Spatial learning in the genetically heterogeneous NIH-HS rat stock and RLA-I/RHA-I rats: revisiting the relationship with unconditioned and conditioned anxiety.
To characterize learning/memory profiles for the first time in the genetically heterogeneous NIH-HS rat stock, and to examine whether these are associated with anxiety, we evaluated NIH-HS rats for spatial learning/memory in the Morris water maze (MWM) and in the following anxiety/fear tests: the elevated zero-maze (ZM; unconditioned anxiety), a context-conditioned fear test and the acquisition of two-way active avoidance (conditioned anxiety). NIH-HS rats were compared with the Roman High- (RHA-I) and Low-Avoidance (RLA-I) rat strains, given the well-known differences between the Roman strains/lines in anxiety-related behavior and in spatial learning/memory. The results show that: (i) As expected, RLA-I rats were more anxious in the ZM test, displayed more frequent context-conditioned freezing episodes and fewer avoidances than RHA-I rats. (ii) Scores of NIH-HS rats in these tests/tasks mostly fell in between those of the Roman rat strains, and were usually closer to the values of the RLA-I strain. (iii) Pigmented NIH-HS (only a small part of NIH-HS rats were albino) rats were the best spatial learners and displayed better spatial memory than the other three (RHA-I, RLA-I and NIH-HS albino) groups. (iv) Albino NIH-HS and RLA-I rats also showed better learning/memory than the RHA-I strain. (v) Within the NIH-HS stock, the most anxious rats in the ZM test presented the best learning and/or memory efficiency (regardless of pigmentation). In summary, NIH-HS rats display a high performance in spatial learning/memory tasks and a passive coping strategy when facing conditioned conflict situations. In addition, unconditioned anxiety in NIH-HS rats predicts better spatial learning/memory.
Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain. Electronic address: esther.martinez@uab.cat.
Esther
E
Martínez-Membrives
Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
Regina
R
López-Aumatell
Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
Gloria
G
Blázquez
Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
Toni
T
Cañete
Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
Adolf
A
Tobeña
Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, Institute of Neurosciences, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain. Electronic address: albert.fernandez.teruel@uab.es.
Alberto
A
Fernández-Teruel
D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000235:genetics*; D001362:Avoidance Learning / Q000502:physiology; D003213:Conditioning, Psychological / Q000502:physiology*; D003463:Cues; D046352:Freezing Reaction, Cataleptic / Q000502:physiology; D018740:Genetic Heterogeneity; D008297:Male; D018782:Maze Learning / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains / Q000502:physiology*; D065853:Spatial Learning / Q000502:physiology*; D013045:Species Specificity; D013223:Statistics as Topic
Anxiety; Fear; Genetically heterogeneous rats; Memory; Pigmentation; Roman rat strains; Spatial learning