The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Chong Leong Puan - One of the best experts on this subject based on the ideXlab platform.
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vocal individuality of large tailed nightjar caprimulgus macrurus in peninsular malaysia
Bioacoustics-the International Journal of Animal Sound and Its Recording, 2018Co-Authors: Phooi Kuan Chang, Chong Leong PuanAbstract:AbstractAll four nightjar Species resident in Peninsular Malaysia are vocally distinct, yet they remain little studied. Conventional field methods based on visual cues to study Diurnal Species may be impractical for nightjars. Alternatively, aural survey can potentially be applied on nightjars provided that individuality in their vocalisations can be proven. Our study aimed to determine the vocal individuality of the common, large-tailed nightjar (Caprimulgus macrurus) in oil palm smallholdings and an isolated forest patch located in Selangor, Peninsular Malaysia. From the call recordings obtained from 22 individuals, results of the Kruskal-Wallis analysis revealed significant differences in all the nine vocal parameters (call length, interquartile range bandwidth, low, high, average, centre and peak frequencies as well as first and third quartile frequencies) measured among individual nightjars (p < 0.001) regardless of study sites. Discriminant Function Analysis showed that more than 94.5% of original g...
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Vocal individuality of large-tailed nightjar (Caprimulgus macrurus) in Peninsular Malaysia
Bioacoustics-the International Journal of Animal Sound and Its Recording, 2017Co-Authors: Phooi Kuan Chang, Chong Leong PuanAbstract:AbstractAll four nightjar Species resident in Peninsular Malaysia are vocally distinct, yet they remain little studied. Conventional field methods based on visual cues to study Diurnal Species may be impractical for nightjars. Alternatively, aural survey can potentially be applied on nightjars provided that individuality in their vocalisations can be proven. Our study aimed to determine the vocal individuality of the common, large-tailed nightjar (Caprimulgus macrurus) in oil palm smallholdings and an isolated forest patch located in Selangor, Peninsular Malaysia. From the call recordings obtained from 22 individuals, results of the Kruskal-Wallis analysis revealed significant differences in all the nine vocal parameters (call length, interquartile range bandwidth, low, high, average, centre and peak frequencies as well as first and third quartile frequencies) measured among individual nightjars (p
Antonio A. Nunez - One of the best experts on this subject based on the ideXlab platform.
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Neuroendocrine Mechanisms of Circadian Rhythms in Diurnal Species
Oxford Research Encyclopedia of Neuroscience, 2018Co-Authors: Laura Smale, Antonio A. NunezAbstract:Circadian rhythms are endogenous daily rhythms evident in behavior and physiology. In mammals, these rhythms are controlled by a hierarchical network of oscillators showing a coherent circadian coordination or coupling. The hypothalamic suprachiasmatic nucleus (SCN) sits on top of the hierarchy and coordinates the phase of oscillators in other brain regions and in peripheral organs, including endocrine glands. The phase of the SCN oscillator, in reference to the daily light-dark cycle, is identical across mammalian Species regardless of whether they are most active during the day or night, that is, Diurnal or nocturnal. However, the extra-SCN or peripheral oscillators are out of phase and are often reversed by 180° across Diurnal and nocturnal mammals. In the endocrine system, with the notable exception of the pattern of pineal melatonin secretion, which features elevated levels at night regardless of the activity profile of the Species, most endocrine rhythms show a 180° reversal when Diurnal and nocturnal Species are compared. There is also evidence of differences between nocturnal and Diurnal Species with respect to their rhythms in sensitivity or responsiveness to hormonal stimulation. One of the major unanswered questions in the field of comparative endocrinology relates to the mechanism responsible for the differential coupling in Diurnal and nocturnal mammals of extra-SCN oscillators and overt circadian rhythms with the SCN oscillator and the light dark cycle. Viable hypotheses include Species-specific switches from excitation to inhibition at key nodes between the SCN and its targets, the presence of extra-SCN signals that converge on SCN targets and reverse the outcome of SCN signals, and changes in oscillatory parameters between the oscillator of the SCN and those outside the SCN resulting in an anti-phase coupling among key oscillators.
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circadian modulation of memory and plasticity gene products in a Diurnal Species
Brain Research, 2014Co-Authors: Carmel A Martinfairey, Antonio A. NunezAbstract:Cognition is modulated by circadian rhythms, in both nocturnal and Diurnal Species. Rhythms of clock gene expression occur in brain regions that are outside the master circadian oscillator of the suprachiasmatic nucleus and that control cognitive functions, perhaps by regulating the expression neural-plasticity genes such as brain derived neurotrophic factor (BDNF) and its high affinity receptor, tyrosine kinase B (TrkB). In the Diurnal grass rat (Arvicanthis niloticus), the hippocampus shows rhythms of clock genes that are 180° out of phase with those of nocturnal rodents. Here, we examined the hypothesis that this reversal extends to the optimal phase for learning a hippocampal-dependent task and to the phase of hippocampal rhythms in BDNF/TrkB expression. We used the Morris water maze (MWM) to test for time of day differences in reference memory and monitored daily patterns of hippocampal BDNF/TrkB expression in grass rats. Grass rats showed superior long-term retention of the MWM, when the training and testing occurred during the day as compared to the night, at a time when nocturnal laboratory rats show superior retention; acquisition of the MWM was not affected by time of day. BDNF/TrkB expression was rhythmic in the hippocampus of grass rats, and the phase of the rhythms was reversed compared to that of nocturnal rodents. Our findings provide correlational evidence for the claim that the circadian regulation of cognition may involve rhythms of BDNF/TrkB expression in the hippocampus and that their phase may contribute to Species differences in the optimal phase for learning.
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Rhythms in a Diurnal brain
Biological Rhythm Research, 2008Co-Authors: Laura Smale, Antonio A. Nunez, Michael D. SchwartzAbstract:The neural mechanisms governing circadian rhythms generate patterns of behavior and physiology that are very different in Diurnal and nocturnal Species. Here we review data bearing on the issue of where and how in the brain these differences might be generated. Molecular data from several Species now confirm that the central circadian clock, located in the suprachiasmatic nucleus (SCN), is coupled to the light – dark cycle in the same manner in nocturnal and Diurnal Species, indicating that the fundamental differences arise from mechanisms coupling the clock to effector systems. Major differences in this coupling become apparent only when one steps beyond the SCN to look at brain regions that directly or indirectly receive input from it. This review focuses on our work on brain regions and cell populations to which the SCN projects in the Diurnal Species Arvicanthis niloticus (Nile grass rats). We have found rhythms in the numbers of cells containing cFos, or PER1, in a number of these regions, and the pa...
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Diurnal and nocturnal rodents show rhythms in orexinergic neurons.
Brain research, 2002Co-Authors: Gladys S Martínez, Laura Smale, Antonio A. NunezAbstract:Orexin (ORX) A and B (hypocretins) are excitatory neuropeptides produced by neurons of the lateral hypothalamus that have been implicated in the regulation of the sleep-wake cycle. In rats, Fos (the product of the cfos gene) expression shows daily rhythms in areas involved in sleep and wakefulness and orexinergic neurons show elevated Fos expression during the night. The present study directly compared the daily pattern of Fos expression in orexinergic neurons in Diurnal (A. niloticus; grass rats) and nocturnal (R. norvegicus; lab rats) rodents. Animals kept on a 12:12 light-dark cycle were perfused at six different Zeitgeber times (ZT), with lights on at ZT 0: 1, 5, 13, 17, 20 and 23. In both nocturnal and Diurnal rodents orexinergic neurons showed rhythms in Fos expression, with more Fos seen during the active phase of each Species. In the Diurnal Species, Fos expression in cells of the lateral hypothalamus that do not produce ORX was elevated at ZT 20, a time when these animals sleep, and was low at ZT 13, a time of peak of activity. These results provide further evidence for a link between activity in orexinergic neurons and wakefulness and that in grass rats, other neurons of the lateral hypothalamus may work in an antagonistic fashion with respect to orexinergic neurons to regulate wakefulness in this Diurnal Species.
Phooi Kuan Chang - One of the best experts on this subject based on the ideXlab platform.
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vocal individuality of large tailed nightjar caprimulgus macrurus in peninsular malaysia
Bioacoustics-the International Journal of Animal Sound and Its Recording, 2018Co-Authors: Phooi Kuan Chang, Chong Leong PuanAbstract:AbstractAll four nightjar Species resident in Peninsular Malaysia are vocally distinct, yet they remain little studied. Conventional field methods based on visual cues to study Diurnal Species may be impractical for nightjars. Alternatively, aural survey can potentially be applied on nightjars provided that individuality in their vocalisations can be proven. Our study aimed to determine the vocal individuality of the common, large-tailed nightjar (Caprimulgus macrurus) in oil palm smallholdings and an isolated forest patch located in Selangor, Peninsular Malaysia. From the call recordings obtained from 22 individuals, results of the Kruskal-Wallis analysis revealed significant differences in all the nine vocal parameters (call length, interquartile range bandwidth, low, high, average, centre and peak frequencies as well as first and third quartile frequencies) measured among individual nightjars (p < 0.001) regardless of study sites. Discriminant Function Analysis showed that more than 94.5% of original g...
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Vocal individuality of large-tailed nightjar (Caprimulgus macrurus) in Peninsular Malaysia
Bioacoustics-the International Journal of Animal Sound and Its Recording, 2017Co-Authors: Phooi Kuan Chang, Chong Leong PuanAbstract:AbstractAll four nightjar Species resident in Peninsular Malaysia are vocally distinct, yet they remain little studied. Conventional field methods based on visual cues to study Diurnal Species may be impractical for nightjars. Alternatively, aural survey can potentially be applied on nightjars provided that individuality in their vocalisations can be proven. Our study aimed to determine the vocal individuality of the common, large-tailed nightjar (Caprimulgus macrurus) in oil palm smallholdings and an isolated forest patch located in Selangor, Peninsular Malaysia. From the call recordings obtained from 22 individuals, results of the Kruskal-Wallis analysis revealed significant differences in all the nine vocal parameters (call length, interquartile range bandwidth, low, high, average, centre and peak frequencies as well as first and third quartile frequencies) measured among individual nightjars (p
R M Buijs - One of the best experts on this subject based on the ideXlab platform.
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opposite actions of hypothalamic vasopressin on circadian corticosterone rhythm in nocturnal versus Diurnal Species
European Journal of Neuroscience, 2008Co-Authors: Andries Kalsbeek, Linda A W Verhagen, Ingrid Schalij, Ewout Foppen, Michel Saboureau, Beatrice Bothorel, R M BuijsAbstract:Relatively little is known about the function of the biological clock and its efferent pathways in Diurnal Species, despite the fact that its major transmitters and neuronal connections are also conserved in humans. The mammalian biological clock is located in the hypothalamic suprachiasmatic nuclei (SCN). Several lines of evidence suggest that the activity cycle of the SCN itself is similar in nocturnal and Diurnal mammals. Previously, we showed that, in the rat, vasopressin (VP) derived from the SCN has a strong inhibitory effect on the release of adrenal corticosterone and is an important component in the generation of a daily rhythm in plasma corticosterone concentrations. In the present study we investigated the role of VP in the control of the daily corticosterone rhythm in a Diurnal rodent, i.e. Arvicanthis ansorgei. Contrary to our previous (rat) results, VP administered to the hypothalamic paraventricular nucleus in A. ansorgei had a stimulatory effect on the release of corticosterone. Moreover, both the morning and evening rise in corticosterone were blocked by the administration of a VP receptor antagonist. These results show that with regard to the circadian control of the corticosterone rhythm in Diurnal and nocturnal rodents, temporal information is carried along the same pathway from the SCN to its target areas, but the response of the target area may be quite different. We propose that the reversed response to VP is due to a change in the phenotype of the target neurons that are contacted by the SCN efferents, i.e. glutamatergic instead of γ-aminobutyric acid (GABA)ergic.
Ewout Foppen - One of the best experts on this subject based on the ideXlab platform.
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opposite actions of hypothalamic vasopressin on circadian corticosterone rhythm in nocturnal versus Diurnal Species
European Journal of Neuroscience, 2008Co-Authors: Andries Kalsbeek, Linda A W Verhagen, Ingrid Schalij, Ewout Foppen, Michel Saboureau, Beatrice Bothorel, R M BuijsAbstract:Relatively little is known about the function of the biological clock and its efferent pathways in Diurnal Species, despite the fact that its major transmitters and neuronal connections are also conserved in humans. The mammalian biological clock is located in the hypothalamic suprachiasmatic nuclei (SCN). Several lines of evidence suggest that the activity cycle of the SCN itself is similar in nocturnal and Diurnal mammals. Previously, we showed that, in the rat, vasopressin (VP) derived from the SCN has a strong inhibitory effect on the release of adrenal corticosterone and is an important component in the generation of a daily rhythm in plasma corticosterone concentrations. In the present study we investigated the role of VP in the control of the daily corticosterone rhythm in a Diurnal rodent, i.e. Arvicanthis ansorgei. Contrary to our previous (rat) results, VP administered to the hypothalamic paraventricular nucleus in A. ansorgei had a stimulatory effect on the release of corticosterone. Moreover, both the morning and evening rise in corticosterone were blocked by the administration of a VP receptor antagonist. These results show that with regard to the circadian control of the corticosterone rhythm in Diurnal and nocturnal rodents, temporal information is carried along the same pathway from the SCN to its target areas, but the response of the target area may be quite different. We propose that the reversed response to VP is due to a change in the phenotype of the target neurons that are contacted by the SCN efferents, i.e. glutamatergic instead of γ-aminobutyric acid (GABA)ergic.