BOLD correlates of edge detection in human auditory cortex.
Edges are important cues defining coherent auditory objects. As a model of auditory edges, sound on- and offset are particularly suitable to study their neural underpinnings because they contrast a specific physical input against no physical input. Change from silence to sound, that is onset, has extensively been studied and elicits transient neural responses bilaterally in auditory cortex. However, neural activity associated with sound onset is not only related to edge detection but also to novel afferent inputs. Edges at the change from sound to silence, that is offset, are not confounded by novel physical input and thus allow to examine neural activity associated with sound edges per se. In the first experiment, we used silent acquisition functional magnetic resonance imaging and found that the offset of pulsed sound activates planum temporale, superior temporal sulcus and planum polare of the right hemisphere. In the planum temporale and the superior temporal sulcus, offset response amplitudes were related to the pulse repetition rate of the preceding stimulation. In the second experiment, we found that these offset-responsive regions were also activated by single sound pulses, onset of sound pulse sequences and single sound pulse omissions within sound pulse sequences. However, they were not active during sustained sound presentation. Thus, our data show that circumscribed areas in right temporal cortex are specifically involved in identifying auditory edges. This operation is crucial for translating acoustic signal time series into coherent auditory objects.
Herdener
Marcus
M
University Hospital of Psychiatry Bern, 3000 Bern, Switzerland. herdener@puk.unibe.ch
Esposito
Fabrizio
F
Di Salle
Francesco
F
Lehmann
Christoph
C
Bach
Dominik R
DR
Scheffler
Klaus
K
Seifritz
Erich
E
D000328:Adult; D001288:Attention / Q000502:physiology; D001303:Auditory Cortex / Q000502:physiology*; D001306:Auditory Pathways / Q000502:physiology; D001307:Auditory Perception / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008144:Loudness Perception / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*
D010100:Oxygen