds the post-infarct area during heart regeneration. (A and E) AFOG staining of a consecutive series of transverse sections of a heart at 14 dpci (A) and at 30 dpci (E) from the top of the ventricle (left upper corner) to the ventricular apex (right bottom corner); v, ventricle; va, valve; ba, bulbus arteriosus; a, atrium. (B...

Distribution of the endothelial cells in the ventricle at 14 dpci. (A) The endothelial cells express GFP under the control of tie-2 promoter [45]. Tropomyosin (blue) labels the myocardium, TNC (red) is expressed in the post-infarct zone. (A') Higher magnification of the framed area in (A) demonstrates formation of new blood vessels in the post-infa...