Neuronal activity in the cortex is often synchronized or oscillatory, with frequencies and temporal dynamics linked to behavioral states. Recent studies suggest that correlated fluctuations may be crucial for processes like attention that control information flow in the brain. Traditional neuroscience has focused on how neurons represent the world and their response properties, but less is known about how neurons communicate. Timing is crucial for information transmission, as shown by studies indicating that microstimulation effects depend on the timing relative to stimulus onset. Cortical networks show complex temporal dynamics, with oscillations in different frequency bands associated with various states. Synchrony, another form of temporal relationship, is important for information processing. Correlated activity can be influenced by factors like expectation, attention, and response latency, and may regulate information flow rather than its meaning. Correlations can be controlled independently of firing rates, affecting information transmission. Studies show that correlations can change rapidly with internal states and may regulate neural information flow. Attention can enhance synchrony in motor and somatosensory cortices, and in visual areas, attention affects both firing rates and synchrony. Gamma oscillations correlate with changes in neuronal latencies, and interocular rivalry can induce changes in synchrony in V1. These findings suggest that temporal correlations may play a key role in controlling signal strength and downstream processing, rather than the nature of the information conveyed. The study highlights the importance of understanding how correlations modulate neural activity and influence information processing in the brain.Neuronal activity in the cortex is often synchronized or oscillatory, with frequencies and temporal dynamics linked to behavioral states. Recent studies suggest that correlated fluctuations may be crucial for processes like attention that control information flow in the brain. Traditional neuroscience has focused on how neurons represent the world and their response properties, but less is known about how neurons communicate. Timing is crucial for information transmission, as shown by studies indicating that microstimulation effects depend on the timing relative to stimulus onset. Cortical networks show complex temporal dynamics, with oscillations in different frequency bands associated with various states. Synchrony, another form of temporal relationship, is important for information processing. Correlated activity can be influenced by factors like expectation, attention, and response latency, and may regulate information flow rather than its meaning. Correlations can be controlled independently of firing rates, affecting information transmission. Studies show that correlations can change rapidly with internal states and may regulate neural information flow. Attention can enhance synchrony in motor and somatosensory cortices, and in visual areas, attention affects both firing rates and synchrony. Gamma oscillations correlate with changes in neuronal latencies, and interocular rivalry can induce changes in synchrony in V1. These findings suggest that temporal correlations may play a key role in controlling signal strength and downstream processing, rather than the nature of the information conveyed. The study highlights the importance of understanding how correlations modulate neural activity and influence information processing in the brain.