Coactivity

Coactivity refers to simultaneous activation of two or more elements within a system, occurring in response to stimuli, tasks, or social interaction. In neuroscience, coactivity is used to describe the coordinated firing or activity of neurons or brain regions within a population. Rather than focusing on single-cell responses, coactivity emphasizes ensembles, where groups of neurons participate together to encode information or drive behavior. Coactive patterns can be identified during specific tasks or spontaneous activity, and are often used to infer functional networks.

Measurement typically involves electrophysiological recordings or calcium imaging to obtain time series of activity. Analysts compute pairwise or multivariate measures such as cross-correlation, joint firing probability, or population vectors to construct coactivity matrices or graphs. Clustering, dimensionality reduction, or network analysis can reveal recurring coactive ensembles. Significance is commonly assessed with trial-shuffle controls, bootstrapping, or permutation tests.

Coactivity provides insight into how information is distributed across neural populations and how ensembles reconfigure with learning or task demands. It is related to concepts of synchronization, functional connectivity, and neural assemblies. However, coactivity is observational and can be influenced by common inputs or recording constraints, so causal inferences require complementary methods.

Outside neuroscience, coactivity can refer to the simultaneous engagement of individuals or devices in a coordinated action, such as joint performances or synchronized sensorimotor tasks. The term is sometimes used interchangeably with co-activation or synchrony.