This project seeks to elucidate how the brain can form predictions about impending reinforcement in a variety of behavioral contexts and learning paradigms, which is a fundamental goal in neuroscience. The project involves obtaining neurophysiological recordings in the amygdala and OFC simultaneously so that one can understand the relationship and timing of activity between the two brain areas. Recent work from the Salzman lab has shown that the amygdala provides a representation of the positive or negative value of visual stimuli during a classical conditioning procedure in which there is a one-to-one mapping between a sensory stimulus and a particular reinforcement outcome. This proposal involves extending this recent work to now examine simultaneously the interrelated neurophysiology of the amygdala and orbitofrontal cortex (OFC) during both simple and more complex forms of reinforcement learning. The amygdala and OFC are central nodes in neural circuitry commonly assumed to link sensory stimuli with affective values so as to drive adaptive cognitive, behavioral, and physiological responses. Dysfunction of these neural circuits likely plays a role in many psychiatric diseases, such as mood, anxiety, addictive and other disorders.
The first aim examines amygdala and OFC single neuron activity local field potentials (LFPs) during learning induced by classical conditioning in order to understand the physiological properties and relative timing dynamics of activity in the two brain areas.
The second aim extends this work by studying the physiology of these brain areas in conditions when motivationally significant stimuli have different meanings depending on the moment-to-moment context in which they are presented. If neural processing in the amygdala and OFC can switch rapidly as the value of a stimulus changes from trial to trial depending upon a contextual cue, it will indicate that rapid context-dependent mechanisms can facilitate the switching between representations of value.
The third aim i nvestigates whether neurons in the amygdala and OFC represent the ?absolute? or the ?relative? value of conditioned stimuli by using a reinforcer revaluation paradigm that manipulates the relative value of a stimulus but holds constant its absolute value. This task requires the integration of information about the overall context of the task in order to judge the relative value of a particular stimulus. For both the second and third aims, we hypothesize that OFC either encodes contextual information about a stimulus (Aim 2), or integrates information about an overall task context (Aim 3) in part to help govern and update neural representations of value. In this scenario, OFC would be part of a cortical mechanism that integrates high-level information in order to help control neural representations of value and the emotional processes that are based on such representations.
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|Saez, A; Rigotti, M; Ostojic, S et al. (2015) Abstract Context Representations in Primate Amygdala and Prefrontal Cortex. Neuron 87:869-81|
|Krug, Kristine; Salzman, C Daniel; Waddell, Scott (2015) Understanding the brain by controlling neural activity. Philos Trans R Soc Lond B Biol Sci 370:20140201|
|Baruni, Jalal K; Lau, Brian; Salzman, C Daniel (2015) Reward expectation differentially modulates attentional behavior and activity in visual area V4. Nat Neurosci 18:1656-63|
|Gore, Felicity; Schwartz, Edmund C; Brangers, Baylor C et al. (2015) Neural Representations of Unconditioned Stimuli in Basolateral Amygdala Mediate Innate and Learned Responses. Cell 162:134-45|
|Gore, Felicity; Schwartz, Edmund C; Salzman, C Daniel (2015) Manipulating neural activity in physiologically classified neurons: triumphs and challenges. Philos Trans R Soc Lond B Biol Sci 370:20140216|
|Peck, Ellen L; Peck, Christopher J; Salzman, C Daniel (2014) Task-dependent spatial selectivity in the primate amygdala. J Neurosci 34:16220-33|
|Peck, Christopher J; Salzman, C Daniel (2014) Amygdala neural activity reflects spatial attention towards stimuli promising reward or threatening punishment. Elife 3:|
|Peck, Christopher J; Salzman, C Daniel (2014) The amygdala and basal forebrain as a pathway for motivationally guided attention. J Neurosci 34:13757-67|
|Peck, Christopher J; Lau, Brian; Salzman, C Daniel (2013) The primate amygdala combines information about space and value. Nat Neurosci 16:340-8|
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