©2018 by McMurray Lab

Research Techniques

Our tools of the trade

We prioritize a systems-level philosophy, but our experiments rely on a wide variety of methods, from molecular to behavioral. Learn about our methods below.

We use a variety of operant and classical conditioning tasks to assess animals' cognitive abilities, and to understand how neural circuit manipulations, drug abuse, or environmental factors such as stress can effect these abilities. The operant tasks we use include probability and delay discounting tasks, reversal learning, go / no-go, and others. These complement our chemogenetic and electrophsyiological approaches (see below), and are often used concurrently with these other methods.

Cognitive / Behavioral Level

Operant and Pavlovian Training

Drug abuse in humans is typically voluntary. Therefore, to effectively model the neurobiological effects of human drug use, we often allow our animals to consume drugs voluntarily. Drugs can be provided in drinking water, via "jello shots", or in the subject's food, and can even be self-administered in an operant chamber during behavioral testing (rat bar).

Cognitive / Behavioral Level

Drug Self-Administration

Direct electrical stimulation of the reward circuitry, called brain stimulation reward, has been used since the 1950s to study reward processing. Our lab uses this method in 2 ways: to determine how drugs influence reward sensitivity, and as a more precise reinforcer in operant tasks. As a reinforcer, brain stimulation is free of many of the confounds associated with food and drug reward, and is highly motivating.

Cognitive / Behavioral Level

Intracranial Self-Stimulation

This approach allows us to record the activity of individual neurons,  groups of neurons, or entire regions while animals are awake and performing various behavioral tasks. We can then relate their behavior with their neural activity, to infer how neurons and brain regions control behavior. Additionally, by combining with other systems-level approaches, we can determine how the computations within a region change as its inputs and outputs are modified.

Systems Level

In Vivo Electrophysiology

Fiber tracing allows us to determine the anatomical connectivity patterns within various circuits of the brain. When combined with immuno-histochemical methods, we can determine not only if brain regions are connected, but also if those connections are inhibitory or excitatory, informing us of their function. This information is critical to our understanding of how regions work together to coordinate behavior.

Systems Level

Tractography

Using viral methods, we can target the expression of a novel receptor system to specific populations of neurons based on their anatomical projections or molecular identity. We can then activate or deactivate these neurons with their selective pharmaceutical ligand, clozapine-n-oxide. This method give us unprecedented control of specific neural circuits. It is also called "Designer Receptors Exclusively Activated by Designer Drugs", and it pairs well with our electrophysiological  and behavioral studies.

Systems Level

Chemogenetics

By labeling the location of specific proteins and enzymes in the brain, we can learn about how changes in an animal's experience alter its neuroanatomy. For example, we can determine how drug abuse changes the adolescent brain, or how differences in maternal care can change the brain systems that control social behavior. Additionally, we can learn how neural systems change and grow during normal development and aging. This approach relies on the Center for Advanced Microscopy at Miami.

Systems / Cellular / Molecular Level

Immunohistochemistry

We use a variety of molecular biology tools to identify the genes that underlie specific behavioral patterns, by studying level of RNA and protein expression. These methods include qPCR, autoradiography, Targeted RNA Expression analysis (T-Rex), and next-generation gene sequencing technologies. These methods rely on the Center for Bioinformatics and Functional Genomics at Miami.

Molecular Level

Genetic, RNA, and Protein Analysis