The blot upon the brain : studies in history and psychology.

  • William Wotherspoon Ireland
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: The blot upon the brain : studies in history and psychology. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

    24/394 (page 12)
    figures of light before he composes himself to sleep after fatiguing mental work. Dr. Kandinsky goes over some of the modern theories on the nature and origin of hallucinations, rejecting them all save the theory of Meynert. This distinguished physician holds that hallucinations are the result of a stimulus applied to the cortex or grey matter of the anterior lobe of the brain. He has demonstrated the anatomical connection of the corpora quadri- gemina, the centres of visual perception, with the cortex of the brain. Through this path travel visual impressions with the sensory impressions of the adaptations of the muscles of the eye to the brain where they are associated with the repre- sentations of space, but the connection with the factors of the representation of space already begins in the corpora quadri- gemina. The grey matter of the anterior part of the brain has for its function the reproduction and association of ideas, and the regulation of the subjective excitement or other parts of the brain, as also the excitation of the centres of the organs of sense at the base of the brain. If an excitation, representing no outward sensation, comes from one of the inferior centres of the organs of sense to the hemispheres of the brain, the centre of consciousness, there are no means of distinguishing this excitation from a real outward impression, and thus a hallucination is produced. In the normal state, the activity of the superior portions of the brain regulates the merely subjective excitations of the organs of sense. In ordinary language, the intellect distinguishes and interprets our sensations ; and by an exertion of the will we pay attention to some of these, and dismiss others. Thus the diminution of mental activity is favourable to the recep- tion of hallucinations. For their production, according to Maynert, two factors are needed—an excitation of the lower ganglia of the brain, the centres of sensation, and a dimin- ished activity of grey matter of the frontal lobes of the brain, the centre of thought. According to the theory of Dr. Luys,^^' hallucinations are * See liis views, explained in a pamphlet by Dr. Ant. Ritti, Tlieorie Pliysiologiqiie de I'Hallucinaticin. Paris, 1874.