The long-term goal of this research is to understand how analyses of complex sounds are modified by brain centers that establish the emotional significance of auditory and other sensory input. The proposed research will examine a newly described direct pathway from the amygdala, a forebrain center mediating emotional expression, to the inferior colliculus (IC), the midbrain integration center of the ascending auditory system. The direct amygdalo-collicular projection may impose emotional content onto auditory processing at a relatively low level of the ascending auditory pathway. Moreover, this projection could mediate effects of auditory cortical activation that have been attributed to the direct cortico-collicular pathway. We hypothesize that the amygdalo-collicular projection modulates the integrative features of acoustic information processing in the IC based on emotional state and/or the emotional significance of recent sensory input. The project will examine how the amygdala modifies integrative auditory responses in the mustached bat's IC, where integrative auditory responses (termed combination-sensitive) analyze social and sonar vocalizations. The functional organization and origin of these responses in the IC and auditory brainstem are well understood. Connectional evidence suggests that amygdalo-collicular projection neurons contact combination-sensitive IC neurons.
In Aim #1 of the proposed research, we will examine responses of single neurons or small clusters of neurons in the basolateral amygdala in response to simple acoustic signals and social and sonar vocalizations. The results will identify acoustic conditions under which the amygdalo-collicular pathway is active, and also develop a physiological """"""""signature"""""""" to identify amygdalo-collicular neurons.
Aim #2 will use anterograde and retrograde tract tracing to examine the organization of the amygdalo-collicular projection and circuits relating the amygdala, auditory cortex, and IC.
Aim #3 will examine how chemical and electrical stimulation of the amygdala affects acoustic information processing for simple acoustic signals and complex vocalizations across the IC, using multi-channel recording methods.
Aim #4 will test, using non-invasive cortical cooling, whether the amygdala affects IC neurons primarily through its direct pathway, or through its connections to auditory cortico-collicular neurons. Relevance: These studies will provide a better understanding of how our processing of acoustic signals including speech is modified by emotion-laden sounds or by our emotional state. They may further our understanding of the role of the amygdala in auditory learning. This work may also improve our understanding of the role of emotional centers in abnormal auditory perceptions such as tinnitus. ? ? ?

National Institute of Health (NIH)
National Institute on Deafness and Other Communication Disorders (NIDCD)
Research Project (R01)
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Auditory System Study Section (AUD)
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Luethke, Lynn E
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Northeast Ohio Medical University
Schools of Medicine
United States
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Grimsley, Jasmine M S; Sheth, Saloni; Vallabh, Neil et al. (2016) Contextual Modulation of Vocal Behavior in Mouse: Newly Identified 12 kHz ""Mid-Frequency"" Vocalization Emitted during Restraint. Front Behav Neurosci 10:38
Gadziola, Marie A; Shanbhag, Sharad J; Wenstrup, Jeffrey J (2016) Two distinct representations of social vocalizations in the basolateral amygdala. J Neurophysiol 115:868-86
Grimsley, Calum A; Longenecker, Ryan J; Rosen, Merri J et al. (2015) An improved approach to separating startle data from noise. J Neurosci Methods 253:206-17
Grimsley, Jasmine M S; Hazlett, Emily G; Wenstrup, Jeffrey J (2013) Coding the meaning of sounds: contextual modulation of auditory responses in the basolateral amygdala. J Neurosci 33:17538-48
Wallace, Mark N; Grimsley, Jasmine M S; Anderson, Lucy A et al. (2013) Representation of individual elements of a complex call sequence in primary auditory cortex. Front Syst Neurosci 7:72
Galazyuk, Alexander V; Wenstrup, Jeffrey J; Hamid, Mohamed A (2012) Tinnitus and underlying brain mechanisms. Curr Opin Otolaryngol Head Neck Surg 20:409-15
Wenstrup, Jeffrey James; Nataraj, Kiran; Sanchez, Jason Tait (2012) Mechanisms of spectral and temporal integration in the mustached bat inferior colliculus. Front Neural Circuits 6:75
Grimsley, Jasmine M S; Gadziola, Marie A; Wenstrup, Jeffrey J (2012) Automated classification of mouse pup isolation syllables: from cluster analysis to an Excel-based ""mouse pup syllable classification calculator"". Front Behav Neurosci 6:89
Grimsley, Jasmine M S; Shanbhag, Sharad J; Palmer, Alan R et al. (2012) Processing of communication calls in Guinea pig auditory cortex. PLoS One 7:e51646
Gadziola, Marie A; Grimsley, Jasmine M S; Faure, Paul A et al. (2012) Social vocalizations of big brown bats vary with behavioral context. PLoS One 7:e44550

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