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A Lateralized Odor Learning Model in Neonatal Rats for Dissecting Neural Circuitry Underpinning Memory Formation
Published on: August 18, 2014
Modulation of olfactory learning in young rats through intrabulbar GABA(B) receptors
Fumino Okutani1, Jing-Ji Zhang, Tomoko Otsuka
1Department of Physiology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan. okutanif@med.kochi-ms.ac.jp
Insights
Gamma-aminobutyric acid type B (GABA(B)) receptors in the olfactory bulb are crucial for aversive olfactory learning in young rats. Manipulating these receptors during training significantly impacts odour aversion development and generalization.
Area of Science:
- Neuroscience
- Olfactory System Research
- Learning and Memory Mechanisms
Background:
- Aversive olfactory learning in rat pups involves the olfactory bulb.
- Gamma-aminobutyric acid type A (GABA(A)) receptors modulate this learning.
- The role of GABA(B) receptors in this process remained unclear.
Purpose of the Study:
- To investigate the role of GABA(B) receptors in the olfactory bulb during aversive olfactory learning.
- To determine how manipulating GABA(B) receptors affects odour aversion in young rats.
Main Methods:
- Infusion of GABA(B) receptor agonist (baclofen) or antagonist (saclofen) into the olfactory bulb during odour-shock pairing.
- Behavioral testing of odour aversion in rat pups post-infusion.
- Assessment of odour aversion generalization to novel odours.
Main Results:
- Baclofen infusion during training prevented aversive olfactory learning in a dose-dependent manner.
- Saclofen infusion during training induced odour aversion and generalization to novel odours, even without foot shock.
- Olfactory aversions were observed even when saclofen was infused without odour exposure.
Conclusions:
- GABA(B) receptors in the olfactory bulb play a significant modulatory role in aversive olfactory learning in young rats.
- These findings highlight GABA(B) receptors as key regulators of olfactory associative learning and odour perception.
Abstract:
After training with an odour paired with foot shock on postnatal day 11, rat pups show an aversion to the odour in testing on postnatal day 12. The mechanisms underlying this aversive olfactory learning involve disinhibition of mitral/tufted cells in the olfactory bulb by the somatosensory stimulation-induced activation of centrifugal noradrenergic fibres originating in the locus coeruleus. The activity of mitral/tufted cells is regulated through gamma-aminobutyric acidA (GABA(A)) receptors in the external plexiform layer and GABA(B) receptors in the glomerular layer. We have previously presented that aversive olfactory learning in young rats is modulated through GABA(A) receptors in the olfactory bulb. In the present study we examined the consequence of manipulating GABA(B) receptors in the olfactory bulb during training. Baclofen, a GABA(B) receptor agonist when infused into the olfactory bulb during the pairing of an odour with foot shock, prevented aversive olfactory learning in a dose-dependent manner. Infusion of saclofen, a GABA(B) receptor antagonist, during training with a citral odour in the absence of foot shock produced aversive responses not only to the odour, but also to strange odours (benzaldehyde and vanillin) not previously presented. Such olfactory aversions were observed even if saclofen was infused without odour exposure. These results suggest that olfactory learning in young rats is modulated through GABA(B) receptors in the olfactory bulb.