title: Top-down laminar organization of the excitatory network in motor cortex.
abstract: Cortical layering is a hallmark of the mammalian neocortex and a major determinant of local synaptic circuit organization in sensory systems. In motor cortex, the laminar organization of cortical circuits has not been resolved, although their input-output operations are crucial for motor control. Here, we developed a general approach for estimating layer-specific connectivity in cortical circuits and applied it to mouse motor cortex. From these data we computed a laminar presynaptic --> postsynaptic connectivity matrix, W(post,pre), revealing a complement of stereotypic pathways dominated by layer 2 outflow to deeper layers. Network modeling predicted, and experiments with disinhibited slices confirmed, that stimuli targeting upper, but not lower, cortical layers effectively evoked network-wide events. Thus, in motor cortex, descending excitation from a preamplifier-like network of upper-layer neurons drives output neurons in lower layers. Our analysis provides a quantitative wiring-diagram framework for further investigation of the excitatory networks mediating cortical mechanisms of motor control.
authors.affiliation: Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Weiler
authors.forename: Lydia
authors.initials: L
authors.lastname: Wood
authors.forename: Jianing
authors.initials: J
authors.lastname: Yu
authors.forename: Sara A
authors.initials: SA
authors.lastname: Solla
authors.forename: Gordon M G
authors.initials: GM
authors.lastname: Shepherd
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001931:Brain Mapping; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D009044:Motor Cortex / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D009415:Nerve Net / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D016571:Neural Networks, Computer; D009434:Neural Pathways / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009924:Organ Culture Techniques; D010775:Photic Stimulation; D010777:Photochemistry; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*
chemical_list: D018698:Glutamic Acid