The MWM result was unexpected as other models, such as Ts65Dn and Tc1 mice are defective in learning in this test (13, 20, 26, 42, 43, 45– 50); a defect similar to the hippocampal deficit observed in DS patients (38, 40, 51).
Consistent with a neural role, PTPN4-deficient mice were shown to have impaired cerebellar function, including defective motor learning [33].
Both Ts65Dn and Ts1Cje mice display craniofacial dysmorphology that directly parallels human DS and defective spatial learning and memory [32], [33], [34], [35], [36], [37], [38], [39], [40].
Forebrain-specific ablation causes defective spatial learning and memory.
Prior to seizure onset, heterozygous mutants are not defective in motor learning or fear conditioning, but do exhibit mild impairment of motor coordination and social discrimination.
Various incarnations of the classic mutagenesis approach envisaged in the early days have provided around one hundred learning defective mutant fly strains.
(3) Although mutant dunce1 flies were defective in visual associative learning, they showed essentially normal motor learning performance in terms of yaw torque distribution in conditioning.
Alternatively, players could be progressively switching from an initial conditional cooperative strategy to a more defective strategy through some learning process (see, e.g., [12] for a review of the different learning processes that could be at work).
