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. 1998 Jun 15;18(12):4425–4438. doi: 10.1523/JNEUROSCI.18-12-04425.1998

Fig. 11.

Fig. 11.

Cs+-induced epileptiform activity originates in the CA3 region. Pairing extracellular Cs+ with SC stimulation induces spontaneous activity. The left panel shows the configuration of the recording and stimulating electrodes. Field electrodes were placed in strata pyramidale CA1 and CA3. The stimulating electrode was initially placed in stratum radiatum of CA2. SC stimulation for 15 min at 1 Hz and subsequent stimulation at 0.1 Hz revealed the appearance of spontaneous discharge that was first detected in CA3. A, Panels show the field recordings at 2, 5, and 7 min after 1 Hz stimulation in Cs+; records were taken in the absence of orthodromic stimulation. B, After an increase in spontaneous activity in CA3, synchronized discharges appeared in CA1 radiatum. Asterisks mark stimulus-induced activation. Unstimulated (spontaneous) synchronous activity increased in frequency and appeared simultaneously in both regions (right).C, After SC resection, CA3 retained spontaneous activity (in the absence of stimulation), whereas CA1 become silent (middle, right panels).