Phantoms in the Brain – Dr V. S. Ramachandran [Professor and Director of the Centre for Brain and Cognition, University of California and visiting fellow All Souls College, Oxford]

We took advantage of an ingenious experiment performed in 1987 by an Italian neurologist Eduardo Bisiach on a patient with neglect and denial.  Bisiach took a syringe filled with ice cold water and irrigated the patient’s left ear canal – a procedure that tests vestibular nerve function.  Within a few seconds the patient’s eyes started to move vigorously in a process called nystagmus.  The cold water sets up a convection current in the ear canals, thereby fooling the brain into thinking the head is moving and into making involuntary correctional eye movements ….when Bisdiach asked the denial patient whether she could use her arms, she calmly replied that she had no use of her left arm.  Amazingly the cold water irrigation of the left ear had brought about a complete [though temporary] remission from the anosognia.