The effects of exercise and two pre-exercise fluid amounts on cognition

Exercise is associated with elevated mood states and arousal. Observational studies support the claim that exercise can help individuals think more “clearly’ with reports of improved mood and feelings of psychological well-being following exercise. However, laboratory studies have produced equivocal results. The purpose of this study is to examine the effect of exercise intensity and two likely pre-exercise fluid amounts consumed by euhydrated athletes on cognitive performance. Fifteen college age students were randomly assigned to either a 150 ml or a 500 ml fluid condition on the first test day and received the other fluid condition on the second test day. Prior to exercise subjects completed baseline computerized cognitive tests then began a treadmill protocol of three 6 min stages at increasing intensity after which subjects completed cognitive tests. A second treadmill portion started at 7.5 mph for 2 min then speed was increased 0.5 mph every 30 s until voluntary exhaustion and final cognitive testing was completed. Our results demonstrate a facilitation of cognitive function in response to exercise with the exception of the match to sample cognitive test which showed lack of facilitation of cognition in the 500 ml condition at moderate exercise. Our research contributes to the growing field of exercise and its effects on cognition. Specifically working memory cognitive tests showed facilitation with exercise. These results may be applicable to a typical exercising population since our study included a common exercise mode (treadmill) at moderate and high intensities and likely fluid amounts

Production of ultrasonic vocalizations by Peromyscus mice in the wild

BACKGROUND: There has been considerable research on rodent ultrasound in the laboratory and these sounds have been well quantified and characterized. Despite the value of research on ultrasound produced by mice in the lab, it is unclear if, and when, these sounds are produced in the wild, and how they function in natural habitats. RESULTS: We have made the first recordings of ultrasonic vocalizations produced by two free-living species of mice in the genus Peromyscus (P. californicus and P. boylii) on long term study grids in California. Over 6 nights, we recorded 65 unique ultrasonic vocalization phrases from Peromyscus. The ultrasonic vocalizations we recorded represent 7 different motifs. Within each motif, there was considerable variation in the acoustic characteristics suggesting individual and contextual variation in the production of ultrasound by these species. CONCLUSION: The discovery of the production of ultrasonic vocalizations by Peromyscus in the wild highlights an underappreciated component in the behavior of these model organisms. The ability to examine the production of ultrasonic vocalizations in the wild offers excellent opportunities to test hypotheses regarding the function of ultrasound produced by rodents in a natural context

To seek or speak? Dual function of an acoustic signal limits its versatility in communication

The perception of different attributes of conspecifics is an integral part of intraspecific communication. It can facilitate the recognition of interaction partners or the assessment of potential mates. Acoustic signals can encode fine-scaled information through the interplay of acoustic variability and specificity. A reliable vocal signature is both unique within a class and variable between classes. Therefore, acoustic complexity might be associated with the number of classes to be discriminated. We investigated the assumption that limitations to signal design may affect the communicative functionality of a signal. To do so, we chose a signal with potentially dual functionality which may therefore display such limitations. In bats, echolocation is used primarily for foraging and orientation but there is increasing support for its additional role in communication. An acoustic analysis of echolocation pulses of the bat Rhinolophus clivosus confirmed sex and individual vocal signatures in echolocation pulses. A habituation edishabituation playback experiment suggested that bats perceived these signatures because listening bats clearly discriminated between the sexes (two classes) and between individuals (representatives of a multiclass category), although to different degrees. The simple acoustic structure of these vocalizations provides sufficient specificity for sex discrimination but has limitations for individual discrimination because pulse parameters of individuals increasingly overlapped with increasing group size. We conclude that selection for the primary function of echolocation restricts the acoustic space available for communication. However, we frequently observed echolocation pulses with conspicuous structural modifications. Statistical analyses revealed that these vocalizations yielded increased individual distinctiveness. Such added systematic variation may indicate a communicative function and perhaps a signalling intent of the emitter, although the latter has yet to be tested. The findings suggest that the required specificity for effective communication could be obtained through modification of echolocation variants when adaptations for orientation and foraging constrain the evolution of complex communication signatures