Neuron-based CommunicationsNeuron-based CommunicationsChallenges Challenges

Dr. Olga KaraNano Communication Centre

Department of Electronic and Communication EngineeringTampere University of Technology

olga.kara@tut.fi

Neuron-based communication in Neuron-based communication in NeurotechnologyNeurotechnology

RoboticsHuman spare parts

Human-computer interactionInformation technology

Effective resource managementSelf-organization

Memory storage and retrieval

Neurotechnology is an integration of neurobiology with information technology and engineering

Robotics and nanoroboticsRobotics and nanorobotics– Robotic vision is one of the most

complex sensory system that takes around 1/3 of human cortex

– Robotic today need camera and huge computational power

– Neurons simplify visual processing, by compressing information at the source and apply specific encodings in a form of spikes.

– To resolve the problem of high speed motor control

– Decision making-The complex network of single biological nano-units – neurons able to solve the complex problems in milliseconds by separating the problem into small problem and resolving them without understanding of global picture.

Bionics - robotic spare partsBionics - robotic spare parts

NanoroboticsNanorobotics• Neurodust by Michel Maharbiz from

Berkeley

• We need some system that will be able to record simultaneously thousands of individual neurons in multiple brain areas.

• Communication???

Dr. Michel Maharbiz: Neural dust system diagram showing the placement of ultrasonic interrogator under the skull and the independent neural dust sensing nodes dispersed throughout the brain.

Source: arXiv:1307.2196v1

Read more at: http://phys.org/news/2013-08-world-itskov-futurists-convene-gf2045.html#jCp

Human Computer InteractionHuman Computer Interaction• Information System Research

– Microsoft – research on the potential of neuroscience

• Cognition• Usability engineering (implement real-time

ergonomic for adaptive fitting of the task to the user). Embedded nanodevices?

• Artificial intelligence (neurochip with real neurons instead of computer components?)

• Diagnostic and monitoring

Information processingInformation processing• Neuron networks perform effective

information processing and transfer• Information coding, transfer and

decoding• Information theory

– Neural system as a communication channel

– Neural coding: how the activity of neuron (measured as output) represent input?

– When neurons face with new information they will try to develop a strategy to encode this information and store it for later usage.

– The mechanism of information compression…

Sensory information processing performed on many levels

Information processingInformation processing

Neural circuitsNeural circuits• Neurons are interconnected

with one another to form circuits with dense synaptic connectivity to process specific information.

• Circuits regulate itself by feedback loop.

• Many neural circuits together form a neural system (as many electronic circuits together form a computer)

Afferent (sender)Afferent (sender)

Interneuron - modulator with

inhibitory properties

Interneuron - modulator with

inhibitory properties

Efferent (receiver) -carry information away from the cell

body

Efferent (receiver) -carry information away from the cell

body

Information coding

Information coding

Information transmissionInformation transmission

Information receiving

Information receiving

Information decoding

Information decoding

Syntesis Release Reception Processing

Information processing in postsynaptic Information processing in postsynaptic neuron (receiver) neuron (receiver)

Resource managementResource management• Effective resource management in the brain

– Two targets can be processed simultaneously even in a limited information capacity situation

– T1 – presented first and occupied short term memory for 500ms, T2 may not be seen

• Brain can be adjusted by training the neurons to effectively distribute brain resources

Self-organization, adaptation and Self-organization, adaptation and learninglearning

• Neurons self-organized in an effective communication network during the development

• Communication within and between network parties– Principles and

mechanism of this process will help to develop effective communication network between nano devices

Neuronal plasticityNeuronal plasticityNeuronal plasticity is a fundamental property of the

neuronal tissue. This enables learning and adaptation.

• Activity in neurons can strengthen or weaken signalling at a synapse.

• High activity of neuron leads to recruitment of more axon terminals from the same neuron. Reduced activity leads to loss of synapses.

• If two synapses are active at the same time, the strength of the postsynaptic response may increase at both synapses, mediated by long-term potentiation.

• Long-term potentiation (LTP) is a long-lasting enhancement in signal transmission between two neurons as a results of synchronous stimulation

• LTP plays a major role in memory formation, that thought to be related to the modification of synaptic strength

MemoryMemory

• Memory is attributed to strengthened synaptic connections among particular brain neurons, yet synaptic membrane components are transient, whereas memories can endure. This suggests synaptic information is encoded and ‘hard-wired’ elsewhere, e.g. at molecular levels within the post-synaptic neuron.

Memory storage and retrievalMemory storage and retrieval• memory is the process in which

information is encoded, stored, and retrieved.

• Encoding or registration: receiving, processing and combining of received information

• Storage: creation of a permanent record of the encoded information

• Retrieval, recall or recollection: calling back the stored information in response to some cue for use in a process or activity

• 1 Sensory memory• 2 Short-term memory• 3 Long-term memory

Atkinson-Shiffrin model

CytoskeletonCytoskeleton• Cytoskeleton : actin filaments, microtubuline and intermediate

filaments establish the form of neuron, maintains synaptic connections. It is a part of eukaryotic (absent in bacteria) cells cytoskeleton.

• In the brain tubulin account for 10-20% of all soluble proteins.• Microtubules are hollow tubes formed from tubulin molecules• Microtubule is electrically polar structures composed of α and β

subunits (which can be a different subtypes, located at different parts of the cell and involved in different functions (mutation may lead to a loss of some specific function (sensitivity in nematode)).

MicrotubulesMicrotubules• Microtubules are dynamically instable and undergo

rapid cycles of growth and shrinkage • Microtubules constructed of α/β heterodimers (α

and β subunits of tubuline) that compose a protofilament s, and form a hollow tubule (24 nm)

• α-tubuline is bound to DTP

• β is bound to GDP in microtubule (as it will hydrolyze from GPT to GDP during the binding process).

• The β tubuline + GTP at the end is called “GTP cup” that will be hydrolysed by binding – the rescue process.

• If GTP at the end hydrolysed without binding the shrinkage will occur - catastrophe

• The number of protofilaments can be different from 10 to 15. In mammalian cells is usually 13

• Microtubules are interconnected by linking proteins (microtubule-associated proteins: MAPs) to other microtubules and cell structures to form cytoskeletal lattice networks

• Microtubule dynamics – growth and shrinkage rates,– rescue and catastrophe frequencies,– sometimes supplemented by pause

duration.

MT formation can be regulated by calcium signals