Which electrophysiological events are thought to generate an EEG signal?

The correct choice identifies that both excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) contribute to generating an EEG signal. EEG signals reflect the summed electrical activity of many neurons, particularly the activity of the postsynaptic potentials that occur in the cerebral cortex.

When excitatory neurotransmitters bind to receptors on the postsynaptic neuron, they lead to EPSPs, which make the neuron more likely to fire an action potential. Conversely, inhibitory neurotransmitters result in IPSPs, which decrease the likelihood of the postsynaptic neuron firing. The combined effects of these potential changes create a complex pattern of electrical activity.

EEG measures this electrical activity primarily through changes in the voltage differences produced by synchronized firing of large groups of neurons, especially those in the cortex. The contributions of both EPSPs and IPSPs are essential, as they essentially represent the net charge and electrical state of neuronal networks, making them integral to understanding brain function as captured by EEG.

By accounting for both types of synaptic activity, the EEG provides insights into the brain's overall electrical activity during different functional states, such as sleep, wakefulness, and patterns observed in various neurological conditions.