The annual Society for Neuroscience (SfN) meeting is the premiere event to attend as a neuroscientist. The sheer number of people who attend can make it hard to find any one voice in the crowd; as usual, however, Triangle area neuroscientists made themselves heard amidst the scientific commotion. In case you missed it, here’s a glimpse of some exciting research presented by local neuroscientists at SfN 2014:
Duke University: The Devil is in the Details
It is well established that first- and second-hand smoke can lead to a series of adverse health effects. Second-hand smoke exposure during pregnancy has also been linked to subsequent hyperactivity in children. Nicotine is an obvious contender for mediating these effects, but it is just one of over 100 components of tobacco smoke which could be at fault.
Dr. Ed Levin’s lab at the Duke University Medical Center is presently determining how these other components are involved in the emergence of developmental problems. In recent studies his laboratory exposed pregnant mother rats to either nicotine alone or to a cocktail of total tobacco smoke extract in order to simulate the levels of toxins found in second-hand smoke. Dr. Levin’s lab found that the developmental problems caused by nicotine were even more severe when mixed with the other components of tobacco smoke. Males were overweight and their offspring were hyperactive and distractible. With the rise of ADHD in children, these studies point to second-hand smoke exposure during pregnancy as a potential causative factor.
NCSU: Descending Like a Pack of Wolves
One of the largest fields of neuroscience surrounds the enjoyable, motivating, and mood-altering neuromodulator dopamine. At SfN this technique called fast scan cyclic voltammetry (FSCV) can provide a clearer understanding of how dopamine levels change on a sub-second timescale while animals engage in rewarding activities.
Using FSCV, the neuroscientists of Dr. Leslie Sombers’ lab discovered that both acetylcholine and endorphins can amplify dopamine release from the main source of dopamine in the brain – the ventral tegmental area (VTA). Counterintuitively, blocking the endorphin receptor MOR also amplifies dopamine release, and does so to a greater extent than activation. Thus, endorphin levels in the VTA are at a critical point where a fluctuation in either direction can result in significant changes in dopamine output. These studies are revealing insights into the fine line between motivation and addiction and may lead to a better understanding of how patients become addicted to morphine (a MOR activator) through altered dopamine function.
UNC-Chapel Hill: Head over Tar-heels for the Brain
Deep brain calcium imaging, proteomic analyses, and circuit tracing are just a few of the variety of techniques that UNC-Chapel Hill neuroscientists are using to investigate brain function. Anel Jaramillo, from Dr. Joyce Besheer’s lab in the Bowles Center for Alcohol Studies, is investigating which brain circuits mediate the sensation of intoxication and how stress can diminish this sensation. In Anel’s studies, rats were trained to report whether they were intoxicated or not by pressing one lever for a reward if they were intoxicated or another lever if they were sober. Anel focused on assessing and modulating activity in the rhomboid nucleus of the thalamus and the insula – both of which are regions involved in interoception, or the sensing of bodily states. She found that it is the inactivation of these regions which results in the feeling of intoxication. Stress, which is associated with a general increase in the basal activity of neurons, counteracts this inactivation in the rhomboid thalamus and blunts the intoxicating feeling of alcohol.
NIEHS: A Healthy Dose of Neuroscience
The development of neural circuits underlying attention and impulsivity are guided in part by norepinephrine signaling from the locus coeruleus (LC) of the brainstem. Yet researchers still don’t know how these processes interact, as knocking out norepinephrine signaling is lethal to the developing fetus. Dr. Patricia Jensen at NIEHS is working to answer this question with a new set of genetic mouse lines that manipulate subpopulations of norepinephrine-releasing neurons in the brainstem. By capitalizing on the rhombomere organization system of the brainstem during development, in combination with multiple types of genetic recombinase proteins, Dr. Jensen can restrict expression of proteins specifically in LC neurons. In order to verify successful genetic manipulation, Dr. Jensen expressed proteins in LC neurons that enabled her to temporarily activate these neurons. These mice showed an anxious phenotype in three different tests of anxiety – a known response to LC stimulation. Future studies entailing the silencing of these neurons will explain how norepinephrine signaling contributes to the proper (and improper) development of attention and impulsivity circuits.
Story by Ted Stanek, Duke University
Article originally published in the February 2015 issue of The Triangle Transmitter