Figure 1. Intranasal instillation of manganese chloride dose-dependently reduces odorant-evoked neurotransmitter release from the olfactory nerve.

(A–C Left) Odorant-evoked neurotransmitter release is visualized in vivo through a cranial window. Pseudocolored response maps show representative odorant-evoked increases in fluorescence relative to pre-odorant baseline across manganese doses. Individual traces display the change in fluorescence of the corresponding glomerulus during odorant presentation (denoted by the horizontal line). The odorant presented was 2-methyl-2-butenal in all three examples. The scale bar in A denotes 500 μm. (A–C Right) Cumulative distribution of glomerular response amplitudes in vehicle- and manganese- exposed olfactory bulbs. (D) Mn dose-dependently reduces the number of olfactory bulb glomeruli receiving odorant-evoked synaptic input, expressed as the ratio of the number of glomeruli receiving input on the Mn-exposed side to that on the contralateral, vehicle-exposed side within each mouse tested. The dashed line at 1 represents no difference between Mn-exposed and vehicle-exposed olfactory bulbs.