In association with the study of oxygen tensions (Project ZOlNS02741-02 LNNS), it was convenient and useful to insert a monopolar recording micro electrode into the parietal cortex near the p02 recording electrode. This arrangement provided a look at massed discharges in gerbils affected by single and multiple transient ischemias produced to study the changes in oxygen tension. Although oxygen tensions dropped within 2.5 seconds to zero, the electrical activity remained substantially unchanged until about 10 seconds when it abruptly terminated. Return of electrical activity was much prolonged requiring hours following 5 minutes of ischemia before returning to preischemic levels. The restoration was very gradual with bursting neural activity.
