1. Genetic enhancement of learning and memory in mice. Tang YP et al.

2. NMDA receptors present in synapse of neurons involved in learning Consist of subunit 1 (NR1) and one of various NR2 subunits. Hypothesis: Increased expression of the NR2B subunit in mice will increase synaptic plasticity and improve memory

3. Methods Created several strains of transgenic mice that overexpressed NR2B subunit in the forebrain. The transgenic mice have normal growth, body weight, mating behavior, and no obvious neurologic deficits. Assays showed about twice as much NR2B protein in the cortex and hippocampus as in the wild type mice, and elevated levels in the amygdala.

4. Performed several tests of learning relevant to the cortex and hippocampus. Researchers were blind to the genotype of each mouse. Report results for two strains

5. Novel object recognition task Training: Animal is put in cage with two objects, allowed to examine them for 5 minutes. Retention test 1: One hour later, the animal is put in the same cage with one previously-seen object and one novel object Retention test 2: 1 or 3 days later, the animal is put in the same cage with one previously-seen object and one novel object. Measure time spent examining the previously- seen object versus the novel object.

6. During training, no significant difference in the amount of time wild type and NR2B mice spent examining the objects. Indicates that both types of mice have the same level of curiosity and motivation to explore objects. During the retention test at 1 hour, both types of mice explored the same amount. During the retention test at 1 or 3 days, the NR2B mice showed much stronger preference for the novel object than did the wild-type mice. Indicates that the NR2B mice have better long-term memory.

7. Did same experiment with transgenic mice from two different genetic strains. Got same results for each strain. Did similar experiments using contextual and cued conditioning (Pavlovian conditioning). NR2B animals had significantly better memory at 1 hour, 1 day, and 10 days.

8. Tested NR2B animals vs. wild type in water maze NR2B mice learned significantly faster than wild-type.