I like the "cool factor" in this study: Ji Z-G , Ito S , Honjoh T , Ohta H , Ishizuka T , et al. 2012 Light-evoked Somatosensory Perception of Transgenic Rats That Express Channelrhodopsin-2 in Dorsal Root Ganglion Cells. PLoS ONE 7(3): e32699. doi:10.1371/journal.pone.0032699.-"We have recently generated several transgenic lines of rat in which channelrhodopsin-2 (ChR2) transgene is driven by the Thy-1.2 promoter. In one of them, W-TChR2V4, some neurons were endowed with photosensitivity by the introduction of the ChR2 gene, coding an algal photoreceptor molecule. The DRG neurons expressing ChR2 were immunohistochemically identified using specific antibodies to the markers of mechanoreceptive or nociceptive neurons. Their peripheral nerve endings in the plantar skin as well as the central endings in the spinal cord were also examined. We identified that ChR2 is expressed in a certain population of large neurons in the DRG of W-TChR2V4. On the basis of their morphology and molecular markers, these neurons were classified as mechanoreceptive but not nociceptive. ChR2 was also distributed in their peripheral sensory nerve endings, some of which were closely associated with CK20-positive cells to form Merkel cell-neurite complexes or with S-100-positive cells to form structures like Meissner's corpuscles. These nerve endings are thus suggested to be involved in the sensing of touch. Each W-TChR2V4 rat showed a sensory-evoked behavior in response to blue LED flashes on the plantar skin. It is thus suggested that each rat acquired an unusual sensory modality of sensing blue light through the skin as touch-pressure. This light-evoked somatosensory perception should facilitate study of how the complex tactile sense emerges in the brain."
The researchers used Blue LED light to fire neurons involved somatosensory or tactile response!
Images. Distribution of ChR2V in the dorsal part of the spinal cord. A–C. Immunohistochemical localizationof ChR2V with the cell-type specific markers, NF200 (A), CGRP (B) or P2X3 (C). Scale bars indicate 40 µm.
Note that the receptors involved in Nociceptive Pain Sensing do not overlap with ChR2V. From this the authors conclude that ChR2V is involved in mechanoreception. This rat model should facilitate future study of how complex tactile perception, such as for texture, size and shape, is generated. We will keep you posted.
In the meantime check out our markers and antibodies for studying Neurotransmission and Synaptic Mechanisms.