Abstract: The retentions of memory were tested in 4 groups of Albino Rats. REMdeprivation was carried out on small platform surrounded by water for 24hrs after discrimination learning in Group 1. The free sleep was returned for24 hrs after REM deprivation in Group 2. The interval between REMdeprivation and learning was 24 hrs free sleep in Group. 3. The free sleep was allowed for 24 hrs after learning in Group 4 which was the control one.Then the retentions of memory were tested in all animals. The experiment demonstrated that REM deprivation had produced aconsiderable impairment to the consolidation of memory in Group 1. Theconsolidation of memory in Group 2 was little better than Group 1. However,the retentions of memory were better in Groups 3 and 4 in both of whichanimals were allowed to sleep freely immediately after learning or imposedto deprive REM sleep afterwards. The results indicated that it is very important for the consolidation ofmemory to sleep freely after learning, but REM deprivation is harmful.

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