A fundamental problem in neuroscience is understanding the biological basis of memory. A prominent hypothesis states that persistent changes in the efficacy of synaptic transmission (i.e., synaptic plasticity) form the neural substrate of memory. A model system that has provided significant evidence in support of this hypothesis is the marine mollusc Aplysia, the withdrawal reflexes of which exhibit long-term memory for a simple form of learning termed sensitization. Long-term sensitization of withdrawal reflexes, lasting at least 24 h, is mediated in part by facilitation of synapses between sensory and motor neurons. This facilitation has been related to enhanced release and uptake of neurotransmitter. Through a combination of computational and experimental work, my research aims at understanding how regulated release and uptake of transmitter can support long-term synaptic facilitation.
Past & Present Projects
1995-1998: During my undergraduate studies at The American College of Greece, I worked for three years in Dr. Nikoletseas’s laboratory of experimental psychology as a research and teaching assistant. I helped develop two paradigms of classical conditioning in the goldfish: Conditioning of the C-start reflex, i.e., the initial component of escape behavior, and of the branchial defensive reflex, i.e., respiratory suppression. Through monitoring these two reflexes, sometimes concurrently, in the unrestrained fish, we studied several phenomena, such as sensory preconditioning, second-order conditioning, pseudoconditioning, latent inhibition, inhibition of delay, and timing of conditioned responses. These studies served primarily an educational purpose, as they were conducted mostly in the context of the Experimental Psychology courses. In that time period, I obtained valuable knowledge on the psychology of Learning, and I contributed to the hands-on training of almost 200 undergraduate students of psychology.
1999-: Whereas my undergraduate research focused on Learning from a psychological perspective, my doctoral research focuses on learning from a biological perspective, through an integration of experimental and computational approaches. As a graduate student of neuroscience at The University of Texas Health Science Center at Houston, I work with Dr. Byrne on cellular mechanisms of Aplysia learning and memory, and with Dr. Baxter on modeling memory storage at glutamatergic synapses. My work includes intracellular recording from Aplysia neurons in isolated ganglia during synaptic stimulation, recordings of neuronal and behavioral responses in reduced tail preparations during peripheral stimulation, computer programming, deterministic and stochastic mathematical modeling. The results of my experimental studies suggest that transmission of physiological activity across sensorimotor synapses is shaped in part by desensitization of postsynaptic glutamate receptors. The results of my computational studies suggest that the mechanisms that have been previously implicated in memory storage at the sensorimotor synapse would be expected to modify the role played by desensitization of receptors. An effect on desensitization of receptors would in turn modify the behavior of this synapse during physiological activity. The next step is to test experimentally the predictions that arise from my model.
Personal note: One of the undergraduates that I had to train (and later collaborate with) in Greece is Diasinou Fioravante, my partner in life and in science.
- Antzoulatos, EG, Cleary, LJ, Eskin, A, Baxter, DA, and Byrne, JH. 2003. Desensitization of postsynaptic glutamate receptors contributes to high-frequency depression of Aplysia sensorimotor connections. Learn & Mem, 10:309-313.
- Phares, GA, Antzoulatos, EG, Baxter, DA, and Byrne, JH. 2003. Burst-induced synaptic depression and its modulation contribute to information transfer at Aplysia sensorimotor synapses: Empirical and computational analyses. J. Neurosci, 23:8392-8401.
- Antzoulatos, EG, and Byrne, JH. Learning insights transmitted by glutamate. Submitted for publication.
- Byrne, JH, Antzoulatos, EG, and Fioravante, D. Aplysia: Neural and molecular mechanisms of simple learning. In: Encyclopedia of Neuroscience, Third Edition, eds. Adelman, G. and Smith, B.H., Elsevier Science, Amsterdam, in press.
- Byrne, JH, Fioravante, D, and Antzoulatos, EG. Cellular and molecular mechanisms of associative and nonassociative learning. In Textbook of Neural Repair and Neurorehabilitation, First Edition, eds. Selzer, M., Cohen, L., Cage, F.H., Clarke, S., and Duncan, P.W. In preparation
- Antzoulatos, EG, Cleary, LJ, Eskin, A, and Byrne, JH. Desensitization of postsynaptic glutamate receptors contributes to high-frequency depression of Aplysia sensorimotor connections. Program No. 291.6. 2003 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience.
- Phares, GA, Antzoulatos, EG, Baxter, DA, and Byrne, JH. Burst-induced synaptic depression and its modulation contribute to information transfer at Aplysia sensorimotor synapses: Empirical and computational analyses. Program No. 291.5.2003 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience.
- Antzoulatos, E, Eskin, A, Byrne, JH, and Baxter, DA. Mathematical Model of Glutamatergic Synapses: Effects of Quantal Size and Content on Synaptic Fidelity. Soc. Neurosci. Abstr., Vol 27, Part 2, p.2449, 2001.
- Antzoulatos, E, Phares, GA, Byrne, JH, and Baxter, DA. Mathematical Model Of Glutamatergic Synaptic Transmission: Role Of Uptake In Plasticity. Soc. Neurosci. Abstr., Vol 26, Part 2, p.1524, 2000.
- Nikoletseas, MM., Xydea, DI, Antzoulatos, EG, and Fioravante, DD. Concurrent Monitoring of the Branchial Defensive Reflex and the C-start Reflex of Goldfish during Differential Conditioning. FASEB Journal, 1999.
- Antzoulatos, EG, Fioravante, DD, Xydea, DI, Angelogianni, P, and Nikoletseas, MM. Inhibition of Delay in Classical Conditioning of the Branchial Defensive Reflex. Soc. Neurosci. Abstr., Vol 24, Part 1, p.441, 1998.
- Fioravante, DD, Antzoulatos, EG, Matsas, R, and Nikoletseas, MM. Pavlovian Conditioning of the Branchial Defensive Reflex at a Minimal Interstimulus Interval. Soc. Neurosci. Abstr., Vol 24, Part 1, p.441, 1998.
- Antzoulatos, EG, Kalyva, AC, Flaherty, CF, and Nikoletseas, MM. Dishabituation of the Branchial Defensive Reflex in Goldfish, Carassius auratus, in Relation to Sensitization and Different Levels of Prior Habituation. Soc. Neurosci. Abstr., Vol 23, Part 2, p.1620, 1997.
- Nikoletseas, MM, Antzoulatos, EG, and Kalyva, AC. Plasticity and Innervation of the Branchial Defensive Reflex in Goldfish (Carassius auratus). 13th Annual Meeting of the Hellenic Society For Neuroscience, 1997.
- Nikoletseas, MM, Antzoulatos, EG, Konstantinidou, AD, and Kalyva AC. Pavlovian Conditioning of the Mauthner Neuron Reflex in the Unrestrained Goldfish, Carassius auratus. Soc. Neurosci. Abstr., Vol 22, Part 3, p.1876, 1996.