Research reportRole of the basolateral amygdala in retrieval of conditioned flavors in the awake rat

- Conditioned flavor increased Fos expression in amygdala basolateral nucleus.
- Both highly and less reinforced flavors induced neuronal activity changes in amygdala.
- In conditioned rats activity decreased during retrieval of less preferred flavor.
- Both flavors might have acquired a biological value through conditioning.

Learned association between odor, taste and further post-ingestive consequence is known as flavor nutrient conditioned preference. Amygdala is supposed to be one of the areas involved in these associations. In the present study, one flavor was associated with a 16% glucose (CS+) whereas another flavor was paired with less reinforcing 4% glucose (CS−). We showed that CS+ presentation after conditioning increased Fos expression in the basolateral nucleus of amygdala (BLA). Furthermore, we performed electrophysiological recordings in the BLA in free moving rats. After preference acquisition, rats were exposed to either the CS+ or the CS−. The proportion of neurons showing a decreased activity during the CS− presentation was significantly higher in conditioned rats compared to controls. Among this neuronal population recorded in conditioned rats, we noticed a significant proportion of neurons that also showed a decreased activity during the CS+ presentation. Our data indicate an involvement of BLA during retrieval of learned flavors. It also suggests that both flavors might have acquired a biological value through conditioning.