BRAIN-WIDE DENDRITIC SIGNALLING ACROSS BEHAVIOURAL MODULATIONS

Dendrites are fundamental to neuronal architecture and their backpropagating from soma, are crucial for synaptic integration and plasticity, their engagement during behaviour across diverse neuronal populations throughout the brain has not been thoroughly studied. Consequently, their contribution to computations at the whole brain is still largely unresolved.
We examine bAP's role in a whole-brain single cell resolution recording during a prior-dependent visual decision-making task and detected clear bAP signatures in neurons from 72 distinct brain regions, including frontal, visual, motor, and somatosensory cortices, as well as subcortical structures such as the medulla, striatum, midbrain, and thalamus. Our single-spike analyses revealed that the amplitude of dendritic bAPs is modulated in a region-specific manner by both sensory inputs and internal states, independent of changes in firing rate.
bAPs also encode task-relevant variables, including stimulus contrast and feedback, with accuracy comparable to that of spikes, but with distinct temporal profiles, suggesting that bAPs and spikes may provide complementary streams of information. The encoding of these variables by bAPs also varied within neocortical and hippocampal hierarchies. Moreover, the influence of state variables—including movement, arousal, engagement, and uncertainty—on bAPs differed across regions: movement generally enhanced bAPs, while cortical areas were more sensitive to higher-order states than subcortical regions. Altogether, our findings establish bAPs as widespread, flexible markers of dendritic excitability, dynamically engaged by both sensory and behavioural factors, and underscore the importance of dendritic computation as a pervasive and underappreciated aspect of neural processing.