Lesion Lab: where is the lesion?

How to use it

• Pick a level, then tap the section to place a lesion. Drag it to move it, and use the slider to change its size.
• The visual pathway shows each eye’s field separately, so you can see why a chiasm lesion is bitemporal and a lesion behind it is homonymous. The cerebellum is drawn unfolded, as in most textbooks.
• At the cortex, choose the left or right hemisphere: the lateral and medial surfaces are shown together, and language deficits appear only on the left, neglect mainly on the right.
• Try an artery. The buttons under the section apply the usual territory of a vessel, such as PICA for the lateral medulla or the ACA, MCA and PCA at the cortex.
• Watch the pathway map. Each damaged tract is marked where it was cut, so you can see why a deficit is on the same side or the opposite side.
• The eye-movement level follows nerves III, IV and VI from their nuclei to the orbit; the eye figure shows the resulting position, ptosis and pupil, as you would see them facing the patient.
• Then switch to Cases: read the story, place the lesion, and check. Your results are saved in this browser, and “Practise weak spots” picks cases from the level you get wrong most.