Brad Pfeiffer, Ph.D.

Brad Pfeiffer performed his graduate studies under the mentorship of Kimberly M. Huber, Ph.D., at the University of Texas Southwestern Medical School, where he studied the synaptic mechanisms underlying Fragile X Syndrome. Dr. Pfeiffer completed his post-doctoral training at Johns Hopkins University under the guidance of Dr. David J. Foster, where he performed in vivo recordings and examined rodent hippocampal function during navigational tasks. Brad joined the faculty at UT Southwestern in 2015, where he is an Assistant Professor in the Department of Neuroscience and an Endowed Scholar in Biomedical Research.

The Pfeiffer lab is interested in three fundamental issues in neuroscience: 1) how experience is encoded at the neuronal level, 2) how such neuronal representations of experience are consolidated into long-term memory, and 3) how neuronal representations of past experience are recalled and used to guide or inform future behaviors. To make these questions more scientifically tractable, the Pfeiffer lab studies rodent spatial navigation as a specific example of more general memory formation and use, and utilizes large-scale, high-density in vivoelectrophysiological recordings to examine the activity patterns of hundreds of neurons simultaneously during free behavior.

The hippocampal formation is a brain region of particular interest in understanding these issues, as it has been shown to be critically important for many types of memory, including episodic and spatial memory. Within the hippocampus, individual excitatory neurons preferentially fire only when the animal is in a spatially restrictive location of an environment; hence, hippocampal neurons are often referred to as 'place cells'. Each place cell represents a unique location of the environment, such that across the entire population of hippocampal neurons, the entirety of any environment can be represented. By recording from a sufficient number of place cells, the physical location of the animal can be identified at any point in time based exclusively upon which hippocampal neurons are active.

During pauses in exploratory behavior, or during post-experience sleep, brief (50-300 ms duration) bursts of neural activity are periodically observed in the hippocampus. These bursts often encode specific sequential information regarding the animal's past or possible future behaviors. Current data and hypotheses alternately link these patterned bursts of activity with the consolidation of past experience into long-term memory or with the recall of previously stored information to inform future behaviors. Therefore, these brief activity patterns, sometimes called 'replay' or 'hippocampal reactivation,' are a primary focus of study in the Pfeiffer lab.