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Differential activation of human core, non-core and auditory-related cortex during speech categorization tasks as revealed by intracranial recordings.

Steinschneider M, Nourski KV, Rhone AE, Kawasaki H, Oya H, Howard MA - Front Neurosci (2014)

Bottom Line: While non-primary auditory cortex located on the posterolateral superior temporal gyrus (PLST) is clearly involved in acoustic-to-phonetic pre-lexical representations, it is unclear what role this region plays in auditory object formation.We found that activity in posteromedial HG and early activity on PLST was robust to sound stimuli regardless of their context, and minimally modulated by tasks.Activity in prefrontal cortex appears directly involved in word object selection.

View Article: PubMed Central - PubMed

Affiliation: Departments of Neurology and Neuroscience, Albert Einstein College of Medicine Bronx, NY, USA.

ABSTRACT
Speech perception requires that sounds be transformed into speech-related objects with lexical and semantic meaning. It is unclear at what level in the auditory pathways this transformation emerges. Primary auditory cortex has been implicated in both representation of acoustic sound attributes and sound objects. While non-primary auditory cortex located on the posterolateral superior temporal gyrus (PLST) is clearly involved in acoustic-to-phonetic pre-lexical representations, it is unclear what role this region plays in auditory object formation. Additional data support the importance of prefrontal cortex in the formation of auditory objects, while other data would implicate this region in auditory object selection. To help clarify the respective roles of auditory and auditory-related cortex in the formation and selection of auditory objects, we examined high gamma activity simultaneously recorded directly from Heschl's gyrus (HG), PLST and prefrontal cortex, while subjects performed auditory semantic detection tasks. Subjects were patients undergoing evaluation for treatment of medically intractable epilepsy. We found that activity in posteromedial HG and early activity on PLST was robust to sound stimuli regardless of their context, and minimally modulated by tasks. Later activity on PLST could be strongly modulated by semantic context, but not by behavioral performance. Activity within prefrontal cortex also was related to semantic context, and did co-vary with behavior. We propose that activity in posteromedial HG and early activity on PLST primarily reflect the representation of spectrotemporal sound attributes. Later activity on PLST represents a pre-lexical processing stage and is an intermediate step in the formation of word objects. Activity in prefrontal cortex appears directly involved in word object selection. The roles of other auditory and auditory-related cortical areas in the formation of word objects remain to be explored.

No MeSH data available.


Related in: MedlinePlus

Representation of acoustic stimulus attributes in HG. (A) MRI of left superior temporal plane in subject L275 showing the locations of recording contacts chronically implanted in HG. Insets: tracings of MRI cross-sections showing the location of three recording contacts (circles) relative to the gray matter of the HG (dark gray shading). (B) High gamma responses to speech sounds differing in pitch, initial stop consonant VOT and POA are shown in the left, middle and right column, respectively. Lines and shaded areas represent mean high gamma ERBP and its standard error, respectively.
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Figure 1: Representation of acoustic stimulus attributes in HG. (A) MRI of left superior temporal plane in subject L275 showing the locations of recording contacts chronically implanted in HG. Insets: tracings of MRI cross-sections showing the location of three recording contacts (circles) relative to the gray matter of the HG (dark gray shading). (B) High gamma responses to speech sounds differing in pitch, initial stop consonant VOT and POA are shown in the left, middle and right column, respectively. Lines and shaded areas represent mean high gamma ERBP and its standard error, respectively.

Mentions: Neural activity on HG primarily represented acoustic attributes of the speech stimuli (Figure 1). Figure 1A illustrates the location of the eight recording contacts that targeted HG along its long axis in subject L275. Mean high gamma power elicited by three acoustic attributes of speech is shown for each recording site (Figure 1B). Responses to the speech stimuli spoken by male talkers were consistently larger compared to those elicited by female talkers (Figure 1B, left column), reflecting differences in their fundamental frequency (male talkers: mean 125 Hz, SD 25 Hz; female talkers: mean 202 Hz, SD 36 Hz). These differences represent a contribution in the high gamma responses of phase locking to the lower fundamental frequency of the male talkers within posteromedial HG [sites (a) through (d)] (cf. Nourski and Brugge, 2011; Steinschneider et al., 2013).


Differential activation of human core, non-core and auditory-related cortex during speech categorization tasks as revealed by intracranial recordings.

Steinschneider M, Nourski KV, Rhone AE, Kawasaki H, Oya H, Howard MA - Front Neurosci (2014)

Representation of acoustic stimulus attributes in HG. (A) MRI of left superior temporal plane in subject L275 showing the locations of recording contacts chronically implanted in HG. Insets: tracings of MRI cross-sections showing the location of three recording contacts (circles) relative to the gray matter of the HG (dark gray shading). (B) High gamma responses to speech sounds differing in pitch, initial stop consonant VOT and POA are shown in the left, middle and right column, respectively. Lines and shaded areas represent mean high gamma ERBP and its standard error, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4128221&req=5

Figure 1: Representation of acoustic stimulus attributes in HG. (A) MRI of left superior temporal plane in subject L275 showing the locations of recording contacts chronically implanted in HG. Insets: tracings of MRI cross-sections showing the location of three recording contacts (circles) relative to the gray matter of the HG (dark gray shading). (B) High gamma responses to speech sounds differing in pitch, initial stop consonant VOT and POA are shown in the left, middle and right column, respectively. Lines and shaded areas represent mean high gamma ERBP and its standard error, respectively.
Mentions: Neural activity on HG primarily represented acoustic attributes of the speech stimuli (Figure 1). Figure 1A illustrates the location of the eight recording contacts that targeted HG along its long axis in subject L275. Mean high gamma power elicited by three acoustic attributes of speech is shown for each recording site (Figure 1B). Responses to the speech stimuli spoken by male talkers were consistently larger compared to those elicited by female talkers (Figure 1B, left column), reflecting differences in their fundamental frequency (male talkers: mean 125 Hz, SD 25 Hz; female talkers: mean 202 Hz, SD 36 Hz). These differences represent a contribution in the high gamma responses of phase locking to the lower fundamental frequency of the male talkers within posteromedial HG [sites (a) through (d)] (cf. Nourski and Brugge, 2011; Steinschneider et al., 2013).

Bottom Line: While non-primary auditory cortex located on the posterolateral superior temporal gyrus (PLST) is clearly involved in acoustic-to-phonetic pre-lexical representations, it is unclear what role this region plays in auditory object formation.We found that activity in posteromedial HG and early activity on PLST was robust to sound stimuli regardless of their context, and minimally modulated by tasks.Activity in prefrontal cortex appears directly involved in word object selection.

View Article: PubMed Central - PubMed

Affiliation: Departments of Neurology and Neuroscience, Albert Einstein College of Medicine Bronx, NY, USA.

ABSTRACT
Speech perception requires that sounds be transformed into speech-related objects with lexical and semantic meaning. It is unclear at what level in the auditory pathways this transformation emerges. Primary auditory cortex has been implicated in both representation of acoustic sound attributes and sound objects. While non-primary auditory cortex located on the posterolateral superior temporal gyrus (PLST) is clearly involved in acoustic-to-phonetic pre-lexical representations, it is unclear what role this region plays in auditory object formation. Additional data support the importance of prefrontal cortex in the formation of auditory objects, while other data would implicate this region in auditory object selection. To help clarify the respective roles of auditory and auditory-related cortex in the formation and selection of auditory objects, we examined high gamma activity simultaneously recorded directly from Heschl's gyrus (HG), PLST and prefrontal cortex, while subjects performed auditory semantic detection tasks. Subjects were patients undergoing evaluation for treatment of medically intractable epilepsy. We found that activity in posteromedial HG and early activity on PLST was robust to sound stimuli regardless of their context, and minimally modulated by tasks. Later activity on PLST could be strongly modulated by semantic context, but not by behavioral performance. Activity within prefrontal cortex also was related to semantic context, and did co-vary with behavior. We propose that activity in posteromedial HG and early activity on PLST primarily reflect the representation of spectrotemporal sound attributes. Later activity on PLST represents a pre-lexical processing stage and is an intermediate step in the formation of word objects. Activity in prefrontal cortex appears directly involved in word object selection. The roles of other auditory and auditory-related cortical areas in the formation of word objects remain to be explored.

No MeSH data available.


Related in: MedlinePlus