Bast Arco, Guest Jason M, Fruengel Rieke, Narayanan Rajeevan T, de Kock Christiaan P J, Oberlaender Marcel
In Silico Brain Sciences Group, Max Planck Institute for Neurobiology of Behavior - caesar; Ludwig-Erhard-Allee 2, Bonn, Germany.
International Max Planck Research School for Brain and Behavior; Ludwig-Erhard-Allee 2, Bonn, Germany.
Nat Commun. 2025 Sep 19;16(1):8327. doi: 10.1038/s41467-025-64152-0.
Dendritic calcium action potentials (APs) enable the main output neurons of the cerebral cortex - pyramidal tract neurons (PTs) - to associate inputs that arrive at different cortical layers. How synaptic inputs evoke calcium APs during in vivo conditions is yet unclear. We combine in vivo recordings in male rats with synaptic input reconstructions, multi-scale modelling and optogenetic manipulations. We find that thalamocortical (TC) synapses, which provide sensory input to cortex, target specifically and most densely the dendritic domain that initiates calcium APs in PTs. Sensory input from thalamus is hence a reliable, but weak source for activating the dendritic calcium domain. Because it is fast and local, this activation enables active dendritic coupling of sensory input with multiple sensory-evoked and ongoing input streams that arrive during and surprisingly before the stimulus. This 'TC coupling' mechanism accounts for the modulation of the first sensory responses that leave the cortex with bursts of APs.
树突状钙动作电位（APs）使大脑皮层的主要输出神经元——锥体束神经元（PTs）——能够关联到达不同皮层层的输入。在体内条件下，突触输入如何引发钙APs尚不清楚。我们将雄性大鼠的体内记录与突触输入重建、多尺度建模和光遗传学操作相结合。我们发现，向皮层提供感觉输入的丘脑皮质（TC）突触专门且最密集地靶向在PTs中启动钙APs的树突域。因此，来自丘脑的感觉输入是激活树突状钙域的可靠但微弱的来源。由于这种激活快速且局部，它能使感觉输入与在刺激期间以及令人惊讶的是在刺激之前到达的多个感觉诱发和持续的输入流进行活跃的树突耦合。这种“TC耦合”机制解释了以APs爆发形式离开皮层的首次感觉反应的调制。
