autaptic circuits for neural vehicles
DESCRIPTION
This presentation develops models for single recurrent neural circuits, known as autapses, where the axon of a neuron synapses onto its own dendrites. Once thought to be curiosities or artefacts of growing cells in vitro, autapses play a key role in the operation of Central Pattern Generators and the cortex where they may function as a simple short-term memory. Biologically plausible, idealized models of the autapse are able to produce persistent behaviours in ‘neural vehicles’. Detailed models are developed to show how excitatory autapses may support both bistability and monostability.TRANSCRIPT
Autaptic Circuits for Neural Vehicles
@SteveBattle blog.stevebattle.me
Sysemia Ltd
#AISB50
Brains and Embodiment
Turing, Intelligent Machinery 1948
Grey Walter, The Living Brain 1953
Neural Vehicles1984 - Valentino Valentino Braitenberg, cyberneticist, neuro-anatomist and
musician, publishes a landmark series of thought experiments. "Vehicles: Experiments in Synthetic Psychology, explores the principles of
intelligence by defining a series of successively more complicated creatures.
Aplysia Feeding CPG
• B31/B32 is a bistable autaptic motor neuron
• Triggered by B63
• Reset by B64
B31/32B63
Protraction Group
Retraction group
ProtractionMuscle
B64
subset of CPG
BistableAutapse
stimulus, s
stimulus, -s
a
x y• Neuron synapses onto itself
• Recurrent excitation
• Saturating activation function
• No fine tuning of gain required
• Extrinsic ‘reset’
• tr=5, a=1, bias=0.5
Multivibrator /Astable• Matsuoka oscillator
• Lateral inhibition
• Adaptation
• tr=1, ta=12, s=2.9, b=5, bias=0
x1,v1 x2,v2s s
Monostable Autapse stimulus, s
a
x, v yv
b• Uses adaptation
• Intrinsic ‘reset’
• small bias prevents random triggering
• tr=3, ta=20, bias=0, a=1.7, b=1
• Whiskers trigger monostable
• monostable drives sustained reverse