Transcript Use of a Novel Whole-brain In Vitro Preparation to

Use of a Novel Whole-brain In Vitro Preparation to Study
Electric Communication in Apteronotus leptorhynchus
Matthew L. Mendoza and G. Troy Smith
McNair Scholars Program, Department of Biological Sciences, University of North Texas, Denton, Texas
Center for Intergrative Study Animal Behavior, Department of Biology, Program in Neuroscience, Indiana, University, Bloomington, Indiana
Weakly Electric Fish
Experiment 1: Production of a Fictive EOD
o Common name: brown ghost
knifefish
o Emit an electric organ discharge
(EOD) from specialized organ in tail
o EOD frequency (EODf) is the
measurement of how often the EOD
is emitted per second
o Surgical removal of brain
o Constant perfusion of Artificial
Cerebrospinal Fluid (ACSF)
o ACSF was saturated with 95% Oxygen and
5% Carbon Dioxide
o Measured action potentials from PMN
1. The PMN in the whole-brain
preparation remains viable after
surgical removal. In fact, the firing rate
of the PMN is strongly correlated to
the fishes natural behavior.
Males have a higher
EODf than females
*
The x-axis is sex and the yaxis is EOD frequency
measured in Hz. We verified
that our fish show a
consistent sexual
dimorphism in their EODf.
EOD and Communication
o EODf: continuously emitted
information-rich badge
o Chirps: brief modulation in EODf, used
for motivational behaviors
o Both communication signals are
sexually dimorphic
n=16
Firing frequencies of
PMN in whole-brain
prep correlates to
EODf
Neural Circuitry
Future Directions
900
880
860
840
820
800
780
760
740
720
700
680
660
640
720
740
760
780
800
820
840
860
880
900
920
940
960
EOD frequency (Hz)
P<0.001* r2=0.835
Experiment 2: Production of Fictive Chirps
In Vivo
o Test the role of neuromodulators
during the modulation of EODf
References Cited
Whole-brain Prep
Isolated in vitro prep
2. Upon chemical stimulation the
whole-brain preparation produced a
fictive chirp that is similar in structure
to the fish’s natural communication
signal.
p<0.001
EOD frequency vs. PMN frequency
PMN firing frequency (Hz)
The x-axis is the fish’s
natural behavior (EODf)
and the y-axis is the
isolated whole-brain prep.
The isolated whole-brain
prep fired at rates similar
to the fish’s natural
behavior.
n=4
Conclusions
Whole-brain prep
Access to Circuit
Ability to apply
drugs
Ability to study
cellular
mechanisms
o Chemical stimulation
1)Iontophoresis
2)Pressure application
o Electrical stimulation
Circuit is fully
intact
Ability to study
behavior
o Tracked electrode with
fluorescent marker
o Most stimulation sites
missed PPn-C
2. Is this reduced system capable
of producing a fictive chirp that
is similar to the fish’s natural
chirping behavior?
After stimulation
1. Does the natural behavior of the
fish (EODf) correlate to the
reduced system’s action potential
firing rate in the PMN?
Before stimulation
Research Questions
After stimulation the whole-brain produced a fictive chirp.
The x-axes are time (sec) and the y-axes are measurements of amplitude (mV) and frequency (Hz).
After stimulation there were fluctuations in frequency and amplitude. As the frequency decreased the
amplitude increased.
1. Dye, J. 1988. An in vitro physiological preparation of a
vertebrate communicatory behavior: chirping in the weakly
electric fish, Apteronous. Journal of Comparative Phyisology.
Vol 163. pp 445-458.
2. Heiligenberg W, Metzner W. Wong C.J.H. 1996. Motor
Control of the Jamming Avoidance Response of
Apteronotus leptorhynchus: Evolutionary Changes of a
Behavior and its Neuronal Substrates. Journal of Comparative
Physiology. Vol 179. Pp. 655-674.
3. Kolodziejski, Johanna A, Nelson S. Brain, Smith G. Troy.
2005. Sex and Species Differences in Neuromodualatory Inout
to a premotor Nucleus: A comparative study of Substance P
and Communication Behavior in Weakly Electric Fis. Journal
Of Neurobiology. Vol 62. Pp. 299-315.
4. Smith G. Troy. 2013. Evolution and Hormonal Regulation of
Sex Differences in the Electrocommunication of Ghost Knife
Fish (Apteronotidae). Behavior, Neurobiology, and
Neuroendocrinology. Hormones, Brain, and Behavior.
5. Zakon H H and Smith G T, 2009 Weakly Electric Fish:
Behavior, Neurobiology, and Neuroendocrinology. Hormones,
Brain and Behavior, 2nd edition, Vol 1. 2009. pp. 611-638.
Acknowledgements
CISAB
Linda Summers
Ali Ossip-Klein
Dr. Hurley and REU Selection Committee
IU Department of Biology
The Smith’s Lab
UNT McNair Scholars Program
Dr. Jannon Fuchs