| First Author | Zolnik TA | Year | 2024 |
| Journal | Neuron | Volume | 112 |
| Issue | 5 | Pages | 805-820.e4 |
| PubMed ID | 38101395 | Mgi Jnum | J:348667 |
| Mgi Id | MGI:7578722 | Doi | 10.1016/j.neuron.2023.11.021 |
| Citation | Zolnik TA, et al. (2023) Layer 6b controls brain state via apical dendrites and the higher-order thalamocortical system. Neuron |
| abstractText | The deepest layer of the cortex (layer 6b [L6b]) contains relatively few neurons, but it is the only cortical layer responsive to the potent wake-promoting neuropeptide orexin/hypocretin. Can these few neurons significantly influence brain state? Here, we show that L6b-photoactivation causes a surprisingly robust enhancement of attention-associated high-gamma oscillations and population spiking while abolishing slow waves in sleep-deprived mice. To explain this powerful impact on brain state, we investigated L6b's synaptic output using optogenetics, electrophysiology, and monoCaTChR ex vivo. We found powerful output in the higher-order thalamus and apical dendrites of L5 pyramidal neurons, via L1a and L5a, as well as in superior colliculus and L6 interneurons. L6b subpopulations with distinct morphologies and short- and long-term plasticities project to these diverse targets. The L1a-targeting subpopulation triggered powerful NMDA-receptor-dependent spikes that elicited burst firing in L5. We conclude that orexin/hypocretin-activated cortical neurons form a multifaceted, fine-tuned circuit for the sustained control of the higher-order thalamocortical system. |
