title: Cell Assembly Signatures Defined by Short-Term Synaptic Plasticity in Cortical Networks.
abstract: The cell assembly (CA) hypothesis has been used as a conceptual framework to explain how groups of neurons form memories. CAs are defined as neuronal pools with synchronous, recurrent and sequential activity patterns. However, neuronal interactions and synaptic properties that define CAs signatures have been difficult to examine because identities and locations of assembly members are usually unknown. In order to study synaptic properties that define CAs, we used optical and electrophysiological approaches to record activity of identified neurons in mouse cortical cultures. Population analysis and graph theory techniques allowed us to find sequential patterns that represent repetitive transitions between network states. Whole cell pair recordings of neurons participating in repeated sequences demonstrated that synchrony is exhibited by groups of neurons with strong synaptic connectivity (concomitant firing) showing short-term synaptic depression (STD), whereas alternation (sequential firing) is seen in groups of neurons with weaker synaptic connections showing short-term synaptic facilitation (STF). Decreasing synaptic weights of a network promoted the generation of sequential activity patterns, whereas increasing synaptic weights restricted state transitions. Thus in simple cortical networks of real neurons, basic signatures of CAs, the properties that underlie perception and memory in Hebb's original description, are already present.
authors.affiliation: Columbia University, Department of Biological Sciences, New York, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Carrillo-Reid
authors.affiliation: Brain Mechanisms for Behavior Unit, Okinawa Institute of Science and Technology Graduate University, 904-0495 Okinawa, Japan.
authors.forename: Violeta G
authors.initials: VG
authors.lastname: Lopez-Huerta
authors.affiliation: Brain Mechanisms for Behavior Unit, Okinawa Institute of Science and Technology Graduate University, 904-0495 Okinawa, Japan.
authors.forename: Marianela
authors.initials: M
authors.lastname: Garcia-Munoz
authors.affiliation: Heinrich Heine University, Dusseldorf, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Theiss
authors.affiliation: Brain Mechanisms for Behavior Unit, Okinawa Institute of Science and Technology Graduate University, 904-0495 Okinawa, Japan.
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Arbuthnott
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001921:Brain / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D051379:Mice; D008959:Models, Neurological; D009434:Neural Pathways / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D061848:Optical Imaging; D018408:Patch-Clamp Techniques; D012815:Signal Processing, Computer-Assisted
chemical_list: D002118:Calcium
keywords: Cell assemblies; calcium imaging; microelectrode arrays; short-term synaptic plasticity; whole cell recordings