My mini-brain under the microscope.

      * * *

      Let me explain.

      My mini-brain was cultivated, nurtured and guided by neuroscientists Selina Wray and Christopher Lovejoy at UCL. That’s their job. They want to understand how brains develop, and in particular why some gene mutations send that process awry and trigger the onset of neurodegenerative diseases such as Alzheimer’s. These conditions, which many of us will confront – close to a million people in the UK are currently thought to be living with some form of dementia – are partly a consequence of ageing, but they can also have genetic roots. Some gene mutations confer particular susceptibility to dementias, and there are inheritable early-onset dementias that can affect people even in their thirties. My “brain in a dish” was grown as part of a large and ambitious project called Created Out of Mind, funded in 2016–18 by the Wellcome Trust to alter public perceptions of dementia and develop new tools for assessing the value of arts-based interventions for people living with these conditions.

      Selina and Chris hope that, by studying the activity of genes in mini-brains cultured from the tissues of people with those genetic mutations, they might come to understand more about the causes, and ultimately find clues that could lead to possible cures. Scientists studying the genetic factors behind the neurodegenerative Huntington’s disease have already found that the baleful effect of one particular gene implicated in the condition can be tempered with drugs that intercept the conversion of the gene to a protein that is prone to “misfolding”. It’s this misfolded form that produces scarring and destruction of brain tissue. Others are working on vaccines that might prevent or remove the clumps of misfolded protein in the brain that seem to trigger Alzheimer’s itself.

      To my knowledge, I do not have genes that make me susceptible to early-onset Alzheimer’s. But the aim of the Brains In A Dish project, coordinated by artist Charlie Murphy, was to explore and explain research like this through the response of its participants. Well, this book is mine.

      I should be very clear what this term “mini-brain” implies. Some researchers reject it, and I see their point. Human neurons grown in a cell culture in this way can’t make a brain, not even in its early fetal form. But these nerve cells do start to create, under the direction of their own genetic programme, some of the features that a real developing brain exhibits. They become specialized into some of the many different cell types – not just neurons – that are found in our mature brains. And they acquire some of the anatomical structure of brains: the well-defined layers of neurons seen in the cortex, the folds and convolutions of the tissues. It’s rather like a very young child’s drawing of a person: not much of a resemblance really, but you can see what they’re getting at. You can see the potential to do a better job. A more neutral term for these lab-grown cell structures is “organoid”: the cells construct something that looks like a crude representation of an organ of the body, reduced in scale. It is possible to grow organoids resembling livers, kidneys, retinas, gut, as well as brains – all in a dish, outside the body. I want to ask what this means, for medicine, fundamental biology, philosophy and our sense of identity.

      There was no rulebook to tell me how I should feel about my mini-brain. Certainly, I didn’t lie awake at night fretting over its welfare; this mass of tissue made from my skin didn’t take on the status of an individual. But I felt oddly fond of those cells, doing their best to fulfil a role in the absence of the guiding influence of their somatic source.¹ There was a curious intimacy involved, a sense of potential that wasn’t present initially in the tiny chunk of arm-flesh excised and placed in a test-tube. This was more than a matter of cells subsisting; this was life in all its teeming, multiplying glory, spilling out from a paring of me.