Preformation and ghosts

Here is another interesting titbit to do with long-dead natural historians (also see entry on Lamarck and clouds).

Charles Bonnet [ref-1][ref-2] was a Swiss biologist who was associated with the theory of preformation, atleast he was one who went to great lengths to explicitly spell it (so Gould(*) tells us). Also, he is often considered to be the first person to use the word "evolution" as a biological term (but Gould(*) notes that the credit really ought to belong to Albrecht von Haller).

Anyway, Charles Bonnet was the first to describe a strange psychological condition. In 1760, he "described vivid, complex visual hallucinations in his psychologically normal 87 year old grandfather, who had cataract operations on both eyes and was practically blind. His grandfather saw pictures of men, women, birds, carriages, buildings, tapestries and scaffolding patterns.".[ref]. This condition is now known as Charles Bonnet's syndrome.

From Paulig and Mentrup (2001)(J Neurology, Neurosurgery and Psychiatry, 2001;70:813-814):

"...We describe a patient with a 2 year history of Charles Bonnet's syndrome with macular degeneration, with persistent and frequent hallucinations that have disappeared after treatment with gabapentin.

The 86 year old woman had a 2 year history of complex visual hallucinations on being admitted to our hospital. A senile macular degeneration had been diagnosed by her ophthalmologist 10 years previously. She complained of a daily and repetitive occurrence of images predominantly showing human beings such as medieval women and knights in bright colours, but also torsos or isolated heads. None of the faces were familiar to her. They were of realistic size, coincided with normal perception of the external space, and mainly emerged when looking at a wall or lying supine facing the ceiling. The hallucinations were exclusively of a visual nature and static, but moved when she moved her eyes. They never occurred when her eyes were closed. She also sometimes experienced hallucinations of tiny homunculi strolling on the floor and climbing on her legs when she tried to step on them. Rarely, the content of the hallucinations changed while being watched---for example, from a female to a male head. The duration of the phenomena ranged from seconds to a few minutes. The patient recognised an increase in hallucinations during exhaustion or inflammatory diseases with raised temperature. A condition which regularly evoked hallucinations was using a mobile phone. A complex pattern of rhomboid shapes emerged with a short latency and faded away soon after having switched off the phone. The patient had full insight into the non-realistic nature of her experiences and she did not feel distressed by them. None the less, she argued that the hallucinations sometimes interfered with perception when she was driving a car; therefore convincing her to seek therapy.

We asked the patient to document the time and content of the hallucinations throughout the day in a pretreatment diary. It showed that they were most likely to occur in the morning and in the evening. The most prevalent features were parts of human beings, predominantly heads. Sometimes, objects such as old fashioned clocks or tombstones were described.

There was no psychiatric history. Medical history showed no diseases apart from hypertension and a severe polyarthrosis. She only irregularly took an antihypertensive medication (an angiotensin II antagonist and a diuretic) and pain killers (tilidine). Her general practitioner also prescribed Ginkgo biloba extract and pentoxifylline to treat the hallucinations, but without any effect. On admission to our hospital she was only taking homeopathic medication.

Neurological examination was normal. A dry atrophic macular degeneration was confirmed by our ophthalmologist. Visual acuity was 0.4 in the left eye and 0.6 in the right eye, without perimetric signs of scotomas. No cognitive dysfunction (mini mental state examination 29/30, above average performance in testing alertness, and selective attention) or additional psychotic symptoms could be found. Laboratory tests were normal. Her EEG and brain SPECT disclosed no pathology. Cranial MRI only showed an age related circumscribed frontal atrophy but no abnormalities in the brain...."

Bizarre -- who knows maybe this is an explanation for why some folks claim to see "ghosts"!?


REFERENCES:
(*) Gould, Stephen J., Ontogeny and phylogeny, 1977, Harvard University Press.


.