Abstract
The centrifugal feedback to the olfactory bulb is mostly targeted on the granule cells, the inhibitory inter-neurons in the olfactory bulb. Using a neural circuit model of the bulb, Li (1990) proposed that such feedback to the granule cells serves the following roles in a context and task dependent manner: (1) odor segmentation by suppressing bulbar responses to ongoing, but already recognized, odors so that a subsequent addition of a foreground odor object can be singled out for recognition, (2) target odor seeking by enhancing bulbar sensitivities to a particular target odor object. I examine the emerging experimental data related to the model predictions: odor adaptation and segmentation in the bulbar activities, input dependency of the centrifugal feedback to the bulb, effect of odor adaptation on odor segmentation and perception, effect of expectation on odor detection and odor perception, effect of odor familiarity on bulbar responses. In addition, the model can be applied to explain how task-dependent feedback can enhance sensitivities in fine odor discrimination (Zhaoping 2016). I will also discuss further experimental investigations that can investigate the role of the centrifugal feedback.
