Odontocete mandibles serve multiple functions, including feeding and hearing. We consider that these two major functions have their primary influence in different parts of the mandibles: the anterior feeding component and the posterior sound reception component, though these divisions are not mutually exclusive. One hypothesis is that sound enters the hearing apparatus via the pan bone of the posterior mandibles (Norris, Evolution and Environment,1968, pp 297-324). Another viewpoint, based on finite element models, suggests that sound enters primarily through the gular region and the opening created by the absent medial lamina of the posterior mandibles. This unambiguous link between form and function has catalyzed this study, which uses Geometric Morphometrics to quantify mandibular shape across all major lineages of Odontoceti. The majority of shape variation was found in the anterior (feeding) region: Jaw Flare (45.0%) and Symphysis Elongation (35.5%). Shape differences in the mandibular foramen, within the posterior (sound reception) region, also accounted for a small portion of the total variation (10.9%). The mandibles are an integral component of the sound reception apparatus in toothed whales and the geometry of the mandibular foramen likely plays a role in hearing. Furthermore, model goodness-of-fit tests indicate that mandibular foramina shapes, which appear conserved, evolved under a selective regime, possibly driven by sound reception requirements across Odontoceti.
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http://dx.doi.org/10.1002/jmor.20040 | DOI Listing |
Biomedicines
December 2024
Department of Psychiatry, Division of Molecular Therapeutics, New York State Psychiatric Institute, Columbia University, New York, NY 10032, USA.
Background/objectives: Learning is classically modeled to consist of an acquisition period followed by a mastery period when the skill no longer requires conscious control and becomes automatic. Dopamine neurons projecting to the ventral striatum (VS) produce a teaching signal that shifts from responding to rewarding or aversive events to anticipating cues, thus facilitating learning. However, the role of the dopamine-receptive neurons in the ventral striatum, particularly in encoding decision-making processes, remains less understood.
View Article and Find Full Text PDFActa Otorhinolaryngol Ital
December 2024
Unit of Audiology, Regional Centre of Cochlear Implants and ENT Diseases, Department of Experimental and Clinical Medicine, Magna Graecia University, Catanzaro, Italy.
Objectives: This research aims to validate the digits-in-noise (DIN) test for the Italian language and develop a version capable of independently assessing both ears while maintaining acceptable administration times.
Methods: Individual digits from 0 to 9 in Italian were recorded and adjusted to equalise recognition probabilities. An iOS application (APP) was developed for the independent ear test using triplets in noise.
PLoS Comput Biol
January 2025
Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland, United States of America.
Characterizing neuronal responses to natural stimuli remains a central goal in sensory neuroscience. In auditory cortical neurons, the stimulus selectivity of elicited spiking activity is summarized by a spectrotemporal receptive field (STRF) that relates neuronal responses to the stimulus spectrogram. Though effective in characterizing primary auditory cortical responses, STRFs of non-primary auditory neurons can be quite intricate, reflecting their mixed selectivity.
View Article and Find Full Text PDFJ Acoust Soc Am
December 2024
Key Laboratory of Underwater Acoustic Communication and Marine Information Technology of the Ministry of Education, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China.
Although air sinuses are prevalent in odontocetes and are an integral component of their sound reception system, the acoustic function of these air-filled structures remains largely unknown. To address this, we developed a numerical model using computed tomography data from a Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) to investigate the role of the air sinuses in sound reception. By comparing sound reception characteristics between model cases with and without the air sinuses, we found that the air sinuses improved sound reception directivity.
View Article and Find Full Text PDFJ Neurodev Disord
December 2024
Department of Psychiatry and Behavioral Neuroscience, College of Medicine, University of Cincinnati, Cincinnati, OH, USA.
Specialization of the brain for language is early emerging and essential for language learning in young children. Fragile X Syndrome (FXS) is a neurogenetic disorder marked by high rates of delays in both expressive and receptive language, but neural activation patterns during speech and language processing are unknown. We report results of a functional Near Infrared Spectroscopy (fNIRS) study of responses to speech and nonspeech sounds in the auditory cortex in a sample of 2- to 10-year-old children with FXS and typically developing controls (FXS n = 23, TDC n = 15, mean age = 6.
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