Cre recombinase-mediated gene deletion in layer 4 of murine sensory cortical areas

Neocortex is striking in its laminar architecture. Tracer studies have uncovered anatomical connectivity among laminae, but the functional connectivity between laminar compartments is still largely unknown. Such functional connectivity can be discerned through spontaneous neural correlations during rest. Previous work demonstrated a robust pattern of mesoscopic resting-state connectivity in macaque primary visual cortex (V1) through interlaminar cross-frequency coupling. Here we investigated whether this pattern generalizes to other cortical areas by comparing resting-state laminar connectivity between V1 and the supplementary eye field (SEF), a frontal area lacking a granular layer 4 (L4). Local field potentials (LFPs) were recorded with linear microelectrode arrays from all laminae of granular V1 and agranular SEF while monkeys rested in darkness. We found substantial differences in the relationship between the amplitude of gamma-band (>30 Hz) LFP and the phase of alpha-band (7–14 Hz) LFP between these areas. In V1, gamma amplitudes in L2/3 and L5 were coupled with alpha-band LFP phase in L5, as previously described. In contrast, in SEF phase-amplitude coupling was prominent within L3 and much weaker across layers. These results suggest that laminar interactions in agranular SEF are unlike those in granular V1. Thus the intrinsic functional connectivity of the cortical microcircuit does not seem to generalize across cortical areas.

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Effects of Locomotion in Auditory Cortex Are Not Mediated by the VIP Network

Frontiers in Neural Circuits ◽

10.3389/fncir.2021.618881 ◽

2021 ◽

Vol 15 ◽

Author(s):

Iryna Yavorska ◽

Michael Wehr

Keyword(s):

Auditory Cortex ◽

Cortical Neurons ◽

Cortical Layers ◽

Firing Rates ◽

Cortical Areas ◽

Layer 4 ◽

Evoked Activity ◽

Opposing Effects ◽

Neuronal Encoding

Movement has a prominent impact on activity in sensory cortex, but has opposing effects on visual and auditory cortex. Both cortical areas feature a vasoactive intestinal peptide-expressing (VIP) disinhibitory circuit, which in visual cortex contributes to the effect of running. In auditory cortex, however, the role of VIP circuitry in running effects remains poorly understood. Running and optogenetic VIP activation are known to differentially modulate sound-evoked activity in auditory cortex, but it is unknown how these effects vary across cortical layers, and whether laminar differences in the roles of VIP circuitry could contribute to the substantial diversity that has been observed in the effects of both movement and VIP activation. Here we asked whether VIP neurons contribute to the effects of running, across the layers of auditory cortex. We found that both running and optogenetic activation of VIP neurons produced diverse changes in the firing rates of auditory cortical neurons, but with distinct effects on spontaneous and evoked activity and with different patterns across cortical layers. On average, running increased spontaneous firing rates but decreased evoked firing rates, resulting in a reduction of the neuronal encoding of sound. This reduction in sound encoding was observed in all cortical layers, but was most pronounced in layer 2/3. In contrast, VIP activation increased both spontaneous and evoked firing rates, and had no net population-wide effect on sound encoding, but strongly suppressed sound encoding in layer 4 narrow-spiking neurons. These results suggest that VIP activation and running act independently, which we then tested by comparing the arithmetic sum of the two effects measured separately to the actual combined effect of running and VIP activation, which were closely matched. We conclude that the effects of locomotion in auditory cortex are not mediated by the VIP network.

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Targeted viral delivery of Cre recombinase induces conditional gene deletion in cardiovascular circuits of the mouse brain

Physiological Genomics ◽

10.1152/physiolgenomics.00048.2004 ◽

2004 ◽

Vol 18 (1) ◽

pp. 25-32 ◽

Cited By ~ 41

Author(s):

Puspha Sinnayah ◽

Timothy E. Lindley ◽

Patrick D. Staber ◽

Beverly L. Davidson ◽

Martin D. Cassell ◽

...

Keyword(s):

Mouse Brain ◽

Targeted Delivery ◽

Gene Deletion ◽

Retrograde Transport ◽

Cell Types ◽

Cre Recombinase ◽

Gene Recombination ◽

Immunodeficiency Virus ◽

Nervous System Function ◽

First Time

The Cre/loxP system has shown promise for investigating genes involved in nervous system function and pathology, although its application for studying central neural regulation of cardiovascular function and disease has not been explored. Here, we report for the first time that recombination of loxP-flanked genes can be achieved in discrete cardiovascular regulatory nuclei of adult mouse brain using targeted delivery of adenovirus (Ad) or feline immunodeficiency virus (FIV) bearing Cre recombinase (Ad-Cre, FIV-Cre). Single stereotaxic microinjections of Ad-Cre or FIV-Cre into specific nuclei along the subfornical organ-hypothalamic-hypophysial and brain stem-parabrachial axes resulted in robust and highly localized gene deletion as early as 7 days and for as long as 3 wk in a reporter mouse model in which Cre recombinase activates β-galactosidase expression. An even greater selectivity in Cre-mediated gene deletion could be achieved in unique subpopulations of cells, such as vasopressin-synthesizing magnocellular neurons, by delivering Ad-Cre via retrograde transport. Moreover, Ad-Cre and FIV-Cre induced gene recombination in differential cell populations within these cardiovascular nuclei. FIV-Cre infection resulted in LacZ activation selectively in neurons, whereas both neuronal and glial cell types underwent gene recombination upon infection with Ad-Cre. These results establish the feasibility of using a combination of viral and Cre/loxP technologies to target specific cardiovascular nuclei in the brain for conditional gene modification and suggest the potential of this approach for determining the functional role of genes within these sites.

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A Cre-loxP solution for defining the brain renin-angiotensin system. Focus on “Targeted viral delivery of Cre recombinase induces conditional gene deletion in cardiovascular circuits of the mouse brain”

Physiological Genomics ◽

10.1152/physiolgenomics.00115.2004 ◽

2004 ◽

Vol 18 (1) ◽

pp. 1-3 ◽

Cited By ~ 4

Author(s):

M. Ian Phillips

Keyword(s):

Mouse Brain ◽

Gene Deletion ◽

Renin Angiotensin System ◽

Cre Recombinase ◽

Angiotensin System ◽

Renin Angiotensin ◽

The Brain ◽

System Focus

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Gene Deletion in Urothelium by Specific Expression of Cre Recombinase

The Journal of Urology ◽

10.1016/s0022-5347(05)00869-4 ◽

2006 ◽

Vol 175 (4) ◽

pp. 1569-1569

Author(s):

L. Mo ◽

J. Cheng ◽

E.Y. Lee ◽

T.T. Sun ◽

X.R. Wu

Keyword(s):

Gene Deletion ◽

Cre Recombinase ◽

Specific Expression

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Synaptic Properties of Thalamic and Intracortical Inputs to Layer 4 of the First- and Higher-Order Cortical Areas in the Auditory and Somatosensory Systems

Journal of Neurophysiology ◽

10.1152/jn.90391.2008 ◽

2008 ◽

Vol 100 (1) ◽

pp. 317-326 ◽

Cited By ~ 96

Author(s):

Charles C. Lee ◽

S. Murray Sherman

Keyword(s):

Information Transfer ◽

Higher Order ◽

Thalamic Nuclei ◽

First Order ◽

Metabotropic Glutamate ◽

Cortical Areas ◽

Layer 4 ◽

Auditory Systems ◽

Initial Processing ◽

Whole Cell Recordings

The thalamus is an essential structure in the mammalian forebrain conveying information topographically from the sensory periphery to primary neocortical areas. Beyond this initial processing stage, “higher-order” thalamocortical connections have been presumed to serve only a modulatory role, or are otherwise functionally disregarded. Here we demonstrate that these “higher-order” thalamic nuclei share similar synaptic properties with the “first-order” thalamic nuclei. Using whole cell recordings from layer 4 neurons in thalamocortical slice preparations in the mouse somatosensory and auditory systems, we found that electrical stimulation in all thalamic nuclei elicited large, glutamatergic excitatory postsynaptic potentials (EPSPs) that depress in response to repetitive stimulation and that fail to activate a metabotropic glutamate response. In contrast, the intracortical inputs from layer 6 to layer 4 exhibit facilitating EPSPs. These data suggest that higher-order thalamocortical projections may serve a functional role similar to the first-order nuclei, whereas both are physiologically distinct from the intracortical layer 6 inputs. These results suggest an alternate route for information transfer between cortical areas via a corticothalamocortical pathway.

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