In several places, McLuhan connects the 'closure' of the senses with medical 'ablation'.

He cites from The Study of Experimental Medicine (1957) by Claude Bernard, who describes how by ablation the medical scientist may 'suppress an organ in the living subject ... and from the disturbance produced in the whole organism ... deduce the function of the missing organ'.1

Describing the 'numbing' effects of new technology, McLuhan says: 'The one area which is numb and unconscious is the area which receives the impact.... there is an exact parallel with ablation in experimental medicine, but in medical ablation observation is properly directed, not to the numb area, but to all the other organs as they are affected ...'2