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Action Potentials/*physiology
Animals
Cerebral Cortex/physiology
Electric Stimulation
Interneurons/*physiology
Microelectrodes
Neurons/physiology
Optogenetics
Patch-Clamp Techniques
Pyramidal Cells/*physiology
Turtles
Visual Cortex/*physiology
*birdsong
*cortex
*dynamics
*replay
*sequences
*synfire
*turtle
Abstract:
Recent studies reveal the occasional impact of single neurons on surround firing statistics and even simple behaviors. Exploiting the advantages of a simple cortex, we examined the influence of single pyramidal neurons on surrounding cortical circuits. Brief activation of single neurons triggered reliable sequences of firing in tens of other excitatory and inhibitory cortical neurons, reflecting cascading activity through local networks, as indicated by delayed yet precisely timed polysynaptic subthreshold potentials. The evoked patterns were specific to the pyramidal cell of origin, extended over hundreds of micrometers from their source, and unfolded over up to 200 ms. Simultaneous activation of pyramidal cell pairs indicated balanced control of population activity, preventing paroxysmal amplification. Single cortical pyramidal neurons can thus trigger reliable postsynaptic activity that can propagate in a reliable fashion through cortex, generating rapidly evolving and non-random firing sequences reminiscent of those observed in mammalian hippocampus during "replay" and in avian song circuits.
