Optogenetic inhibition of CA1 neuronal activity prevented recall of contextual fear memory in tTA-CaMKIIα × TetO-ArchT mice.

<p><b>(A)</b> Experimental timeline. Following contextual fear conditioning (i.e., training), light was delivered to the CA1 during test 1 but not during test 2. Experimental setting for <b>(B)</b> fear conditioning and <b>(C)</b> laser delivery. <b>(D)</b> tTA-CaMKIIα × TetO-ArchT mice showed more freezing during test 2 than during test 1, indicating that inhibition of CA1 neuronal activity transiently prevented the recall of a contextual fear memory. Co: cortex; Or: stratum oriens; Pyr: stratum pyramidale; Rad: stratum radiatum; Mol: molecular cell layer; Gr: granule cell layer