Article

An optogenetic toolbox designed for primates

Department of Bioengineering, Stanford University, Stanford, California, USA.
Nature Neuroscience (Impact Factor: 14.98). 01/2011; 14(3):387-97. DOI: 10.1038/nn.2749
Source: PubMed

ABSTRACT Optogenetics is a technique for controlling subpopulations of neurons in the intact brain using light. This technique has the potential to enhance basic systems neuroscience research and to inform the mechanisms and treatment of brain injury and disease. Before launching large-scale primate studies, the method needs to be further characterized and adapted for use in the primate brain. We assessed the safety and efficiency of two viral vector systems (lentivirus and adeno-associated virus), two human promoters (human synapsin (hSyn) and human thymocyte-1 (hThy-1)) and three excitatory and inhibitory mammalian codon-optimized opsins (channelrhodopsin-2, enhanced Natronomonas pharaonis halorhodopsin and the step-function opsin), which we characterized electrophysiologically, histologically and behaviorally in rhesus monkeys (Macaca mulatta). We also introduced a new device for measuring in vivo fluorescence over time, allowing minimally invasive assessment of construct expression in the intact brain. We present a set of optogenetic tools designed for optogenetic experiments in the non-human primate brain.

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Available from: Charu Ramakrishnan, Aug 16, 2015
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    • "The use of optogenetics in humans for treatment of neurological disorders has been extensively discussed (Peled, 2011; Kumar et al., 2013; Touriño et al., 2013), however, clinical application of optogenetics technology is, to our knowledge, currently not feasible. Extending optogenetic methods to species beyond rodents has only been stably, safely and efficiently applied in the rhesus macaque, a non-human primate (Han et al., 2009; Diester et al., 2011; Han et al., 2011; Cavanaugh et al., 2012; Gerits et al., 2012; Jazayeri et al., 2012). Further studies and clinical trials will be required to safely express and photostimulate opsins in the human brain. "
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    ABSTRACT: The medial prefrontal cortex (mPFC) is critically involved in numerous cognitive functions, including attention, inhibitory control, habit formation, working memory and long-term memory. Moreover, through its dense interconnectivity with subcortical regions (e.g., thalamus, striatum, amygdala and hippocampus), the mPFC is thought to exert top-down executive control over the processing of aversive and appetitive stimuli. Because the mPFC has been implicated in the processing of a wide range of cognitive and emotional stimuli, it is thought to function as a central hub in the brain circuitry mediating symptoms of psychiatric disorders. New optogenetics technology enables anatomical and functional dissection of mPFC circuitry with unprecedented spatial and temporal resolution. This provides important novel insights in the contribution of specific neuronal subpopulations and their connectivity to mPFC function in health and disease states. In this review, we present the current knowledge obtained with optogenetic methods concerning mPFC function and dysfunction and integrate this with findings from traditional intervention approaches used to investigate the mPFC circuitry in animal models of cognitive processing and psychiatric disorders.
    Frontiers in Systems Neuroscience 12/2014; 8:230. DOI:10.3389/fnsys.2014.00230
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    • "As the experimental applications of ChR2 move to include biophysically diverse interneurons (Markram et al., 2004; Katzel et al., 2011; Schultheis et al., 2011; English et al., 2012; Chiu et al., 2013; Owen et al., 2013), a fuller understanding of its possibilities and limitations becomes essential. Although ChR2 expression, trafficking, and activation has been achieved in most types of nervous tissue (Li et al., 2005; Nagel et al., 2005; Bi et al., 2006; Schroll et al., 2006; Adamantidis et al., 2007; Zhang et al., 2007; Douglass et al., 2008; Mahoney et al., 2008; Baier and Scott, 2009; Guo et al., 2009; Han et al., 2009; Liu et al., 2009; Zhu et al., 2009; Gourine et al., 2010; Hagglund et al., 2010; Diester and et al, 2011; Figueiredo et al., 2011; Sasaki et al., 2012; Ljaschenko et al., 2013), little consideration has been given to the kinetics that constrain light-induced firing properties in different neuronal subtypes. Factors that affect the degree of neuronal photostimulation, including intrinsic differences in firing dynamics, membrane properties, and channel composition differ among neuronal cell types. "
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    ABSTRACT: eLife digest The brain is a highly complex structure composed of trillions of interconnecting nerve cells. The pattern of connections between these cells gives rise to the various brain circuits that govern how the brain functions. Understanding how the brain is wired together is important for determining how ‘faulty circuits’ contribute to various neurological disorders. New optogenetic technique tools allow neuroscientists to turn on specific neurons simply by shining light on them. These techniques involve genetically manipulating the organisms so that their neurons express proteins that are activated when they are exposed to light of a particular wavelength. However, it is important to understand the limitations of this approach—including the possibility that the light might actually turn off some neurons—when using it to study animal behavior. Now, Herman, Huang et al. show that shining light pulses for long durations onto neurons expressing a light-activated protein called channelrhodopsin-2 causes the neurons to become silenced rather than activated. Moreover, certain types of neurons, called interneurons, are more susceptible to this effect—termed ‘depolarization block’—than the other types of neurons. Researchers need to be mindful of this effect when channelrhodopsin-2 is used in optogenetic experiments to study the behavior of living animals. However, this silencing property could be useful in experiments that investigate situations in which depolarization block is thought to contribute to brain function and health: such as in the treatments of schizophrenia and Parkinson’s disease. DOI: http://dx.doi.org/10.7554/eLife.01481.002
    eLife Sciences 01/2014; 3:e01481. DOI:10.7554/eLife.01481 · 8.52 Impact Factor
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    • "In order to enable the evolution of delivery technologies, new optogenetic toolkits are being developed in nonhuman primates [34], [61], [224], [225]. In the case of viral gene delivery, human safety is also an issue. "
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    ABSTRACT: The brain is a large network of interconnected neurons where each cell functions as a nonlinear processing element. Unraveling the mysteries of information processing in the complex networks of the brain requires versatile neurostimulation and imaging techniques. Optogenetics is a new stimulation method which allows the activity of neurons to be modulated by light. For this purpose, the cell-types of interest are genetically targeted to produce light-sensitive proteins. Once these proteins are expressed, neural activity can be controlled by exposing the cells to light of appropriate wavelengths. Optogenetics provides a unique combination of features, including multimodal control over neural function and genetic targeting of specific cell-types. Together, these versatile features combine to a powerful experimental approach, suitable for the study of the circuitry of psychiatric and neurological disorders. The advent of optogenetics was followed by extensive research aimed to produce new lines of light-sensitive proteins and to develop new technologies: for example, to control the distribution of light inside the brain tissue or to combine optogenetics with other modalities including electrophysiology, electrocorticography, nonlinear microscopy, and functional magnetic resonance imaging. In this paper, the authors review some of the recent advances in the field of optogenetics and related technologies and provide their vision for the future of the field.
    01/2014; 7:3-30. DOI:10.1109/RBME.2013.2294796
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