title: Heterogeneous attractor cell assemblies for motor planning in premotor cortex.
abstract: Cognitive functions like motor planning rely on the concerted activity of multiple neuronal assemblies underlying still elusive computational strategies. During reaching tasks, we observed stereotyped sudden transitions (STs) between low and high multiunit activity of monkey dorsal premotor cortex (PMd) predicting forthcoming actions on a single-trial basis. Occurrence of STs was observed even when movement was delayed or successfully canceled after a stop signal, excluding a mere substrate of the motor execution. An attractor model accounts for upward STs and high-frequency modulations of field potentials, indicative of local synaptic reverberation. We found in vivo compelling evidence that motor plans in PMd emerge from the coactivation of such attractor modules, heterogeneous in the strength of local synaptic self-excitation. Modules with strong coupling early reacted with variable times to weak inputs, priming a chain reaction of both upward and downward STs in other modules. Such web of "flip-flops" rapidly converged to a stereotyped distributed representation of the motor program, as prescribed by the long-standing theory of associative networks.
authors.affiliation: Department of Technologies and Health, Istituto Superiore di Sanità, 00161 Rome, Italy. maurizio.mattia@iss.it
authors.forename: Maurizio
authors.initials: M
authors.lastname: Mattia
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Pani
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mirabella
authors.forename: Stefania
authors.initials: S
authors.lastname: Costa
authors.forename: Paolo
authors.initials: P
authors.lastname: Del Giudice
authors.forename: Stefano
authors.initials: S
authors.lastname: Ferraina
mesh_terms: D000818:Animals; D033182:Intention; D008253:Macaca mulatta; D008297:Male; D009044:Motor Cortex / Q000166:cytology* / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology*; D011897:Random Allocation