The animal preference for complexity is most clearly demonstrated when the environmental change takes the form of an increase in complexity. Therefore, one of the potential difficulties in interpretation is that the preference for perceptual novelty may be confounded with the change in environmental complexity. In this study, the environmental complexity was controlled by manipulating with tunnels inside the experimental chamber. Adding new tunnels triggered a very profound change in behaviour, which was demonstrated by the animals’ prolonged stay in the proximity of the novel objects, sniffing, touching, and climbing on top of the tunnels. The removal of the tunnels from the test arena turned out to have the least influence on behaviour compared to the other manipulations used in this study. The reduction of complexity of the tunnels had a moderate effect on rat behavior. Tunnels are important elements in the rats’ environment, since they provide various possibilities for hiding, resting or moving inside the tunnel. They may be treated as a good example of affordances in rat-environment interactions. The results of this study may therefore serve as a basis for constructing a modified theory of animal curiosity which could incorporate the concept of ecological psychology.

Selective breeding of laboratory rats resulted in changes of their behavior. Concomitantly, the albino strains developed vision related pathologies. These alterations certainly occurred on the background of modifications in brain morphology. The aim of the study was to assess and compare volumes of major structures in brains of wild-captive, laboratory albino and laboratory pigmented rats. High resolution T2-weighted images of brains of adult male Warsaw Wild Captive Pisula-Stryjek rats (WWCPS, a model of wild type), laboratory pigmented (Brown Norway strain, BN) and albino rats (Wistar strain, WI) were obtained with a 7T small animal-dedicated magnetic resonance tomograph. Volume quantification of whole brains and 50 brain structures within each brain were performed with the digital Schwarz rat brain atlas and a custom-made MATLAB/SPM8 scripts. Brain volumes were scaled to body mass, whereas volumes of brain structures were normalized to individual brain volumes. Normalized brain volume was similar in WWCPS and BN, but lower in WI. Normalized neocortex volume was smaller in both laboratory strains than in WWCPS and the visual cortex was smaller in albino WI rats than in WWCPS and BN. Relative volumes of phylogenetically older structures, such as hippocampus, amygdala, nucleus accumbens and olfactory nuclei, also displayed certain strain-related differences. The present data shows that selective breeding of laboratory rats markedly affected brain morphology, the neocortex being most significantly altered. In particular, albino rats display reduced volume of the visual cortex, possibly related to retinal degeneration and the development of blindness.

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Objective Sinus tachycardia is frequently reported in systemic lupus erythematosus (SLE), while there are limited data on post-exercise ability to slow heart rate (i.e. heart rate recovery, HRR) in this group of patients. Methods We studied consecutive 70 patients with SLE and 30 healthy controls. All examined individuals underwent detailed clinical examination, echocardiography, Holter monitoring with heart rate variability and treadmill stress test using Bruce's protocol. HRR values were calculated as the difference between maximum HR during exercise and HR at the first (HRR1) and third (HRR3) minute of rest. Individuals with coronary artery disease, diabetes mellitus and suspected pulmonary hypertension were excluded from further analysis ( n = 15). Results Fifty-five SLE patients were eligible for this study: aged 41.5 ± 12.4 years, 87.3% women, SLICC/ACR-DI score 3.58 ± 1.85. In the SLE group 36.4% patients received beta-blockers, usually for previously detected sinus tachycardia and/or arterial hypertension. Mean HRR1 (36.9 ± 12.6 vs 49.5 ± 18.6, p = 0.0004) and HRR3 (55.5 ± 14.3 vs 69.2 ± 16.4, p = 0.0001) were significantly lower in SLE than in healthy individuals. Significantly negative correlations between SLICC/ACR-DI score and HRR1 ( r = -0.299, p = 0.01), HRR3 ( r = -0.361, p = 0.001) and exercise capacity ( r = -0.422, p < 0.0001) were revealed. Additionally, beta-blocker treatment was also revealed to alter significantly HRR1, HRR3 and exercise capacity in SLE. Conclusion Patients with SLE are characterized by attenuated HRR after exercise. In our study impaired HRR was associated with disease severity and beta-blocker treatment and probably with disease duration. The use of HRR assessment in SLE can be used as an additional marker of cardiac autonomic nervous system dysfunction.