The article by Salinas and Sejnowski explores the role of correlated neuronal activity in the flow of neural information. It highlights that while traditional research in systems neuroscience focuses on how neurons represent the world, the communication between neurons is equally important. The authors discuss the concept of temporally correlated activity, which refers to the non-independent firing patterns of neurons, and how this can modulate postsynaptic activity. They review recent findings that suggest correlations can be controlled independently of firing rates, potentially serving to regulate the flow of information rather than its meaning. The article also examines how changes in correlations are linked to processes such as expectation, attention, response latency, and rivalry, which affect the strength of neural signals but not their content. Experimental studies in various brain regions, including the motor cortex, somatosensory cortex, and visual cortex, support the idea that correlations can dynamically change in response to internal states and modulate downstream neural activity. The authors conclude that correlations might play a crucial role in controlling the strength of neural signals, influencing the circuits that receive these signals, and potentially regulating synaptic plasticity.The article by Salinas and Sejnowski explores the role of correlated neuronal activity in the flow of neural information. It highlights that while traditional research in systems neuroscience focuses on how neurons represent the world, the communication between neurons is equally important. The authors discuss the concept of temporally correlated activity, which refers to the non-independent firing patterns of neurons, and how this can modulate postsynaptic activity. They review recent findings that suggest correlations can be controlled independently of firing rates, potentially serving to regulate the flow of information rather than its meaning. The article also examines how changes in correlations are linked to processes such as expectation, attention, response latency, and rivalry, which affect the strength of neural signals but not their content. Experimental studies in various brain regions, including the motor cortex, somatosensory cortex, and visual cortex, support the idea that correlations can dynamically change in response to internal states and modulate downstream neural activity. The authors conclude that correlations might play a crucial role in controlling the strength of neural signals, influencing the circuits that receive these signals, and potentially regulating synaptic plasticity.