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In order to successfully navigate through space, animals must rely on multiple cognitive processes, including orientation in space, memory of object locations, and navigational decisions based on that information. Although highly-controlled behavioral tasks are valuable for isolating and targeting specific processes, they risk producing a narrow understanding of complex behavior in natural contexts. The Traveling Salesperson Problem (TSP) is an optimization problem that can be used to study naturalistic foraging behaviors, in which subjects select routes between multiple baited targets. Foraging is a spontaneous, yet complex, behavior, involving decision-making, attention, course planning, and memory. Previous research found that hippocampal lesions in rats impaired TSP task performance, particularly on measures of spatial memory. Although traditional laboratory tests have shown the medial entorhinal cortex (MEC) to play an important role in spatial memory, if and how the MEC is involved in finding efficient solutions to the TSP remains unknown. In the current study, rats were trained on the TSP, learning to retrieve bait from targets in a variety of spatial configurations. After recovering from either an MEC lesion or control sham surgery, the rats were tested on eight new configurations. Our results showed that, similar to rats with hippocampal lesions, MEC-lesioned rats were impaired on measures of spatial memory, but not spatial decision-making, with greatest impairments on configurations requiring a global navigational strategy for selecting the optimal route. These findings suggest that the MEC is important for effective spatial navigation, especially when global cue processing is required., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Cerebral hypoxia-ischemia can lead to motor and sensory impairments which can be dependent on the extent of infarcted regions. Since a better understanding of the neurochemical mechanisms involved in this injury is needed, the use of zebrafish as a cerebral hypoxia model has become quite promising because it could improve the knowledge about hypoxia-ischemia. In the current study, we aimed to investigate the spontaneous recovery of brain and behavioral impairments induced by hypoxia in adult zebrafish. Brain injury levels were analyzed by spectrophotometric measurement of mitochondrial dehydrogenase activity by staining with 2,3,5-triphenyltetrazolium chloride, and behavioral profiles were assessed by the open tank test. The induction of hypoxia substantially decreased mitochondrial activity in the brain and impaired behavior. The spontaneous recovery of fish subjected to hypoxia was assessed after 1, 3, 6, 24, and 48h under normoxia. The quantification of brain injury levels showed a significant increase until 24h after hypoxia, but after 48h this effect was completely reversed. Regarding behavioral parameters, we verified that locomotor activity and vertical exploration were impaired by hypoxia and these effects were reversed after 3h under normoxia. Taken together, these results show that zebrafish exhibited transient cerebral and behavioral impairments when submitted to hypoxia, and 1h under normoxic conditions was insufficient to reverse both effects. Therefore, our data help to elucidate the time window of spontaneous recovery in zebrafish after hypoxia and also the behavioral phenotypes involved in this phenomenon., (Copyright © 2013 Elsevier B.V. All rights reserved.)