Ketamine-Midazolam Anesthesia Induces Total Inhibition of Cortical Activity in the Brain of Newborn Rats.

The effects of general anesthetics ketamine and midazolam, the drugs that cause neuroapoptosis at the early stages of CNS development, on electrical activity of the somatosensory cortex in newborn rats were studied using extracellular recording of local field potentials and action potentials of cortical neurons. Combined administration of ketamine (40 mg/kg) and midazolam (9 mg/kg) induced surgical coma and almost completely suppressed early oscillatory patterns and neuronal firing. These effects persisted over 3 h after injection of the anesthetics. We concluded that general anesthesia induced by combined administration of ketamine and midazolam profoundly suppressed cortical activity in newborn rats, which can trigger neuroapoptosis in the developing brain.

Gamma oscillations in the somatosensory cortex of newborn rats.

Here we addressed a question of whether gamma oscillations previously described in the whisker-related barrel cortex are a universal pattern of activity in the somatosensory cortex of newborn rats. Intracortical recording of local field potentials and action potentials in neurons using multisite silicon electrodes in 2-7-day-old rats showed that mechanical stimulation of single fingers or specific areas on the plantar or back side of the foot evoked early gamma oscillations followed by spindle-burst oscillations in the corresponding regions of the somatosensory cortex. Early gamma oscillations had maximum amplitude in layer IV of the somatosensory cortex and effectively synchronized action potentials in layer IV neurons. It was concluded that early gamma oscillations evoked by activation of the topographic sensory input are a universal activity pattern of the entire somatosensory cortex of newborn rats.