Spatial Attention Related SEP Amplitude Modulations Covary with BOLD Signal in S1—A Simultaneous EEG—fMRI Study

• Published in: Cerebral cortex (New York, N.Y. 1991) Vol. 18; no. 11; pp. 2686 - 2700
• Main Authors: Schubert, Ruth, Ritter, Petra, Wüstenberg, Torsten, Preuschhof, Claudia, Curio, Gabriel, Sommer, Werner, Villringer, Arno
• Format: Journal Article
• Language: English
• Published: United States Oxford University Press 01.11.2008; Oxford Publishing Limited (England)
• Subjects: Adult; Attention - physiology; braille; correlation; Electroencephalography; Evoked Potentials, Somatosensory - physiology; Female; Fingers - physiology; Functional Laterality - physiology; Humans; Magnetic Resonance Imaging; Male; Models, Neurological; P50; primary somatosensory cortex; Probability; Somatosensory Cortex - physiology; Space Perception - physiology; spatial-selective attention; tactile; Touch - physiology; Young Adult; P50; primary somatosensory cortex; correlation; tactile; braille; spatial-selective attention
• ISSN: 1047-3211; 1460-2199; 1460-2199
• DOI: 10.1093/cercor/bhn029

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.