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Behavioural flexibility is a cognition-related function that enables subjects to adapt to a changing environment. Orbitofrontal cortex (OFC) and hippocampus (HC) have been involved in cognitive flexibility, but the interaction between these structures might be of particular functional significance. We applied a disconnection model in C57BL/6JRj mice to investigate the importance of OFC and ventral HC (vHC) interaction. Spatial acquisition and reversal performance in the Morris water maze (MWM) was compared between animals with small contralateral excitotoxic lesions to OFC and vHC, ipsilateral lesions (i.e., OFC-vHC lesions in the same hemisphere), as well as small bilateral OFC or vHC lesions. Spatial learning and memory performance was mostly unimpaired or only slightly impaired in our brain-lesioned animals compared to sham-lesioned control mice. However, contralaterally lesioned mice were significantly impaired during the early phase of reversal learning, whereas the other lesion groups performed similar to controls. These mice might also have experienced some difficulties using cognitively advanced search strategies. Additional non-mnemonic tests indicated that none of the defects could be reduced to motor, motivational or anxiety-related changes. Our findings support the particular role of PFC-HC interaction in advanced cognitive processes and flexibility., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In newborns, hypoxia elicits defensive behaviors including awakening from sleep, body movements and crying. An inability to produce this defense response is a risk factor for sudden infant death syndrome and other respiratory control disorders. In this study, we examined the possibility that the defense response to hypoxia in newborns is partly determined by early exposure to hypoxia. We explored this possibility in 6-day-old mice, which resemble human preterm infants of approximately 25-30 weeks' gestational age. Ultrasonic vocalizations (USVs) were recorded as a marker for the defense response to hypoxia. In a conditioning experiment, newborn mice were exposed to two artificial odors (conditioned stimuli, CS). For acquisition (two trials), pups were exposed to one odor (CS+) in a hypoxic gas mixture (10% O2, which was the unconditioned stimulus, US) and to another odor (CS-) in air. Then, the pups were exposed to each odor while breathing air. Newborn mice produced significantly more USVs when exposed to the odor previously paired with hypoxia than to the control odor. Thus, associative learning may shape the defense response to hypoxia in newborns.

Alzheimer's disease (AD) patients typically present short-term memory deficits, before long-term memory capacity declines with disease progression. Several studies have described learning and memory deficits in the APP23 mouse model. Our group reported a decline of learning and memory capacities from the age of 3 months onwards using a hidden-platform Morris water maze (MWM). The aim of the present study was to evaluate working and reference memory in APP23 mice in the same plus-shaped water maze. The transgenic mice had slower learning curves; however, consolidation of the learned information appeared intact in this learning paradigm. This report demonstrates impairment of working memory in this transgenic Alzheimer model.