ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary 1. L3 is a prothoracic auditory interneuron which has an ascending axon projecting to the brain. It is rather broadly tuned and most sensitive to carrier frequencies around 16 kHz (mean threshold=60 dB) and at 4–5 kHz (mean threshold=70 dB, Fig. 1). 2. During open field stimulation L3's excitatory response increases rather linearly as sound intensity is increased and is 10–15 dB more sensitive to ipsilateral stimulation (Fig. 2). With closed field stimulation L3 is 45 dB more sensitive to ipsilateral sound at 16 kHz, and at least 20 dB more sensitive at 5 kHz (Fig. 3). With closed field sound, contralateral stimulation at subthreshold intensities (5 and 16 kHz) usually results in hyperpolarization (Fig. 3). 3. L3's excitatory response to 16 kHz on the ipsilateral side is suppressed by low frequencies on the same side and by low and high frequency sounds from the contralateral side (Fig. 4). 4. In open and closed field conditions, the number of spikes/syllable decrements in response to successive syllables of each chirp (Fig. 5). This response is dependent on the syllable period (SP) of the song, with the greatest decrement occurring in response to SPs of 50–70 ms; longer and shorter SPs cause less decrement (Figs. 6–7). At both 5 kHz and 16 kHz the ability of L3 to encode syllables (standard SD = 23 ms) within a chirp is dependent on the SP. At short SPs L3 fires throughout the chirp, while at longer SPs (50–200 ms) L3 responds with a distinct burst of firing for each pulse. At SPs of 200 ms or more, no decrement occurs (Fig. 8).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00610881
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