The Man Who Mistook His Wife for a Hat: "On the Level"

He was walking, now, confidently, swiftly, but canted over, improbably, a good twenty degrees, his centre of gravity way off to the left, maintaining his balance by the narrowest possible margin.

We have five senses in which we glory and which we recognise and celebrate, senses that constitute the sensible world for us.

Perhaps it will only be in this space age, with the paradoxical license and hazards of gravity-free life, that we will truly appreciate our inner ears, our vestibules and all the other obscure receptors and reflexes that govern our body orientation.

Perhaps it will only be in this space age, with the paradoxical license and hazards of gravity-free life, that we will truly appreciate our inner ears, our vestibules and all the other obscure receptors and reflexes that govern our body orientation.

Yet their absence can be quite conspicuous. If there is defective (or distorted) sensation in our overlooked secret senses, what we then experience is profoundly strange, an almost incommunicable equivalent to being blind or being deaf.

'Let me think, let me think,' he murmured, half to himself, drawing his shaggy white brows down over his eyes and emphasising each point with his powerful, gnarled hands.

Parts of the inner ear are indeed physically—literally—like levels; the labyrinth consists of semicircular canals containing liquid whose motion is continually monitored...Mr MacGregor’s homely symbol applies not just to the labyrinth but also to the complex integration of the three secret senses: the labyrinthine, the proprioceptive, and the visual.

The most profound (and most practical) studies of such integrations—and of their singular disintegrations in Parkinsonism—were made by the late, great Purdon Martin and are to be found in his remarkable book The Basal Ganglia and Posture (originally published in 1967, but continually revised and expanded in the ensuing years; he was just completing a new edition when he died recently).

The most profound (and most practical) studies of such integrations—and of their singular disintegrations in Parkinsonism—were made by the late, great Purdon Martin and are to be found in his remarkable book The Basal Ganglia and Posture (originally published in 1967, but continually revised and expanded in the ensuing years; he was just completing a new edition when he died recently).

In the section on 'tilting reactions’ Purdon Martin emphasises the threefold contribution to the maintenance of a stable and upright posture, and he notes how commonly its subtle balance is upset in Parkinsonism—how, in particular, 'it is usual for the labyrinthine element to be lost before the proprioceptive and the visual’.

This triple control system, he implies, is such that one sense, one control, can compensate for the others—not wholly (since the senses differ in their capabilities) but in part, at least, and to a useful degree.

We do not tilt or lean or fall over the moment we close our eyes. But the precariously balanced Parkinsonian may do so.

Thus patients who have been surgically deprived of their labyrinths (as is sometimes done to relieve the intolerable, crippling vertigo of severe Ménière’s disease), while at first unable to stand upright or take a single step, may learn to employ and to enhance their proprioception quite wonderfully...

Purdon Martin was endlessly thoughtful and ingenious in designing a variety of mechanisms and methods that made it possible for even severely disabled Parkinsonians to achieve an artificial normality of gait and posture—lines painted on the floor, counterweights in the belt, loudly ticking pacemakers—to set the cadence for walking.

Purdon Martin was endlessly thoughtful and ingenious in designing a variety of mechanisms and methods that made it possible for even severely disabled Parkinsonians to achieve an artificial normality of gait and posture—lines painted on the floor, counterweights in the belt, loudly ticking pacemakers—to set the cadence for walking.

But he had not, to my knowledge, devised a prosthesis for the correction of impaired tilting and higher vestibular reflexes, the problem that afflicted Mr MacGregor.

But he had not, to my knowledge, devised a prosthesis for the correction of impaired tilting and higher vestibular reflexes, the problem that afflicted Mr MacGregor.

In a couple of weeks we had completed a prototype, a pair of somewhat Heath Robinsonish spirit spectacles: ‘The world's first pair!' said Mr MacGregor, in glee and triumph. He donned them.

They looked a bit cumbersome and odd, but scarcely more so than the bulky hearing-aid spectacles that were coming in at the time.

This worked, in a fashion—at least he stopped tilting: but it was a continuous, exhausting exercise. And then, over the ensuing weeks, it got easier and easier; keeping an eye on his 'instruments' became unconscious, like keeping an eye on the instrument panel of one's car while being free to think, chat, and do other things.