Hannah M. ter Hofstede, Holger R. Goerlitz, Fernando Montealegre-Z,
Daniel Robert & Marc W. Holderied (2011): Tympanal mechanics and neural
responses in the ears of a noctuid moth. Naturwissenschaften 98 (12),
1057-1061.
Abstract: Ears evolved in many groups of moths to detect the echolocation
calls of predatory bats. Although the neurophysiology of bat detection has
been intensively studied in moths for decades, the relationship between
sound-induced movement of the noctuid tympanic membrane and action
potentials in the auditory sensory cells (A1 and A2) has received little
attention. Using laser Doppler vibrometry, we measured the velocity and
displacement of the tympanum in response to pure tone pulses for moths that
were intact or prepared for neural recording. When recording from the
auditory nerve, the displacement of the tympanum at the neural threshold
remained constant across frequencies, whereas velocity varied with
frequency. This suggests that the key biophysical parameter for triggering
action potentials in the sensory cells of noctuid moths is tympanum
displacement, not velocity. The validity of studies on the neurophysiology
of moth hearing rests on the assumption that the dissection and recording
procedures do not affect the biomechanics of the ear. There were no
consistent differences in tympanal velocity or displacement when moths were
intact or prepared for neural recordings for sound levels close to neural
threshold, indicating that this and other neurophysiological studies provide
good estimates of what intact moths hear at threshold.
URL: http://www.springerlink.com/content/u4026g0780607103/
For reprints please contact Marc Holderied (email:
Stefan Schöneich & Berthold Hedwig (2011): Neural basis of singing in
crickets: central pattern generation in abdominal ganglia.
Naturwissenschaften 98 (12), 1069-1073.
Abstract: The neural mechanisms underlying cricket singing behavior have
been the focus of several studies, but the central pattern generator (CPG)
for singing has not been localized conclusively. To test if the abdominal
ganglia contribute to the singing motor pattern and to analyze if parts of
the singing CPG are located in these ganglia, we systematically truncated
the abdominal nerve cord of fictively singing crickets while recording the
singing motor pattern from a front-wing nerve. Severing the connectives
anywhere between terminal ganglion and abdominal ganglion A3 did not
preclude singing, although the motor pattern became more variable and
failure-prone as more ganglia were disconnected. Singing terminated
immediately and permanently after transecting the connectives between the
metathoracic ganglion complex and the first unfused abdominal ganglion A3.
The contribution of abdominal ganglia for singing pattern generation was
confirmed by intracellular interneuron recordings and current injections.
During fictive singing, an ascending interneuron with its soma and dendrite
in A3 depolarized rhythmically. It spiked 10 ms before the wing-opener
activity and hyperpolarized in phase with the wing-closer activity.
Depolarizing current injection elicited rhythmic membrane potential
oscillations and spike bursts that elicited additional syllables and
reliably reset the ongoing chirp rhythm. Our results disclose that the
abdominal ganglion A3 is directly involved in generating the singing motor
pattern, whereas the more posterior ganglia seem to provide only stabilizing
feedback to the CPG circuit. Localizing the singing CPG in the anterior
abdominal neuromeres now allows analyzing its circuitry at the level of
identified interneurons in subsequent studies.
URL: http://www.springerlink.com/content/9137h71465235j60/
For reprints please contact Berthold Hedwig (email:
Irena Schneiderová & Richard Policht (2012): Acoustic analysis of the alarm
call of the Anatolian ground squirrel Spermophilus xanthoprymnus: a
description and comparison with alarm calls of the Taurus S. taurensis and
European S. citellus ground squirrels. Naturwissenschaften 99 (1), 55-64.
Abstract: The Anatolian ground squirrel Spermophilus xanthoprymnus like
other ground-dwelling sciurids, emits alarm calls in the presence of
predators. In this study, we provide a description of the acoustic structure
of alarm call of this species and compare it to those of two closely related
species, the Taurus ground squirrel Spermophilus taurensis and the European
ground squirrel Spermophilus citellus. The alarm call of S. xanthoprymnus is
a tonal sound mostly consisting of two different elements?the first element
has low frequency modulation while the second element is highly frequency
modulated. A similar basic structure can be found in the alarm calls of some
other old world ground squirrel species of the genus Spermophilus, including
S. taurensis and S. citellus. Despite this similarity, we found that these
three species can be clearly distinguished on the basis of their alarm
calls. Differences in the acoustic structure of S. xanthoprymnus and S.
taurensis calls are especially remarkable, as these two species were
considered to be conspecific until 2007. S. xanthoprymnus and S. taurensis
were also demonstrated to have closer acoustic similarity, which is in
contrast to results based on molecular data indicating that S. taurensis is
most closely related to S. citellus.
URL: http://www.springerlink.com/content/x814289458074718/
For reprints please contact Irena Schneiderová (email:
Kind regards
Sonja Amoser
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Dr. Sonja Amoser
Steinrieglstraße 286
3400 Weidlingbach
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