Shimon Marom - Research interests

Membrane excitability

The study of excitability, from Galvani and elmholtz, through Adrian, Hodgkin and Huxley, Neher and Sakmann, all the way to McKinnon’s elucidation of a channel protein structure, should no-doubt make us physiologists very proud of our discipline. But there is still a long way to go. Present concepts and technologies make it possible to implement the biophysical understanding of excitability in the more general context of mechanisms underlying the emergence and maintenance of functional cellular organization. Accordingly, the body of our theoretical and experimental studies reflects the idea of membrane excitability as a toy model for self-organization of cellular function. These studies address parameterisation of high-dimensional models of excitability, adaptation over extended ranges of time scales, critical self-organization, multiplicity of system states and its impacts on scaling of rates, modeling state-dependent processes, response entrainment, resilience of function to parametric variations, and the effects of spatial extension (e.g., axonal conduction) on the dynamics of excitability.

Neural networks

It is generally believed that behaviors are not mapped to single spikes generated by any one neuron, but rather to groups of spikes. These functional spiking neural activity groups may originate from a single neuron or from populations of neurons firing in synchronic or diachronic manners. The structure of the vast majority of behaviorally relevant neural activity groups is not predetermined by genetics, nor dictated by some sort of an ‘all-knowing teacher’, homunculus. Rather, neural activity groups are formed and modulated throughout life in a dynamic, activity-dependent manner, conforming to evolution and environmental constraints. The formation of neural activity groups is learning; their conservation is memory. Of the various alternatives, large random cortical networks developing ex vivo are probably the most appropriate experimental model systems for studying the universals governing formation, adaptation, and conservation of neural activity groups. These networks demonstrate extensive functional connectivity and sensitivity of that connectivity to activity. Moreover, the networks are relatively free of predefined constraints and intervening variables. Alternative experimental models (acute in-vivo, or acute in-vitro) allow one to explore ‘what-is-there’, but not ‘how-it-got-to-be-there’. The latter question is tightly related to development. The body of our network studies implements advanced electronic (multi-electrode array) to interface with large scale developing cortical neural networks. These studies address learning under closed loop settings, adaptation over extended ranges of time scales, stimulus representation, embodiment, dynamics over structure, neuromodulation, impacts of modularity, and more.

Psychology & Physiology

Out of a developing sense of unease with the nature of the present dialogue between brain science and psychology, I sought understanding, not so much of this or that recent biological finding, but of the roots that feed the stance of neurophysiology toward depth psychology. While meandering in the chasm between physiology and psychology, contemplating the recent history of possible-impossible relations, the text evolved into an essay, a monograph titled Science, Psychoanalysis, and the Brain: Space for Dialogue (Cambridge University Press [read online], download; תרגום לעברית; Italian translation). The essay is an invitation, issued by a practicing physiologist, intended for dynamically oriented theory-sensitive psychologists and physiologists. It is an invitation to a space where reflections on neurophysiology are expressed and guided by depth psychology in mind; a space where neurophysiology resumes its traditional, humbled attitude toward matters of the psyche, and where the intellectual autonomy of depth psychology is acknowledged. The underlying assumption is that in the basic sense, as opposed to the applied science sense, the meaning of neurophysiological and neuroanatomical observables resides in their interpretation in light of psychological theories. A dialogue based on such terms, where psychology provides a theoretical framework that contributes to physiology, is beneficial to both parties: Neurophysiology gains something that is currently wanted – constraints and guidelines in phrasing meaningful questions. Psychology might gain further motivation to crystalize its multifaceted concepts. At all events, both camps might enrich the spectrum of metaphors available to them within their own disciplinary realms.