Techniques
Chronic intermittent ethanol vapor
Chronic intermittent ethanol vapor is a well-established approach to induce alcohol dependence in rodents. In mice this is combined with two-bottle choice drinking sessions of alcohol and water to measure excessive alcohol consumption in alcohol dependent subjects. We use this approach to study alcohol dependence in mice. The lab has a number of alcohol vapor chambers to study alcohol dependence.
Voluntary methods of drug consumption
Voluntary consumption of drugs is considered the gold standard for measuring substance use disorders in preclinical animal models. There are several methods to achieve voluntary consumption including voluntary drinking and operant self-administration of drugs. Two of the most common drinking paradigms are two-bottle choice of alcohol (or another drug) and water, and drinking in the dark, which is thought to model binge-like drinking using single-bottle access for short periods of time. The lab has a number of operant boxes to examine drug self-administration. Operant self-administration involves the animal pressing a lever to receive a drug reward (either intravenous infusion or oral liquid). We use these techniques to study alcohol and intravenous self-administration to examine opioid use disorders as well as other substance use disorders.
Minipump implantation
Minipumps provide a forced consumption model of drug usage that controls intake of drug usage. Minipumps can be paired with techniques that may not be possible using voluntary consumption models. We use the minipump model of drug use to contrast against voluntary consumption models.
Chemogenetics
Designer receptors exclusively activated by a designer drug (DREADDs) are a class of chemogenetically engineered receptors activated by small molecules. DREADDs can be used to activate or inhibit neuronal activity in specific brain regions or cell types. DREADDs are engineered G-protein coupled receptors that have been modified to be activated exclusively by synthetic compounds (e.g., clozapine-N-oxide). DREADDs can be expressed in specific brain regions with stereotaxic injection of an Adeno-associated virus encoding Cre or flippase DNA recombinases. We use chemogenetics such as DREADDs to manipulate neural circuits associated with substance use.
Behavioral assays
Behavioral assays are used to assess the affective state of the rodent after manipulation. Common tests include: tail flick, von Frey, elevated plus maze, open field, bottle-brush, digging and marble burying, novelty suppressed feeding, novel object recognition, etc..These are standard procedures we regularly use in most experiments at a relevant experimental timepoint.
Immunohistochemistry
Immunohistochemistry is a traditional approach to stain tissue, in our case brain slices, for protein of interest. We regularly use this approach to mark activated neurons (e.g., staining for Fos protein) and to identify cell types of neurons (e.g., GABAergic/Glutamatergic etc.). We use a Keyence or Confocal microscope for imaging of traditional slice immunohistochemistry.
Whole-brain imaging of neural activity (iDISCO+/SHIELD)
The lab uses clearing approaches such as iDISCO+ and SHIELD to study brain wide tissue. These clearing approaches enable immunohistochemical staining that leaves large tissue intact instead of requiring sectioning. The tissue is immunostained for proteins of interest and then optically cleared for visualization using a light-sheet microscope.
Light sheet microscopy
We use light-sheet microscopy to visualize tissue that has been optically cleared and immunostained using iDISCO+. The microscope takes digital sections a few micrometers apart to create a stack of individual digitally imaged sections. These images can be reconstructed to create 3D structures and analyze protein signaling throughout the brain. The lab has our own light sheet microscope to perform these visualizations.
Network analysis
Network neuroscience is a computational approach that measures the functional connectivity, or co-activation of nodes (brain regions) across the brain in a given cognitive state. This approach can be used to determine how the brain is structured. Further, network neuroscience can identify brain regions that are critical nodes for network communication (e.g., hub brain regions). We are also interested in examining common features across different neural networks.
