Attention and visual interference stimulation affect somatosensory processing: a magnetoencephalographic study

In our previous study, continuous visual (cartoon and random dot motion) and auditory (music) stimulation changed the somatosensory evoked magnetic fields following electrical stimulation of the median nerve in human subjects. They enhanced the middle-latency components (3M and 4M) generated in the contralateral primary somatosensory cortex, and reduced the MI component generated in the ipsilateral secondary somatosensory cortex. We speculated that such interference effects were caused by activation of polymodal neurons in areas 5 and/or 7 of the parietal lobe as well as in the medial superior temporal region and superior temporal sulcus. However, we could not exclude the effect of attention on such interference effects. In the present study, to know the effect of attention on visual and auditory interference in these changes, we stimulated the bilateral median nerves unilaterally in a random order, and asked subjects to count the number of times the left median nerve was stimulated while visual or auditory interference was applied. Five components (1M-5M) were identified in the hemisphere contralateral to the stimulated nerve and only one component (MI) was found in the ipsilateral hemisphere. The 3M and 4M components (33-75 ms in latency) were enhanced by both attention and visual interference stimulation but not by auditory stimulation. The 5M component (70-115 ms) and MI component (70-133 ms) were enhanced by attention, but were not changed by attention together with visual or auditory interference. Summarizing the results of our previous study and the present study, (1) visual interference alone enhanced the 3M and 4M but reduced the MI, and (2) attention alone also enhanced the 3M and 4M, and enhanced the 5M and MI. As a result, (3) visual interference with attention enhanced the 3M and 4M more, and showed no significant change of the 5M and MI. This was compatible with a summation of the effects caused by visual interference alone and attention alone, but some interactions between visual interference and attention might have taken place. The locations of dipoles of all components were not significantly changed by attention or any interference stimulation. These findings support the idea that there are significant interactions of activities relating to somatosensory stimulation, visual stimulation and cognitive function, in both the primary and the secondary somatosensory cortex in humans.

[1]  H Suzuki,et al.  Effects of tactile interference stimulation on somatosensory evoked magnetic fields following tibial nerve stimulation. , 1996, Electroencephalography and clinical neurophysiology.

[2]  T. P. S. Powell,et al.  The cortico-cortical connections of area 7b, PF, in the parietal lobe of the monkey , 1987, Brain Research.

[3]  J. Hyvärinen,et al.  Function of the parietal associative area 7 as revealed from cellular discharges in alert monkeys. , 1974, Brain : a journal of neurology.

[4]  Akinori Nakamura,et al.  Effects of tactile interference stimulation on somatosensory evoked magnetic fields , 1996 .

[5]  R. Hari,et al.  Separate finger representations at the human second somatosensory cortex , 1990, Neuroscience.

[6]  J E Desmedt,et al.  The cognitive P40, N60 and P100 components of somatosensory evoked potentials and the earliest electrical signs of sensory processing in man. , 1983, Electroencephalography and clinical neurophysiology.

[7]  F Mauguière,et al.  Activation of a distributed somatosensory cortical network in the human brain: a dipole modelling study of magnetic fields evoked by median nerve stimulation. Part II: Effects of stimulus rate, attention and stimulus detection. , 1997, Electroencephalography and clinical neurophysiology.

[8]  H Suzuki,et al.  Human cortical area responding to stimuli in apparent motion , 1997, Neuroreport.

[9]  V. Jousmäki,et al.  Activation of a distributed somatosensory cortical network in the human brain. A dipole modelling study of magnetic fields evoked by median nerve stimulation. Part I: Location and activation timing of SEF sources. , 1997, Electroencephalography and clinical neurophysiology.

[10]  R. Kakigi,et al.  Magnetic response of human extrastriate cortex in the detection of coherent and incoherent motion , 2000, Neuroscience.

[11]  F. Mauguière,et al.  Mapping study of somatosensory evoked potentials during selective spatial attention. , 1991, Electroencephalography and clinical neurophysiology.

[12]  T. P. S. Powell,et al.  The projection of the primary somatic sensory cortex upon area 5 in the monkey , 1985, Brain Research Reviews.

[13]  H Burton,et al.  Tactile attention tasks enhance activation in somatosensory regions of parietal cortex: a positron emission tomography study. , 1999, Cerebral cortex.

[14]  Ryusuke Kakigi,et al.  Effects of visual and auditory stimulation on somatosensory evoked magnetic fields , 1999, Clinical Neurophysiology.

[15]  Mark W. Woolrich,et al.  Attention to touch modulates activity in both primary and secondary somatosensory areas. , 2000 .

[16]  H Suzuki,et al.  Effects of movement and movement imagery on somatosensory evoked magnetic fields following posterior tibial nerve stimulation. , 1997, Brain research. Cognitive brain research.

[17]  Sachiko Koyama,et al.  Gating of somatosensory evoked responses during active finger movements: magnetoencephalographic studies , 1995, Journal of the Neurological Sciences.

[18]  J. Sarvas.  Basic mathematical and electromagnetic concepts of the biomagnetic inverse problem. , 1987, Physics in medicine and biology.

[19]  Hiroshi Shibasaki,et al.  Attention modulates both primary and second somatosensory cortical activities in humans: a magnetoencephalographic study. , 1998, Journal of neurophysiology.

[20]  P Berg,et al.  Magnetic source imaging of tactile input shows task‐independent attention effects in SII , 2000, Neuroreport.

[21]  R. Hari,et al.  Functional Organization of the Human First and Second Somatosensory Cortices: a Neuromagnetic Study , 1993, The European journal of neuroscience.

[22]  C Tomberg,et al.  Mapping early somatosensory evoked potentials in selective attention: critical evaluation of control conditions used for titrating by difference the cognitive P30, P40, P100 and N140. , 1989, Electroencephalography and clinical neurophysiology.

[23]  T. Powell,et al.  The ipsilateral cortico-cortical connections of area 7b, PF, in the parietal and tempral lobes of the monkey , 1990, Brain Research.