You are informed by a friend that whenever he is feeling sad, he smells his wife's perfume and reports feeling better instantaneously. Although there may be many explanations for this phenomenon, one possible physiological explanation is that:
the primary projections of the olfactory system innervate the limbic system through the amygdala and the hippocampal formation.
the primary projections of the olfactory system innervate the limbic system through the thalamus.
the primary projections of the olfactory system innervate the somatosensory cortex through the amygdala and the hippocampal formation.
the primary projections of the olfactory system innervate the somatosensory cortex through the thalamus.