One of the earliest to attempts to localise specific functions to anatomical regions of the brain was that of Franz Joseph Gall,¹ who distinguished six varieties of memory, which he localised in the frontal lobes. Auburtin in 1864 related the faculty of language to the frontal lobes, and Broca² and Dax highlighted the left side of the brain.³ The right hemisphere was in some ways regarded as the minor hemisphere, a mirror of the left but without the hierarchically important function of language. Visual and sensory functions were thought to be equally represented in both sides of the brain. Hughlings Jackson first suggested in 1876 the possibility that right hemisphere lesions could produce symptoms and dysfunction not encountered in those with comparably placed lesions of the left hemisphere. Although his paper, addressed to an ophthalmic readership, concentrated on the absence of papilloedema, he undoubtedly described imperception, though not specifically denial of hemiparesis. Jackson⁴ reported a patient with:

“Imperception followed by left hemiplegia, in which the upper arm suffered more than the lower arm, and the leg more than the arm—no optic neuritis [papilloedema]: large glioma of the right posterior lobe.”⁵

His patient, Eliza T, aet 59, was under Dr Down's care in March 1875. The history was of two months pain in the head and “neuralgia”.

“ . . .She could not find her way from her own house to Victoria Park, a short walk with which she was familiar for 30 years; nor could she find her way home . . . in dressing herself, put her things on wrong side . . ..”

She developed fluctuating drowsiness, confusion, misidentified time, letters, and faces, and developed left sided hemiparesis.

“ . . .When set to read 12 Snellen . . . having got to the end of the line she did not know where to go . . . but no discoverable anaesthesia on the left side . . . On trying her for hemiopia, no results were obtained for it was impossible to make her keep her eye fixed on the central point. The only noticeable thing was that she sometimes kept her eye on the central point when asked if she could see an object on her right, but invariably looked at one place on her left. . . .“

Dr Gowers performed the autopsy, summarising it as:

“A large gliomatous tumour in the hinder part of the right temporo-sphenoidal lobe: other smaller growths near and in right hippocampus major.”

Strictly, anosognosia refers to lack of awareness of the existence of disease.⁶ The interest of this case is Jackson's novel use of the name imperception.⁷ Later workers described lack of awareness, unconcern, or indifference to the disability, even a delusional,⁶ denial of illness or reference of the paralysed limb to someone else, often the examiner. Unilateral sensory changes are common accompaniments. It is often a transient phenomenon. Jackson's patient showed a number of dysphasic errors, which with a possible hemianopia (that was untestable) might explain some of her signs. Jackson reported, “She did not know objects, persons and places”. However, he did not object to confusion, loss or defect of memory, or imbecility as contributory factors. But he maintained:

“there was what I would call imperception, a defect as special as aphasia. These admissions [mentioned above] leave the statement that she had imperception untouched . . . I confess, however, that I have little direct evidence as to the localisation of the morbid changes causing imperception.”

According to Lord Brain, Hughlings Jackson was the first to recognise both agnosia and apraxia. Pick, later, in 1898 recorded a left hemiplegic who was not aware of his disability. Anton in 1896 (anosognosia for blindness), and F Mueller in 1892 had drawn attention to the same paradox. Jackson called this agnosia: “imperception”.⁸ Indeed, he went on to state that:

“the right posterior lobe is the `leading' side, the left more automatic in terms of visual ideation . . . for most of our mental operations are carried on in visual ideas.”

The imperception of Jackson's patient was probably anosognosia.⁷ Babinski however, provided the name, and fully described the syndrome of anosognosia in left hemiplegia⁸ that enhanced Jackson's idea of specific minor hemisphere syndromes. Babinski remarked:

“I have seen some hemiplegics who, without being ignorant of its existence of their paralysis, seem to attach no importance to it.”

In 1918 he wrote:

“Could it be that anosognosia is peculiar to lesions of the right hemisphere?”