Research

The Burwell Laboratory studies the structure and function of the cortical regions that surround the hippocampus. For over half a century, the hippocampus has been the focus of research on the neural basis of memory. In primates this system is referred to as the medial temporal lobe (MTL). In rats, we prefer to use the term hippocampal system (HS) because the cortex of the rat brain is smooth and is not divided into discrete lobes. The HS consists of several interconnected structures, including the hippocampal formation(the dentate gyrus, fields CA3, CA2, and CA1, and the subiculum) and the parahippocampal region (perirhinal (PER), postrhinal(POR)/parahippocampal, and entorhinal cortices, the pre- and parasubiculum). These regions exhibit substantial cellular, structural, and connectional homology across rodent and primate brains. Because of this homology, we think that rodents provide an excellent animal model of human MTL function and the neural bases of memory.

Current Areas of Interest

The postrhinal cortex and attention: Research conducted in the Burwell lab suggests that the connectivity between the posterior parietal and postrhinal cortices provides a gateway for attention into the medial temporal lobe memory system. 

How environmental context is represented in the brain: Our studies suggest that the postrhinal cortex combines spatial information from the posterior parietal and retrosplenial cortices with object information from perirhinal cortex to form representations of context.

Understanding representations of objects and landmarks: Our studies suggest that there are two classes of items processed in the hippocampus, some are used for orientation (landmarks) and others are used for other purposes, for example defining context or associative learning.

Methods

Our primary technique to address questions of interest is electrophysiology in behaving animals. We have three Plexon data collection systems, each interfaced with a Plexon CinePlex tracking system and a Med Associates behavioral control system. Each system is interfaced with our Floor Projection Maze system for testing visual information processing in rodents.

In recent years, the lab has utilized a novel behavioral apparatus for studying visual information processing in rodents. The Floor Projection Maze provides opportunities to study a variety of visually guided behaviors in rodents. One such task is the Biconditional Discrimination Task in which the pattern on the floor determines which object is correct. 

Although we do use experimental lesion approaches, we are also now also combining multisite recording with optogenetic approaches to both activate and suppress neuronal activity in behaving animals. 

We use behavior, electrophysiology, and optogenetics to understand how hippocampal and parahippocampal structures interact to support memory and other cognitive processes. These very powerful tools allow us to modulate both neuronal activity and behavior.

Funding

National Science Foundation (NSF) Award: Cognitive Functions of the Postrhinal Cortex (07/2012-06/2016). PI: Burwell

NSF EFRI Award (EFRI 0937848) Dynamic Sensing and Actuating of Sensory and Motor Neural Microcircuits, 2009-2013, PI: Arto Nurmikko, Co-PI: Burwell.

DARPA: Brain Reorganization and Plasticity to Accelerate Injury Recovery: Multi-scale and Multi-modal Models Enabled by Next Generation Neurotechnology, 09/2010-08/2014, Stanford PI: Krishna Shenoy, Brown PI: Arto Nurmikko, Co-PI: Burwell.