TY - JOUR

T1 - The effect of stimulus context on pitch representations in the human auditory cortex

AU - Garcia, Daphne

AU - Hall, Deborah A.

AU - Plack, Christopher J.

PY - 2010/6

Y1 - 2010/6

N2 - Neuroimaging studies of pitch coding seek to identify pitch-related responses separate from responses to other properties of the stimulus, such as its energy onset, and other general aspects of the listening context. The current study reports the first attempt to evaluate these modulatory influences using functional magnetic resonance imaging (fMRI) measures of cortical pitch representations. Stimulus context was manipulated using a 'classical stimulation paradigm' (whereby successive pitch stimuli were separated by gaps of silence) and a 'continuous stimulation paradigm' (whereby successive pitch stimuli were interspersed with noise to maintain a stable envelope). Pitch responses were measured for two types of pitch-evoking stimuli; a harmonic-complex tone and a complex Huggins pitch. Results for a group of 15 normally hearing listeners revealed that context effects were mostly observed in primary auditory regions, while the most significant pitch responses were localized to posterior nonprimary auditory cortex, specifically planum temporale. Sensitivity to pitch was greater for the continuous stimulation conditions perhaps because they better controlled for concurrent responses to the noise energy onset and reduced the potential problem of a non-linear fMRI response becoming saturated. These results provide support for hierarchical processing within human auditory cortex, with some parts of primary auditory cortex engaged by general auditory energy, some parts of planum temporale specifically responsible for representing pitch information and adjacent regions that are responsible for complex higher-level auditory processing such as representing pitch information as a function of listening context. 

AB - Neuroimaging studies of pitch coding seek to identify pitch-related responses separate from responses to other properties of the stimulus, such as its energy onset, and other general aspects of the listening context. The current study reports the first attempt to evaluate these modulatory influences using functional magnetic resonance imaging (fMRI) measures of cortical pitch representations. Stimulus context was manipulated using a 'classical stimulation paradigm' (whereby successive pitch stimuli were separated by gaps of silence) and a 'continuous stimulation paradigm' (whereby successive pitch stimuli were interspersed with noise to maintain a stable envelope). Pitch responses were measured for two types of pitch-evoking stimuli; a harmonic-complex tone and a complex Huggins pitch. Results for a group of 15 normally hearing listeners revealed that context effects were mostly observed in primary auditory regions, while the most significant pitch responses were localized to posterior nonprimary auditory cortex, specifically planum temporale. Sensitivity to pitch was greater for the continuous stimulation conditions perhaps because they better controlled for concurrent responses to the noise energy onset and reduced the potential problem of a non-linear fMRI response becoming saturated. These results provide support for hierarchical processing within human auditory cortex, with some parts of primary auditory cortex engaged by general auditory energy, some parts of planum temporale specifically responsible for representing pitch information and adjacent regions that are responsible for complex higher-level auditory processing such as representing pitch information as a function of listening context. 

KW - COMPLEX SOUNDS

KW - FREQUENCY DISCRIMINATION

KW - AMPLITUDE-MODULATION

KW - TEMPORAL STRUCTURE

KW - HESCHLS GYRUS

KW - HUMAN BRAIN

KW - FMRI

KW - ORGANIZATION

KW - ACTIVATION

KW - RESPONSES

UR - http://www.scopus.com/inward/record.url?scp=77951974652&partnerID=8YFLogxK

U2 - 10.1016/j.neuroimage.2010.02.079

DO - 10.1016/j.neuroimage.2010.02.079

M3 - Journal article

VL - 51

SP - 808

EP - 816

JO - NeuroImage

JF - NeuroImage

SN - 1053-8119

IS - 2

ER -