PT  - JOURNAL ARTICLE
AU  - Cho, YH
AU  - Beracochea, D
AU  - Jaffard, R
TI  - Extended temporal gradient for the retrograde and anterograde amnesia produced by ibotenate entorhinal cortex lesions in mice
AID  - 10.1523/JNEUROSCI.13-04-01759.1993
DP  - 1993 Apr 01
TA  - The Journal of Neuroscience
PG  - 1759--1766
VI  - 13
IP  - 4
4099  - http://www.jneurosci.org/content/13/4/1759.short
4100  - http://www.jneurosci.org/content/13/4/1759.full
SO  - J. Neurosci.1993 Apr 01; 13
AB  - Effects of ibotenic entorhinal cortex (EC) lesions on both retrograde and anterograde amnesia in mice were assessed using two-choice discrimination tasks learned at different intervals before surgery in two eight-arm radial mazes. The results indicated that EC-lesioned mice were severely impaired in postoperative retention of discrimination problems learned 3 d or 2 weeks prior to surgery, but showed no deficit on problems learned between 4, and up to 6 weeks before surgery, as compared to sham-operated controls. When trained on a novel two-choice discrimination problem (not acquired preoperatively), experimental subjects demonstrated quite normal rates of acquisition, but were impaired in learning its reversal. Furthermore, they exhibited a faster rate of forgetting (anterograde amnesia) relative to controls over a 2- week retention interval. These results indicate that approximately 4 weeks is required before memory for a two-choice spatial discrimination problem no longer depends on the integrity of the entorhinal cortex, and suggests that, beyond this time, an EC-independent memory storage system is capable of supporting the retrieval of information. The data, together with complementary behavioral results, are discussed in the context of current theories of memory storage.