Do greater mouse-eared bats experience a trade-off between energy conservation and learning?

Abstract

Bats, some species of rodents and some birds are able to save energy during the summer period by decreasing their body temperature and falling into torpor. Some studies indicate that torpor prevents sleeping and causes effects similar to sleep deprivation. Impairment of processes stabilizing memory slows down learning accuracy and speed. We conducted two experiments to test whether greater mouse-eared bats, Myotis myotis, which commonly use torpor during the summer period, experience a trade-off between energy savings and learning abilities. We compared learning speed and accuracy in bats that were exposed to low (7°C) and higher ambient temperatures (22°C) between training and experimental sessions. Tests were conducted in experiments with food reward (food search) and without food reward (perch search). Time spent with the skin temperature above 30°C was significantly longer for bats exposed to 22°C than for those exposed to 7°C, and longer in experiments with food reward than without food reward. We observed only a very weak tendency for better accuracy and shorter search times in bats exposed to 22°C than in those exposed to 7°C. Our data indicate that memory consolidation of bats under natural conditions is not affected by daily torpor when bats are in good condition and may therefore defend against a rapid fall into torpor. We suggest that homeostatic processes connected with the circadian rhythm allow protection of the consolidation of memory for relatively simple tasks despite time spent in torpor. KEY WORDS: Life history, Memory consolidation, Memory retention, Normothermy, Torpor INTRODUCTIONLong-term memory is important for many animals in a variety of different contexts (Roth et al., 2010). Good memory allows for quick and effective rediscovering of food resources and hides, identification of conspecifics, etc. (Shettleworth, 2001;Stoddard et al., 1991). Storage of accurate memories is an active and costly process involving maintenance and repair of neural structures (Dukas, 1999). Therefore, animals may experience conflicts between the benefits and costs of memory retention (the keeping of memory over prolonged periods of time) (Chancellor et al., 2011;Roth and Pravosudov, 2009); for example, food-catching birds living in harsh climates have developed a larger hippocampus volume than those from milder areas, which may result in enhanced spatial memory and better survival in birds from harsh climates. A memory RESEARCH ARTICLE1 Sensory Ecology Group, Max Planck Institute for Ornithology, Eberhard-GwinnerStraße 11, 82319 Seewiesen, Germany. is normally formed after repeated learning events (Smid et al., 2007) and sleep enhances this process (Palchykova et al., 2002;Roth et al., 2010). Sleep deprivation has negative effects on both memory consolidation [the storage of initial memory representations into long-term memory by stabilization, enhancement and integration processes (Stickgold, 2005)] and retention (Graves et al., 2003;Guan et al., 2004).Recently, an interesting conflict between energ...

In Layman's Terms: Semi-Open Relation Extraction from Scientific Texts

“…An issue for humans is the sheer amount of OIE extractions and the high proportion of uninformative extractions. We show that our approach (Ruczyski et al, 2014). The TRADE-OFF relations are extracted by a narrow IE system trained on FOBIE.…”

Re-examining extreme sleep duration in bats: implications for sleep phylogeny, ecology, and function

“…As in other animals, the relationship between sleep and torpor in bats is insufficiently understood [ 79 ]. Functionally, these states are thought to be distinguishable.…”

Re-examining extreme sleep duration in bats: implications for sleep phylogeny, ecology and function

“…As in other animals, the relationship between sleep and torpor in bats is unknown (Ruczynski et al, 2014). Using currently accepted criteria, it is possible for these states to coincide (Strijkstra et al, 1999;Royo et al, 2019;Huang et al, 2021, see Box 2).…”