Open Access Publications

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Open access publications by faculty, postdocs, and graduate students in the Department of Psychological and Brain Sciences

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Browsing Open Access Publications by Author "Asok, Arun"

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    Corticotropin releasing factor type-1 receptor antagonism in the dorsolateral bed nucleus of the stria terminalis disrupts contextually conditioned fear, but not unconditioned fear to a predator odor
    (Elsevier, 2016-04-27) Asok, Arun; Schulkin, Jay; Rosen, Jeffrey B.; Arun Asok, Jay Schulkin & Jeffrey B. Rosen; Asok, Arun; Rosen, Jeffrey B.
    The bed nucleus of the stria terminalis (BNST) plays a critical role in fear and anxiety. The BNST is important for contextual fear learning, but the mechanisms regulating this function remain unclear. One candidate mechanism is corticotropin-releasing-factor (CRF) acting at CRF type 1 receptors (CRFr1s). Yet, there has been little progress in elucidating if CRFr1s in the BNST are involved in different types of fear (conditioned and/or unconditioned). Therefore, the present study investigated the effect of antalarmin, a potent CRFr1 receptor antagonist, injected intracerebroventricularly (ICV) and into the dorsolateral BNST (LBNST) during single trial contextual fear conditioning or exposure to the predator odor 2,5-dihydro-2,4,5- trimethylthiazoline (TMT). Neither ICV nor LBNST antalarmin disrupted unconditioned freezing to TMT. In contrast, ICV and LBNST antalarmin disrupted the retention of contextual fear when tested 24 hours later. Neither ICV nor LBNST antalarmin affected baseline or post-shock freezing – indicating antalarmin does not interfere with the early phases of contextual fear acquisition. Antalarmin did not (1) permanently affect the ability to learn and express contextual fear, (2) change responsivity to footshocks, or (3) affect the ability to freeze. Our findings highlight an important role for CRFr1s within the LBNST during contextually conditioned fear, but not unconditioned predator odor fear.
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    The smell of fear: innate threat of 2,5-dihydro-2,4,5-trimethylthiazoline, a single molecule component of a predator odor.
    (Frontiers Media S.A., 2015-08-25) Rosen, Jeffrey B.; Asok, Arun; Chakraborty, Trisha; Jeffrey B.Rosen, Arun Asok and Trisha Chakraborty; Rosen, Jeffrey B.; Asok, Arun; Chakraborty, Trisha
    In the last several years, the importance of understanding what innate threat and fear is, in addition to learning of threat and fear, has become evident. Odors from predators are ecologically relevant stimuli used by prey animals as warnings for the presence of danger. Of importance, these odors are not necessarily noxious or painful, but they have innate threat-like properties. This review summarizes the progress made on the behavioral and neuroanatomical fundamentals of innate fear of the predator odor, 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), a component of fox feces. TMT is one of several single molecule components of predator odors that have been isolated in the last several years. Isolation of these single molecules has allowed for rapid advances in delineating the behavioral constraints and selective neuroanatomical pathways of predator odor induced fear. In naïve mice and rats, TMT induces a number of fear and defensive behaviors, including robust freezing, indicating it is an innate threat stimulus. However, there are a number of behavioral constraints that we do not yet understand. Similarly, while some of the early olfactory sensory pathways for TMT-induced fear are being delineated, the pathways from olfactory systems to emotional and motor output regions are less well understood. This review will focus on what we know and what we still need to learn about the behavior and neuroanatomy of TMT-induced fear.
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