By using echolocation system echolocating bats have the ability to complete the tasks of detection, localization and classification of the targets. Among the three fundamental tasks, the study of how bats use echolocation to classify targets was investigated later, and most of previous studies were focused on the analysis of simple targets. However, the echoes that bats received are mostly returning from complex objects or structures, which are so complex that they must be described by stochastic statistical approach. In recent years, the study on classification of complex echoes returning from different plants in frequency modulation (FM) bats has made significant progress. In this review article, we will briefly introduce and comment on some progress of studies based on the behavioral evidence, acoustic cues, relevant classification models, and neural bases underlying different classification cues to distinguish plants through classification of echoes in FM bats.
Animals ; Chiroptera ; physiology ; Echolocation ; Nervous System Physiological Phenomena

The ventral nucleus of the lateral lemniscus (VNLL) is an important nucleus in the central auditory pathway which connects the lower brainstem and the midbrain inferior colliculus (IC). Previous studies have demonstrated that neurons in the VNLL could respond to sound signal parameters. Frequency tuning curves (FTCs) of VNLL neurons are generally wider than FTCs of IC neurons, suggesting that the VNLL does not enhance abilities of frequency discrimination and coding. Two types of rate-intensity functions (RIFs) are found in the VNLL: monotonic and non-monotonic RIFs. Intensity-tuning of VNLL neurons are affected by the temporal firing patterns during processing and encoding intensity. There are multiple temporal firing patterns in VNLL neurons. Onset pattern has a precise timing characteristic which is well suited to encode temporal features of stimuli, and also very important to animal behavior including bat's echolocation. The VNLL accepts inputs from lower nuclei, uploads glycine inhibitory outputs to IC, and modulates response characteristics generating and acoustic signal processing of IC neurons. Recent research suggests that fast inhibitory projection from the VNLL may delay the first spike latency of IC neurons, and the delayed inhibitory projection from the VNLL may mediate the temporal firing patterns of IC neurons. But how inhibitory inputs from the VNLL integrate in IC, and how inhibitory inputs from the VNLL enhance the ability of detecting sound signal of IC neurons are not very clear and need more direct evidence at the level of neurons. These questions will help further understand the role of upload during IC processes acoustic signal, which are our research target in the future. This article reviews the current literature regarding the roles of the VNLL in sound signal processing and the auditory ascending transmission, including advances in the relevant research in our laboratory.
Acoustic Stimulation ; Animals ; Auditory Pathways ; Chiroptera ; Echolocation ; Neurons ; physiology ; Pons ; cytology

Adenovirus remains a significant threat to public health. Recent studies showed that bats can harbor diverse adenoviruses. To further investigate the distribution and genetic diversity of bat adenoviruses in China, we collected throat and anal swab samples of 11 bat species from 6 provinces of China, including Beijing, Hunan, Jiangxi, Yunnan, Guizhou and Hainan. Nested PCR was used to identify potential bat adenoviruses from the samples, and positive results were cloned and sequenced for genetic diversity study. In addition, nucleotide sequence alignments based on corresponding amino acid sequence similarities were used for phylogenetic analyses. Our results showed that about 20% of bat species in China are positive to adenoviruses, and Myotis ricketti is likely to be the most important host of bat adenoviruses in all locations. Moreover, we identified two diverse sequences of bat adenoviruses from the same sample of Ia io in Guizhou province of China. In general, the average nucleotide and amino acid sequence similarities of the conserved region of DNA polymerases of bat adenoviruses are 66.6% and 74.7%, respectively. The differences between bat species and their residences environments may have driven the adaptive evolution of the viruses, leading to the genetic diversity of the bat adenoviruses.
Adenoviridae ; classification ; genetics ; isolation & purification ; physiology ; Animals ; China ; Chiroptera ; virology ; Genetic Variation ; Host Specificity ; Phylogeny

The effects of sound duration and sound pattern on the recovery cycles of inferior collicular (IC) neurons in constant frequency-frequency modulation (CF-FM) bats were explored in this study. Five leaf-nosed bats, Hipposideros armiger (4 males, 1 female, 43-50 g body weight), were used as subjects. The extracellular responses of IC neurons to paired sound stimuli with different duration and patterns were recorded, and the recovery was counted as the ratio of the second response to the first response. Totally, 169 sound-sensitive IC neurons were recorded in the experiment. According to the interpulse interval (IPI) of paired sounds when neurons reached 50% recovery (50% IPI), the recovery cycles of these IC neurons were classified into 3 types: fast recovery (F, the 50% IPI was less than 15 ms), short recovery (S, the 50% IPI was between 15.1 and 30 ms) and long recovery (L, the 50% IPI was more than 30 ms). When paired CF stimuli with 2 ms duration was used, the ratio of F neurons was 32.3%, and it decreased to 18.1% and 18.2% respectively when 5 and 7 ms CF stimuli were used. The ratios of S and L neurons were 41.5%, 33.7%, 29.1% and 26.2%, 48.2%, 52.7% respectively when 2, 5 and 7 ms CF stimuli were used. The average 50% IPI determined after stimulation with paired 2 ms, 5 ms and 7 ms CF sounds were (30.2 ± 27.6), (39.9 ± 29.1) and (49.4 ± 34.7) ms, respectively, and the difference among them was significant (P< 0.01). When the stimuli of paired 2 ms CF sounds were shifted to paired 2 ms FM sounds, the proportion of F, S and L neurons changed from 32.3%, 41.5%, 26.2% to 47.7%, 24.6%, 27.7%, respectively, and the average 50% IPI decreased from (30.2 ± 27.6) to (23.9 ± 19.0) ms (P< 0.05, n = 65). When paired 5+2 ms CF-FM pulses were used instead of 7 ms CF sounds, the proportion of F, S and L neurons changed from 18.2%, 29.1%, 52.7% to 29.1%, 27.3%, 43.6%, respectively, and the average 50% IPI decreased from (49.4 ± 34.7) to (36.3 ± 29.4) ms (P< 0.05, n = 55). All these results suggest that the CF and FM components in echolocation signal of CF-FM bats play different roles during bats' hunting and preying on. The FM component of CF-FM signal presenting in the terminal phase can increase the number of F type neurons and decrease the recovery cycles of IC neurons for processing high repetition echo information, which ensures the bat to analyze the target range and surface texture more accurately.
Acoustic Stimulation ; methods ; Action Potentials ; physiology ; Animals ; Chiroptera ; physiology ; Echolocation ; physiology ; Female ; Inferior Colliculi ; cytology ; physiology ; Male ; Neurons ; classification ; physiology ; Refractory Period, Electrophysiological ; physiology

Temporal features of sound convey information vital for behaviors as diverse as speech recognition by human and echolocation by bats. However, auditory stimuli presented in temporal proximity might interfere with each other. Although much progress has been made in the description of this phenomenon from psychophysical studies, the neural mechanism responsible for its formation at central auditory structures especially at the inferior colliculus (IC), a midbrain auditory nucleus which practically receives massive bilateral projections from all the major auditory structures in the brainstem, remains unclear. This study was designed to investigate it in vivo by using electrophysiological recording from the inferior collicular neurons of the big brown bat, Eptesicus fuscus. In our results, the responses of 12 (38%, n= 31) neurons to the test sound (leading sound) were obviously inhibited by the masker (lagging sound). The inhibitory effects in these neurons were correlated with the inter-stimulus level difference (SLD) and the inter-stimulus onset asynchrony (SOA) interval. The strength of backward masking increased with the masker intensity increasing, the test sound intensity decreasing and the SOA interval shortening. There were no obvious effects of backward masking on the responses of many other neurons (52%, 16/31), and yet in a part of these neurons, the neural inhibition of responses to the test sound was observed at the special SLD and the special SOA intervals. Moreover, few of the 31 sampled IC neurons (10%, 3/31) displayed facilitating responses to the test sound at the special SLD and the special SOA intervals. These data demonstrate that a lot of IC neurons are involved in the generation of the backward masking of acoustical perception. It is conjectured that the temporal dynamic integration between the leading inhibitory inputs evoked by the masker sound and the excitatory inputs evoked by the test sound might play a key role in shaping the acoustical response characteristics of the IC neurons.
Acoustic Stimulation ; Animals ; Auditory Perception ; physiology ; Chiroptera ; physiology ; Echolocation ; physiology ; Evoked Potentials, Auditory ; Inferior Colliculi ; cytology ; physiology ; Male ; Neurons ; physiology ; Perceptual Masking ; physiology

The present study was performed in order to test the effects of diphenylhydantoin (DPH) and two central nervous system (CNS) stimulants, intermittent light stimulation(ILS) and pentylenetetrazol (Metrazol) on body temperature (Tb) during cold exposure in the bat DHP delayed the onset of entry into hibernation in both the oriental discoloured bats and the little brown bats and formed long and prominent plateaus that were not found in the normal and the controls. The responses of body temperature to the ILS were sensitive and the body temperature fell dramatically in the big brown bats. Metrazol effects on body temperature were obvious but; seemed dose-dependent. The experimental results further support the hypothesis that hibernation is an epileptic fit as suggested by serveral researchers.
Animal ; Body Temperature/drug effects ; Body Temperature Regulation ; Chiroptera/physiology* ; Female ; Hibernation* ; Light ; Male ; Pentylenetetrazole/pharmacology ; Phenytoin/pharmacology