Giovanni Berlucchi

The body in the brain revisited

Corporeal awareness is a difficult concept which refers to perception, knowledge and evaluation of one’s own body as well as of other bodies. We discuss here some controversies regarding the significance of the concepts of body schema and body image, as variously entertained by different authors, for the understanding of corporeal awareness, and consider some newly proposed alternatives. We describe some recent discoveries of cortical areas specialized for the processing of bodily forms and bodily actions, as revealed by neuroimaging, neurophysiological, and lesion studies. We further describe new empirical and theoretical evidence for the importance of interoception, in addition to exteroception and proprioception, for corporeal awareness, and discuss how itch, a typical interoceptive input, has been wrongly excluded from the classic concept of the proprioceptive–tactile body schema. Finally, we consider the role of the insular cortex as the terminal cortical station of interoception and other bodily signals, along with Craig’s proposal that the human insular cortex sets our species apart from other species by supporting consciousness of the body and the self. We conclude that corporeal awareness depends on the spatiotemporally distributed activity of many bodies in the brain, none of which is isomorphic with the actual body.

Neuronal plasticity: historical roots and evolution of meaning

In this paper, we outline some important milestones in the history of the term “plasticity” in reference to the nervous system. Credit is given to William James for first adopting the term to denote changes in nervous paths associated with the establishment of habits; to Eugenio Tanzi for first identifying the articulations between neurons, not yet called synapses, as possible sites of neural plasticity; to Ernesto Lugaro for first linking neural plasticity with synaptic plasticity; and to Cajal for complementing Tanzi’s hypothesis with his own hypothesis of plasticity as the result of the formation of new connections between cortical neurons. Cajal’s early use of the word plasticity is demonstrated, and his subsequent avoidance of the term is tentatively accounted for by the fact that other authors extended it to mean neuronal reactions partly pathological and no doubt quite different from those putatively associated with normal learning. Evidence is furnished that in the first two decades of the twentieth century the theory was generally accepted that learning is based on a reduced resistance at exercized synapses, and that neural processes become associated by coactivation. Subsequently the theory fell in disgrace when Lashley’s ideas about mass action and functional equipotentiality of the cortex tended to outmode models of the brain based on orthodox neural circuitry. The synaptic plasticity theory of learning was rehabilitated in the late 1940s when Konorski and particularly Hebb argued successfully that there was no better alternative way to think about the modifiability of the brain by experience and practice. Hebb’s influential hypothesis about the mechanism of adult learning contained elements strikingly similar to the early speculations of James, Tanzi and Cajal, but Hebb did not acknowledge specifically these roots of his thinking about the brain, though he was fully aware that he had resurrected old ideas wrongly neglected for a long time. Lately the concept of neural plasticity has been complicated by attributing considerably different meanings to it. A scholarly paper by Paillard is used to show how an analysis in depth can clarify some confusion engendered by an unrestricted use of the concept and term of neural plasticity.

Classical disconnection studies of the corpus callosum.

The corpus callosum is one of the most prominent fiber systems of the mammalian brain. Early reports of animals in which the callosum was cut, often confused the effects attributable to callosum damage with those caused by lesions of other brain structures. Early clinical reports also failed to establish the role of the callosum in humans. Two sorts of evidence began to reveal the functions of the corpus callosum. People with callosal damage cannot read text presented in the left visual field, and animals in which the callosum is divided, and sensory input restricted to one hemisphere, fail to show interhemispheric transfer of learning. These functional findings are consistent with anatomical and physiological studies of the role of the corpus callosum in communication between the hemispheres.

K.M. Bykov and transfer between the hemispheres.

Experiments in the laboratory of Roger Sperry showed that section of the corpus callosum blocks the normally strong transfer of information between the two hemispheres of the brain. In some of the papers from Sperrys lab, work by Bykov in Pavlovs lab was cited, since he appeared to have found similar results earlier. At the time, the only source on Bykovs experiment that was easily available was an abstract in a German journal. Although Bykov was the author of the paper, he did not write the abstract. The author of the abstract was Mark Serejski. Recently we obtained a copy of Bykovs original article in Russian, and arranged for it to be translated into English. The full article makes it clear that the abstract was somewhat misleading both in the methods and the results of Bykovs study. Here we present an English translations of Bykovs paper and the Serejski abstract, along with comments on the discrepancies between the two.

British roots of Italian neurophysiology in the early 20th century

Summary The recent Congress of the Italian Society of Neuroscience in Verona attracted several hundred participants, attesting to the vitality of a scientific enterprise that was started 23 years ago with the Societys first meeting in Rome. During the first Congress in Rome, four eminent Italian scientists were appointed honorary members of the Society in recognition of their outstanding contributions to neuroscience: the neurobiologist Rita Levi-Montalcini, the neuropharmacologists Daniele Bovet and Vittorio Erspamer, and the neurophysiologist Giuseppe Moruzzi. Their world-famous work inspired and provided the climate that encouraged the development of the neurosciences in Italy, and inspires Italian neuroscientists to this day. I have benefited from Moruzzis teaching throughout my scientific career, and my purpose here is to tell how Moruzzis teacher Mario Camis, and Moruzzi himself, benefited in turn from the teachings of the British founders of modern neurophysiology, Charles Scott Sherrington and Edgar Douglas Adrian.