To investigate the functions of regions within the brain, developmental neuroscience studies have often relied on permanent lesions. As an alternative to permanent lesions, scientists at Yerkes National Primate Research Center sought to test whether chemogenetic techniques could be applied to produce a transient inhibition of the amygdala, well known for regulating emotional responses, in infant non-human primates.
Their findings were recently published online by eNeuro, an open access journal of the Society for Neuroscience.
Amygdala — image from NIMH
Chemogenetics is a way of engineering cells so that they selectively respond to designer drugs, which have minimal effects elsewhere in the brain. It involves injection of a viral vector carrying genes encoding receptors responsive to the designer drug – in this case, clozapine-N-oxide, a metabolite of the antipsychotic clozapine. The technique has mostly been tested in rodents.
“This proof-of-principle study is the first to demonstrate that chemogenetic tools can be used in young infant nonhuman primates to address developmental behavioral neuroscience questions,” says Jessica Raper, PhD, first author of the eNeuro paper and a research associate at Yerkes. “Considering its reversibility and reduced invasiveness, this technique holds promise for developmental studies in which more invasive techniques cannot be employed.” Read more
Neuroscientists at Emory University School of Medicine have discovered a focal pathway in the brain that when electrically stimulated causes immediate laughter, followed by a sense of calm and happiness, even during awake brain surgery. The effects of stimulation were observed in an epilepsy patient undergoing diagnostic monitoring for seizure diagnosis. These effects were then harnessed to help her complete a separate awake brain surgery two days later.
The behavioral effects of direct electrical stimulation of the cingulum bundle, a white matter tract in the brain, were confirmed in two other epilepsy patients undergoing diagnostic monitoring. The findings are scheduled for publication in the Journal of Clinical Investigation.
Emory neurosurgeons see the technique as a “potentially transformative” way to calm some patients during awake brain surgery, even those who are not especially anxious. For optimal protection of critical brain functions during surgery, patients may need to be awake and not sedated, so that doctors can talk with them, assess their language skills, and detect impairments that may arise from resection. Read more
The results were published in the Feb. 24 issue of Nature.
The hormone, called PACAP (pituitary adenylate cyclase-activating polypeptide), is known to act throughout the body and the brain, modulating central nervous system activity, metabolism, blood pressure, pain sensitivity and immune function. The identification of PACAP as an indicator of PTSD may lead to new diagnostic tools and eventually, to new treatments for anxiety disorders.
â€œFew biological markers have been available for PTSD or for psychiatric diseases in general,â€ says first author Kerry Ressler, MD, PhD, associate professor of psychiatry and behavioral sciences at Emory University School of Medicine and a researcher at Yerkes National Primate Research Center. â€œThese results give us a new window into the biology of PTSD.â€