Reorganization of cortical population activity imaged throughout long-term sensory deprivation

Abstract

Sensory maps are reshaped by experience. It is unknown how map plasticity occurs in vivo in functionally diverse neuronal populations because activity of the same cells has not been tracked over long time periods. Here we used repeated two-photon imaging of a genetic calcium indicator to measure whisker-evoked responsiveness of the same layer 2/3 neurons in adult mouse barrel cortex over weeks, first with whiskers intact, then during continued trimming of all but one whisker. Across the baseline period, neurons displayed heterogeneous yet stable responsiveness. During sensory deprivation, responses to trimmed whisker stimulation globally decreased, whereas responses to spared whisker stimulation increased for the least active neurons and decreased for the most active neurons. These findings suggest that recruitment of inactive, 'silent' neurons is part of a convergent redistribution of population activity underlying sensory map plasticity. Sensory-driven responsiveness is a key property controlling experience-dependent activity changes in individual neurons.

Long-term In Vivo Calcium Imaging of Astrocytes Reveals Distinct Cellular Compartment Responses to Sensory Stimulation

“…It is possible that different processes are activated at different times based on the local synaptic responses (Grienberger and Konnerth 2012). Our group has previously shown that a sparse population of neurons responds reliably over different time points to whisker stimulation (Margolis et al 2012;Mayrhofer et al 2015). However, different synapses within the arbour of these neurons could be activated at each time point and this may cause the spatial diversity we observed in responding astrocyte processes.…”

Behaviour-dependent recruitment of long-range projection neurons in somatosensory cortex

“…Cranial window implantation and habituation. To allow long-term in vivo calcium imaging, a cranial window was implanted 24 h after virus injections over S1 as described 33 . A metal post for head fixation was implanted on the skull, contralateral to the cranial window, using dental acrylic.…”

Design and performance of an ultra-flexible two-photon microscope for in vivo research

“…To demonstrate the capabilities of the microscope for in vivo imaging, adeno-associated virus (AAV) carrying the pyruvate FRET nanosensor Pyronic [24] (AAV6 under human synapsin promoter or AAV9 under GFAP) injected mouse was implanted with a chronic window [9], [10]. The mouse was anesthetized with a mixture of fentanyl (0.05 mg per kg bodyweight; Sintenyl, Sintetica, Switzerland), midazolam (5 mg per kg bodyweight; Dormicum, Roche) and medetomidine (0.5 mg per kg bodyweight; Domitor, Orion Pharma) intraperitoneally.…”

“…Other genetically encoded indicators suitable for 2PLSM, for instance to measure metabolite concentrations, are emerging. Recent applications are recordings of activity from the same population of neurons over long time periods during motor learning, plasticity and stimulus stability [8][9][10], targeted electrophysiological recording of genetically identified neurons to understand circuit function [11,12], as well as monitoring structure and activity changes on the dendrite level (reviewed in [13]). …”