Jeffrey Tasker, a neuroscience professor at Tulane University, studies the neurological circuits of the amygdala, the emotion-processing center for fear and trauma. 

Tasker has been a professor in the Department of Cell and Molecular Biology at Tulane for 34 years and helped found the neuroscience major in 2000. Tasker has been the Catherine and Hunter Pierson Chair in Neuroscience for 20 years and is the first named chair in neuroscience at Tulane.  

As part of the executive committee of the Tulane Brain Institute, Tasker specializes in neurophysiology, the study of the nervous system and its role in neurological and psychiatric conditions. He runs two labs, one through the Veterans Affairs Hospital and one at Tulane, the Tasker Laboratory. For the past 25 years, his labs have focused on the brain’s response to stress. 

“We work a lot on something called stress modulation, so modulation of circuits and synapses by stress hormones, and specifically glucocorticoids, [hormones that help regulate the immune system] and neurotransmitters,” Tasker said. “Right now, we’re focusing on norepinephrine.” 

By introducing light-sensitive proteins called opsins into a neuron’s genome, scientists can use light to activate or deactivate a neuron. This technique, called optogenetics, is one of many that Tasker’s lab uses to target and manipulate specific neurons to understand their role in neurological behaviors.  

In 2019, Tasker was awarded a $2.1 million five-year grant from the National Institutes of Health to study stress and its effects on brain circuitry and behavior. Tasker discussed what his lab has done with the NIH funding. 

“Usually, emotion is related to the amygdala … and 20% of the cells are inhibitory [interneurons], and their job is to keep everything inhibited, except when they release from inhibition,” Tasker said. “We’re interested in how those inhibitory inter neurons control network brain oscillations … specifically in the basolateral amygdala, and how that relates to sheer memory formation.” 

Tasker’s lab experiments with mice to study brain waves in the amygdala. On the first day, the mice were put in a brightly lit box for five minutes, then transferred to a dark box and exposed to a strong foot shock for ten seconds. In the following days, the mice were exposed to the lit chamber to remind them of the previous shock. These reminders, coupled with light exposure and an additional shock on the seventh day, reinforced the fear response.  

Tasker explains that through this “traumatic exposure with reminders,” the mice learned to associate light with a foot shock, similar to how environmental triggers for humans are associated with traumatic stress. 

“There is no perfect animal model for the human condition, so … as much as a mouse can have PTSD … it recapitulates some of the symptoms of PTSD life, [that is the] inability to extinguish fear memories. There’s an enhanced startle response, and there’s a little bit of enhanced anxiety,” Tasker said. 

Tasker and his team concluded that parvalbumin-expressing neurons are actively involved in fear extinction. Parvalbumin, or PV, is a calcium-binding protein that is used to identify specific inhibitory interneurons in the cortex. Inhibiting these PV neurons showed similar alterations in brain wave oscillations as mice that were exposed to trauma. The similar changes in electrical activity of the PV neurons suggest that PV neurons are directly involved in fear extinction, or the unlearning of a fear. 

“Extinction is not loss of a memory,” Tasker said. “All memories are formed and then extinguished if you don’t reinforce them, but that extinction is not necessarily loss of a memory that’s formed. It’s the formation of a new memory that inhibits the old memory.” 

Tasker and his lab also received a grant from the U.S. Department of Veteran Affairs to study the plasticity of amygdala circuits, as well as an additional grant from the NIH to research neural circuits in the hypothalamus and their role in regulating neuroendocrine responses to acute psychological stress compared to physical stressors.  

“Overcoming that traumatic memory is learning that [a triggering stimulus is] not necessarily threatening. And so you overlay over your traumatic memory a safe memory. … Whereas somebody with PTSD, they have trouble establishing or forming that safe memory to suppress the traumatic memory,” Tasker said. 

Tasker credits his lab manager and research professor, Laura Harrison, a Ph.D. student who is graduating this semester, Matthew Watson and former Ph.D. student, Xin Fu, who first studied PV neurons. Tasker also works with research professor, Gajanan Shelkar, postdoctoral fellow, Lise Harbom, Ph.D. student, Maria Najjar and associate professor of psychology, Jonathon Fadok. 

“Being able to be in a position to do biomedical research, which means having somebody support it in terms of a job and also getting funding, is a huge privilege because it’s so expensive,” Tasker said. “Somebody’s giving us that money to pretty much ask questions and try to find out the answer and follow our own kind of interests and directions.” 

While at Tulane, Tasker received the Professor of the Year award for the Honor’s Program in 2009 as well as the Outstanding Research Award from Tulane University School of Science and Engineering in 2015. In 2024, Tasker was one of the two researchers who received the Research, Scholarship and Artistic Achievement Hall of Fame award. 

When asked about the difficulties he faced throughout his career, Tasker said that funding has always been the greatest challenge. 

“I think that scientists of all stripes right now, but especially biomedical scientists, are facing … enormous difficulties getting and maintaining funding, and then just knowing what the future of biomedical research is going to look like and what the opportunities are and which opportunities will no longer be there,” Tasker said. 

Despite these difficulties, Tasker stresses the importance of continued research in the biomedical field. 

“I don’t think our thirst, actually our need for knowledge in the biomedical realm, will ever go away,” Tasker said. “This is knowledge. This is just a pursuit of knowledge.”