Optogenetics.pptx

OPTOGENETICS

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

 Traditional BMI method is based on electrical

stimulation.  This method requires implanting electrodes deep into the brain.

 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.

It can excite the particular neuron with approximately 10% higher precision. 2. Activity recording can be conducted easily 3. Target cell can be restricted only to certain cells 1.

 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

 Infrared  High frequency or near field communication  Ultrahigh frequency  Ultrasound

 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

 3 main components

1. 2. 3.   

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.,

 Composed of

1. 2. 3. 4.

5.  

 

Copper coil A Chip Capacitor Rectifier µ-ILED Bilayer encapsulation of parylene and PDMS Comparatively cheap Loss less Easier to use

 Fully implantable

 Allows animals to freely

move  Consist of: 1. Power receiving coil 2. Rectifier 3. Circuit board 4. Blue µ-LED

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.

 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

 Introduction of a foreign gene into human brain  Threat of infection  cost

 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

 Communication challenges  Interfacing to molecular communications  Nanoscale dual stimulation and recording  Ethical issue