Garcia P, Linster C, Hasselmo ME, Baxter MG (1999) Selective cholinergic lesions of the horizontal limb of the diagonal band of Broca affect odor perception in rats. Neuroscience 1999 Abstracts 559.2. Society for Neuroscience, Miami, FL.
Summary: We have recently shown, in behavioral experiments with rats, that perceptual similarities between aliphatic aldehydes can be at least partially predicted from the neural responses in the olfactory bulb (Linster and Hasselmo, Physiol. Behav., in press). These experiments showed that an overlap in neural responses to “similar” odorants, as seen in the olfactory bulb (Imamura et al., J. Neurophysiol. 68: 1986, 1992), is predictive of a greater perceptual similarity of these odorants in a behavioral task. Computational models of the olfactory bulb (OB) predict that cholinergic input to the olfactory bulb arising from the horizontal limb of the diagonal band of Broca (HDB) modulates the neural representation of odorants in rats (Linster and Hasselmo, Behav. Brain. Res., 84:117, 1997), possibly leading to a change in perceptual similarity as measured by the behavioral response. We now report a behavioral test of these predictions. The cholinergic neurons of the HDB were lesioned using the specific cholinergic toxin 192 IgG-saporin. Two groups of male Sprague-Dawley rats (10 lesioned and 8 sham-operated rats) were trained to retrieve a reward from a cup filled with bedding covering a cotton swab saturated with odorant. We trained rats on a series of six aliphatic aldehydes and tested generalization between all pairs of odorants as well as with a control odor (n-amyl-acetate). Generalization was quantified as the amount of time spent digging in response to a test odor compared to the response to the conditioned odor (in the absence of reward). Our behavioral paradigm showed no difference between the two groups in the response to the conditioned or control odors. However, the two groups differed significantly in response to the test odors. Although sham-operated rats did not generalize to aldehydes differing by more than 2 carbons from the trained odor, lesioned rats generalized to all aldehydes tested. This work was supported by NSF grant IBN-9723947.
Related Products: 192-IgG-SAP (Cat. #IT-01)