electrophysiological brain activity

Electrophysiological brain activity refers to the electrical signals in the brain generated by neurons. We differentiate between:

1. Primary currents (direct result of neural activity)

   • Action potential currents

     • ~1-2 ms duration

     • propagate along the axon of the neuron

     • caused by sodium and potassium ion flow across axonal membrane

       

   • Post-synaptic currents

     • 10-100ms duration

     • occur at dendrites and soma when neurons receive synaptic input

     • caused by binding of neurotransmitters to receptors which creates ion flow

     • summation in space and time

       

2. Secondary currents (induced by primary currents):

   • Volume conduction currents

     • Brain is a conductive medium so electric potentials spread through tissues to surrounding neural structures (gray matter, white matter, CSF, skull, scalp)