The olfactory bulb has neurons, microglia, astrocytes and other neural cells that are also present in the brain. While environmental toxins inhaled through the nasal route directly deposit in the olfactory bulb and lungs. Odors take a direct route to the limbic system, including the amygdala and the hippocampus, the regions related to emotion and memory. Through this route the toxins can affect smell, memory and motor functions.