09 April 2013

Photonics for a healthier brain!

Brain mapping -- using light to observe and track neuron activity in the brain -- holds much promise for treating some of the most troubling conditions. Among its goals are treatment of stroke, epilepsy, Alzheimer's disease, and even depression.

The field is claiming the attention of R&D funders as well.

A White House announcement last week of a potential$100 million funding pot for brain research, as part of the presidential budget proposal for fiscal year 2014, made waves that echoed the response to an announcement last month of a far-reaching brain research program in Europe.

As Mike Hatcher, editor of, noted, the White House-proposed BRAIN (Brain Research through Advancing Innovative Neurotechnoloiges) initiative still requires backing by a fractious Congress. “But if the public-private scheme does go ahead it will mirror an even larger funding proposal in Europe, where -- along with graphene research -- the ‘Human Brain Project’ was earmarked as one of only two flagship, long-term science programs,” Hatcher said.

Optogenetics: a new tool

“Critics have suggested that a fundamental difficulty with brain research is the lack of tools available to stimulate and monitor specific neural functions,” he said.”That, possibly, is where photonics comes in -- more specifically in the emerging form of ‘optogenetics’."

Developers of optogenetics -- the use of light to control neurons in living tissue -- were recently announced as winners of Denmark's €1 million annual brain research prize. Winners are Gero Miesenböck (University of Oxford), Ernst Bamberg (Max-Planck Institute of Biophysics), Peter Hegemann (Humboldt University), Georg Nagel (University of Würzburg), Ed Boyden (Massachusetts Institute of Technology), and Karl Deisseroth (Stanford University).

The brain prize-awarding body (the Grete Lundbeck European Brain Research Prize Foundation) said of the winners, "Together these scientists laid the foundations for the revolutionary technique optogenetics, which will provide us with entirely new, fundamental knowledge of the complicated functions of the brain (and make) it easier to investigate diseases of the brain such as Parkinson's disease, Alzheimer's disease, epilepsy, pain disorders, schizophrenia, ADHD and addiction."

Activated by photonics

At SPIE Photonics West in January 2012, a standing-room-only audience heard Deisseroth describe some of the implications for the understanding of behavior.

Above, Britton Chance, seen as a central figure in
the development of brain imaging techniques,
demonstrates a head-worn brain-imaging device.
Based on their work in the 1970s and ’80s, he and
collaborators made a critical discovery that
spurred the biomedical use of diffuse light.
Temporally short, near-infrared (NIR) light
pulses were injected into the brain (the light
diffused through the skull), and the changes in the
temporal shapes of the pulses were measured upon
exit. The changes in shape quantitatively revealed the
blood oxygen dynamics of the animal and, soon
thereafter, the human brain in 1988. Since this
experiment, the field of photon migration and optical
imaging and spectroscopy has grown dramatically.
(From the Journal of Biomedical Optics, April 2000, editorial
by Arjun Yodh (University of Pennsylvania) and
Bruce Tromberg (University of California/Irvine).
Current advances exploit developments in both the biochemical markers added into neural circuitry, and the optical methods used to then activate or regulate them -- the twin principles on which optogenetics is based, Deisseroth said.

Some of the most fascinating work involves mapping the neural dynamics accompanying the manifestation of certain depressive symptoms, a potentially profound area of study.

Once the neural circuitry involved in depressive states is mapped, it might then be possible to affect those mental states by changing the behavior of the neurons. Deisseroth described how similar optogenetics approaches were now shedding light on the influence of dopamine on risk/reward behavior, and on the significance of certain neurons to cocaine addiction.

"It is still early days with a great deal left to understand about the causal dynamics involved in these states of mind, but it is a very interesting area," he said.

Optogenetics, diffusion tensor and other magnetic resonance imaging (MRI) techniques, spectroscopy, optical coherence tomography (OCT), and multimodal microscopy are among techniques being tested for the toolkit. Recent video interviews on the topic include work by Joe Culver (Washington University at St. Louis) and Elizabeth Hillman (Columbia University).

Solving the brain's mysteries

The recent funding proposals reflect both the interest and the need to solve the brain’s mysteries.

The European Commission announcement said,"The ‘Human Brain Project’ will create the world's largest experimental facility for developing the most detailed model of the brain, for studying how the human brain works and ultimately to develop personalised treatment of neurological and related diseases. This research lays the scientific and technical foundations for medical progress that has the potential to will dramatically improve the quality of life for millions of Europeans.”

President Obama’s remarks in announcing the BRAIN initiative touched on similar points, and were heavy on photonics: "In the last decade alone, scientists have made a number of landmark discoveries that now create the opportunity to unlock the mysteries of the brain, including the sequencing of the human genome, the development of new tools for mapping neuronal connections, the increasing resolution of imaging technologies, and the explosion of nanoscience … by combining advanced genetic and optical techniques, scientists can now use pulses of light to determine how specific cell activities in the brain affect behavior. In addition, through the integration of neuroscience and physics, researchers can now use high-resolution imaging technologies to observe how the brain is structurally and functionally connected in living humans.”

We're looking forward to new developments in these amazing photonics technologies!

1 comment:

  1. Indeed, there is much more to come. The New York Times reported today on how Karl Deisseroth and colleagues at Stanford University have made a whole mouse brain, and part of a human brain, as clear as Jell-O, "so that networks of neurons that receive and send information can be highlighted in stunning color and viewed in all their three-dimensional complexity without slicing up the organ."