Abstract #4674
Evidence for Sensitivity Adjustment in the Auditory Cortex during Audio-Visual cross-modal fMRI
Johannes Bernarding 1 , Sebastian Baecke 1 , Claus Tempelmann 2 , and Andre Brechmann 3
1
Medical Faculty, Institute for Biometry and
Medical Informatics, Otto-von-Guericke University,
Magdeburg, Sachsen-Anhalt, Germany,
2
Medical
Faculty, Clinic for Neurology, Otto-von-Guericke
University, Magdeburg, Sachsen-Anhalt, Germany,
3
Leibniz
Institute for Neurobiology, Magdeburg, Sachsen-Anhalt,
Germany
In a cross-modal audio-visual fMRI study an unusual
linear ramp-like increase of the hemodynamic response
function (HRF) was observed in the auditory cortex
during isolated visual stimulation while during coupled
audio-visual stimulation the well-known block-design HRF
was seen. It is hypothesized that expecting coupled
visual-acoustic stimuli while only an isolated visual
stimulus was presented led to an decrease of the
cortical sensitivity threshold thus increasing
unconsciously the perception of the ambient constant
scanner noise. This result may be interpreted as
evidence that internal expectations can lead to strongly
changed perceptions even if external stimuli remain
constant.
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