Nonassociative learning processes determine expression and extinction of conditioned fear in mice
AUTOR(ES)
Kamprath, Kornelia
FONTE
Cold Spring Harbor Laboratory Press
RESUMO
Freezing to a tone following auditory fear conditioning is commonly considered as a measure of the strength of the tone-shock association. The decrease in freezing on repeated nonreinforced tone presentation following conditioning, in turn, is attributed to the formation of an inhibitory association between tone and shock that leads to a suppression of the expression of fear. This study challenges these concepts for auditory fear conditioning in mice. We show that acquisition of conditioned fear by a few tone-shock pairings is accompanied by a nonassociative sensitization process. As a consequence, the freezing response of conditioned mice seems to be determined by both associative and nonassociative memory components. Our data suggest that the intensity of freezing as a function of footshock intensity is primarily determined by the nonassociative component, whereas the associative component is more or less categorical. We next demonstrate that the decrease in freezing on repeated nonreinforced tone presentation following conditioning shows fundamental properties of habituation. Thus, it might be regarded as a habituation-like process, which abolishes the influence of sensitization on the freezing response to the tone without affecting the expression of the associative memory component. Taken together, this study merges the dual-process theory of habituation with the concept of classical fear conditioning and demonstrates that sensitization and habituation as two nonassociative learning processes may critically determine the expression of conditioned fear in mice.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=534706Documentos Relacionados
- CB1 Cannabinoid Receptors Modulate Kinase and Phosphatase Activity During Extinction of Conditioned Fear in Mice
- Systemic blockade of D2-like dopamine receptors facilitates extinction of conditioned fear in mice
- Reciprocal patterns of c-Fos expression in the medial prefrontal cortex and amygdala after extinction and renewal of conditioned fear
- Memory for Extinction of Conditioned Fear Is Long-lasting and Persists Following Spontaneous Recovery
- AX+, BX- Discrimination Learning in the Fear-Potentiated Startle Paradigm: Possible Relevance to Inhibitory Fear Learning in Extinction