Download Simple Cyclic Movements as a Distinct Autism Feature

Department of Informatics, Nicolaus Copernicus University, Toruń
Institute of Computer Science, Maria Curie-Skłodowska University, Lublin
Simple Cyclic Movements
as a Distinct Autism Feature:
Computational Approach
Krzysztof Dobosz
Dariusz Mikołajewski
Grzegorz M. Wójcik
Włodzisław Duch
The 12th Cracow Grid Workshop, 22-24 October 2012
Simple Cyclic Movements as a Distinct Autism Feature
Autism – Introduction
Leo Kanner: „extreme aloneness from
the beginning of life and anxiously obsessive
desire for the preservation of sameness”
Leo Kanner: „Autistic disturbances of affective contact”,
Nervous Child 1943, 2: 217–250
 Incidence of ASD: estimated to 6 per 1,000
 Depends on sex: 4 times more boys suffer from
autism than girls
 Different forms of autism: „typical” autism,
regressive autism, Asperger syndrome, Rett
syndrome, Pervasive Developmental Disorder –
Not Otherwise Specified (PDD–NOS), etc.
 Autism epidemics?
Simple Cyclic Movements as a Distinct Autism Feature
Autism – Symptoms
Simple Cyclic Movements as a Distinct Autism Feature
Autism – Diagnostic Features
There are at least several common diagnostic features typical for ASD:
 preference to be alone and difficulty in mixing with other children
 insistence on sameness, resists changes in routine
 difficulty in expressing needs, gestures/pointing instead of words, not
responsive to verbal cues (acts as deaf)
 inappropriate attachment to objects, spins objects, sustained odd play
 inappropriate laughing and giggling, may not want cuddling or act cuddly
 noticeable physical overactivity or extreme
underactivity
 tantrums – extreme distress for no apparent
reason
 apparent insensitivity to pain
 little or no eye contact
 echolalia
Simple Cyclic Movements as a Distinct Autism Feature
Research Problem
 Diverse etiology: genetic mutations, immunologic/metabolic system
disorders, etc.
 Many different theories: Minicolumnopathy, Mirror Neuron System,
Underconnectivity Theory, Function Connectivity Theory, EmpathizingSystemizing Theory, etc.
 We are „data rich and theory poor” – lack of complete theory with
satisfactory predictive power
 Lack of good computational models joining different levels of analysis:
genes
proteins
neurons
brain
regions
activation
cognitive
functions
(attention)
behavior
Simple Cyclic Movements as a Distinct Autism Feature
Emergent Simulator




developed since 1995 (previous version known as PDP++)
open source, modular, object-oriented, based on C++
cross-platform: MS Windows, Mac OS X, Unix/Linux (GPL)
some built-in visualization methods (cluster plots, PCA, SVD,
MDS)
 point neurons based on Hodgkin-Huxley model
 3 types of ion channels: K+, Na+, Cl accommodation mechanism controlling
neural fatigue (K+)
 different types of noise: synaptic,
membrane, etc.
 dedicated LEABRA algorithm (Local,
Error-driven and Associative, Biologically
Realistic Algorithm) – combining Hebbian
learning and error-driven learning
Simple Cyclic Movements as a Distinct Autism Feature
GENESIS / NESSIE Enviroment
 GENESIS – GEneral NEural SImulation System
 developed since 1988 at California Institute of Technology
(J. M. Bower)
 compartmental neurons and Hodgkin-Huxley model
 NESSIE – NEuroinformatic
System for Science, Industry
and Education
 developed at Institute of
Computer Science, Maria
Curie-Skłodowska University,
Lublin
 provides easy-access to
simulations in GENESIS
software
Simple Cyclic Movements as a Distinct Autism Feature
Model of Simple Cyclic Movements
Output
layer
18 x 6
Hidden
layer
18 x 6
Input
layer
4x8
 Input layer – reflecting movement planning processes
 Output layer – reflecting processes within motor cortex areas: activation of groups
of neurons in this layer depends on patterns presented in the Input layer
 Decussating of pyramids was built into the model
 Adjacent patterns in the Output layer are overlapping
Simple Cyclic Movements as a Distinct Autism Feature
Input & Output Patterns
left hand
right hand
left arm
right arm
left leg
right leg
left foot
right foot
left hand
left arm
left leg
left foot
right hand
right arm
right leg
right foot
Different body parts
are represented by
partially overlapping
areas in the primary
motor cortex
Simple Cyclic Movements as a Distinct Autism Feature
Emergent Model Results
 For each input pattern several sequences of neural activations
occurring cyclically in the Output layer (motor cortex)
 Similar behavior like repetitive and stereotyped movements (RSM)
typical for patients with ASD (especially young children)
 Lack of neural noise leads to high repeatability of simulations
 Appropriate level of noise resulted in changes in neurodynamics of the
motor cortex layer preventing sequences of activation to follow
cyclically and activating different areas of the layer
 This corresponds to normal brain dynamics
Simple Cyclic Movements as a Distinct Autism Feature
GENESIS Implementation
 Moving from point neurons to full compartmental Hodgkin-Huxley
cells will let observe the influence of other substantial parameters on
the dynamics of the network
 Parameters such as the capacitance of soma, its time constant and the
value of potentials responsible for the ionic currents must also play an
important role in signal transmission
 Good simulation of Hodgkin-Huxley neurons requires high
computational power – simulation of 1 ms of biological activity of a
HH cell using first order Euler’s method with constant time interval of
1 ms requires 1200 floating point operations
 Such simulation most effectively can be conducted in cluster-based
environment (for large networks grid architecture may be necessary)
Simple Cyclic Movements as a Distinct Autism Feature
Cluster Architecture
 Consists of eight double-processor Xenon Quad Core machines
 Detailed cluster configuration:
 4 Intel Xeon Quad-Core E5320 1,86 GHz
processors
 12 Intel Xeon Quad-Core E5405 2 GHz
processors
 each node of the cluster offers 8 GB of
RAM
 7 TB of hard disk in total
 Simulation of 1 second of biological activity
of the system takes several seconds of the
production run of the cluster (still far from
real-time simulations)
Simple Cyclic Movements as a Distinct Autism Feature
Future Work
1.
Investigate the influence of different parameters on the model
behavior including cell dimensions, ion channels conductance, neural
fatigue mechanism, strength of connections, number of units, etc.
2.
More detailed analysis of attractor dynamics
using visualization methods such as Recurrence
Plots, Fuzzy Symbolic Dynamics, etc.
3.
Joining results of computational modeling on functional segregation
and integration with genetic data to provide insight into possible
genetic basis of autism
4.
Moving the model to the parallel GENESIS environment and with the
increased number of neurons and connections prepare it to
production runs in grid-based structures
Contact: [email protected]
Thank you for your attention