MedScape – by Megan BrooksElectrical stimulation of a specific brain region may help individuals anticipate a challenge and have the confidence and determination to overcome it, new research suggests.
The findings from this novel study conducted by investigators at Stanford University in California showing neuromodulation of the anterior midcingulate cortex (aMCC) evokes such a response may have potential clinical implications for psychopathologic conditions involving a reduced capacity to endure psychological or physical stress.
“We identified the precise anatomical coordinates of neuronal populations (and their associated network) that support complex psychological and behavioral states associated with perseverance. This is the first step towards exploring their operational pathophysiology in various neuropsychiatric disorders,” Josef Parvizi, MD, PhD, of the Department of Neurology and Neurological Sciences at Stanford, toldMedscape Medical News.
The findings raise the possibility that innate differences in a specific brain network might be the cause of individual differences in coping with physical or psychological distress, Dr. Parvizi added.
“If so, these innate differences can potentially be identified in childhood and be modified by behavioral therapy, medication, or, as suggested here, electrical stimulation,” he said.
The study was published online December 5 in Neuron.
Unexplored Territory
The anterior cingulate cortex (ACC) is known to be involved in functions such as emotion, pain, and cognitive control, but until now, the subjective correlates of ACC activity have remained largely unexplored.
“EBS [electrical brain stimulation] studies of the ACC are exceedingly uncommon because this part of the brain is very rarely implanted for clinical reasons,” the researchers write.
The study involved 2 patients with refractory epilepsy who had intracranial depth electrodes implanted to localize the source of seizure activity.
In both patients, electrical stimulation of the aMCC caused a “strikingly” similar and consistent set of perceptual and behavioral changes of the physical and psychological nature.
The patients reported a sense of an imminent challenge; a high degree of motivation to fight the challenge; a high degree of confidence that they would be able to overcome the challenge; and a physical sensation of “shakiness” or “hot flashes” in the chest and neck region with increased heart rate.
This set of complex autonomic, emotional, and cognitive “will to persevere” changes were absent during sham trials and when electrical current was delivered below a certain threshold and when stimulation occurred in regions outside the aMCC, the researchers say.
Brain imaging studies conducted in the Functional Imaging in Neuropsychiatric Disorders (FIND) Laboratory at Stanford indicate that the region of stimulation is part of a larger functional network involving many other regions of the brain that are known to play a key role in both emotion and attention.
“Our findings are of clinical relevance given the recent focus on cingulate dysfunction in neuropsychiatric disorders,” the investigators write.
They note that the findings may be helpful in interpreting variable therapeutic responses to cingulate surgeries in conditions such as obsessive-compulsive disorder (OCD).
“While many patients show measurable therapeutic responses, many others have no response and/or require repeated surgeries. Though there are other possible explanations, it is clear that adjacent regions of the anterior cingulate have distinct functional roles and these variable response profiles might relate to relatively coarse and anatomical targeting,” they add.
The researchers note that the findings suggest “individualized functional assays for segregating the large mantle of the cingulate gyrus should ultimately allow for safer and more effective therapeutic targeting.”
Unique Glimpse
Commenting on the study for Medscape Medical News, Alexander J. Shackman, PhD, of the Affective and Translational Neuroscience Laboratory at the University of Maryland in College Park, said that during the past decade, there has been “considerable progress in deciphering the contribution of this enigmatic region to the normal and disordered mind; much of what we have learned is based on mechanistic studies in animals or noninvasive neurophysiological studies (fMRI [functional magnetic resonance imaging], scalp-recorded EEG [electroencephalography]) in humans. Thus, the focus of the report by Parvizi and colleagues is particularly timely and interesting.”
Dr. Shackman, who was not involved in the study, said it offers a “unique glimpse” into the complex subjective state associated with activation of the anterior cingulate.
“For a number of years, it was unclear whether this region should be considered ’emotional,’ ‘cognitive,’ or some more complex blend of the two. The present results are broadly consistent with other evidence favoring the blend hypothesis,” he said.
However, he cautioned that although these new data are important, they are not without limitations.
“In particular, the study relied on a small sample of patients afflicted with intractable epilepsy, which may limit how well the authors’ conclusions generalize to healthy individuals. Likewise, the main conclusions of the study depend on the introspective reports of laypeople. Given known limitations of self-report, it will be important to incorporate more objective measures of emotion and cognition in future research,” he said.
The study was funded by the Stanford NeuroVentures Program. The authors and Dr. Shackman have disclosed no relevant financial relationships.
Neuron. Published online December 5, 2013. Abstract