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Traditional artificial intelligence and computer
science approaches have had limited success in producing machines
capable of matching the intelligence of even the simplest of organisms.
The long-term goal of our lab is to learn how to take advantage
of the synthesis between biological and artificial systems to produce
a machine that can handle difficult tasks in real time. The current
project explores topics such as creativity and plasticity (learning)
in such a hybrid system. Dissociated embryonic cortical rat tissue
is cultured on a MultiElectrode Array (MEA), which acts as an interface
between the neurons and a computer. Software records and analyzes
electrical data from the electrodes, and encodes stimulation patterns
that are fed back to these electrodes. A simplified form of post-analysis
data is sent to a computer at the Biennale of Electronic Arts Perth
Conference (BEAP) in Australia once per second, and this data is
used to control a robotic drawing arm. Video snap shots and audio
from the audience is sent back to our lab, and this information
is encoded into stimulation patterns to provide a feedback system
for the neural network. Several interesting questions arise from
such a system: are the drawings produced a form of truly creative
art? Can patterns of dynamic stimulation (encoded in real-time based
on video or audio feedback from the audience) be linked to patterns
on paper? If given static stimulation (perhaps if the stimulus represents
a snapshot for an extended period of time), are the drawings reproducible
or will they change over time, and if so is this a form of learning?
MEART is a bio-cybernetic research & development
project exploring aspects of creativity and artistry in the age
of new biological technologies. The first public outcome of this
project, called Fish & Chips was displayed at the Arts Electronica
Festival, Australia, in 2001. The robotic control segment consisted
of fish neurons cultured directly on silicon chips. A good connection
was made with only a few neurons, and thus the robotic drawing arm
was controlled by a small selection of neurons from within a larger
network. Stage 2, on display at BEAP from July 31 – Aug 26,
2002, is now known as MultiElectrode array ART (MEART). Brain tissue
from rat cortex is cultured on a dish over a grid of 60 electrodes
in a 2mm2 area (the MEA). Each electrode may record from several
neurons and also stimulate these same neurons. Thus, compared to
stage 1, a much greater amount of information from the living neural
network is available to provide control in the robot. Providing
the cultured neurons with this robotic “body” sets up
a framework in which we can conduct experiments to study neural
plasticity and data encoding within cultured neural networks.
Cell Culture
- We used 60-electrode glass MEAs from MultiChannel Systems, 10-um
diameter electrodes and 200um or 500um inter-electrode spacing.
- Polyethylene imine solution was used to coat the bottom of the
dish to enhance electrical signals.
- Laminin was applied to allow the cells a substrate to adhere
to.
- Cells were prepared using papain digestion of embryonic-day-18
rat frontal lobe cortex, and applied to the dish.
- To prevent osmolality change due to evaporation and to prevent
infection, the MEA was sealed with fluorinated ethylene propylene,
a membrane permeable to CO2 and O2, but impermeable to water vapor
and microbes.
Software provided by MultiChannel
systems for recording was modified and enhanced for this project:
A module was built to integrate the activity of a given electrode
over a period of 500 milliseconds. The value for each electrode
decays exponentially over time, but is incremented with each spike
at that electrode. At the end of the 500ms interval the value for
each electrode is normalized over 0 – 256 and sent via TCP
connection to a computer at BEAP.
Robotic Arm Movement: At the current
stage, the 60 electrode values received in BEAP are used to calculate
regions in the dish particularly active, and the robotic arm draws
a line from its current position to the newly calculated position.
Feedback: Every 30 minutes a picture
from a camera at BEAP is sent to the Lab for Neuroengineering via
TCP. The image is converted to a stimulation pattern to be applied
on 8 electrodes in the MEA. Another system available for stimulation
involves a real-time approach, whereby audio is recorded at BEAP
and encoded into a 1 bit signal used to turn a programmed pattern
of stimulation OFF and ON.
From the first drawing produced by MEART, one can
see several concentrations of lines, which look like ink blots.
These concentrations represent the most active channels in the dish.
A line is drawn between different regions when there is a change
in activity in the MEA. The drawing above does not reflect any feedback
systems.
Through the month of August while MEART is operational we hope
to experiment with varying feedback systems and drawing algorithms.
For example, instead of moving the arm to a point on paper representing
the most active region of the MEA, we can classify signals received
in the MEA by various patterns using a back-propagation artificial
neural network, and use detected patterns to indicate desired movement
in the robotic arm. By comparing various forms of feedback stimulation
we will find how static stimulation (same stimulation over a long
period) affects the system compared to dynamic stimulation (in real-time)
and, of course, compared to the system working with no stimulation
as shown above. Through these comparisons we hope that plasticity
in the network will be expressed on paper. In conclusion, MEART
takes the basic components of the brain (isolated neurons), and
attaches them to a mechanical body through the mediation of a digital
processing engine to attempt and create an entity that will seemingly
evolve, learn and become conditioned to express its growth experiences
through “art activity”. The combined elements of unpredictability
and “temperament” with the ability to learn and adapt,
create an artistic entity that is both dependent, and independent,
from its creator and its creator’s intentions.
This material is based upon work supported by the Howard Hughes
Medical Institute under Grant No. 52003071 and by the CBN - STC
Program of the National Science Foundation under Agreement #IBN-9876754
Rat brain tissue is cultured on a dish over a grid
of electrodes. The electrodes are used to record signals from the
brain tissue, and to stimulate the brain tissue. In this way we
are able to "talk" to the brain tissue using a computer.
The computer is used to send signals to a robotic arm in australia
which draws pictures in real-time. We hope that these drawings may
provide us with a new way of looking at the data encoded in the
brain tissue.
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