2. What is Optogenetics? In how far has optogenetics to do with control?
Optogenetics combines optical methods (eg flashes of light from a laser or LED) with genetic methods to transfer to a specific group of neurons cDNA encoding proteins sensitive to light of microbial origin (called opsins). This is a breakthrough technology that began its development in 2005 by Karl Deisseroth of Stanford University.
“Optogenetics is a technology that allows targeted, fast control of precisely defined events in biological systems as complex as freely moving mammals. By delivering optical control at the speed (millisecond- scale) and with the precision (cell type–specific) required for biological processing, optogenetic approaches have opened new landscapes for the study of biology, both in health and disease.” (Deisseroth 2010)
In 2010 the journal Nature named it the most important scientific Method of the year. According to its inventor Karl Deisseroth “Optogenetic technology combines genetic targeting of specific neurons or proteins with optical technology for imaging or control of the targets within intact, living neural circuits.“(Deisseroth et al 2006). Optogenetics tools allow the control of electrophysiological properties of neurons in vivo by light, but as well it is used designate not the manipulation but the visual discovery by cell visualization in the optogenetic process.The bases of Optogenetics can be found in the study of a unicellular organism, the alga Chlamydomonas reinhardtii and its ability to move towards a light source. Peter Hegemann ,Georg Nagel, and Ernst Bamberg, discovered a protein called Channelrodopsin 2 ( ChR2 ) from which this alga makes use to move towards light. By the stimulation with light of 473nm (blue light )[c], the channel ChR2 opens allowing the passage of ions through the cell electrochemical gradient (H + > Na + > K + > Ca +). A few years after this discovery of ChR2, Karl Deisseroth used genetic engineering methods by which he introduced the ChR2 gene in rodent neurons. After 2 months the neurons expressed sufficient levels of ChR2 in the soma and dendrites to allow a single pulse of blue light, directed through an optical fiber, to open ChR2 and allow the influx of Na + into neuron , causing a depolarization of the membrane potential and action potential without affecting the neurons found in the environment that don’t express ChR2 , and as such these neurons are not sensitive to the light beam . That is, when the ChR2 is expressed in the neuronal membrane , it can literally transform light pulses changes in membrane potential, triggering the generation of electrical pulses or potential Action.´
3. Optogenetic as behavioral Remote Control Tool
Different types of Optogenetic Control? Optogenetic tools have since 2005 – that is from the start been declared biotechnological tools of remote controlling behavior such as the manipulation/stimulation of the flight behavior of Drosophila flies as shown in Susana Lima and Gero Miesenböck 2005 article: ”Remote Control of Behavior Resource through Genetically Targeted Photostimulation of Neurons”
“Optically gated ion channels were expressed in circumscribed groups of neurons in the Drosophila CNS so that broad illumination of flies evoked action potentials only in genetically designated target cells. Flies harboring the “phototriggers” in different sets of neurons responded to laser light with behaviors specific to the sites of phototrigger expression. Photostimulation of neurons in the giant fiber system elicited the characteristic escape behaviors of jumping, wing beating, and flight; photostimulation of dopaminergic neurons caused changes in locomotor activity and locomotor patterns. These responses reflected the direct optical activation of central neuronal targets rather than confounding visual input, as they persisted unabated in carriers of a mutation that eliminates phototransduction.“ Lima& Miesenbröck 2005, 141
More on Optogenetic and its ethical implications of this "radical enhancement" tool soon to come...
Alexander Gerner firstname.lastname@example.org
 On the contrary to Carl Craver (see Carl Carver upcoming (under revision) who is preoccupied with the intervention part only and not as well with the visualization part I propose that the introduction of light into cells for the purpose of visualization is already a first step of manipulation and thus a visual methodological enhancement. Thus I distinguish for conceptual reasons a) optogenetic visualization from b) optogenetic intervention in the brain, however ontologically both poles are not to be separated, but co-dependent on each other and have to be seen in coordination.