NEUROPATHOLOGY

Abstract

TuIE hypothalamic centres of the autonomic system were the first objects to study, but more recently evidence has been adduced to show that centres in the cortex, especially in the motor cortex, were concerned with autonomiic activity. To investigate this the conduction of cortical impulses to vegetative organs was studied in 35 cats. In a first series of experimeints ' extrapyramidal ' centrifugal fibres arising from the hypothalamus were severed. In a second series of experiments a transverse section of both pyramidal tracts was made. After the lesion on either of these systems had been performed, the effects of stimulation of the motor cortex and the frontal lobe were noted on the pupil, the blood vessels, the sweat glands, and the urinary bladder. In both groups of experiments the cortical stimulation elicited reactions of the above-mentioned organs. Severance of the hypothalamic pathways impaired most the conduction of corticofugal impulses to the dilator of the pupil, least the conduction to the bladder. It is concluded that there exists a double (pyramidal and extrapyramidal) conduction of corticofugal impulses to the autonomic centres in the cord. R. G. G.