Kinetics of memory consolidation: role of amnesic treatment parameters.

The consolidation theory states that with the passage of time the engram of a recent learning experience grows increasingly resistant to disruption by amnesic treatment. The time required to reach complete resistance ("consolidation time") is a controversial issue; current estimates range from 10(1) to 10(5) seconds. The present study suggests a parsimonious interpretation of the divergence, namely, that weak amnesic treatments fail to block memory consolidation but do slow its rate, so that post-treatment consolidation inflates the retention scores measured 24 hours later and leads to variably shortened "consolidation times."This study utilized 2880 neonate chicks trained in a one-trial avoidance paradigm. Retrograde amnesia was induced by treatment with flurothyl (CF(3)CH(2)-OCH(2)CF(3)) vapor. Apparent "consolidation times" determined by conventional data analysis varied widely as a function of flurothyl concentration and exposure time, ranging from 4 minutes under weak amnesic conditions (0.85% flurothyl; 1-min exposure) to 24 hours under strong conditions (1.7% flurothyl; 8-min exposure). With 1.7% flurothyl, the consolidation half-time was found to be 9.8 hours.