Transcranial Electrical Stimulation for Noninvasive Study of Menopausal/Perimenopausal Symptoms

The purpose of this study is to assess the tolerability of transcranial electrical stimulation of the brain, and explore the response of TES on menopausal/perimenopausal symptoms including vasomotor effects , depression/anxiety, memory-problems. Electrical stimulation comprises a pattern of electrical currents that are delivered into the skin non-invasively using an array of electrodes adhered to the skin surface. Pain administration and sensory testing may be performed using thermodes, which are devices attached to limbs whose temperature is controlled using a computer (heat and cold pain). Temperature will be varied across time and heat/cold delivered to assess any changes in self-reported pain and/or non-invasive Electroencephalography (EEG) and functional Near-Infrared Spectroscopy (fNIRS). Examining the association of locations of current delivery with changes in self-reported pain and EEG/fNIRS recordings will help assess the spatiotemporal dynamics in the brain relevant to pain perception and the nature of their effects on pain (e.g. increase or decrease). Prior to testing the effects on pain, the individual's primary motor cortex may be localized by delivering short pulses at locations close to the motor cortex and measuring muscle responses using electromyography (EMG) electrodes placed on muscles (e.g. on the arms and legs).

The participant's resting state and pain-evoked brain activity will also be recorded using non-invasive Electroencephalography (EEG) and functional Near-Infrared Spectroscopy (fNIRS).

The stimulation techniques - called SharpFocus Transcranial Electrical Stimulation (SharpFocus TES) - consist of patch arrays (a set of electrodes arranged in a grid and embedded in a flexible substrate that conforms to the skin surface) or individual electrodes being installed at various locations including the head, arms, and legs. Some of the electrodes on the scalp inject current for brain stimulation. The rest of the electrodes are for recording. Conductive cream, gel, or hydrogel is placed between the electrode and skin to improve adhesion and conductivity. Additionally, or alternatively, classic cup (e.g. gold-cup) electrodes (10 mm diameter or 6 mm diameter), used routinely in the clinic, might also be used, especially for participants with thick or long hair. A multichannel electrical stimulator connects to the electrode array to deliver pulses of electrical current that are varied in timing, intensity, and location to allow fine-grained control of the site(s) of stimulation in the brain.

For sensory effects, participants will be asked to report any modulation of pain sensation they feel on electrical stimulation. Experiments will be performed to measure effects on muscle activity and perceived sensations.

Results from these experiments will be used to verify and refine computational models that have been developed to simulate biophysical effects of SharpFocus TES. Furthermore, it will aid in the understanding of how the central nervous system affects several of the symptoms seen in menopause/perimenopause. The ultimate goal of this research is to create a wearable interface that can stimulate parts of the cortex for a variety of applications pertaining to menopause/perimenopause.

• Pain Catastrophizing Scale [Time frame: Upon enrollment to 22 days]
• Impulsive Behavior Scale [Time frame: Upon enrollment to 22 days]
• Brief Pain Inventory [Time frame: Upon enrollment to 22 days.]
• Electromyography Recording [Time frame: Upon enrollment to 22 days]
• Sternal Skin Conductance [Time frame: Upon enrollment to 22 days]
• Functional Near-Infrared Spectroscopy [Time frame: Upon enrollment to 22 days]
• Electroencephalogram [Time frame: Upon enrollment to 22 days]
• Heat Pain Thresholding [Time frame: Upon enrollment to 22 days]
• Pressure Pain Thresholding [Time frame: Upon enrollment to 22 days]