Sound Producing Mechanisms in Recent Reptiles: Review and Comment

Reptiles produce sound by three categories of devices: thoseinvolving massive air expulsions or movements, those involvingmodulations of intermittent air movements through a modifiedglottis, and those involving rubbing or vibration of the integument.Each ocours in numerous species and there is good evidence ofmultiple origins. Most of the devices are used as predator deterrents,but there are a few cases of sound being used as an intraspecificcommunicating device. The various structures are here discussed.One may ask the general question whether the distribution ofreptilian sensory modalities may not have forced this rathermiscellaneous distribution of signalling devices.     

Correction to: Study of Energy Harvesting from Low-Frequency Vibration with Ferromagnetic Powder and Non-magnetic Fluid

Plasmonics - The original version of this article unfortunately contained a mistake. Reference #38 is incorrect. The correct reference is given below.     

Mechanisms of Sound Production in Delphinid Cetaceans: A Review and some Anatomical Considerations

The past literature describing the possible sites of the sound-producingmechanisms in delphinid cetaceans is reviewed. The morphologyof the nasal sac system of delphinids which has been implicatedin the production of sounds, by most investigations, is discussedwith special emphasis placed on the physical characteristicsof these sounds. New data on the histological structure of theepithelia throughout the nasal region of a delphinid are presentedwith some suggestions as to its function. The presence and structureof glandular tissues are described along with a discussion oftheir potential role in the production of sound. It is concludedthat the theories implicating the nasal sac systems of odontocetecetaceans in the production of sound are additionally supportedby certain anatomical specializations adjacent to the tissuesof this system.     

Enhanced D1 and D2 Inhibitions Induced by Low-Frequency Trains of Conditioning Stimuli: Differential Effects on H- and T-Reflexes and Possible Mechanisms

Mechanically evoked reflexes have been postulated to be less sensitive to presynaptic inhibition (PSI) than the H-reflex. This has implications on investigations of spinal cord neurophysiology that are based on the T-reflex. Preceding studies have shown an enhanced effect of PSI on the H-reflex when a train of ~10 conditioning stimuli at 1 Hz was applied to the nerve of the antagonist muscle. The main questions to be addressed in the present study are if indeed T-reflexes are less sensitive to PSI and whether (and to what extent and by what possible mechanisms) the effect of low frequency conditioning, found previously for the H-reflex, can be reproduced on T-reflexes from the soleus muscle. We explored two different conditioning-to-test (C-T) intervals: 15 and 100 ms (corresponding to D1 and D2 inhibitions, respectively). Test stimuli consisted of either electrical pulses applied to the posterior tibial nerve to elicit H-reflexes or mechanical percussion to the Achilles tendon to elicit T-reflexes. The 1 Hz train of conditioning electrical stimuli delivered to the common peroneal nerve induced a stronger effect of PSI as compared to a single conditioning pulse, for both reflexes (T and H), regardless of C-T-intervals. Moreover, the conditioning train of pulses (with respect to a single conditioning pulse) was proportionally more effective for T-reflexes as compared to H-reflexes (irrespective of the C-T interval), which might be associated with the differential contingent of Ia afferents activated by mechanical and electrical test stimuli. A conceivable explanation for the enhanced PSI effect in response to a train of stimuli is the occurrence of homosynaptic depression at synapses on inhibitory interneurons interposed within the PSI pathway. The present results add to the discussion of the sensitivity of the stretch reflex pathway to PSI and its functional role.