CROSS-SECTION OF THE BRAINSTEM: NEURONS (BLUE-GRAY) ARE IN CLOSE CONTACT WITH IMMUNE CELLS (PURPLE). THE THREADLIKE BLUE STRUCTURES ARE EXTENSIONS OF THE NEURONS, WHICH CAN REACH ALL THE WAY INTO DISTANT ORGANS IN THE FORM OF NERVE FIBERS. ACCORDING TO THE STUDY, THE IMMUNE CELLS AND NEURONS IN THE BRAINSTEM CAN BE ACTIVATED DIRECTLY VIA THE NERVE FIBERS AS A RESULT OF INFLAMMATION IN THE LUNGS.