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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

High gamma responses to speech stimuli and the subject's behavioral performance. Data recorded from sites (a to e) (see Figure 3A) in response to target animal stimuli are plotted separately for trials that were associated with fast behavioral responses (17 trials; orange), slow responses (17 trials; purple), misses (11 trials; black), and non-target trials from a tone detection task (200 trials; blue). Lines and shaded areas represent mean high gamma ERBP and its standard error. Horizontal box plots denote the timing of behavioral responses to the target stimuli (medians, 10th, 25th, 75th, and 90th percentiles). See Figure 3A for location of the sites.
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Figure 6: High gamma responses to speech stimuli and the subject's behavioral performance. Data recorded from sites (a to e) (see Figure 3A) in response to target animal stimuli are plotted separately for trials that were associated with fast behavioral responses (17 trials; orange), slow responses (17 trials; purple), misses (11 trials; black), and non-target trials from a tone detection task (200 trials; blue). Lines and shaded areas represent mean high gamma ERBP and its standard error. Horizontal box plots denote the timing of behavioral responses to the target stimuli (medians, 10th, 25th, 75th, and 90th percentiles). See Figure 3A for location of the sites.

Mentions: Different response patterns elicited by target stimuli were noted between activity simultaneously recorded from PLST and IFG in subject L275. High gamma activity on PLST elicited by target stimuli (animals) did not significantly vary as a function of whether the subject responded rapidly or slowly or when the target was missed altogether (Figure 6, left column). In comparison, the same words when they were not relevant non-targets (tone detection task) elicited comparable early activity, but markedly diminished responses later in time [sites (a) and (c) in Figure 6]. In contrast to activity on PLST, activity within pars opercularis of IFG could be significantly modulated by the presence and timing of the behavioral response. This finding is exemplified at site (e) located on the dorsal portion of the pars opercularis (see Figure 6), where faster response times were associated with earlier peaks of activity when contrasted with slower behavioral responses. Additionally, misses were associated with markedly decreased responses compared to hits, and there was no response when the same stimulus was presented as a non-relevant, non-target during a tone detection task. For subject L258, parcelation of single-trial high gamma activity based on behavioral performance did not reveal consistent differences between PLST and IFG. This was due to highly variable responses and low response magnitudes, particularly in IFG.


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)

High gamma responses to speech stimuli and the subject's behavioral performance. Data recorded from sites (a to e) (see Figure 3A) in response to target animal stimuli are plotted separately for trials that were associated with fast behavioral responses (17 trials; orange), slow responses (17 trials; purple), misses (11 trials; black), and non-target trials from a tone detection task (200 trials; blue). Lines and shaded areas represent mean high gamma ERBP and its standard error. Horizontal box plots denote the timing of behavioral responses to the target stimuli (medians, 10th, 25th, 75th, and 90th percentiles). See Figure 3A for location of the sites.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 6: High gamma responses to speech stimuli and the subject's behavioral performance. Data recorded from sites (a to e) (see Figure 3A) in response to target animal stimuli are plotted separately for trials that were associated with fast behavioral responses (17 trials; orange), slow responses (17 trials; purple), misses (11 trials; black), and non-target trials from a tone detection task (200 trials; blue). Lines and shaded areas represent mean high gamma ERBP and its standard error. Horizontal box plots denote the timing of behavioral responses to the target stimuli (medians, 10th, 25th, 75th, and 90th percentiles). See Figure 3A for location of the sites.
Mentions: Different response patterns elicited by target stimuli were noted between activity simultaneously recorded from PLST and IFG in subject L275. High gamma activity on PLST elicited by target stimuli (animals) did not significantly vary as a function of whether the subject responded rapidly or slowly or when the target was missed altogether (Figure 6, left column). In comparison, the same words when they were not relevant non-targets (tone detection task) elicited comparable early activity, but markedly diminished responses later in time [sites (a) and (c) in Figure 6]. In contrast to activity on PLST, activity within pars opercularis of IFG could be significantly modulated by the presence and timing of the behavioral response. This finding is exemplified at site (e) located on the dorsal portion of the pars opercularis (see Figure 6), where faster response times were associated with earlier peaks of activity when contrasted with slower behavioral responses. Additionally, misses were associated with markedly decreased responses compared to hits, and there was no response when the same stimulus was presented as a non-relevant, non-target during a tone detection task. For subject L258, parcelation of single-trial high gamma activity based on behavioral performance did not reveal consistent differences between PLST and IFG. This was due to highly variable responses and low response magnitudes, particularly in IFG.

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