Elsevier

Brain Research Reviews

Volume 55, Issue 2, October 2007, Pages 406-410
Brain Research Reviews

Review
The sensory neuron and the triumph of Camillo Golgi

https://doi.org/10.1016/j.brainresrev.2007.01.008Get rights and content

Abstract

While Golgi's concept of the sensory neuron provided sound reasons for his rejection of the polarity principles underlying the ‘neuron doctrine’, it is now apparent that his concern about recovery of function after injury and the vast modern findings of ephemerality of connexin-clustered connections in the cerebral cortex and elsewhere in the central nervous system, and credibly termed ‘reticularist’, has somewhat eclipsed the polarized neuron doctrine of reflex physiology with the “fixed and immutable” connections championed by Cajal. Although Golgi's view was not the result of incisive reasoning based on subsequently confirmed observation, both principles espoused by these combatant Nobel laureate partners have proven robustly operative in different spheres and time frames of neural activity that have vastly enhanced contemporary understanding of neural connectivity.

Section snippets

The cell theory and the nature of cell contacts

The view that all plant and animal tissues are constructed of cells was a widely accepted notion by the mid-19th century and neither Golgi nor Cajal explicitly challenged Schleiden's and Schwann's concept, but even Cajal made statements implying he ‘hedged his bet’ about the nature of the unseen separation, noting that “neuronal discontinuity… could sustain some exceptions” (Bullock et al., 2005), although he could hardly have imagined neuronal and glial gap junctions as a means of continuity

Recovery of function

The excellent and insightful Mazzarello biography (Mazzarello, 1999) of Golgi elaborates on how he was profoundly impressed by the time course of functional recovery in humans following strokes and other acute injuries of the brain, emphasizing his professional immersion in neuropathology (Macchi, 1999). Yet, Golgi was not in dispute with the general thesis that interrupted axons in the central nervous system displayed limited propensity for re-growth and the absence of mitotic figures in

The polarity of the sensory neuron

The seemingly prototypic dorsal root sensory ganglion cell provided the initial vehicle for Golgi to express his reluctance in accepting Waldeyer's ‘neuron doctrine’ and while his rhetoric in the 1906 Nobel lecture was not a model of clarity, the validity of his argument is to be reckoned with in defining the terms ‘axon’ and ‘dendrite’. The adult sensory ganglion cell is unipolar and its peripheral processes were called ‘protoplasmic processes’; the extensively branched neurites later known as

The unsolved problems of sensory neurons

The seeming ‘simplicity’ of the sensory neuron remains misleading and perhaps Golgi displayed mischievous wisdom in opening his attack on the neuron doctrine by drawing attention to unresolved issues. The long ‘glomerular’ arrangement of large initial axons before the bifurcation, described in elegant detail by Cajal, was a puzzling and unexplained condition, but Golgi chose not to attack something for which he too could not offer a somewhat satisfactory explanation. Instead, his clumsily

A modern retrospective view

The ‘neuron doctrine’ became the framework of connectionist neuroanatomy in the 20th century and through his tremendous effort and accomplishment, Cajal's eminence appropriately thrived, while Golgi's reputation withered with neglect and suffered some needless and inappropriate abuse. Re-reading Golgi's Nobel lecture, I was struck by my mistaken negative recollection of Golgi's argument, rejecting him as a defeated warrior—a remnant of growing up in a scientific milieu that often proffered

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