man with headache, pain in the back of the head, 3d rendering

skull pain headaches neurons synapses neural network circuit brain nerve cells neurology stimuli impulses alzheimer's parkinson's tumor alpha-synuclein amnesia elderly assistance attention cerebro clinic cure decline cit degeneration dopamine exams slowness disease memory hospital parkinson protein research memories substance black tremor old age study analyze cause solution linguistic problems language cognition light rendering neuron degenerative diseases person headache back head man