404046723-OPTOGENETICS-pptx pre see my.pptx

OPTOGENETIC

1. OPTOGENETICS

2. NEURONS AND SIGNALS Nervous system is made up of billions of cells called neuron Signals travel along the fibres as a wave of electric charge A chemical called neurotransmitter at the end of synapses flood into the gap between two neuron It triggers a new signal in the next neuron

3. FOCAL BRAIN STIMULATION Traditional BMI method is based on electrical stimulation. This method requires implanting electrodes deep into the brain.

4. OPTOGENETICS It is a neuromodulation technique employed in neuroscience that uses a combination of technique from optics and genetics to control and monitor the activities of individual neuron. Optogenetics was first invented in 2006 by KARL DEISSEROTH It paves the way for new therapies that could target a number of psychiatric disorders.

5. WHY OPTOGETICS...? It can excite the particular neuron with approximately 10% higher precision. Activity recording can be conducted easily Target cell can be restricted only to certain cells

6. What is the idea..?? Viruses are engineered to infect neurons with a special type of channel, which are sensitive to light Channelrhodopsin is used to excite the nerve Halorhodopsin is used to inhibit the nerve

7. CURRENT DEVELOPMENTS Infrared High frequency or near field communication Ultrahigh frequency Ultrasound

8. Wireless optofluidic system Metal cannulas and fibre optics is replaced by 4 microfluidic channelsmade of elastomer polydimethylsiloxane and µ-ILED Operating voltage-3.6V Major disadvantage is the need for line of sight

9. Wireless LED stimulator 3 main components IR transmitter LED stimulator Small LEDs 12V DC power to operate IR transmitter 3.7 Li battery for LED Using IR brings an advantage in terms of weight,cost,complexity ...etc.,

10. Flexible near field wireless optoelectronics Composed of Copper coil A Chip Capacitor Rectifier µ-ILED Bilayer encapsulation of parylene and PDMS Comparatively cheap Loss less Easier to use

11. Fully internal optogenetics Fully implantable Allows animals to freely move Consist of: Power receiving coil Rectifier Circuit board Blue µ-LED

12. COMPARISON Wireless technology Frequency Pros Cons Infrared (IR) 300 GHz–430 THz Low power consumption; multi-band transmissions. LoS between base station and implanted unit; requires a battery unit for the head unit. High frequency (HF) 3–30 MHz Medium propagation loss in biological tissue; cheap and easy to manufacture; supports energy harvesting circuitry. Coil dimension of approx. 1 cm; requires surface mounted chip (NFC). Ultra high frequency (UHF) 300 MHz–3 GHz Smaller coil diameter than HF circuitry; cheap and easy to manufacture;Supports energy harvesting circuitry. High propagation loss in biological tissue Ultrasound [9] ≥ 20 kHz Low propagation loss in biological tissue; size of hundreds of mm; supports energy harvesting circuitry; safe utilization in human tissue. Complex circuit manufacturing; difficulty in ultrasound frequency addressing.

13. Advantages Specificity Virus is only injected into a very small part of brain, and only a certain class of neuron. Response time is faster than other treatment Optogenetics is less invasive than electrical stimulation

14. Disadvantage Introduction of a foreign gene into human brain Threat of infection cost

15. Assumed future benefits Knowing what causes the brain of Alzheimer patients to fail Using light emitting neural prosthetics to replace the electrodes used in deep brain stimulation, which currently activates or silence a broad range of neuron. Treatment of Parkinson’s disease, epilepsy and depression

16. Future challenges Communication challenges Interfacing to molecular communications Nanoscale dual stimulation and recording Ethical issue

17. Optogenetics Offer Opecificity at a Cellular Level Image source: https://www.scientifica.uk.com/learning-zone/optogenetics-shedding-light-on-the-brains-secrets

18. Optogenetics Toolbox Source: Mahmoudi, P., Veladi, H., & Pakdel, F. G. (2017). Optogenetics, Tools and Applications in Neurobiology. Journal of medical signals and sensors, 7(2), 71–79.

19. Optogenetics Toolbox Schematic Source: Mukerjee, S., & Lazartigues, E. (2019). Next-Generation Tools to Study Autonomic Regulation In Vivo. Neuroscience bulletin, 35(1), 113–123. https://doi.org/10.1007/s12264-018-0319-2

20. A Closer Look at the Opsins: Channelrhodopsin Chlamydomonas reinhardtii: Channelrhodopsin Source: By A2-33 - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=18392488 and By Dartmouth Electron Microscope Facility, Dartmouth College - Source and public domain notice at http://remf.dartmouth.edu/imagesindex.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2787116 Blue green algae Chlamydomonas reinhardtii Genetically engineered channelrhodopsin tagged with RFP (red fluorescent protein) at the cytoplasmic C-terminal. Source: By Millencolin - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4570860

21. A Closer Look at Opsins: Archaerhodopsin-3 Halorubrum sodomense Archaerhodopsin-3 Source: By ArchaerhodopsinGuy - Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=101358124 Archaerhodopsin : an outwards proton pump Source: Han X. (2012). In vivo application of optogenetics for neural circuit analysis.  ACS chemical neuroscience ,  3 (8), 577–584. https://doi.org/10.1021/cn300065j

22. A Closer Look at Opsins: Halorhodopsin Natronomonas pharaonic halorhodopsin Source: https://www.rcsb.org/structure/3a7k Halorhodopsin: an inwards chloride pump Source: Han X. (2012). In vivo application of optogenetics for neural circuit analysis.  ACS chemical neuroscience ,  3 (8), 577–584. https://doi.org/10.1021/cn300065j

23. What is Optogenetics? Controlling Neurons with Light Using Light-Sensitive Ion Channels Genetically Transfected into specific cells