Olfactory-mediated fear-potentiated startle.

Paschall, Gayla Y.; Davis, Michael

doi:10.1037/0735-7044.116.1.4

Cited by 50 publications

(48 citation statements)

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“…The present study investigated the role of the amygdala and the BNST in freezing elicited by an unlearned olfactory stimulus. Several recent studies have used an odor as a conditioned stimulus (CS) in a fear-conditioning paradigm (Otto et al, 1997;Richardson et al, 1999;Paschall and Davis, 2002). It has been shown that olfactory fear conditioning is mediated by the basolateral nucleus of the amygdala (Cousens and Otto, 1998).…”

Section: Role Of the Amygdala In Tmt-induced Freezingmentioning

confidence: 99%

Temporary Inactivation of the Bed Nucleus of the Stria Terminalis But Not of the Amygdala Blocks Freezing Induced by Trimethylthiazoline, a Component of Fox Feces

2003

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Presentation of trimethylthiazoline (TMT, a component of fox feces) to laboratory rats elicits freezing, a prominent behavioral sign of anxiety or fear. The present study investigated the neural basis of this unlearned response. Muscimol, a GABA A receptor agonist, was injected (4.4 nmol/0.5 l) into the bed nucleus of the stria terminalis (BNST) as well as into the amygdala, two brain areas known to be involved in anxiety and fear. Temporary inactivation of the BNST but not of the amygdala significantly blocked TMT-induced freezing. This effect was not caused by an enhancement of motor activity after BNST inactivation. In addition, these results confirm previous studies showing that freezing is possible despite amygdala inactivation. These results, and other findings in the literature, suggest that the BNST is critically involved in unlearned fear, whereas the amygdala is more involved in the acquisition and expression of learned fear.

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Section: Role Of the Amygdala In Tmt-induced Freezingmentioning

confidence: 99%

Temporary Inactivation of the Bed Nucleus of the Stria Terminalis But Not of the Amygdala Blocks Freezing Induced by Trimethylthiazoline, a Component of Fox Feces

2003

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“…These findings are addressed in the Discussion. Overall, the results of both experiments suggest that olfactory cues serve as efficient S1 and S2 stimuli in second-order fear-potentiated startle paradigms when only a small number of first and second-order training trials are presented.Recently, we reported that discrete (4-sec) olfactory cues paired with footshock serve as effective conditioned stimuli (CSs) for potentiating the acoustic startle response in rats using the fear-potentiated startle paradigm (Paschall and Davis 2002). In those studies, amyl acetate (5%) had no significant effect on startle in untrained rats, but potentiated startle in animals receiving 1, 2, 5, or 10 odor-shock pairings.…”

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“…Recently, we reported that discrete (4-sec) olfactory cues paired with footshock serve as effective conditioned stimuli (CSs) for potentiating the acoustic startle response in rats using the fear-potentiated startle paradigm (Paschall and Davis 2002). In those studies, amyl acetate (5%) had no significant effect on startle in untrained rats, but potentiated startle in animals receiving 1, 2, 5, or 10 odor-shock pairings.…”

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confidence: 99%

“…Domjan 1998). Because the motivational value of both the first and second-order stimuli are acquired rather than innate (as is the motivational value of the US), second-order conditioning techniques may help reveal the neural mechanisms that underlie the acquisition, expression, and representation of fear memories (for review, see Gewirtz and Davis 1998).Olfactory-mediated fear-potentiated startle is such a robust effect that even a single-training trial can support learning (Paschall and Davis 2002). Therefore, in the current studies, we used a small number of first-order and secondorder training trials on separate days to investigate secondorder olfactory-mediated fear-potentiated startle.…”

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Second-Order Olfactory-Mediated Fear-Potentiated Startle

Paschall¹,

Davis²

2002

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Recently, we reported that discrete (4-sec) olfactory cues paired with footshock serve as effective conditioned stimuli (CSs) for potentiating the acoustic startle response in rats using the fear-potentiated startle paradigm. Because odors are such salient cues for the rat, and because of the robust olfactory conditioning observed previously, the current studies investigated second-order fear conditioning using olfactory and visual cues. In Experiments 1 and 2, we used a small number of first-order and second-order training trials on separate days to investigate second-order fear-potentiated startle. Significant potentiated startle was observed in animals receiving Paired/Paired training in both studies, but surprisingly, control animals in the Unpaired/Paired group (Exp. 1) also showed significant potentiated startle to a light S2 at testing. These findings are addressed in the Discussion. Overall, the results of both experiments suggest that olfactory cues serve as efficient S1 and S2 stimuli in second-order fear-potentiated startle paradigms when only a small number of first and second-order training trials are presented.Recently, we reported that discrete (4-sec) olfactory cues paired with footshock serve as effective conditioned stimuli (CSs) for potentiating the acoustic startle response in rats using the fear-potentiated startle paradigm (Paschall and Davis 2002). In those studies, amyl acetate (5%) had no significant effect on startle in untrained rats, but potentiated startle in animals receiving 1, 2, 5, or 10 odor-shock pairings. Olfactory-mediated fear-potentiated startle decreased, but was still significant up to 40 d after conditioning, and could be measured using test trials separated by as little as 30 sec. Those studies confirmed a previous report by Richardson et al. (1999), showing that ambient odors are also effective CSs for potentiating the startle response. Because odors are such salient cues for the rat, and because of the robust olfactory conditioning observed previously, the current studies investigated second-order olfactory fear conditioning.Pavlov (1927) proposed that once a stimulus has been conditioned, it can serve the role of an unconditioned stimulus (US). In first-order Pavlovian conditioning, a previously neutral stimulus (i.e., a light), is paired with a biologically significant US that can be either aversive (i.e., footshock) or rewarding (i.e., food). The animal learns an association between the CS and the US, and later exhibits a conditioned response (CR) to that stimulus in the absence of the US. Conditioning of a second neutral stimulus (S2) with the previously conditioned (and now excitatory) firstorder stimulus (S1) is known as higher-order (or secondorder) conditioning. When later tested with S2, the animal exhibits a CR, although S2 was never paired directly with the US.The existence of second-order conditioning is important, as it increases the range of situations in which classical conditioning occurs, even without a primary unconditioned stimulus (cf. Domjan 1998...

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“…However, the role of nNOS transmission in an aversive learning to odors is still unknown. Recent studies have shown that odors can be associated with foot shock in the Pavlovian fear conditioning paradigm, and the odor-CS acquires aversive valence to induce fear responses, such as freezing and potentiated startle responses (Otto et al 2000;Paschall and Davis 2002;Jones et al 2005). Olfactory fear processing may differ from contextual or auditory/visual fear.…”

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Neuronal nitric-oxide synthase deficiency impairs the long-term memory of olfactory fear learning and increases odor generalization

2013

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Experience-induced changes associated with odor learning are mediated by a number of signaling molecules, including nitric oxide (NO), which is predominantly synthesized by neuronal nitric oxide synthase (nNOS) in the brain. In the current study, we investigated the role of nNOS in the acquisition and retention of conditioned olfactory fear. Mice lacking nNOS received six training trials, each consisting of an odor-CS co-terminating with a foot shock-US. Mice showed reduced freezing responses to the trained odor 24 h and 7 d after training, compared to wild-type mice. Pretraining systemic injections of the NO donor, molsidomine, rescued fear retention in nNOS knockout mice. In wildtype mice, pretraining systemic injections of L-NAME, a nonspecific nNOS blocker, disrupted odor-CS fear retention in a dose-dependent manner. To evaluate whether NO signaling is involved in generalization of fear memories, nNOS knockout mice and wild-type mice receiving L-NAME were trained to one odor and tested with a series of similar odors. In both cases, we found increased generalization, as measured by increased freezing to similar, unpaired odors. Despite the impairment in fear memory retention and generalization, neither mice receiving injections of L-NAME nor nNOS knockout mice showed any deficits in either novel odor investigation time or odor habituation, suggesting intact olfactory perception and short-term memory olfactory learning. These results support a necessary role for neuronal NO signaling in the normal expression and generalization of olfactory conditioned fear.The ability to learn and retain memories is dependent on several transmitters. Currently, there is much interest in the involvement of nitric oxide (NO) signaling in long-term memory formation (Bredt and Snyder 1992;Hawkins et al. 1994;Garthwaite 2008;Kelley et al. 2011). NO is generated from the amino acid L-arginine by the enzyme NO synthase (NOS) and functions as a retrograde neurotransmitter. Due to the diffusible nature of NO and its relationship with NMDA receptor activation, neurons containing the neuronal isoform of NOS (nNOS) could be involved in driving synaptic strength changes during learning processes such as longterm memory Zhuo et al. 1994;Garthwaite 2008).Fear conditioning is a useful tool in studying the neuronal mechanisms involved in the formation of long-term memory and fear-related systems. Rodents can quickly and reliably learn a fear association between a conditioned stimulus (CS) and an aversive stimulus (US), such as a foot shock (Young and Fanselow 1992). The role nNOS plays in fear learning has been investigated using contextual fear conditioning, as well as visual and auditory cues as the CS (Schafe et al. 2005;Kelley et al. 2010Kelley et al. , 2011Overeem et al. 2010). And although the nNOS inhibitor 7-nitroindazole showed no disruption in the acquisition and expression of the contextual fear conditioning (Maren 1998), it was demonstrated that animals lacking the nNOS gene (Nos1or nNOS knockout) have shown deficits in fear condit...

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Olfactory-mediated fear-potentiated startle.

Cited by 50 publications

References 32 publications

Temporary Inactivation of the Bed Nucleus of the Stria Terminalis But Not of the Amygdala Blocks Freezing Induced by Trimethylthiazoline, a Component of Fox Feces

Temporary Inactivation of the Bed Nucleus of the Stria Terminalis But Not of the Amygdala Blocks Freezing Induced by Trimethylthiazoline, a Component of Fox Feces

Second-Order Olfactory-Mediated Fear-Potentiated Startle

Neuronal nitric-oxide synthase deficiency impairs the long-term memory of olfactory fear learning and increases odor generalization

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