For the millions of patients suffering from treatment-resistant depression, new bioengineering research is pointing the way to personalised breakthroughs.
Magnetoencephalography (MEG) measures the magnetic fields generated by the brain’s electrical activity. It provides detailed information about the timing and location of brain activity with high temporal resolution, making it a valuable tool for research and clinical applications. The non-invasive neuroimaging technique has traditionally been used to map brain function and identify the source of neuro-pathology.
But now the technology is helping spearhead research that could transform treatment for the 30% of people with severe depression who don’t respond to conventional antidepressant medications.
“Most people with depression take pharmaceuticals, but for a significant number, they simply don’t work,” said Associate Professor Tatiana Kameneva from Swinburne University’s School of Engineering. “For this group of patients, we urgently need new treatment strategies.”
Cutting-edge technology shows early promise
Established in 2011, the Swinburne Neuroimaging Facility houses one of three MEG scanners in the southern hemisphere, alongside MRI and electroencephalography (EEG) laboratories.
This brain imaging equipment helps researchers visualise brain structure, function and connectivity with great precision. The MEG scanner measures the tiny magnetic fields generated by neuron activity, allowing researchers to track brain function in real-time with millisecond precision.
“The brain’s magnetic signals are incredibly small compared to the Earth’s magnetic field,” Associate Professor Kameneva said. “Recording these subtle brain responses while actively stimulating is technically demanding, but our equipment makes it possible.”
Transcutaneous vagus nerve stimulation (tVNS) is a non-invasive technique that uses electrodes placed in the ear to deliver gentle electrical pulses – generates stimulus.
Targeting the vagus nerve
The vagus nerve is the longest in the human body, extending from the brainstem to the heart, lungs and digestive tract. It has been a target for treating depression for decades, but traditional approaches required surgical implantation.
“The vagus nerve has a branch that extends to the ear called the auricular branch,” Associate Professor Kameneva said. “By stimulating this accessible branch, we can influence brain networks without surgery.”
While tVNS technology isn’t new, using it to treat severe depression while recording brain activity, is a novel approach. Previous research relied on subjective patient reports to gauge effectiveness. Associate Professor Kameneva’s team developed the idea of stimulating the nerve and monitoring brain activity at the same time.
Associate Professor Kameneva said tVNS is more subtle than transcranial magnetic stimulation (TMS), another non-invasive technique that uses magnetic fields for stimulation, rather than electrical pulses such as tVNS. Patients experience a mild tingling sensation on their ear during the 10-minute stimulation sessions. “There’s no pain involved, which makes it highly acceptable to patients,” she says.
Personalising stimulation
Different stimulation frequencies impact different parts of the brain. Specific neural networks implicated in depression can be targetted by altering the frequency of electrical pulses.
“We found that the brain responds differently to different frequencies of stimulation,” Associate Professor Kameneva said. “For example, stimulating at 24 Hertz affects different brain areas than stimulating at 1 Hertz.”
Stimulation frequencies can either increase or decrease the connectivity between neurological networks. This allows researchers to potentially rebalance brain activity patterns that have been disrupted by depression.
Initial studies of healthy participants showed tVNS activates key brain networks involved in depression, including the default mode network, central executive network and salience network. These areas support emotional regulation, attention and cognitive control, functions disrupted by depression.
Collaborative research
Complex conditions like depression require expertise from multiple fields to develop effective treatments. Associate Professor Kameneva is part of the Iverson Health Innovation Research Institute at Swinburne that brings together researchers from neuroscience, biomedical engineering, psychology and data analytics. Connecting engineers with clinicians and industry partners accelerates the development of new medical technologies and treatments and boosts the translation of research into real-world clinical applications.
“Being embedded within the Iverson Institute has been crucial for this research,” Associate Professor Kameneva said. “We have engineers working alongside neuroscientists and psychologists, all focused on solving different aspects of the same problem.”
Having tested the technology on healthy participants, the team has begun testing people with depression. Preliminary results showed promising signs. “We’re seeing similar patterns as we observed in our healthy participant studies – different brain regions respond to different stimulation protocols,” she said.
The next step will be longer-term trials to determine the long-term effects of the treatment. There are also plans for portable tVNS devices at home to facilitate daily sessions over several weeks.
“Our vision is to first image a patient’s brain using our advanced facilities, determine the optimal stimulation parameters for their specific neural profile, then provide them with a personalised stimulation device they can use at home,” Associate Professor Kameneva said. “After a month of treatment, they would return for another brain scan to assess the changes.”
Associate Professor Kameneva sees potential applications for the technology to treat other neurological conditions. She said it could be adapted for chronic pain, anxiety and addiction, with “any condition involving dysregulation of these brain networks might benefit from personalised neuromodulation”.
Further information about Swinburne’s research in this area is available here.
