201. A plastic brain for a changing environment
- Author
-
Giuseppe Vallar, Costanza Papagno, Papagno, C, and Vallar, G
- Subjects
Neuronal Plasticity ,Artificial neural network ,Cognitive Neuroscience ,Neuropsychology ,Brain ,Experimental and Cognitive Psychology ,Plasticity ,Environment ,M-PSI/02 - PSICOBIOLOGIA E PSICOLOGIA FISIOLOGICA ,Fully developed ,Neuropsychology and Physiological Psychology ,Malleability ,Neuroplasticity ,Neural system ,Humans ,Empirical evidence ,Psychology ,brain plasticity ,Cognitive psychology - Abstract
Neuropsychological Laboratory, IRCCS Istituto Auxologico Italiano, Milano, ItalyA few years ago a brief communication on Nature reportedlearning-induced plasticity in the gray matter of the brains ofvolunteers who had learned to juggle (Draganski et al., 2004).These individuals showed a transient and selective structuralchange in brain areas associated with the processing andstorage of complex visual motion. This discovery of astimulus-dependent alteration in the brain's macroscopicstructure contradicted the traditional, and at that time pre-vailing, view that cortical plasticity is associated with func-tional, rather than anatomical, changes (Draganski & May,2008). This finding gave also impetus to the study of neuro-plasticity, suggesting that in the gray matter not only reduc-tion of volume is possible, such as in ageing, but alsoincrement. There may be, however, some abuse of the term“neuroplasticity” (used with “gay abandon”, as suggested byBuchtel, 1978). Following Paillard (see Will, Dalrymple-Alford,Wolff, & Cassel, 2008), changes in the nervous system shouldbe called “plastic” only when the connectivity network of thesystem undergoes lasting changes in the structure that linkstogether its elements. Furthermore, changes,to be considered“plastic”, should be both structural and functional, namelyonly when a given system (here, a set of cortico-subcorticalnetworks) achieves a novel function, either by transformingits pattern of internal connectivity, or by changing the ele-ments of which it is made, or both. Random (backgroundnoise) and systematic variations, namely, operating errorsbeyond the flexibility of the system, as well as vicariousstrategies used to achieve a given behavioral goal should notbe regarded as plastic changes. With reference to the life spanof the living organism, the distinction may be drawn betweenthe structural malleability of the system during development,within the range of genetic competence (termed by Paillardgenetic plasticity), and the capacity of the fully developed sys-tem to change its own structure, and to expand its behavioralrepertoire, namely: the adaptive plasticity of a system whichhas already completed its maturation. The possibility that agiven neural system achieves a novel function does notnecessarily mean that the functional (psychological, cogni-tive) architecture changes. The function may be “novel”, withreference to the previous activity of that neural network, butnot per se, namely: the plastic system may replace, at least inpart, another damaged network, taking over and maintainingthe functional properties of the latter. This is a key assump-tion, in order to make meaningful inferences from the path-ological behavior of brain-damaged patients to the functionalorganizationofthenormalsystem(discussioninVallar,2000).Finally,plasticityreferstoachangeinstructureinresponsetoan external force, and the maintenance of that shape afterremoval of the force, in contrast to “elasticity”, which impliesthe return to the previous form, when the force is removed(Berlucchi & Buchtel, 2009).While convincing empirical evidence suggesting thatplastic changes may occur in the brain is quite recent, therootsof the conceptof “neuroplasticity” maybe tracedback tothe second half of the XIX century. Berlucchi and Buchtel(2009) pointed out that the Italian psychiatrist ErnestoLugaro (1870e1940) was the first to introduce the term “plas-ticity” (also used by the North American psychologist WilliamJames,todenotechangesinnervouspathsassociatedwiththeestablishment of habits) in order to link neuroplasticity tosynaptic plasticity as early as 1906. By this term Lugaro meantthat the anatomoefunctional relations between neuronsmight change in an adaptive way along our life span, in orderto allow psychic maturation, learning, as well as functionalrecovery after brain damage. Lugaro's concept of plasticitywas inspired by a neural hypothesis of learning and memoryput forward in 1893 by his mentor Eugenio Tanzi, whopostulated that practice and experience promote neuronalgrowth and identified the articulation between neurons assites of neural plasticity. Cajal (references in Berlucchi &
- Published
- 2014