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Distinct gamma-band components reflect the short-term memory maintenance of different sound lateralization angles.

Kaiser J, Heidegger T, Wibral M, Altmann CF, Lutzenberger W - Cereb. Cortex (2008)

Bottom Line: Distinct GBA components were found for each sample stimulus in different sensors over parieto-occipital cortex contralateral to the side of stimulation peaking during the middle 200-300 ms of the delay phase.The differentiation between "preferred" and "nonpreferred" stimuli during the final 100 ms of the delay phase correlated with task performance.These findings suggest that the observed GBA components reflect the activity of distinct networks tuned to spatial sound features which contribute to the maintenance of task-relevant information in short-term memory.

View Article: PubMed Central - PubMed

Affiliation: Institute of Medical Psychology, Johann Wolfgang Goethe-University, 60528 Frankfurt am Main, Germany. j.kaiser@med.uni-frankfurt.de

ABSTRACT
Oscillatory activity in human electro- or magnetoencephalogram has been related to cortical stimulus representations and their modulation by cognitive processes. Whereas previous work has focused on gamma-band activity (GBA) during attention or maintenance of representations, there is little evidence for GBA reflecting individual stimulus representations. The present study aimed at identifying stimulus-specific GBA components during auditory spatial short-term memory. A total of 28 adults were assigned to 1 of 2 groups who were presented with only right- or left-lateralized sounds, respectively. In each group, 2 sample stimuli were used which differed in their lateralization angles (15 degrees or 45 degrees) with respect to the midsagittal plane. Statistical probability mapping served to identify spectral amplitude differences between 15 degrees versus 45 degrees stimuli. Distinct GBA components were found for each sample stimulus in different sensors over parieto-occipital cortex contralateral to the side of stimulation peaking during the middle 200-300 ms of the delay phase. The differentiation between "preferred" and "nonpreferred" stimuli during the final 100 ms of the delay phase correlated with task performance. These findings suggest that the observed GBA components reflect the activity of distinct networks tuned to spatial sound features which contribute to the maintenance of task-relevant information in short-term memory.

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Amplitudes and standard errors of the differentiation index for ten 100-ms time windows between 0.3 and 1.2 s after trial onset for groups of 10 good, 8 medium, and 10 bad task performers.
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fig7: Amplitudes and standard errors of the differentiation index for ten 100-ms time windows between 0.3 and 1.2 s after trial onset for groups of 10 good, 8 medium, and 10 bad task performers.

Mentions: As the correlation between performance and differentiation score was observed for a time window when in the group average, there was no differentiation between the 2 sample stimuli; for exploratory purposes, we split the subject group into 3 groups of 10 good, 8 medium, and 10 poor performers. The mean amplitudes and standard errors of the differentiation index in these 3 groups are plotted in Figure 7 for ten 100-ms time windows between 0.3 s after trial onset (onset of S1) and 1.2 s (end of the delay phase). Good performers upheld the consistent differentiation for longer than average or poor performers whose differentiation score decreased or even changed its sign prior to the onset of S2. The figure further suggests that there were no substantial differences in amplitude variability between groups.


Distinct gamma-band components reflect the short-term memory maintenance of different sound lateralization angles.

Kaiser J, Heidegger T, Wibral M, Altmann CF, Lutzenberger W - Cereb. Cortex (2008)

Amplitudes and standard errors of the differentiation index for ten 100-ms time windows between 0.3 and 1.2 s after trial onset for groups of 10 good, 8 medium, and 10 bad task performers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2536701&req=5

fig7: Amplitudes and standard errors of the differentiation index for ten 100-ms time windows between 0.3 and 1.2 s after trial onset for groups of 10 good, 8 medium, and 10 bad task performers.
Mentions: As the correlation between performance and differentiation score was observed for a time window when in the group average, there was no differentiation between the 2 sample stimuli; for exploratory purposes, we split the subject group into 3 groups of 10 good, 8 medium, and 10 poor performers. The mean amplitudes and standard errors of the differentiation index in these 3 groups are plotted in Figure 7 for ten 100-ms time windows between 0.3 s after trial onset (onset of S1) and 1.2 s (end of the delay phase). Good performers upheld the consistent differentiation for longer than average or poor performers whose differentiation score decreased or even changed its sign prior to the onset of S2. The figure further suggests that there were no substantial differences in amplitude variability between groups.

Bottom Line: Distinct GBA components were found for each sample stimulus in different sensors over parieto-occipital cortex contralateral to the side of stimulation peaking during the middle 200-300 ms of the delay phase.The differentiation between "preferred" and "nonpreferred" stimuli during the final 100 ms of the delay phase correlated with task performance.These findings suggest that the observed GBA components reflect the activity of distinct networks tuned to spatial sound features which contribute to the maintenance of task-relevant information in short-term memory.

View Article: PubMed Central - PubMed

Affiliation: Institute of Medical Psychology, Johann Wolfgang Goethe-University, 60528 Frankfurt am Main, Germany. j.kaiser@med.uni-frankfurt.de

ABSTRACT
Oscillatory activity in human electro- or magnetoencephalogram has been related to cortical stimulus representations and their modulation by cognitive processes. Whereas previous work has focused on gamma-band activity (GBA) during attention or maintenance of representations, there is little evidence for GBA reflecting individual stimulus representations. The present study aimed at identifying stimulus-specific GBA components during auditory spatial short-term memory. A total of 28 adults were assigned to 1 of 2 groups who were presented with only right- or left-lateralized sounds, respectively. In each group, 2 sample stimuli were used which differed in their lateralization angles (15 degrees or 45 degrees) with respect to the midsagittal plane. Statistical probability mapping served to identify spectral amplitude differences between 15 degrees versus 45 degrees stimuli. Distinct GBA components were found for each sample stimulus in different sensors over parieto-occipital cortex contralateral to the side of stimulation peaking during the middle 200-300 ms of the delay phase. The differentiation between "preferred" and "nonpreferred" stimuli during the final 100 ms of the delay phase correlated with task performance. These findings suggest that the observed GBA components reflect the activity of distinct networks tuned to spatial sound features which contribute to the maintenance of task-relevant information in short-term memory.

Show MeSH