Thalamic Terminals Regulate Fear Memory Retrieval and Retention
Mentor 1
Fred Helmstetter
Location
Union Wisconsin Room
Start Date
27-4-2018 1:00 PM
Description
Pavlovian fear conditioning is a behavioral procedure that is used to examine memory formation and retrieval. Fear conditioning involves an initially neutral cue, the conditioned stimulus (CS), paired with an aversive stimulus, the unconditioned stimulus (UCS). After several pairings, a new memory is formed and memory strength can be measured by presenting the CS during a retrieval session. Importantly, the process of retrieval can trigger cellular changes that alter the memory. The amygdala is a critical brain site for plastic changes during learning but little is known about how the sensory inputs to the amygdala regulate fear memory at retrieval. The medial geniculate nucleus (MgN) of the thalamus encodes auditory information representing the CS and sends direct neural projections to the amygdala. The projections from the MgN to the amygdala play an important role in the brain circuit for auditory fear conditioning. Much of what we know about the brain regions modulating fear expression at retrieval and later fear retention is from pharmacological approaches that render the brain region inactive for several hours. Optogenetics provides a more temporarily precise way to manipulate neuronal activity using light sensitive ion channels and specifically allows for the manipulation of input from the MgN to the lateral amygdala. In the current study, groups of rats were presented with an auditory cue paired with a UCS during a training session. The next day, groups are exposed to a retrieval session and activity from the MgN in the amygdala is selectively silenced during CS presentation. Our results suggest the activity from the MgN in the amygdala during auditory cue presentation at retrieval is critical for fear responding.
Thalamic Terminals Regulate Fear Memory Retrieval and Retention
Union Wisconsin Room
Pavlovian fear conditioning is a behavioral procedure that is used to examine memory formation and retrieval. Fear conditioning involves an initially neutral cue, the conditioned stimulus (CS), paired with an aversive stimulus, the unconditioned stimulus (UCS). After several pairings, a new memory is formed and memory strength can be measured by presenting the CS during a retrieval session. Importantly, the process of retrieval can trigger cellular changes that alter the memory. The amygdala is a critical brain site for plastic changes during learning but little is known about how the sensory inputs to the amygdala regulate fear memory at retrieval. The medial geniculate nucleus (MgN) of the thalamus encodes auditory information representing the CS and sends direct neural projections to the amygdala. The projections from the MgN to the amygdala play an important role in the brain circuit for auditory fear conditioning. Much of what we know about the brain regions modulating fear expression at retrieval and later fear retention is from pharmacological approaches that render the brain region inactive for several hours. Optogenetics provides a more temporarily precise way to manipulate neuronal activity using light sensitive ion channels and specifically allows for the manipulation of input from the MgN to the lateral amygdala. In the current study, groups of rats were presented with an auditory cue paired with a UCS during a training session. The next day, groups are exposed to a retrieval session and activity from the MgN in the amygdala is selectively silenced during CS presentation. Our results suggest the activity from the MgN in the amygdala during auditory cue presentation at retrieval is critical for fear responding.
