Neuronal Darwinism. The paradoxical impact of neuroscience in research and psychological practice
The development of neuroscience has accelerated enormously in the past decade. Many practical applications have benefited from these new scientific discoveries.
These implications have had the further merit of suggesting new working hypotheses, in the theoretical and epistemological reflection on the one hand and in the development of new intervention techniques in medicine and psychology, on the other.
In this article I would like to summarize the ingenious intuition of Gerald Edelman, Nobel Prize in Medicine in 1972 for his research on antibodies, known as the theory of selection of neuronal groups, and the theoretical and heuristic implications of this theory in research in psychology. The first element to analyze is, without doubt, the approach that Edelman used in addressing the theme of the formation and functioning of brain activity, from the embryo to adulthood, an approach that the same borrowed from research in field of immunology which earned him the Nobel Prize for Medicine, as already mentioned. In summary, he opposed the prevailing idea in the scientific world according to which the antibodies of the vertebrate immune system are formed as a consequence and adaptation to the characteristics of the antigen to which they must respond; that is, it would mean assuming that the antigen contains the information necessary for the formation of a corresponding antibody that will be modeled on the basis of the information contained in the antigen itself. This way of interpreting the cellular mechanism of the immune system’s response is called educationism, an interpretation to which Edelman opposes the idea of selection or selectionism. This second view consists precisely of a Darwinian population principle, according to which, in the immense number of antibodies already present in the organism,
Edelman’s intuition was that this principle could apply to any biological system, including brain and synaptic development; So the brain is also a selective recognition system? According to the theory of selection of neuronal groups certainly yes. In fact, with all due respect to the most irreducible positivists, the somatic selection, already of epigenetic nature therefore, begins in the embryonic phase, through the formation of neuronal groups which, downloading simultaneously, are wired together forming an individual map (primary repertoire), always different from individual to individual, even in the case of homozygous twins. At this point it is easy to understand how experience and interaction with the environment will produce individual synaptic configurations in the newborn that cannot be traced back to the genetic dictation, through selective work to strengthen or weaken the neural groups functional to a better adaptive response, represented by healthy or dissociated internal operating models depending on the adequacy of the primary care available (secondary repertoire). But let’s see more closely what is the mechanism at work in somatic selection; the concept and term that sums up this complex competence of brain nerve cells used by Edelman is re-entry. It means something different and more than just the concept of feedback or feedback; it is a complex and sophisticated mechanism that more than a mere exchange of signals that modify the interior from the outside, it consists in the formation of so-called re-entering circuits which represent the constructive way our brain has to communicate above all with itself. The external stimuli, therefore, produce a subsequent processing at the neural level, as a sort of (individual) self-organization of the brain itself, which will strengthen those incessant exchanges of synaptic connections (cyclic, ring rather than linear) that will establish themselves through a simultaneous discharge, such as those most suitable to respond to the need for adaptation, selectively oriented.
In this sense, re-entry resembles an emergent property that arises from the intrinsic self-organizing qualities of the brain itself. The dynamic nuclei that are formed by the activity of the re-entering circuits, then, demonstrate how it is the output functionality that directs the entire mechanism and not the anatomy, since the global re-entrant maps that form precisely the dynamic nuclei, always variable, connect neurons distant from each other as well as different in specific function.
Fig .1 (from Edelman G., Larger than the sky, Turin, Einaudi, 2004, p.38). Three separate fields or maps whose connections produce a functionally equal output response at different times.
What matters most compared to this traffic of re-entering connections that are strengthened and weakened according to the adaptive needs that condition their mutual exchange is the final consequence of the process, i.e. the fact that in particular circuits and in particular map configurations, even anatomically distant from each other, neurons discharge simultaneously, are synchronized independently of the anatomical region of their location.
Chiasmus therefore consists in the fact that different cells (neural aggregates) can perform and perform the same function as well as the same dynamic nucleus can perform different functions at different times.
Fig. 2 (from Edelman G., Second nature. Brain science and human knowledge, Cortina, 2007, p. 25). The mutual connections between the thalamus-cortical regions and between various regions of the cortex are highlighted. The reciprocal connections integrate and synchronize the activities of different specific neural maps.
The brain proves to be a generator of diversity; our author has coined a curious acrostic, God (generator of diversity), to highlight the fundamental structural characteristic underlying the theory of the selection of neuronal groups.
The encounter with the signals that come from an unknown world, not yet categorized and therefore ambiguous, produces and facilitates the differential amplification of those particular configurations that best adapt to respond to the challenge of adaptation, at all levels and at all levels. development phase, throughout the life of the individual.
Very interesting in this description of the properties of the reentering maps is the observation that there would be no higher regulatory center that coordinates the neural activities responsible for a particular function; rather it is precisely the very activity of synchronization of groups of neurons from different brain areas and regions that open determined ways and configurations under the thrust of the reentering connections that produces the consequent adaptive and functional response that will correspond to the infinite possible states of consciousness and subjective experiences conscious, but also unconscious, according to a frankly inexhaustible scheme in relation to any quantitative and taxonomically controllable regulatory criterion.
So what is evident and what are the consequences of this new scientific knowledge regarding research in psychology? If from the side of one of the sciences considered hard, hot (compared to the human sciences, soft) come holistic and non-causal-reductive considerations, therefore according to a non-deterministic epistemology, what should we think about the psychological sciences? The search for a dignified scientific status was born with psychology itself, if we think that the first chair of psychology in a scientific faculty dates back to the University of Geneva in 1891 with Theodore Flournoy, as reconstructed from the fundamental work of Sonu Shamdasani in his story on birth of modern psychology (in Italy we will have to wait for 1978 for the first degree course in psychology). A legitimate and comprehensible ambition which, however, paradoxically, together with the (sometimes sadly spasmodic) search for objective and incontrovertible scientific validation, leads towards the inevitable positioning of psychological theories and practices in the order of the human sciences, along that line which represents an uninterrupted continuum at the end of which there are natural sciences. In this sense, the final thrust, which closes the game definitively, comes precisely from the most objective and mathematically coherent science possible, physics. We know how contemporary particle physics, if on the one hand it produces forecasts and practical and technological applications that have never been so precise and accurate in the history of human knowledge, on the other it underlines how the theoretical and conceptual framework of quantum mechanics is probabilistic, holistic, non-deterministic. The paradox is demanding from the point of view of the philosophy of science but, at the same time, it illuminates with respect to what predisposition we psychologists must assume in the face of both research and investigation work, both in the interpretation and care of patients. The turn, in the last decade, towards an ever greater attention to the relational aspects of therapy compared to the previous historical wars of religion between the various theoretical approaches, in psychoanalysis, in psychiatry, in psychology tout court,
I conclude the epistemological reflection, citing the research carried out at the University College of London (Karmiloff-Smith, Johnson), research that is part of that area of evolutionary psychology studies that began around the 90s of the last century and which represent an integration and overcoming of the historical dichotomy between innatism and behaviorism, or, even better, between a conception of the infant’s mind as a tabula rasa (John Locke’s English empiricism) which attributes to the environment and experience the whole responsibility and impact on the child’s development and, conversely, a conception of the child’s mind equipped with innate structures and programmed to perform certain tasks, once the environment and experience have activated them. Continuing the studies on the evolutionary stages of Piaget,
In this sense, the genetic code (very small in number compared to the initial expectations, 30 thousand genes against the expected 100 thousand) cannot contain the information necessary to explain the enormous complexity of human cognitive development, nor the infinite variability of behavior; any predisposition derived from the genetic code not only requires interaction with the environment to take shape but, above all, must be considered as the predisposition to form representations interacting both with the external world and with the internal world, and certainly not as existence of innate representations already present in the brain itself.
The representations then are not already present in the genetic code, rather the genes prove to be the catalysts guarantors of a process rather than holders of a pre-existing content, this is the difference. Evolutionary psychologists point out that the innate component is limited to the mechanism of focusing attention in a certain way, this would only be the constraint, a content-free algorithm that binds and directs simply how attention and perception will emerge at the level early and primitive. Morton and Johnson have conducted experiments on newborns in this sense, demonstrating how the ability of the human face to recognize other infants’ stimuli is innate; have named this mechanism not acquired Conspec, to underline the characteristic attributable to the entire human species which, however, is limited to the tendency to pay attention generically to human faces without recognizing their peculiarities and differences; in fact the ability to discern and distinguish for example the face of the mother from that of the father depends on learning and emerges a few weeks later and depends on Conspec only to the extent that it represents an extension of what it ensures, that is, that the child lends attention to human faces.
There is therefore no particular predetermined image in the infant’s mind but, as we have seen, the innate tendency to turn around and be attracted to any human face compared to other images that arise in the visual field. It is a sensorimotor reflex devoid of intentionality and understanding of meaning, whose biological substrate would reside in the subcortical structures that would simply constrain the perceptive and attentive response in the way we have seen. At the cortical level, however, the authors indicate that the representations are not pre-specified and predetermined, since they need and emerge from the complex interactions between the brain and the environment and from the mutual relationship between internal brain areas.
In this sense, the principles of self-organization and emergence prevail in the interpretation of mental development over deterministic and innatist conceptions in a strong sense.