Tagged: Brain Mapping
For many feminists, this effort to better understand female sexuality can be a means of empowerment, and it is not surprising that neuroscience research has branched into this area. Many people, rightfully so, believe that to understand our body and mind we must also understand the mechanisms of behavior in the brain. Yet due to its complexity, much of neuroscience research gets misinterpreted, reduced, or even generalized when written about for the public sphere.
Naomi Wolf’s Vagina: A New Biography, attempts to explain female sexuality by pulling from both subjective accounts and neuroscience to support her arguments. But what exactly does neuroscience research have to contribute to our knowledge of female sexuality? Although Wolf’s attempt at writing such a boldly stated book is admirable, it fell short, especially in terms of the science. Wolf misinterprets the roles of dopamine, oxytocin and serotonin in the brain and how they could plausibly influence a female’s romantic relationships.
As Maia Szalavits so eloquently wrote:
“The kind of oversimplification seen in Wolf’s book and, sadly, in many other popular accounts of neuroscience, threatens to perpetuate a psychological myth. Rather than illuminating the complex interplay between mind and body, it portrays human beings — especially women — as automatons, enslaved by brain chemicals we cannot control.”
So what does neuroscience have to say about female sexuality? At last year’s Society for Neuroscience Conference in Washington D.C., a 3D movie was presented of the brain during a female orgasm. Barry Komisaruk, a professor of psychology at Rutgers University, used fMRI (functional magnetic resonance imaging) to map brain activity in several women. The women were required to masturbate to an orgasm in the fMRI machine. (fMRI results are brain images reflecting activation in specific areas, and these areas are said to be lit up.) More
Here’s a great video summary from Nature on the recent advances in the field of connectomics by researchers at the Max Planck Institute in Germany and Harvard University:
You are unique, just like everyone else.
Connectomics is the study of the structural and functional connections among brain cells; its product is the “connectome,” a detailed map of those connections. The idea is that such information will be monumental in our understanding of the healthy and diseased brain. Sebastian Seung thinks that a complete connectome of the human brain will be one of the great prizes in 21st-century neuroscience.
Efforts to construct brain connectomes are split into two categories: ones that use imaging techniques like MRI, PET, and DT, thus focusing on macroscopic connections or tracts; and those that use electron microscopy to map the tinniest of axons (0.2-20 microns in diameter) and individual synapses.
While this may sound daunting, it also seems the obvious thing to do in order to really understand how the brain works. After all, don’t all our memories, personalities, and behaviors dependent on the structure of the brain, down to the microscopic level? So why is connectomics so new? Because the three-pound enigma that can contemplate all things big and small – from protons and electrons, to planets and stars, to galaxies and the whole universe – contains more parts than anything we’ve ever studied before. The human brain, we’ve been told, holds 100 billion neurons, with close to one quadrillion synaptic connections total; storing all of that information in one brain would take one Exabyte of data (that’s one trillion Gigabytes).
Jeff Lichtman and colleages at Harvard remain hopeful. They are developing novel tools to automate the tedious task of scanning brain slices. They expect the connectome to reveal differences in the way healthy and diseased brains are wired.
The effort is laudable, considering its scope and ambition, but it begs the question: does all behavior, experience, perception, etc depend on the structure of synapses and connectivity of neurons? More pointedly, does structure determine all function – chemical and electrical? Sure, larger synapses or more dendritic spines make stronger connections and more efficient transmission of information, but a snap-shot connectome won’t take into account temporal dynamics and enzymatic processes, which play a big role in the active brain.
In his TED talk, Sebastian Seung says that to test the hypothesis that “I am my connectome,” we could try to read out memories from someone’s connectome. But memories are not just synaptic connections – they are also assemblies of neurons in time or firing sequence. The connectome does not take those into account. And Seung fails to explain how we could actually verify any of those personal memories, since current methods of constructing a connectome involve cutting the brain into thousands of 30-micron slices.
If we could devise some non-invasive methods to construct a human connectome at the synapse level, what ethical issues would we face? Could a personal connectome be the ultimate breach of privacy? Could it redefine or “undefine” what we consider to be normal brains/mental states?
Constructing a comprehensive human connectome is a great challenge. A bigger challenge would be to model the electrical dynamics of the 100 billion human neurons. But perhaps the most important quest for neuroscience isn’t building a connectome, but learning how neuronal activity creates experience.
Neurocartography – Narayanan Kasthuri and Jeff Lichtman via NIH Public Access
Sebastian Seung: I am my connectome – TED.com
Seeking the Connectome, a Mental Map, Slice by Slice – NYTimes.com