Somatosensory stimulation suppresses the excitability of pyramidal cells in the hippocampal CA1 region in rats

The hippocampal region of the brain is important for encoding environment inputs and memory formation. However, the underlying mechanisms are unclear. To investigate the behavior of indi-vidual neurons in response to somatosensory inputs in the hippocampal CA1 region, we recorded and analyzed changes in local ifeld potentials and the ifring rates of individual pyramidal cells and interneurons during tail clamping in urethane-anesthetized rats. We also explored the mechanisms underlying the neuronal responses. Somatosensory stimulation, in the form of tail clamping, chan-ged local ifeld potentials into theta rhythm-dominated waveforms, decreased the spike ifring of py-ramidal cells, and increased interneuron ifring. In addition, somatosensory stimulation attenuated orthodromic-evoked population spikes. These results suggest that somatosensory stimulation sup-presses the excitability of pyramidal cells in the hippocampal CA1 region. Increased inhibition by local interneurons might underlie this effect. These ifndings provide insight into the mechanisms of signal processing in the hippocampus and suggest that sensory stimulation might have thera-peutic potential for brain disorders associated with neuronal hyperexcitability.

A New Technique for Attention Management and Somatosensory Processing in Hypnotherapy: Mental Access/Somatosensory Access (MASSA)

The author introduces a new hypnotherapeutic technique termed “Mental Access/Somatosensory Access” (MASSA). MASSA is designed to utilize an external somatosensory stimulus in the context of hypnotherapy, based on a Bottom-Up/Top-Down Paradigm, which complements and mutually reinforces hypnotic inductions by using imbedded suggestions. The intervention’s algorithm includes a combination of real-time stimulation through one of the following somatosensory modalities: sensorimotor activation of the palms, visual, auditory, vibration, thermal, olfaction or oropharyngeal. These modalities are accompanied by guided hypnotic dissociation and suggestions. Somatosensory stimulation amplifies patients’ engagement in the procedure, focusing their attention on a stimulus and on the hypnotic experience during the intervention. A stream of closed questions with imbedded suggestions, presented by the therapist, is designed using suggestive presuppositions, termed by the author “The Create and Verify Principle” (CVP). This principle facilitates effective pacing and helps transform patients’ sensory and mental experiences. Imbedded suggestions followed by real-time stimulation, maintain a focus on the somatosensory content, boost the hypnotic experience, and gradually combine awareness of the somatosensory stimulation experience (Bottom-Up regulation) with memory, imagination, emotions and meanings, for mental access of resources and adaptive coping (Top-Down regulation). In the first part of this article, the author briefly introduces the neurophysiological mechanism behind the suggestive, somatosensory, attention-management intervention and provides an example of a basic algorithm of the MASSA technique. The second part includes clinical samples with scripts of successfully treated patients, who experienced tension headache, psychogenic balance disorder, tinnitus. .

Combined monitoring of evoked potentials during microsurgery for lesions adjacent to the brainstem and intracranial aneurysms

Background Neurophysiologic monitoring during surgery is to prevent permanent neurological injury resulting from surgical manipulation. To improve the accuracy and sensitivity of intraoperative neuromonitoring, combined monitoring of transcranial electrical stimulation motor evoked potentials （TES-MEPs）, somatosensory evoked potentials （SSEPs） and brainstem auditory evoked potentials （BAEPs） was attempted in microsurgery for lesions adjacent to the brainstem and intracranial aneurysms. Methods Monitoring of combined TES-MEPs with SSEPs was attempted in 68 consecutive patients with lesions adjacent to the brainstem as well as intracranial aneurysms. Among them, 31 patients （31 operations, 28 of posterior cranial fossa tumors, 3 of posterior circulation aneurysms） were also subjected to monitoring of BAEPs. The correlation of monitoring results and clinical outcome was studied prospectively. Results Combined monitoring of evoked potentials （EPs） was done in 64 （94.1%） of the 68 patients. MEPs monitoring was impossible for 4 patients （5.9%）. No complication was observed during the combined monitoring in all the patients. In 45 （66.2%） of the 68 patients, EPs were stable, and they were neurologically intact. Motor dysfunction was detected by MEPs in 8 patients, SSEPs in 5, and BAEPs in 4, respectively. Conclusions A close relationship exists between postoperative motor function and the results of TES-MEPs monitoring TES-MEPs are superior to SSEPs and BAEPs in detecting motor dysfunction, but combined EPs serve as a safe, effective and invasive method for intraoperative monitoring of the function of the motor nervous system. Monitoring of combined EPs during microsurgery for lesions adjacent to the brainstem and intracranial aneurysms may detect potentially hazardous maneuvers and improve the safety of subsequent procedures.