Abstract
There are many different components involved in the formation of a memory. Research has shown that mammalian learning is a complex system that requires the recruitment of multiple brain regions and cell types. This active network then works together to bring together the multiple components of a particular memory.\r It is evolutionarily advantageous for an animal to be able to associate the taste of a toxin with its negative symptoms. Many animals, in particular mammals, have an ability to learn to avoid foods that are toxic on a trial and error basis. We can elicit this behavior in a controlled fashion in lab animals and study the anatomy and biochemistry involved. Conditioned Taste Aversion (CTA) is a robust form of one-trial taste learning that dates back to the 1960’s.(Garcia et al., 1967) During CTA an aversion to a novel taste is created by pairing the taste with a toxic compound. As part of a larger effort to study the genetic, cell type specific, and network changes involved in gustatory memory formation we are tracing connections of neurons activated during CTA.\r During gustatory learning, neurons in many different brain regions are activated and can be visualized through their expression of immediate early genes like FOS. These regions include the Gustatory Cortex (GC), and substructures of the Amygdala: The Central Amygdala (CA) and the Basolateral Amygdala (BLA). (Yamamoto et al., 2007) Increased functional interactions between these regions has been shown to take place during CTA (Grossman et al., 2008), but the physical connections of the participating neurons are unknown. \r Using viral injections and confocal fluorescent imaging, we were able to show that excitatory cells involved in CTA project to the Gustatory Cortex. We were also able to show learning dependent Amygdalar projections to novel regions of the brain, including the Lateral Septum (LS) and the Ventromedial Hypothalamus (VMH).