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High-Field Functional Imaging of Pitch Processing in Auditory Cortex of the Cat.

Butler BE, Hall AJ, Lomber SG - PLoS ONE (2015)

Bottom Line: Rather, cortical areas surrounding the posterior ectosylvian sulcus responded preferentially to the IRN stimulus when compared to narrowband noise, with group analyses revealing bilateral activity centred in the posterior auditory field (PAF).This study demonstrates that fMRI is useful for identifying pitch-related processing in cat cortex, and identifies cortical areas that warrant further investigation.Moreover, we have taken the first steps in identifying a useful animal model for the study of pitch perception.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada; Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada.

ABSTRACT
The perception of pitch is a widely studied and hotly debated topic in human hearing. Many of these studies combine functional imaging techniques with stimuli designed to disambiguate the percept of pitch from frequency information present in the stimulus. While useful in identifying potential "pitch centres" in cortex, the existence of truly pitch-responsive neurons requires single neuron-level measures that can only be undertaken in animal models. While a number of animals have been shown to be sensitive to pitch, few studies have addressed the location of cortical generators of pitch percepts in non-human models. The current study uses high-field functional magnetic resonance imaging (fMRI) of the feline brain in an attempt to identify regions of cortex that show increased activity in response to pitch-evoking stimuli. Cats were presented with iterated rippled noise (IRN) stimuli, narrowband noise stimuli with the same spectral profile but no perceivable pitch, and a processed IRN stimulus in which phase components were randomized to preserve slowly changing modulations in the absence of pitch (IRNo). Pitch-related activity was not observed to occur in either primary auditory cortex (A1) or the anterior auditory field (AAF) which comprise the core auditory cortex in cats. Rather, cortical areas surrounding the posterior ectosylvian sulcus responded preferentially to the IRN stimulus when compared to narrowband noise, with group analyses revealing bilateral activity centred in the posterior auditory field (PAF). This study demonstrates that fMRI is useful for identifying pitch-related processing in cat cortex, and identifies cortical areas that warrant further investigation. Moreover, we have taken the first steps in identifying a useful animal model for the study of pitch perception.

No MeSH data available.


Related in: MedlinePlus

Summary of the areas of cat auditory cortex that respond to pitch-evoking stimuli at the individual-animal level.Individual-level analyses revealed clusters of pitch-related BOLD activity (IRN-NBN contrast) that spread across a number of areas of auditory cortex. Shading marks areas where significant peaks of BOLD activity were located in at least one animal.
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pone.0134362.g005: Summary of the areas of cat auditory cortex that respond to pitch-evoking stimuli at the individual-animal level.Individual-level analyses revealed clusters of pitch-related BOLD activity (IRN-NBN contrast) that spread across a number of areas of auditory cortex. Shading marks areas where significant peaks of BOLD activity were located in at least one animal.

Mentions: Single-animal based analysis of pitch perception revealed large clusters of BOLD activity that encompassed a number of fields of the cat auditory cortex, primarily those surrounding the posterior ectosylvian sulcus (see Fig 5 for a summary). This area has previously been considered as a candidate for processing auditory patterns in the spectral and temporal domains, such as those found in communicative signals [26]. Group-level analysis revealed that pitch-related BOLD activity is centred over the posterior auditory field (PAF). The presence of pitch-responsive neurons in PAF satisfies a number of a priori hypotheses based on human and animal studies. Maximal pitch-related activation was not observed to occur in either primary auditory cortex (A1) or the anterior auditory field (AAF), which comprise the core auditory cortex in the cat [27]. Rather, it was localized to an area of auditory cortex that is functionally upstream from A1/AAF that has been shown to receive direct projections from core areas [27]. Interestingly, the cluster of activity in the left hemisphere did extend over the portion of A1 that a previous optical imaging study [2] determined corresponds to a periodicity of 400 Hz (the pitch elicited by the IRN stimulus in the current study). The locus of maximal activity was the dorsal aspect of PAF, which is located adjacent to the low-frequency border of A1, providing analogous homology to that observed in the marmoset [12]. While the IRN-NBN contrast revealed strong, bilateral activation of PAF, the IRN-IRNo contrast failed to reveal any significant activity.


High-Field Functional Imaging of Pitch Processing in Auditory Cortex of the Cat.

Butler BE, Hall AJ, Lomber SG - PLoS ONE (2015)

Summary of the areas of cat auditory cortex that respond to pitch-evoking stimuli at the individual-animal level.Individual-level analyses revealed clusters of pitch-related BOLD activity (IRN-NBN contrast) that spread across a number of areas of auditory cortex. Shading marks areas where significant peaks of BOLD activity were located in at least one animal.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520558&req=5

pone.0134362.g005: Summary of the areas of cat auditory cortex that respond to pitch-evoking stimuli at the individual-animal level.Individual-level analyses revealed clusters of pitch-related BOLD activity (IRN-NBN contrast) that spread across a number of areas of auditory cortex. Shading marks areas where significant peaks of BOLD activity were located in at least one animal.
Mentions: Single-animal based analysis of pitch perception revealed large clusters of BOLD activity that encompassed a number of fields of the cat auditory cortex, primarily those surrounding the posterior ectosylvian sulcus (see Fig 5 for a summary). This area has previously been considered as a candidate for processing auditory patterns in the spectral and temporal domains, such as those found in communicative signals [26]. Group-level analysis revealed that pitch-related BOLD activity is centred over the posterior auditory field (PAF). The presence of pitch-responsive neurons in PAF satisfies a number of a priori hypotheses based on human and animal studies. Maximal pitch-related activation was not observed to occur in either primary auditory cortex (A1) or the anterior auditory field (AAF), which comprise the core auditory cortex in the cat [27]. Rather, it was localized to an area of auditory cortex that is functionally upstream from A1/AAF that has been shown to receive direct projections from core areas [27]. Interestingly, the cluster of activity in the left hemisphere did extend over the portion of A1 that a previous optical imaging study [2] determined corresponds to a periodicity of 400 Hz (the pitch elicited by the IRN stimulus in the current study). The locus of maximal activity was the dorsal aspect of PAF, which is located adjacent to the low-frequency border of A1, providing analogous homology to that observed in the marmoset [12]. While the IRN-NBN contrast revealed strong, bilateral activation of PAF, the IRN-IRNo contrast failed to reveal any significant activity.

Bottom Line: Rather, cortical areas surrounding the posterior ectosylvian sulcus responded preferentially to the IRN stimulus when compared to narrowband noise, with group analyses revealing bilateral activity centred in the posterior auditory field (PAF).This study demonstrates that fMRI is useful for identifying pitch-related processing in cat cortex, and identifies cortical areas that warrant further investigation.Moreover, we have taken the first steps in identifying a useful animal model for the study of pitch perception.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada; Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada.

ABSTRACT
The perception of pitch is a widely studied and hotly debated topic in human hearing. Many of these studies combine functional imaging techniques with stimuli designed to disambiguate the percept of pitch from frequency information present in the stimulus. While useful in identifying potential "pitch centres" in cortex, the existence of truly pitch-responsive neurons requires single neuron-level measures that can only be undertaken in animal models. While a number of animals have been shown to be sensitive to pitch, few studies have addressed the location of cortical generators of pitch percepts in non-human models. The current study uses high-field functional magnetic resonance imaging (fMRI) of the feline brain in an attempt to identify regions of cortex that show increased activity in response to pitch-evoking stimuli. Cats were presented with iterated rippled noise (IRN) stimuli, narrowband noise stimuli with the same spectral profile but no perceivable pitch, and a processed IRN stimulus in which phase components were randomized to preserve slowly changing modulations in the absence of pitch (IRNo). Pitch-related activity was not observed to occur in either primary auditory cortex (A1) or the anterior auditory field (AAF) which comprise the core auditory cortex in cats. Rather, cortical areas surrounding the posterior ectosylvian sulcus responded preferentially to the IRN stimulus when compared to narrowband noise, with group analyses revealing bilateral activity centred in the posterior auditory field (PAF). This study demonstrates that fMRI is useful for identifying pitch-related processing in cat cortex, and identifies cortical areas that warrant further investigation. Moreover, we have taken the first steps in identifying a useful animal model for the study of pitch perception.

No MeSH data available.


Related in: MedlinePlus