Kainic acid increases activity only of some cortical neurons in the rat

The influence of a subconvulsant dose of kainic acid (KA) on the activity of neurons was studied in the sensorimotor cortical area of urethane-anesthetized rats. A total of 41 neurons was recorded, 38 of these in layer V (probably pyramidal cells). The activity of 18 neurons was recorded before as well as more than 30 min after KA administration (6 mg/kg i.p.). Nine out of these 18 neurons increased their firing rate significantly even 20 min after KA injection, whereas the remaining neurons did not change their activity. Altogether, the increase in the firing rate was significant. KA was found to enhance markedly the firing rate of a part of cortical neurons at very early stages of its action.