Light enhances learned fear
- 16 August 2011
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 108 (33), 13788-13793
- https://doi.org/10.1073/pnas.1103214108
Abstract
The ability to learn, remember, and respond to emotional events is a powerful survival strategy. However, dysregulated behavioral and physiological responses to these memories are maladaptive. To fully understand learned fear and the pathologies that arise during response malfunction we must reveal the environmental variables that influence learned fear responses. Light, a ubiquitous environmental feature, modulates cognition and anxiety. We hypothesized that light modulates responses to learned fear. Using tone-cued fear conditioning, we found that light enhances behavioral responses to learned fear in C57BL/6J mice. Mice in light freeze more in response to a conditioned cue than mice in darkness. The absence of significant freezing during a 2-wk habituation period and during intertrial intervals indicated that light specifically modulates freezing to the learned acoustic cue rather than the context of the experimental chamber. Repeating our assay in two photoreceptor mutant models, Pde6b(rd1/rd1) and Opn4(-/-) mice, revealed that light-dependent enhancement of conditioned fear is driven primarily by the rods and/or cones. By repeating our protocol with an altered lighting regimen, we found that lighting conditions acutely modulate responses when altered between conditioning and testing. This is manifested either as an enhancement of freezing when light is added during testing or as a depression of freezing when light is removed during testing. Acute enhancement, but not depression, requires both rod/cone- and melanopsin-dependent photoreception. Our results demonstrate a modulation by light of behavioral responses to learned fear.Keywords
This publication has 33 references indexed in Scilit:
- Amygdala regulates risk of predation in rats foraging in a dynamic fear environmentProceedings of the National Academy of Sciences of the United States of America, 2010
- Spectral quality of light modulates emotional brain responses in humansProceedings of the National Academy of Sciences of the United States of America, 2010
- The emerging roles of melanopsin in behavioral adaptation to lightTrends in Molecular Medicine, 2010
- Automated assessment of Pavlovian conditioned freezing and shock reactivity in mice using the VideoFreeze systemFrontiers in Behavioral Neuroscience, 2010
- Activation of the septohippocampal system differentiates anxiety from fear in startle paradigmsNeuroscience, 2009
- The evolution of irradiance detection: melanopsin and the non-visual opsinsPhilosophical Transactions Of The Royal Society B-Biological Sciences, 2009
- Phasic vs Sustained Fear in Rats and Humans: Role of the Extended Amygdala in Fear vs AnxietyNeuropsychopharmacology, 2009
- Effects of rat sex differences and lighting on locomotor exploration of a circular open field with free-standing central corners and without peripheral wallsBehavioural Brain Research, 2009
- Central projections of melanopsin‐expressing retinal ganglion cells in the mouseJournal of Comparative Neurology, 2006
- Prevalence, Severity, and Comorbidity of 12-Month DSM-IV Disorders in the National Comorbidity Survey ReplicationArchives of General Psychiatry, 2005