Evolution of air-borne vocalization: Insights from neural studies in the archeobatrachian species Bombina orientalis.

Vocalization of tetrapods evolved as an air-driven mechanism. Thus, it is conceivable that the underlaying neural network might have evolved from more ancient respiratory circuits and be made up of homologous components that generate breathing rhythms across vertebrates. In this context, the extant species of stem anurans provide an opportunity to analyze the connection of the neural circuits of lung ventilation and vocalization.

Head adaptation for sound production and feeding strategy in dolphins (Odontoceti: Delphinida).

Head morphology in toothed whales evolved under selective pressures on feeding strategy and sound production. The postnatal development of the skull (n = 207) and mandible (n = 219) of six Delphinida species which differ in feeding strategy but exhibit similar sound emission patterns, including two narrow-band high-frequency species, were investigated through 3D morphometrics. Morphological changes throughout ontogeny were demonstrated based on the main source of variation (i.

Consequences of hyperphosphorylated tau on the morphology and excitability of hippocampal neurons in aged tau transgenic mice.

The intracellular accumulation of hyperphosphorylated tau characterizes many neurodegenerative diseases such as Alzheimer's disease and frontotemporal dementia. A critical role for tau is supported by studies in transgenic mouse models expressing the P301L mutation with accumulation of hyperphosphorylated human tau in hippocampal pyramidal neurons of aged mice. Especially, the somatodendritic mislocalization of hyperphosphorylated tau seems to affect the neuronal network of the hippocampus.

Sound Generating Structures of the Humpback Dolphin Sousa plumbea (Cuvier, 1829) and the Directionality in Dolphin Sounds.

The macroscopic morphology of structures involved in sound generation in the Indian Ocean humpback dolphin (Sousa plumbea) were described for the first time using computed tomography imaging and standard gross dissection techniques. The Indian Ocean humpback dolphin may represent a useful comparative model to the bottlenose dolphin (Tursiops sp.) to provide insights into the functional anatomy of the sound production in dolphins, since these coastal dolphins exhibit similar body size and share similarities on acoustic behavior.

Molecular parallelism in fast-twitch muscle proteins in echolocating mammals.

Detecting associations between genomic changes and phenotypic differences is fundamental to understanding how phenotypes evolved. By systematically screening for parallel amino acid substitutions, we detected known as well as novel cases (Strc, Tecta, and Cabp2) of parallelism between echolocating bats and toothed whales in proteins that could contribute to high-frequency hearing adaptations. Our screen also showed that echolocating mammals exhibit an unusually high number of parallel substitutions in fast-twitch muscle fiber proteins.

Multivariate Meta-Analysis of Brain-Mass Correlations in Eutherian Mammals.

The general assumption that brain size differences are an adequate proxy for subtler differences in brain organization turned neurobiologists toward the question why some groups of mammals such as primates, elephants, and whales have such remarkably large brains. In this meta-analysis, an extensive sample of eutherian mammals (115 species distributed in 14 orders) provided data about several different biological traits and measures of brain size such as absolute brain mass (AB), relative brain mass (RB; quotient from AB and body mass), and encephalization quotient (EQ). These data were analyzed by established multivariate statistics without taking specific phylogenetic information into account.

Precocious Ossification of the Tympanoperiotic Bone in Fetal and Newborn Dolphins: An Evolutionary Adaptation to the Aquatic Environment?

The present study, performed with a dual-energy X-ray (DXA) bone densitometer on a series of fetal and newborn striped and short-beaked common dolphins, shows that the bone density of the area of the tympanic bulla within the tympanoperiotic complex starts with 0.483 g cm(-2) in 5- to 6-month-old specimens of striped (or common) dolphin fetuses and reaches 1.841 g cm(-2) in newborn striped dolphins, with values consistently higher than in other parts of the skull or elsewhere in the skeleton.

Histological and ultrastructural aspects of the nasal complex in the harbour porpoise, Phocoena phocoena.

During the evolution of odontocetes, the nasal complex was modified into a complicated system of passages and diverticulae. It is generally accepted that these are essential structures for nasal sound production. However, the mechanism of sound generation and the functional significance of the epicranial nasal complex are not fully understood.

Functional morphology of the nasal complex in the harbor porpoise (Phocoena phocoena l.).

Toothed whales (Odontoceti, Cetacea) are the only aquatic mammals known to echolocate, and probably all of them are able to produce click sounds and to synthesize their echoes into a three-dimensional "acoustic image" of their environment. In contrast to other mammals, toothed whales generate their vocalizations (i.e.

Functional morphology of the hyolaryngeal complex of the harbor porpoise (Phocoena phocoena): implications for its role in sound production and respiration.

In several publications, it was shown that echolocation sound generation in the nasal (epicranial) complex of toothed whales (Odontoceti) is pneumatically driven. Modern hypotheses consider the larynx and its surrounding musculature to produce the initial air pressure: (a) contraction of the strong pipelike palatopharyngeal sphincter muscle complex, which connects the choanae with the epiglottic spout of the larynx, should provide much of the power for this process and (b) muscles suspending the larynx/hyoid complex from the skull base and the mandibles may support these pistonlike laryngeal movements. Here, we describe the morphology and topography of the larynx, the hyoid apparatus, and the relevant musculature in the harbor porpoise (Phocoena phocoena) with respect to odontocete vocalization and respiration.

Interlaminar differences of intrinsic properties of pyramidal neurons in the auditory cortex of mice.

Cortical information processing depends crucially upon intrinsic neuronal properties modulating a given synaptic input, in addition to integration of excitatory and inhibitory inputs. These intrinsic mechanisms are poorly understood in sensory cortex areas. We therefore investigated neuronal properties in slices of the auditory cortex (AC) of normal hearing mice using whole-cell patch-clamp recordings of pyramidal neurons in layers II/III, IV, V, and VI in the current- and voltage clamp mode.

Head morphology in perinatal dolphins: a window into phylogeny and ontogeny.

In this paper on the ontogenesis and evolutionary biology of odontocete cetaceans (toothed whales), we investigate the head morphology of three perinatal pantropical spotted dolphins (Stenella attenuata) with the following methods: computer-assisted tomography, magnetic resonance imaging, conventional X-ray imaging, cryo-sectioning as well as gross dissection. Comparison of these anatomical methods reveals that for a complete structural analysis, a combination of modern imaging techniques and conventional morphological methods is needed. In addition to the perinatal dolphins, we include series of microslides of fetal odontocetes (S.