Biology subjects

Kandler, S.

Publications and source records attributed to Kandler, S..

4 recordsLinked to original sources

bioRxiv2024

NMDA receptor activation drives early synapse formation in vivo

The rules governing neural circuit formation in mammalian central nervous systems are poorly understood. NMDA receptors are involved in synaptic plasticity mechanisms in mature neurons, but their contribution to circuit formation and dendritic maturation remains controversial. Using pharmacological and genetic interventions to disrupt NMDA receptor signaling in hippocampal CA1 pyramidal neurons in vitro and in vivo, we identify an early critical window for a synapse-specific function in wiring Schaffer collateral connections and dendritic arborization. Through in vivo imaging, we show that NMDA receptors are frequently activated during early development and elicit minute-long calcium transients, which immediately precede the emergence of filopodia. These results demonstrate that NMDA receptors drive synapto- and dendritogenesis during development, challenging the view that these processes are primarily mediated by molecular cues.

neuroscience↗

bioRxiv2023

Divergent Recruitment of Developmentally-Defined Neuronal Ensembles Supports Memory Dynamics

Memories are dynamic constructs whose properties change with time and experience. The biological mechanisms underpinning these dynamics remain elusive, particularly concerning how shifts in the composition of memory-encoding neuronal ensembles influence a memory properties evolution over time. By leveraging a developmental approach to target distinct subpopulations of principal neurons, we show that memory encoding results in the concurrent establishment of multiple memory traces in the mouse hippocampus. Two of these traces are instantiated in subpopulations of early- and late-born neurons and follow distinct reactivation trajectories post-encoding. Notably, the divergent recruitment of these subpopulations underpins memory ensembles gradual reorganization, and modulates memory persistence and plasticity across multiple learning episodes. Thus, our findings reveal profound and intricate relationships between ensemble dynamics and memories progression over time.

neuroscience↗

bioRxiv2018

Astrocytes integrate local sensory and brain-wide neuromodulatory signals.

Astrocytes play multiple functions in the central nervous system, from control of blood flow through to modulation of synaptic activity. Transient increases in intracellular Ca2+ are thought to control these activities. The prevailing concept is that these Ca2+ transients are triggered by distinct pathways, with little mechanistic and functional overlap. Here we demonstrate that astrocytes in visual cortex of mice encode local visual signals in conjunction with arousal state, functioning as multi-modal integrators. Such activity adds an additional layer of complexity to astrocyte function and may enable astrocytes to specifically and subtly regulate local network activity and plasticity.

neuroscience↗

bioRxiv2017

Encoding of Tactile Context in the Mouse Visual Cortex

Multisensory integration is key for perception and animal survival yet how information from separate senses is integrated has been debated for decades. In the cortex, information from each sense is first processed in primary sensory areas and then combined in association areas. An alternative hypothesis to this hierarchical model is that primary sensory cortices partake in multisensory encoding. We probed tactile and visual responses in primary somatosensory and visual cortices in awake behaving animals using two-photon calcium imaging from layer 2/3 excitatory neurons. In support of an hierarchical model we found segregation of visual and tactile responses. Tactile stimuli evoked responses in S1 neurons. In striking contrast, V1 neurons failed to respond to tactile stimuli. This was true for passive whisker stimulation and for stimulation during active whisking. Furthermore, responses of V1 neurons to congruent visuo-tactile cues during active exploration, a condition where vision precedes touch, were completely abolished in darkness. The rostro-lateral area of the visual cortex responded to both visual and tactile aspects of the stimuli and may form a substrate for encoding multisensory signals during active exploration. Our results indicate that primary sensory areas mainly encode their primary sense and that the impact of other modalities may be restricted to modulatory effects.

neuroscience↗