Reversible hepatic decerebration.

Since James Parkinson (1817) first characterized the shaking palsy as a unique condition, significant confusion has remained concerning the causes and treatments of Parkinson's disease (PD). Through the 19th century, a wide variety of approaches were attempted in an effort to reduce its cardinal signs--rigidity, tremor, and bradykinesia--but to little effect. Today, approaching 200 years after Parkinson's seminal work, this disorder is commonly treated by surgical means, inducing a lesion in one specific portion of a small nucleus in the central nervous system (Desaloms et al., 1998, Lang et al., 1999). The notion of providing a lesion to the nervous system as a therapy for PD, however, began in earnest at the beginning of the 20th century. The first attempt to alleviate the symptoms of PD through surgical means involved a section of the dorsal roots of the spinal cord supplying the affected limb (also known as dorsal rhizotomy). Although ultimately resulting in disastrous effects, these early surgical attempts proceeded from a firm body of clinical and experimental research on both the central and peripheral nervous systems. After briefly reviewing the use and failure of dorsal rhizotomy as a treatment for parkinsonian rigidity, this paper will examine the manner in which clinicians and scientists justified the procedure.

Decerebrate State↗

PubMed2001

Low-dimensional control: tonus (1963).

In 1963, an article on "Tonus" (tone), written by Nikolai A. Bernstein and Yakov M. Kots, appeared in the second edition of the Bols'aja Medicinskaja Enciclopedija [Grand Medical Encyclopedia]. The paper is now published for the first time in the English language, with Mark L. Latash as translator. In accordance with then contemporary neurophysiology and neuropsychology, the paper presented "tone" as a graded phenomenon (as opposed to all-or-none), serving to prepare the segmental level for phasic contractions. Influenced by Granit and Matthews, the authors proposed that the suprasegmental level controls the threshold and the slope of the stretch reflex. In their introduction to the present edition, the editors understand this proposal in the context of low-dimensional control, that is, control in terms of one or a few variables (as opposed to central commands specifying all the details). Selected episodes from the history of low dimensional control and its logical counterpart, spinal intelligence, are used to illustrate how difficult these ideas were to accept. As so often in new scientific developments, confusion was the rule, and in this respect the paper on "Tonus" is no exception. In the epilogue, Kots gives his personal memories of the context in which the paper was written. At the time, he was working on "equitonometry" (equi-tono-metry), measuring tonic balance with gravity eliminated. Results of equitonometric research quite naturally led to the idea that suprasegmental centers control the threshold and the slope of the tonic stretch reflex. As Kots remembers, that was "no big deal".

Decerebrate State↗