Unwiring the brain

As the new year has rolled on, I have started to enter the “business” end of the year, as it were.  Classes have wrapped up for the most part, and now I am spending most of my time getting my research project up and running. I’m hoping to finish up my thesis in the early part of the summer so that I will have time both to intellectually decompress before starting my PhD in the fall (as well as a chance for some final adventures before putting down some proper roots).

My project is applying a technique called optogenetics to the study of “place cells” in the hippocampus.  The hippocampus is a structure deep in the brain which is associated with episodic memory consolidation (patients with hippocampal lesions experience anterograde amnesia – they retain previous memories but will not even remember the therapist they meet each day).  Neural recordings taken from the rat hippocampus have revealed cells with spatial tuned firing fields: for example, one neuron will fire whenever the rat is in a particular corner of the arena.  These “place cells” collectively form something of a mental GPS system through which the rat can represent and navigate space.  By understanding the dynamics of spatial representation in the brain, we hope to gain general insight into the function of hippocampal circuits, and into how to repair them when they go wrong (as they do in Alzheimer’s disease).

The particular stimulation technique we are using – optogenetics –  uses light to directly stimulate activity (thus ‘opto-‘) in genetically targeted neurons (‘-genetics’).  This light-sensitivity is not natural: neurons are normally driven by electrical signals, but the genetic expression of microbe-derived opsin proteins (similar to those that allow your eye to sense light) endows the neurons with this sensitivity.  The optogenetics toolkit is relatively well-established worldwide, but this is (to my knowledge) the first implementation of the technique in Trinity (and indeed in Ireland).

A mouse with an optical fiber in its brain (John Carnett/Popular Science)

As a scientist who cares about the moral dimensions of research, the implications of these and other emerging techniques in neurotechnology are not lost on me.  The prospect that a brain can be precisely manipulated by light (or indeed by any stimulus) is both fascinating and disturbing.  President Obama recently launched the BRAIN initiative to fund research towards mapping all of the connections in the human brain (the human “connectome”), and many have drawn analogy between this project and the human genome project.  While different in import respects, I think the comparison is apt in terms of the ambitious scale and scientific consequences of both projects: the sequencing of the human genome was arguably the greatest technical milestone since the moon landing.

The prospect of knowing the genomes of individual persons has already raised a host of ethical questions; the prospect of mapping a human connectome would undoubtedly create even more.  Suppose a person’s consciousness can be reduced to this physical substrate: to the pattern of structural and functional connectivity in her brain, and to the computational rules that give rise to higher cognition.  What then of a world in which a brain can be unwired and decoded; even downloaded, emulated, or build from scratch?  For now this remains the domain of science fiction, but science is moving in this direction.  At what speed, it is hard to say.  Human curiosity is a powerful force; if we do ever reach such a day, we will require an equal measure of wisdom to ensure that we responsibly manage this knowledge and any new technologies it enables.

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