Biology subjects

Petreanu, L.

Publications and source records attributed to Petreanu, L..

3 recordsLinked to original sources

bioRxiv2023

Auditory cortex conveys non-topographic sound localization signals to visual cortex.

Perception requires binding spatiotemporally congruent multimodal sensory stimuli. The auditory cortex (AC) sends projections to the primary visual cortex (V1), which could provide signals for binding spatially corresponding audio-visual stimuli. However, it is unknown whether AC inputs in V1 encode sound location. We used dual-color two-photon axonal calcium imaging and an array of speakers to measure the auditory spatial information that AC transmits to V1. We found that AC relays information about the location of ipsilateral and contralateral sound sources to V1. Sound location could be accurately decoded by sampling AC axons in V1, providing a substrate for making location-specific audiovisual associations. However, AC inputs were not retinotopically arranged in V1, and audio-visual modulations of V1 neurons did not depend on the spatial congruency of the sound and light stimuli. The distributed, non-topographic sound localization signals provided by AC might allow the association of specific audiovisual spatial patterns in V1 neurons.

neuroscience↗

bioRxiv2022

Visual experience instructs the organization of cortical feedback inputs to primary visual cortex.

Cortical feedback (FB) projections are thought to modulate lower-order activity depending on learned expectations. However, whether FB inputs become bound to specific lower-order neurons depending on experience is unknown. We measured the effects of dark rearing and manipulations of experienced visual statistics on the retinotopic specificity of projections from the lateromedial (LM) visual area to layer 1 of the mouse primary visual cortex (V1). LM inputs were, on average, retinotopically matched with V1 neurons irrespective of visual experience. While the orientation tuning of LM axons determined the retinotopic position of the V1 neurons they innervated, this organization was absent in dark-reared mice. Restricting visual experience to a narrow range of orientations revealed that visual experience exerts an instructive role in the retinotopic organization of LM inputs in V1. Our observations support theories of hierarchical computation proposing that inputs from higher-order neurons to lower-order ones reflect learned hierarchical associations.

neuroscience↗

bioRxiv2019

Laminar-specific cortico-cortical loops in mouse visual cortex

Many theories propose recurrent interactions across the cortical hierarchy, but it is unclear if cortical circuits are selectively wired to implement looped computations. Using subcellular channelrhodopsin-2-assisted circuit mapping in mouse visual cortex, we compared feedforward (FF) or feedback (FB) cortico-cortical input to cells projecting back to the input source (looped neurons) with cells projecting to a different cortical or subcortical area (non-looped neurons). Despite having different laminar innervation patterns, FF and FB afferents showed similar cell-type selectivity, making stronger connections with looped neurons versus non-looped neurons in layer (L) 5 and L6, but not in L2/3. FB inputs preferentially innervated the apical tufts of looped L5 neurons, but not their perisomatic dendrites. Our results reveal that interareal cortical connections are selectively wired into monosynaptic excitatory loops involving L6 and the apical dendrites of L5 neurons, supporting a role of these circuit elements in hierarchical recurrent computations.

neuroscience↗