RESUMEN
Thousands of species use vocal signals to communicate with one another.Vocalisations carry rich information, yet characterising and analysing these high-dimensional signals is difficult and prone to human bias. Moreover, animal vocalisations are ethologically relevant stimuli whose representation by auditory neurons is an important subject of research in sensory neuroscience. A method that can efficiently generate naturalistic vocalisation waveforms would offer an unlimited supply of stimuli to probe neuronal computations. While unsupervised learning methods allow for the projection of vocalisations into low-dimensional latent spaces learned from the waveforms themselves, and generative modelling allows for the synthesis of novel vocalisations for use in downstream tasks, there is currently no method that would combine these tasks to produce naturalistic vocalisation waveforms for stimulus playback. Here, we demonstrate BiWaveGAN: a bidirectional Generative Adversarial Network (GAN) capable of learning a latent representation of ultrasonic vocalisations (USVs) from mice. We show that BiWaveGAN can be used to generate, and interpolate between, realistic vocalisation waveforms. We then use these synthesised stimuli along with natural USVs to probe the sensory input space of mouse auditory cortical neurons. We show that stimuli generated from our method evoke neuronal responses as effectively as real vocalisations, and produce receptive fields with the same predictive power. BiWaveGAN is not restricted to mouse USVs but can be used to synthesise naturalistic vocalisations of any animal species and interpolate between vocalisations of the same or different species, which could be useful for probing categorical boundaries in representations of ethologically relevant auditory signals.
RESUMEN
INTRODUCTION: Acute bouts of heat stress and exercise have been shown to independently increase heat shock protein levels; however, the combination of these two stressors on HSP-72 expression in human skeletal muscle has not been established. The purpose of this study was to determine the effect of a bout of exercise in the heat on HSP-72 expression. METHODS: There were eight recreationally active men (Age = 26.4 +/- 3.1 yr, V(O2)peak = 4.01 +/- 0.25 L min(- 1)) who completed two 30-min bouts of cycle ergometry at 75% of V(O2)peak in a hot (39 degrees C; RH 30%) and cold (9 degrees C; RH 61%) environment. Muscle biopsies were obtained from the vastus lateralis prior to, 6 h post, and 24 h post-exercise to measure HSP-72 protein. Core rectal temperature (Tc), average skin temperature (T(SK)), intramuscular temperature (T(IM)), heart rate (HR), oxygen uptake (V(O2)), sweat rate (SR), and plasma cortisol were measured to determine thermal loads. RESULTS: No significant interactions were present between V(O2) (2.80 +/- 0.2 vs. 2.65 +/- 0.1 L min(-1)) or plasma cortisol (27.1 +/- 2 vs. 19.2 +/- 4 microg dl(-1)) when comparing HT and CD. HR (184 +/- 5 vs. 159 +/- 7 bpm), T(IM) (40.7 +/- 0.2 vs. 40.0 +/- 0.2 degrees C), Tc (38.3 +/- 0.2 vs. 37.9 +/- 0.1 degrees C), T(SK) (36.7 +/- 0.2 vs. 29.6 +/- 0.8 degrees C), and SR (2.0 +/- 0.2 vs. 1.2 +/- 0.2 L h(-1)) were significantly greater when comparing HT and CD. HSP-72 was not altered as a result of either treatment (4.04 +/- 0.87 vs. 2.91 +/- 1.58 ng microg(-1) protein for HT and CD at 6 h post-exercise). DISCUSSION: Exercise in the heat produced a greater thermal load than exercise in the cold; however, no significant increases in HSP-72 were seen when comparing hot and cold conditions.