Maja Zorovic and Berthold Herwig (2013): Descending brain neurons in the
cricket Gryllus bimaculatus (de Geer): auditory responses and impact on
walking. J. Comp. Physiol. A 199 (1), 25-34.
Abstract: The activity of four types of sound-sensitive descending brain
neurons in the cricket Gryllus bimaculatus was recorded intracellularly
while animals were standing or walking on an open-loop trackball system. In
a neuron with a contralaterally descending axon, the male calling song
elicited responses that copied the pulse pattern of the song during
standing and walking. The accuracy of pulse copying increased during
walking. Neurons with ipsilaterally descending axons responded weakly to
sound only during standing. The responses were mainly to the first pulse of
each chirp, whereas the complete pulse pattern of a chirp was not copied.
During walking the auditory responses were suppressed in these neurons. The
spiking activity of all four neuron types was significantly correlated to
forward walking velocity, indicating their relevance for walking.
Additionally, injection of depolarizing current elicited walking and/or
steering in three of four neuron types described. In none of the neurons
was the spiking activity both sufficient and necessary to elicit and
maintain walking behaviour. Some neurons showed arborisations in the
lateral accessory lobes, pointing to the relevance of this brain region for
cricket audition and descending motor control.
URL: http://link.springer.com/article/10.1007/s00359-012-0765-7
For reprints please contact Berthold Hedwig (email:
Tobias Riede, Nadja Schilling & Franz Goller (2013): The acoustic effect of
vocal tract adjustments in zebra finches. J. Comp. Physiol. A 199 (1), 57-
69.
Abstract: Vocal production in songbirds requires the control of the
respiratory system, the syrinx as sound source and the vocal tract as
acoustic filter. Vocal tract movements consist of beak, tongue and hyoid
movements, which change the volume of the oropharyngeal-esophageal cavity
(OEC), glottal movements and tracheal length changes. The respective
contributions of each movement to filter properties are not completely
understood, but the effects of this filtering are thought to be very
important for acoustic communication in birds. One of the most striking
movements of the upper vocal tract during vocal behavior in songbirds
involves the OEC. This study measured the acoustic effect of OEC
adjustments in zebra finches by comparing resonance acoustics between an
utterance with OEC expansion (calls) and a similar utterance without OEC
expansion (respiratory sounds induced by a bilateral syringeal
denervation). X-ray cineradiography confirmed the presence of an OEC motor
pattern during song and call production, and a custom-built Hall-effect
collar system confirmed that OEC expansion movements were not present
during respiratory sounds. The spectral emphasis during zebra finch call
production ranging between 2.5 and 5 kHz was not present during respiratory
sounds, indicating strongly that it can be attributed to the OEC expansion.
URL: http://link.springer.com/article/10.1007/s00359-012-0768-4
For reprints please contact Tobias Riede (email:
Meike Linnenschmidt, Magnus Wahlberg & Janni Damsgaard Hansen (2013): The
modulation rate transfer function of a harbour porpoise (Phocoena
phocoena). J. Comp. Physiol. A 199 (2), 115-126.
Abstract: During echolocation, toothed whales produce ultrasonic clicks at
extremely rapid rates and listen for the returning echoes. The auditory
brainstem response (ABR) duration was evaluated in terms of latency between
single peaks: 5.5 ms (from peak I to VII), 3.4 ms (I-VI), and 1.4 ms (II-
IV). In comparison to the killer whale and the bottlenose dolphin, the ABR
of the harbour porpoise has shorter intervals between the peaks and
consequently a shorter ABR duration. This indicates that the ABR duration
and peak latencies are possibly related to the relative size of the
auditory structures of the central nervous system and thus to the animal’s
size. The ABR to a sinusoidal amplitude modulated stimulus at 125 kHz
(sensitivity threshold 63 dB re 1 μPa rms) was evaluated to determine the
modulation rate transfer function of a harbour porpoise. The ABR showed
distinct envelope following responses up to a modulation rate of 1,900 Hz.
The corresponding calculated equivalent rectangular duration of 263 μs
indicates a good temporal resolution in the harbour porpoise auditory
system similar to the one for the bottlenose dolphin. The results explain
how the harbour porpoise can follow clicks and echoes during echolocation
with very short inter click intervals.
URL: http://link.springer.com/article/10.1007/s00359-012-0772-8
For reprints please contact Meike Linnenschmidt (email:
Arne Feinkohl & Georg M. Klump (2013): Azimuthal sound localization in the
European starling (Sturnus vulgaris): II. Psychophysical results. J. Comp.
Physiol. A 199 (2), 127-138.
Abstract: Small songbirds have a difficult analysis problem: their head is
small compared to the wavelengths of sounds used for communication
providing only small interaural time and level differences. Klump and
Larsen (1992) measured the physical binaural cues in the European starling
(Sturnus vulgaris) that allow the comparison of acoustical cues and
perception. We determined the starling’s minimum audible angle (MAA) in an
operant Go/NoGo procedure for different spectral and temporal stimulus
conditions. The MAA for broadband noise with closed-loop localization
reached 17°, while the starling’s MAA for open-loop localization of
broadband noise reached 29°. No substantial difference between open-loop
and closed-loop localization was found in 2 kHz pure tones. The closed-loop
MAA improved from 26° to 19° with an increase in pure tone frequency from
1 to 4 kHz. This finding is in line with the physical cues available. While
the starlings can only make use of interaural time difference cues at lower
frequencies (e.g., 1 and 2 kHz), additional interaural level difference
cues become available at higher frequencies (e.g., 4 kHz or higher, Klump
and Larsen 1992). An improvement of the starling’s MAA with an increasing
number of standard stimulus presentations prior to the test stimulus has
important implications for determining relative (MAA) localization
thresholds.
URL: http://link.springer.com/article/10.1007/s00359-012-0774-6
For reprints please contact Georg M. Klump (email:
oldenburg.de)
Daria Genzel & Lutz Wiegrebe (2013): Size does not matter: size-invariant
echo-acoustic object classification. J. Comp. Physiol. A 199 (2), 159-168.
Abstract: Echolocating bats can not only extract spatial information from
the auditory analysis of their ultrasonic emissions, they can also
discriminate, classify and identify the three-dimensional shape of objects
reflecting their emissions. Effective object recognition requires the
segregation of size and shape information. Previous studies have shown
that, like in visual object recognition, bats can transfer an echo-acoustic
object discrimination task to objects of different size and that they
spontaneously classify scaled versions of virtual echo-acoustic objects
according to trained virtual-object standards. The current study aims to
bridge the gap between these previous findings using a different class of
real objects and a classification-instead of a discrimination paradigm.
Echolocating bats (Phyllostomus discolor) were trained to classify an
object as either a sphere or an hour-glass shaped object. The bats
spontaneously generalised this classification to objects of the same shape.
The generalisation cannot be explained based on similarities of the power
spectra or temporal structures of the echo-acoustic object images and thus
require dedicated neural mechanisms dealing with size-invariant echo-
acoustic object analysis. Control experiments with human listeners
classifying the echo-acoustic images of the objects confirm the universal
validity of auditory size invariance. The current data thus corroborate and
extend previous psychophysical evidence for sonar auditory-object
normalisation and suggest that the underlying auditory mechanisms following
the initial neural extraction of the echo-acoustic images in echolocating
bats may be very similar in bats and humans.
URL: http://link.springer.com/article/10.1007/s00359-012-0777-3
For reprints please contact Daria Genzel (email:
Kind regards
Sonja
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Dr. Sonja Amoser
Steinrieglstraße 286
3400 Weidlingbach
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