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Modulation Channels in Biomimic Artificial

NeuronsRichard B. Wells

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The Biomimic Concept• Purpose: Lay Out the General Architecture for Biomimic

Neurons• Biomimic is a Subset of Biomimetic

– Biomimic = Mimicking the Neuron or Glial Cell

• The Artificial Neuron as a State Machine– Classical Artificial Neurons After Training Are “Combinational

Analog Logic”– Biological Neurons Are Better Modeled as Analog State Machines

• “Information relates not so much to what you do say as to what you could say– Warren Weaver, 1964

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Short-Term vs. Long-Term Adaptation

• Conventional Adaptation = LTP, LTD• Modulation = Short-Term Adaptation• Short-Term Modulations => The Neuron as

a State Machine• “In order to understand the style of

computation practiced by nervous systems, we must study their hardware.”– Christof Koch, 1999

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Three Basic Modulation Mechanisms in Biological

Neurons• Voltage-Gated Ionic Channels (VGCs)

– Classical Hodgkin-Huxley Model– Generally NOT “Inputs” (NMDA = ?)

• Ionotropic Channels -Synaptic Signal Inputs

• Metabotropic Receptors – “Control Inputs”– “Intrinsic” vs. “Extrinsic” Information?

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Voltage-Gated Channels

• VGCs Most Directly Control the Action Potential

• They Are “Feedback Circuits” Mediated Through the Integration of Membrane Potential

• They Occur in Great Variety but Follow A Generalized Architectural Scheme

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Inactivating & Non-inactivating VGCs

hmGtVG p, pmGtVG ,

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Principal Classes of VGCs

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Ionotropic Channels• Principal Transmission Inputs of Neuron• IC s Recruit VGCs Through PSPs

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The IC Synapse is a State Machine

• Basic Mode is a Non-Retriggerable Monostable Multivibrator

• Tetanic Facilitation = Input-Dependent Synaptic Weight

• Delay, Conduction Time Can Be Modulated (Phosphorylation)

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Metabotropic Receptor Processes

• Their Role is Entirely Modulatory• 2nd Messenger Processes Essential for Stabilization

of Synaptic Weight Changes (LTP, LTD)• Indirect Effects on Ion Current Flow, Generation

of Retrograde Messengers, Modulation of IC Neurotransmitter Actions

• They Have Traditionally Been Ignored in Artificial Neurons

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Comparison of MSMS and IC

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Primary Systems & Effects

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Putting It All Together

AnalogIntegration

Core

APGeneration

VGCFSM 's

CaBuffer Thr

MSMFSM 's

ICFSM 's

EINTX's

IINTX'S

EMNTX'S

IMNTX'S

TMIS'S

TMOS'S

AP

APMODULATION

THRESHOLDMODULATION

Vm

WEIGHTCONTROL

CURRENTCONTROL

CaCURRENT

GATEMODULATION

WEIGHTCONTROL

CURRENTCONTROL

CaLEVEL

CaWEIGHTCONTROL

GATEMODULATION

CaCURRENTCOMMAND

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Thank You. Questions?