Previous research has indicated that visuospatial orienting of attention is not related to any single brain EEG frequency band but that each of the latter bands has a distinct oscillatory activity and time course. However, in different studies a single frequency band or diverse bands have often been investigated, spanning from alpha to gamma bands. Besides, scarce knowledge is available about the EEG oscillatory neurodynamics underpinning the diverse endogenous and exogenous orienting modes. In this study we investigated whether these orienting modes are related to a same or different oscillatory activity in the delta, theta, alpha, and beta bands. To separate the two attention modes, we administered a modified Attention Network Test (ANT) to college students while high-density (128 ch.) EEG recordings were carried out. Offline, both the EEG power spectrum and the “Compressed Density Spectral Array (CSDA)”, as well as the Morlet Wavelet transform, were computed, to visualize, globally and/or over time, the spectral information for the forenamed bands in the two orienting modes separately. These visualizations of EEG spectrum revealed that the two orienting modes have a distinct set of oscillatory neurodynamics both in neuroanatomical space and time. Indeed, during endogenous orienting of cued visual attention there was a highest increase of frequency density (measured in uV2/Hz), sustained over time and related to both the spatially informative cue and target stimulus, for all the EEG bands at the P3 and P4 scalp parietal sites, compatible with neural generators located in the intraparietal sulcus (IPS). This activity went along with a burst of phasic activity for all, but the delta, frequency bands, about 200-400 ms after target delivery at F3 and F4 prefrontal locations, compatible with generators located in the frontal eye field (FEF). During exogenous attention there was a diverse pattern of oscillations. Both the parietal and prefrontal scalp sites showed a burst of long-lasting oscillations for all, but the beta, bands going from 100 ms after the spatially neutral cue till ~ 400-500 ms after the target. Notably, beta band showed a phasic increase between ~ 100-350 ms after cue at both the prefrontal and parietal, as well temporo-parietal, scalp sites, the latter compatible with neural generators in the temporo-parietal junction (TPJ), which was largest over the right hemisphere for the posterior sites. All in all, these findings indicate that the two orienting modes of visual attention are associated with partly distinct brain neuroanatomic networks characterized by diverse oscillatory activities and time course.
Fronto-temporal-parietal control of endogenous and exogenous orienting of visuospatial attention through distinct neurodynamic modulation of brain EEG oscillations
Zani A;
2012-01-01
Abstract
Previous research has indicated that visuospatial orienting of attention is not related to any single brain EEG frequency band but that each of the latter bands has a distinct oscillatory activity and time course. However, in different studies a single frequency band or diverse bands have often been investigated, spanning from alpha to gamma bands. Besides, scarce knowledge is available about the EEG oscillatory neurodynamics underpinning the diverse endogenous and exogenous orienting modes. In this study we investigated whether these orienting modes are related to a same or different oscillatory activity in the delta, theta, alpha, and beta bands. To separate the two attention modes, we administered a modified Attention Network Test (ANT) to college students while high-density (128 ch.) EEG recordings were carried out. Offline, both the EEG power spectrum and the “Compressed Density Spectral Array (CSDA)”, as well as the Morlet Wavelet transform, were computed, to visualize, globally and/or over time, the spectral information for the forenamed bands in the two orienting modes separately. These visualizations of EEG spectrum revealed that the two orienting modes have a distinct set of oscillatory neurodynamics both in neuroanatomical space and time. Indeed, during endogenous orienting of cued visual attention there was a highest increase of frequency density (measured in uV2/Hz), sustained over time and related to both the spatially informative cue and target stimulus, for all the EEG bands at the P3 and P4 scalp parietal sites, compatible with neural generators located in the intraparietal sulcus (IPS). This activity went along with a burst of phasic activity for all, but the delta, frequency bands, about 200-400 ms after target delivery at F3 and F4 prefrontal locations, compatible with generators located in the frontal eye field (FEF). During exogenous attention there was a diverse pattern of oscillations. Both the parietal and prefrontal scalp sites showed a burst of long-lasting oscillations for all, but the beta, bands going from 100 ms after the spatially neutral cue till ~ 400-500 ms after the target. Notably, beta band showed a phasic increase between ~ 100-350 ms after cue at both the prefrontal and parietal, as well temporo-parietal, scalp sites, the latter compatible with neural generators in the temporo-parietal junction (TPJ), which was largest over the right hemisphere for the posterior sites. All in all, these findings indicate that the two orienting modes of visual attention are associated with partly distinct brain neuroanatomic networks characterized by diverse oscillatory activities and time course.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
