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Hinojosa, A. J.

Publications and source records attributed to Hinojosa, A. J..

3 recordsLinked to original sources

Distinct Disinhibitory Circuits Link Short-Term Adaptation to Familiarity and Reward Learning in Visual Cortex

Sensory cortices filter repeated inputs through rapid adaptation over seconds and experience-driven learning over days. Although these forms of plasticity occur simultaneously, it is not known how they interact within cortical circuits. We combined two-photon calcium imaging, data-driven circuit modelling and optogenetics to investigate how short-term adaptation in layer 2/3 of mouse V1 is shaped by stimulus familiarity and reward association. Habituation reduced the fraction of pyramidal cells responsive to a visual stimulus, whereas reward association maintained overall responsivity. In contrast, both forms of learning shifted pyramidal cell adaptation from depression toward sensitization, but through distinct circuit mechanisms. Habituation reduced disinhibition through the VIP[->]SST[->]PC pathway by weakening feedback activation of VIPs and VIP[->]SST connections. Reward association counteracted this effect by increasing disinhibition through the SST[->]PV[->]PC pathway, strengthening SST[->]PV connections while reducing SST[->]PC inputs. Despite engaging distinct disinhibitory circuits and producing divergent effects on pyramidal cell responsivity, both forms of learning converged on a reduced PV:SST input ratio to pyramidal cells, thereby biasing V1 toward sensitizing adaptation. These results identify changes in cortical circuits that link the plasticity of fast adaptation to simple forms of learning.

neuroscience↗

Opposing forms of adaptation in mouse visual cortex are controlled by distinct inhibitory microcircuits and gated by locomotion

Cortical processing of sensory signals adjusts to changes in both the external world and the internal state of the animal. We investigated the neural circuitry by which these processes interact in the primary visual cortex of mice. An increase in contrast caused as many pyramidal cells (PCs) to sensitize as depress, reflecting the dynamics of adaptation in different types of interneuron (PV, SST and VIP). Optogenetic manipulations demonstrate that the net effect within PCs reflects the balance of PV inputs, driving depression, and a subset of SST interneurons, driving sensitization. Locomotor behaviour increased the gain of PC responses by disinhibition through both the VIP->SST and SST->PV pathways, thereby maintaining the balance between opposing forms of plasticity. These experiments reveal how inhibitory microcircuits interact to purpose different subsets of PCs for the signalling of increases or decreases in contrast while also allowing for behavioural control of gain across the population.

neuroscience↗

Correction of z-motion artefacts to allow population imaging of synaptic activity in awake behaving mice

Functional imaging of head-fixed, awake, behaving mice using two-photon imaging of fluorescent activity reporters has become a powerful tool in the studying the function of the brain. Motion artefacts are an inevitable problem during such experiments and are routinely corrected for in x and y dimensions. However, axial (z) shifts of several microns can also occur, leading to intensity fluctuations in structures such as synapses that are small compared to the axial point-spread function of the microscope. Here we present a simple strategy to correct z-motion artefacts arising over the course of a time-series experiment in a single optical plane. Displacement in z was calculated using dye-filled blood vessels as an anatomical marker, providing high contrast images and accuracy to within [~]0.1 {micro}m. The axial profiles of ROIs corresponding to synapses were described using a Moffat function and this \"ROI-spread function\" used to correct activity traces on an ROI-by-ROI basis. We demonstrate the accuracy and utility of the procedures in simulation experiments using fluorescent beads and then apply them to correcting measurements of synaptic activity in populations of vasoactive-intestinal peptide (VIP) interneurons expressing the synaptic reporter SyGCaMP6f. Correction of z-motion artefacts had a substantial impact on the apparent correlation between synaptic activity and running speed, demonstrating the importance of correcting for these artefacts for the interpretation of in vivo imaging experiments in awake mice.\n\nSummary of Key PointsO_LIMotion artefacts associated with motor behaviour are an inevitable problem of multiphoton imaging in awake behaving animals, particularly imaging synapses.\nC_LIO_LICorrection of axial motion usually requires volumetric imaging resulting in slower rates of acquisition.\nC_LIO_LIWe describe a method that is easy to implement to correct z-motion artefacts that allows population imaging of synaptic activity while scanning a single plane in a standard multiphoton microscope.\nC_LIO_LIThe method uses a reference volume acquired in two colour channels - an activity reporter and an anatomical marker of blood vessels. The procedure estimates the z-displacement in every frame and applies an intensity correction in which the z point-spread function for each synapse is modelled as a Moffat function.\nC_LIO_LIWe demonstrate that the method allows synaptic calcium activity signals to be collected from populations of synaptic boutons in mouse primary visual cortex during locomotion.\nC_LI

neuroscience↗