The goal of this research is to understand how the amygdala (AM;a brain center that processes the emotional significance of sensory stimuli) influences the processing of auditory information in auditory cortex (AC). Individuals/animals pay more attention to significant versus insignificant stimuli. The mechanisms associated with this process have not been determined. It is presumed that information about the significance of auditory stimuli is transmitted to AC via direct and indirect projections from the AM, and that subsequent changes in cortical activity alter the attention of the animal to relevant auditory cues. Conditioning experiments that enhance the behavioral relevance of auditory cues have been shown to elicit both short and long-term changes in the spiking activity of neurons in auditory cortex (reviewed by Weinberger, 2007;Suga, 2008). The specific goals of this proposal are to provide information about the morphology and termination pattern of the direct amygdalo-auditory cortex projection and begin to clarify the function of amygdalar inputs on cortical processing. My general hypothesis is that the direct AM-AC projection terminated throughout the AC and influences the spiking response of AC neurons to sound. Relevance: The amygdala mediates emotion, and influences memory and learning. Abnormal processing in the amygdala has been linked to numerous psychiatric disorders that include auditory hallucinations (e.g., schizophrenia, bipolar disorder). It is likely that these auditory hallucinations are initiated by amygdalar projections to AC. By understanding the role of amygdalo-cortical projections, we can obtain a clearer picture of: 1) how normal auditory perception is processed, and 2) how abnormal processing can results in these auditory dysfunctions.
These studies will provide a better understanding of how processing of acoustic signals, including speech, is modified by an individual's emotional state. They may also further our understanding of abnormal auditory perceptions such as tinnitus or the auditory hallucinations associated with psychiatric disorders such as schizophrenia and bipolar disorder.