Reduction of somatosensory evoked fields in the primary somatosensory cortex in a one-back task

• Published in: Experimental brain research Vol. 168; no. 1-2; pp. 98 - 105
• Main Authors: Huonker, Ralph, Weiss, Thomas, Miltner, Wolfgang H. R.
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.01.2006; Springer Nature B.V
• Subjects: Adult; Attention - physiology; Biological and medical sciences; Brain Mapping; Evoked Potentials, Somatosensory - physiology; Female; Fundamental and applied biological sciences. Psychology; Humans; Magnetoencephalography - methods; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; Multivariate Analysis; Physical Stimulation - methods; Psychomotor Performance - physiology; Somatosensory Cortex - physiology; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Vertebrates: nervous system and sense organs; Human; Receptive field; Cross-modal attention; Magnetoencephalography; Central nervous system; Stimulus sequence; Hand; Somatosensory evoked magnetic fields (SEF); Somatosensory system; Encephalon; Somatosensory cortex; Visual stimulus; Magnetoencephalography (MEG); Somesthetic pathway; Dipole; Magnetic field
• ISSN: 0014-4819; 1432-1106
• DOI: 10.1007/s00221-005-0072-4

In the present study, responses of the somatosensory cortex to sensory input of ten human volunteers were investigated during a one-back task with different conditions of attention. During an condition of attention subjects were requested to detect a predefined sequence of tactile stimuli applied to two different fingers of the dominant hand while a series of visual stimuli was presented simultaneously with an asynchronous stimulus-onset to the tactile stimuli. During an condition of distraction subjects received the identical series of visual and tactile stimuli like in the condition of attention but were now requested to detect a predefined stimulus sequence within the visual stimulus domain. In both conditions, somatosensory evoked magnetic fields (SEFs) to the tactile stimuli were recorded by means of a 31-channel magnetoencephalograph (MEG) from subjects' contralateral primary somatosensory cortex. The mean global field power, the dipole strength, the maximum current density, and the first component of the singular value decomposition (SVD) of magnetic fields were used to compare early components of the SEF in the conditions of attention versus distraction. Surprisingly, results revealed significant decreases of measures of all four parameters during the condition of attention as compared to the condition of distraction indicating that early responses of the primary somatosensory cortex became significantly reduced in the condition of attention. We hypothesize that changes in the centre-periphery-relationship of receptive fields in the primary somatosensory cortex may account for this unexpected result.