Spatial attention related SEP amplitude modulations covary with BOLD signal in S1--a simultaneous EEG--fMRI study

Cereb Cortex. 2008 Nov;18(11):2686-700. doi: 10.1093/cercor/bhn029. Epub 2008 Mar 27.

Abstract

Recent studies investigating the influence of spatial-selective attention on primary somatosensory processing have produced inconsistent results. The aim of this study was to explore the influence of tactile spatial-selective attention on spatiotemporal aspects of evoked neuronal activity in the primary somatosensory cortex (S1). We employed simultaneous electroencephalography (EEG)-functional magnetic resonance imaging (fMRI) in 14 right-handed subjects during bilateral index finger Braille stimulation to investigate the relationship between attentional effects on somatosensory evoked potential (SEP) components and the blood oxygenation level-dependent (BOLD) signal. The 1st reliable EEG response following left tactile stimulation (P50) was significantly enhanced by spatial-selective attention, which has not been reported before. FMRI analysis revealed increased activity in contralateral S1. Remarkably, the effect of attention on the P50 component as well as long-latency SEP components starting at 190 ms for left stimuli correlated with attentional effects on the BOLD signal in contralateral S1. The implications are 2-fold: First, the correlation between early and long-latency SEP components and the BOLD effect suggest that spatial-selective attention enhances processing in S1 at 2 time points: During an early passage of the signal and during a later passage, probably via re-entrant feedback from higher cortical areas. Second, attentional modulations of the fast electrophysiological signals and the slow hemodynamic response are linearly related in S1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Attention / physiology*
  • Electroencephalography
  • Evoked Potentials, Somatosensory / physiology*
  • Female
  • Fingers / physiology
  • Functional Laterality / physiology
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Models, Neurological
  • Probability
  • Somatosensory Cortex / physiology*
  • Space Perception / physiology*
  • Touch / physiology*
  • Young Adult