Nobel Stains

Microscopic anatomy of sensory receptors

Experiences following stimulation of the senses have been recorded for millennia, and they could be related to the gross anatomy of the sense organs. Examination of their microanatomy was to await the development of achromatic microscopes in the early nineteenth century. Among the microscopic structures that were isolated and described were specialized sensory cells, called receptors, and they could be related to the stimuli that excited them. Those located in well-defined sense organs (like the eyes, ears, nose, and tongue) were named on the basis of their morphology, whereas the receptors in or beneath the surface of the skin were generally named after those who first described them. Illustrations of early representations of sensory receptors are combined with "perceptual portraits" of the microanatomists who described them.

Receptor Visionaries

Sensory receptors were described and illustrated after they had been observed with the aid of microscopes. Most descriptions were made in the 19th century after the introduction of achromatic lenses in microscopes. In some senses (like vision), receptors were named according to their morphology whereas in others (like touch), they are known by the names of those who initially described them. Illustrations of the receptors from original sources are here combined with portraits of their originators.

Vision and visualization

The art of visual communication is not restricted to the fine arts. Scientists also apply art in communicating their ideas graphically. Diagrams of anatomical structures, like the eye and visual pathways, and figures displaying specific visual phenomena have assisted in the communication of visual ideas for centuries. It is often the case that the development of a discipline can be traced through graphical representations and this is explored here in the context of concepts of visual science. As with any science, vision can be subdivided in a variety of ways. The classification adopted is in terms of optics, anatomy, and visual phenomena; each of these can in turn be further subdivided. Optics can be considered in terms of the nature of light and its transmission through the eye. Understanding of the gross anatomy of the eye and visual pathways was initially dependent upon the skills of the anatomist whereas microanatomy relied to a large extent on the instruments that could resolve cellular detail, allied to the observational skills of the microscopist. Visual phenomena could often be displayed on the printed page, although novel instruments expanded the scope of seeing, particularly in the nineteenth century.

The sensory neuron and the triumph of Camillo Golgi

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.

Molecular networks of brain and immunity

Exciting complexity of natural phenomena can be based on rather simple biophysical principles. For example, the genetic code is based on a double-helix of DNA formed by planar geometry of weak hydrogen bounds. On the examples of cytokine networks, immune synapse, psychoneuroimmunology and systems biology, this review paper attempts to show how molecular networks both in brain and immunity can be studied using common principles of protein-protein interactions.

Image, eye, and retina (invited review)

Advances in understanding the initial stages of the visual process have been made over the centuries. This heritage will be reviewed with respect to the passage of light through the eye, as well as its gross anatomy and microscopic structure. The links between image formation in the camera and the eye were integrated with the anatomy of the eye in the seventeenth century. They drew attention to the problem of accommodation and to corrections for errors of refraction. Investigations of the structure of the retina were to await the invention of achromatic microscopes in the early nineteenth century. An armory of devices for examining vision and the eye were to follow later in the century. These transformed the study of vision from an observational to an experimental discipline.

Whither withered Golgi? A retrospective evaluation of reticularist and synaptic constructs

The 100th anniversary of the shared first Nobel prize in neuroscience by Camillo Golgi and Ramon y Cajal invites reappraisal of the merits of the arguments adduced by these two combative scientists in the light of contemporary knowledge. Guided by cogent reasons for reluctance in accepting the inviolable polarity principle of the neuron doctrine and concern for explaining cerebral recovery of function, Golgi joined the 'reticularists' of his generation. Modern observations of axo-axonic and dendro-dendritic synapses, gap-junction interconnections, rules for the direction and mode of analog or impulse conduction, the myriad diversity of ion channels and gating principles and the complexities of synaptic plasticity have eclipsed the polarized neuron doctrine explanations of reflex physiology and the 'fixed and immutable' connections successfully championed by Cajal. Without violating the cell theory, expanded modes of neuronal and glial communication have encompassed reticularist notions and provided insight into the long-term changes underlying synaptic and extra-synaptic neural patterns. Both laureates espoused operative principles that have survived in different modes and distinctive temporal domains. Together, they reflect the roots of our contemporary understanding of neural interaction.