Vibrations influences regional blood flow and oxidative metabolism in the brain

Scientists from the medical university that awards the annual Nobel prizes in the field of physiology and medicine (Karolinska Institute, Sweden) aimed to study the brain patterns of activity as a result of hand stimulation by a vibration. In particular, the authors wanted to illustrate in positron emission tomography (PET) whether vibrational stimulation will cause increases and decreases in regional cerebral blood flow (rCBF) and whether these changes will correlate with changes in regional cerebral oxygen metabolism (rCMRO). In addition, the authors wished to map in detail the brain structures showing significant changes in rCBF and rCMRO during vibrational stimulation.

• Right hand vibration stimulation increased rCBF and rCMRO in the somatosensory system, but decreased rCBF and rCMRO in other systems, including the prefrontal and paralimbic structures.
• The increases and decreases in rCBF correlated with the increases and decreases in rCMRO, respectively.

Prepared on the basis of:

Vibratory stimulation increases and decreases the regional cerebral blood flow and oxidative metabolism: a positron emission tomography (PET) study. Seitz RJ, Roland PE. Acta Neurol Scand. 1992 Jul;86(1):60-7.

Study population

The study involved 5 neurologically healthy right-handed men aged 20-35 years.

Test procedure

The subjects were comfortably placed on the PET scanner bed in a supine position. During the examination, their eyes were closed and covered from the light thanks to the use of a special helmet on the head. In addition, they breathed through the tube and could not move or speak. A catheter was placed in the right brachial vein to deliver markers of the brain activity being tested.

A vibration stimulus was applied to the right hand, and rCBF as well as rCMRO were measured with PET during vibration delivery as well as during control rest periods (without vibration).

Use of vibration in the study

The vibration stimulation of the right hand was started 10 s before the administration of the markers and continued for the duration of the measurements. A vibrator (Model 91, Daito, Japan) was used which generated 130 Hz vibrations with an amplitude of 2 mm.

Results

The vibrational stimulation induced increases and decreases in rCBF correlating with increases and decreases in rCMRO, respectively.

The increases were in the left primary somatosensory area, the left secondary somatosensory area, the left retroinsular field, the left anterior parietal cortex, the left primary motor area, and the left supplementary motor area.

On the other hand, decreases were observed in the superior parietal cortex, in the areas of paralimbic association and in the left globus pallidus.

The changes in rCBF and rCMRO were balanced in such a way that the global mean CBF and CMRO did not change.

Comment

Vibration frequencies above 40 Hz specifically activate the muscle spindle terminals and the cutaneous Pacinian receptors. Signals from these receptors are synchronously transmitted through the nerves to the somatosensory cortex. In the presented study, the authors observed changes in the brain’s oxidative metabolism correlating with regional changes in synaptic activity, resulting from the delivery of vibrations to the hands of healthy men.

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