MORPHOLOGY AND PHYSIOLOGY OF LOCAL AUDITORY INTERNEURONS IN THE PROTHORACIC GANGLION OF THE CRICKET ACHETA-DOMESTICUS

Citation
O. Stiedl et al., MORPHOLOGY AND PHYSIOLOGY OF LOCAL AUDITORY INTERNEURONS IN THE PROTHORACIC GANGLION OF THE CRICKET ACHETA-DOMESTICUS, The Journal of experimental zoology, 279(1), 1997, pp. 43-53
Citations number
39
Categorie Soggetti
Zoology
ISSN journal
0022104X
Volume
279
Issue
1
Year of publication
1997
Pages
43 - 53
Database
ISI
SICI code
0022-104X(1997)279:1<43:MAPOLA>2.0.ZU;2-M
Abstract
The omega-neuron 2 (ON2) is an auditory interneuron in Acheta domestic us that could play an important role in prothoracic auditory informati on processing. ON2 neurons were intracellularly recorded and iontophor etically stained with lucifer-yellow. The morphology of ON2 is similar to that described in other cricket species. Wholemounts and transvers e sections of prothoracic ganglia show that ON2 branches cover the sam e regions as the omega-neuron 1 (ON1) branches except that ON2 has cro ssover branches in the anterior ring tract from both the ipsilateral a nd contralateral side. Auditory responses of ON2 are measured with spi king thresholds of about 60 dB SPL at 16 kHz (courtship song frequency ) and about 80 dB SPL at 5 kHz (calling song frequency) under open fie ld and closed field (monaural) stimulation. Open and closed field stim ulations show almost identical threshold curves and response magnitude s to soma-ipsilateral and soma-contralateral stimulation. These data d o not support a function of ON2 for directional hearing. In addition t o excitation, ON2 receives inhibitory inputs from both ears at 5 and 1 6 kHz. Subthreshold inhibition is obvious in responses with open and c losed field stimulation at 5 kHz. Responses show mixed excitation and inhibition at intensities above 80 dB SPL at 5 and 16 kHz. These data confirm previous immunohistochemical results showing GABAergic input t o ON2 in Gryllus bimaculatus. Two newly described local neurons (''LN1 '', ''LN2''), which are probably nonspiking and have low 5-kHz thresho lds, could be candidates for the inhibitory input to ON2. (C) 1997 Wil ey-Liss, Inc.