Under free field conditions, we used single unit extracellular recording to study the detection of acoustic signals by neurons in the ventral nucleus of the lateral lemniscus(VNLL) in Kunming mouse(Mus musculus). The ...Under free field conditions, we used single unit extracellular recording to study the detection of acoustic signals by neurons in the ventral nucleus of the lateral lemniscus(VNLL) in Kunming mouse(Mus musculus). The results indicate two types of firing patterns in VNLL neurons: onset and sustained. The first spike latency(FSL) of onset neurons was shorter than that of sustained neurons. With increasing sound intensity, the FSL of onset neurons remained stable and that of sustained neurons was shortened, indicating that onset neurons are characterized by precise timing. By comparing the values of Q10 and Q30 of the frequency tuning curve, no differences between onset and sustained neurons were found, suggesting that firing pattern and frequency tuning are not correlated. Among the three types of rate-intensity function(RIF) found in VNLL neurons, the proportion of monotonic RIF is the largest, followed by saturated RIF, and non-monotonic RIF. The dynamic range(DR) in onset neurons was shorter than in sustained neurons, indicating different capabilities in intensity tuning of different firing patterns and that these differences are correlated with the type of RIF. Our results also show that the best frequency of VNLL neurons was negatively correlated with depth, supporting the view point that the VNLL has frequency topologic organization.展开更多
The ultrasonic communication in Concave-eared torrent flogs Odorrana tormota is believed to be an adaptation to avoid masking by the intense low-frequency noise of the rushing stream in their habitat. The acoustic ada...The ultrasonic communication in Concave-eared torrent flogs Odorrana tormota is believed to be an adaptation to avoid masking by the intense low-frequency noise of the rushing stream in their habitat. The acoustic adaptation hypothesis for ultrasonic origin predicts that some organisms subjecting to persistent acoustic interference from broadband, low-frequency en- vironmental noise, might shift their signal frequency upward into frequency bands with lower noise energy. In other words, low-frequency environmental noise might cause upward shifts of species＇ vocalization frequencies making their signals more conspicuous. Presently, it is unclear whether male O. tormota adjust their signal features in response to a change in the ambient noise level. We tested the prediction of the acoustic adaptation hypothesis by recording the vocalizations of male O. tormota in- habiting two streams with different background noise levels in Huangshan in central China and comparing their call features in- cluding the fundamental frequency （F0）. Results showed that the spectrotemporal characteristics of the vocal signals of males in the two habitats were indifferent, except the duration of the call harmonic segments and three parameters related to the call fun- damental frequency （F0）. In terms of the F0, the pooled and individual frog data showed that flogs inhabiting the noisier habitat tended to emit calls having higher F0. The higher F0 increases the signal-to-noise ratio, thus benefiting the detection of vocaliza- tion. Thus, similar to several anuran species, concave-eared torrent frogs also display noise-dependent adjustment of vocal pitch in their vocalizations for making them more audible展开更多
Existing methods of physiological signal analysis based on nonlinear dynamic theories only examine the complexity difference of the signals under a single sampling frequency.We developed a technique to measure the mul...Existing methods of physiological signal analysis based on nonlinear dynamic theories only examine the complexity difference of the signals under a single sampling frequency.We developed a technique to measure the multifractal characteristic parameter intimately associated with physiological activities through a frequency scale factor.This parameter is highly sensitive to physiological and pathological status.Mice received various drugs to imitate different physiological and pathological conditions,and the distributions of mass exponent spectrum curvature with scale factors from the electrocardiogram (ECG) signals of healthy and drug injected mice were determined.Next,we determined the characteristic frequency scope in which the signal was of the highest complexity and most sensitive to impaired cardiac function,and examined the relationships between heart rate,heartbeat dynamic complexity,and sensitive frequency scope of the ECG signal.We found that all animals exhibited a scale factor range in which the absolute magnitudes of ECG mass exponent spectrum curvature achieve the maximum,and this range (or frequency scope) is not changed with calculated data points or maximal coarse-grained scale factor.Further,the heart rate of mice was not necessarily associated with the nonlinear complexity of cardiac dynamics,but closely related to the most sensitive ECG frequency scope determined by characterization of this complex dynamic features for certain heartbeat conditions.Finally,we found that the health status of the hearts of mice was directly related to the heartbeat dynamic complexity,both of which were positively correlated within the scale factor around the extremum region of the multifractal parameter.With increasing heart rate,the sensitive frequency scope increased to a relatively high location.In conclusion,these data provide important theoretical and practical data for the early diagnosis of cardiac disorders.展开更多
基金This study was supported by the National Natural Science Foundation of China （31000493） and the Central China Normal University Independent Scientific Research Project Fund for Youth Scholars （11A01025）
文摘Under free field conditions, we used single unit extracellular recording to study the detection of acoustic signals by neurons in the ventral nucleus of the lateral lemniscus(VNLL) in Kunming mouse(Mus musculus). The results indicate two types of firing patterns in VNLL neurons: onset and sustained. The first spike latency(FSL) of onset neurons was shorter than that of sustained neurons. With increasing sound intensity, the FSL of onset neurons remained stable and that of sustained neurons was shortened, indicating that onset neurons are characterized by precise timing. By comparing the values of Q10 and Q30 of the frequency tuning curve, no differences between onset and sustained neurons were found, suggesting that firing pattern and frequency tuning are not correlated. Among the three types of rate-intensity function(RIF) found in VNLL neurons, the proportion of monotonic RIF is the largest, followed by saturated RIF, and non-monotonic RIF. The dynamic range(DR) in onset neurons was shorter than in sustained neurons, indicating different capabilities in intensity tuning of different firing patterns and that these differences are correlated with the type of RIF. Our results also show that the best frequency of VNLL neurons was negatively correlated with depth, supporting the view point that the VNLL has frequency topologic organization.
文摘The ultrasonic communication in Concave-eared torrent flogs Odorrana tormota is believed to be an adaptation to avoid masking by the intense low-frequency noise of the rushing stream in their habitat. The acoustic adaptation hypothesis for ultrasonic origin predicts that some organisms subjecting to persistent acoustic interference from broadband, low-frequency en- vironmental noise, might shift their signal frequency upward into frequency bands with lower noise energy. In other words, low-frequency environmental noise might cause upward shifts of species＇ vocalization frequencies making their signals more conspicuous. Presently, it is unclear whether male O. tormota adjust their signal features in response to a change in the ambient noise level. We tested the prediction of the acoustic adaptation hypothesis by recording the vocalizations of male O. tormota in- habiting two streams with different background noise levels in Huangshan in central China and comparing their call features in- cluding the fundamental frequency （F0）. Results showed that the spectrotemporal characteristics of the vocal signals of males in the two habitats were indifferent, except the duration of the call harmonic segments and three parameters related to the call fun- damental frequency （F0）. In terms of the F0, the pooled and individual frog data showed that flogs inhabiting the noisier habitat tended to emit calls having higher F0. The higher F0 increases the signal-to-noise ratio, thus benefiting the detection of vocaliza- tion. Thus, similar to several anuran species, concave-eared torrent frogs also display noise-dependent adjustment of vocal pitch in their vocalizations for making them more audible
基金supported by the National Natural Science Foundation of China (Grant No. 61003169)the Ph.D. Programs Foundation of Ministry of Education of China (Grant No. 20090095120013)the Technology Funding Project of China University of Mining and Technology (Grant No. 2008C004)
文摘Existing methods of physiological signal analysis based on nonlinear dynamic theories only examine the complexity difference of the signals under a single sampling frequency.We developed a technique to measure the multifractal characteristic parameter intimately associated with physiological activities through a frequency scale factor.This parameter is highly sensitive to physiological and pathological status.Mice received various drugs to imitate different physiological and pathological conditions,and the distributions of mass exponent spectrum curvature with scale factors from the electrocardiogram (ECG) signals of healthy and drug injected mice were determined.Next,we determined the characteristic frequency scope in which the signal was of the highest complexity and most sensitive to impaired cardiac function,and examined the relationships between heart rate,heartbeat dynamic complexity,and sensitive frequency scope of the ECG signal.We found that all animals exhibited a scale factor range in which the absolute magnitudes of ECG mass exponent spectrum curvature achieve the maximum,and this range (or frequency scope) is not changed with calculated data points or maximal coarse-grained scale factor.Further,the heart rate of mice was not necessarily associated with the nonlinear complexity of cardiac dynamics,but closely related to the most sensitive ECG frequency scope determined by characterization of this complex dynamic features for certain heartbeat conditions.Finally,we found that the health status of the hearts of mice was directly related to the heartbeat dynamic complexity,both of which were positively correlated within the scale factor around the extremum region of the multifractal parameter.With increasing heart rate,the sensitive frequency scope increased to a relatively high location.In conclusion,these data provide important theoretical and practical data for the early diagnosis of cardiac disorders.
