The role of the basal forebrain can also be more specifically tested by use of the immunotoxin IgG-saporin, which acts to selectively kill cholinergic cells in the basal forebrain. Lesions of the cholinergic cells in one hemisphere, and inferior temporal cortex in the opposite hemisphere, can help us to understand further the role of basal forebrain interactions with cortex, as well as identifying the role of a specific transmitter system (acetylcholine) in this interaction.