From:
"Sukie Crandall"
Date: 2008-02-16 00:12:28 UTC
Subject: [ferrethealth] abstract (ferret auditory cortex)
To: ferrethealth@yahoogroups.com
J Neurophysiol. 2008 Feb 13 [Epub ahead of print]
Responses of auditory cortex to complex stimuli: functional
organization revealed using intrinsic optical signals.
Nelken I, Bizley JK, Nodal FR, Ahmed B, King AJ, Schnupp JW.
Neurobiology, Hebrew University, Jerusalem, Israel.
We used optical imaging of intrinsic signals to study the
large-scale organization of ferret auditory cortex in response
to complex sounds. Cortical responses were collected during
continuous stimulation by sequences of sounds with varying
frequency, period, or interaural level differences. We used a
set of stimuli that differ in spectral structure, but have the
same periodicity and therefore evoke the same pitch percept
(click trains, sinusoidally amplitude modulated tones and iterated
ripple noise). These stimuli failed to reveal a consistent
periodotopic map across the auditory fields imaged. Rather,
gradients of period sensitivity differed for the different types of
periodic stimuli. Binaural interactions were studied both with
single contralateral, ipsilateral and diotic broadband noise bursts,
and with sequences of broadband noise bursts with varying level
presented contralaterally, ipsilaterally or in opposite phase to both
ears. Contralateral responses were generally largest and ipsilateral
responses were smallest when using single noise bursts, but the
extent of the activated area was large and comparable in all three
aural configurations. Modulating the amplitude in counter phase to
the two ears generally produced weaker modulation of the optical
signals than the modulation produced by the monaural stimuli.
These results suggest that binaural interactions seen in cortex are
most likely predominantly due to subcortical processing. Thus, our
optical imaging data do not support the theory that the primary or
non-primary cortical fields imaged are topographically organized to
form consistent maps of systematically varying sensitivity either to
stimulus pitch, or to simple binaural properties of the acoustic stimuli.
PMID: 18272880 [PubMed - as supplied by publisher]
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