Ohm's
Law, Kirchoff's Current Laws, and the electronic "equivalent
circuit model" are standard tools for explaining the central
physiological properties of neurons and neuronal membranes in
terms of simple electronic components and circuits.
However, most introductory neuroscience students who are
presented with these tools have had little or no prior exposure
to electronics. Electronic formulas and circuit diagrams
presented as theoretical constructs are of little practical use
to them in understanding and predicting neuronal behavior.
The Do-It-Yourself Neuron
(DIYN) addresses three common problems in the introductory
neurophysiology course:
1) Electrical laws
and electronic equivalent circuits are central theoretical
constructs in explaining neuronal behavior,
but
often make less intuitive sense to students than do the
phenomena they are invoked to explain.
2) In vivo
and in vitro laboratory exercises provide
practical applications of classroom concepts,
but
require the student to simultaneously master surgical
techniques, micromanipulation, complex electronic instrumentation, and
theoretical concepts in a time-critical setting.
3) Computer
simulations provide rapid, convenient, reproducible results,
but
may allow students to simply "twiddle" parameters without
mastering the underlying concepts.
Hardware models can effectively bridge between conventional
"wet" and computer lab exercises. In particular they offer
the following advantages:
1) They are durable,
reusable, and cheap (generally under $50 to construct - see
below).
2) They use much of the same
data collection instrumentation (e.g. cables, amplifiers, stimulators, computers) as recording from living tissue. This
familiarizes the student with this instrumentation prior to
applying it to time-critical in vivo or in
vitro recording.
3) They
provide practical insight into unfamiliar properties of both
neurons (e.g. membrane capacitance, current spread) and recording
instrumentation (e.g. signal filtering, impedance matching).
4) They
provide consistent, reproducible results and a respite from the
demands and frustrations of working with living preparations.
5) They can be
successfully adapted for use at all levels of instruction, from
middle-school science campers to neurobiology students to
college English professors.
The Do-It-Yourself Neuron currently includes
hardware boards and associated exercises for studying properties
of RC filters and membrane patches, resistor-ladder and RC cable
properties involved in membrane current spread, current flow
across electrical synapses, and action potential gating
kinetics.
Each DIYN board takes from
1 to 3 hours to build. Approximate materials costs for
construction of the various DIYN boards are:
RCSCM - $20
GECM - $50 (+ $90 for three DC power adapters)
RCTM, RLCPM - $25
CECM - $60 (+ $90 for three DC power adapters)
RCCPM - $60 (set of three boards)
BIO325
Neurobiology is a laboratory-based introduction to
cellular-to-systems level neurobiology, focusing on traditional
electrophysiological methods. It combines and interweaves
DIYN laboratory exercises with exercises from two other
sources: invertebrate "wet" labs primarily from
Crawdad, A CD-ROM Manual for
Neurophysiology and
computer simulations from
Neurons in Action 2: Tutorials and
Simulations Using Neuron.
A more detailed
description of the DIYN project and samples of student-generated
results are available online in a poster (PowerPoint format) or upon request from
brhoades@wesleyancollege.edu .
Development of the
models and course exercises of the Do-It-Yourself Neuron was
supported by funds from the Munroe family of Georgia and
NSF DUE/CCLI grant #9950546. |