Grad Appreciation Week Poster Session Winner, Max Mehlman
Congratulations to Max Mehlman, graduate student in the Department of Psychological and Brain Sciences, who was one of four winners of the Graduate Poster Session held recently in Alumni Hall! (Below is a summary of Mehlman’s poster.)
Poster title: Head Direction Cell Activity in the Dorsal Striatum and Medial Precentral Cortex Requires Intact Anterodorsal Thalamic Nuclei
Humans have a remarkable capacity for processing spatial information. This enables us to form internal representations of our physical environments, or “mental maps,” and understand our position and orientation with them. Such knowledge facilitates efficient navigation, an evolutionarily favored ability that helped our ancestors acquire food, shelter, and mates. Most people take these spatial abilities for granted, unaware of the tremendous multimodal information processing involved. Such an elegant system begs the question: “How does it work?”
Recording the activity of single neurons in freely moving rodents, researchers have discovered specialized cell types that encode spatial information. Head direction cells are one type of these “spatial cells”; these neurons display activity related to the direction the animal is facing. An individual head direction cell fires maximally when the animal is oriented in one specific direction, called the preferred firing direction, and remains inactive when the animal faces outside of this direction. Thus, the head direction cell system is continually signaling the animal’s current direction, functioning much like a compass and providing animals with a sense of direction.
While most rodent head direction cells reside within a well-studied set of connected brain structures called the limbic system, small numbers are found elsewhere in the brain. Such regions include the dorsal striatum and medial precentral cortex; both regions are involved in motor control. To examine whether head direction cell activity in these regions depend upon output from head direction cells in the limbic system or is generated independently, I performed a brain lesion that eliminates head direction cell activity throughout the limbic system. I subsequently observed the activity of neurons in the dorsal striatum and medial precentral cortex. The lesion eliminated head direction cell activity in these two regions, and I concluded that the activity of dorsal striatum and medial precentral cortex head direction cells reflects output from the limbic system rather than functioning as an entirely independent and parallel representation of directional heading.
poster summary by Max Mehlman
Mehlman, along with the other poster winners, explains his research in this video: