Slugs, take your mark!

Welcome to my third homepage!!!

By Akira Sakurai, Neuroscience Institute, GSU.

I am interested in how “brain” produces a series of body motions or a patterned behavior. What is the neuronal mechanism of body motion and how does it switch from one motion to the other?

There is a growing awareness that the changes in motion or behavior are more likely caused by changes in the neuronal network configuration rather than switching between different sets of networks for distinct functions. Neuromodulation plays critical roles in such network configuration.

Ichiro’s state-of-art batting technique is originated from his central nervous system: brain and spinal cord.

Using central nervous system of a mollusk Tritonia diomedea, I have recently shown that a single neuromodulatory neuron can produce diverse neuromodulatory actions, depending on the timing and previous firing history of the target motor circuit (Sakurai and Katz, 2003, 2009, Sakurai et al., 2006, 2007).

The escape swim behavior of a sea slug

Tritonia diomedea

Tritonia shows a stereotypical escape swim behavior when attached by a monstrous sea star. The motor nerve output is produced by a central pattern generator circuit in the brain that consists of three types of interneurons.

I am studying how synaptic strength among these neurons is modulated during and after this escape swim behavior.

· Tritonia brain

· Tritonia swim CPG

· Cool movies of Tritonia by Dr. Russel Wyeth

In my previous work I also studied crustacean cardiac ganglion and showed that the proprioceptive feedback has strong modulatory effects on the memebrane properties of the heart pacemaker neurons. I would like to keep focusing on the neuromodulation of the synaptic and the membrane properties in simple neuronal networks to address questions.

By using such simple systems with direct behavioral relevance, I believe the mechanism and function of neuromodulation can be addressed more clearly from the intracellular signaling to the behavioral significance.

A selected list of my publications about the neuromodulation in the Tritonia brain

1. A. Sakurai and P.S. Katz (2009b) Functional recovery following lesion of a central pattern generator. J Neurosci 29: 13115-13125.

2. A. Sakurai and P.S. Katz (2009) State-, timing-, and pattern-dependent neuromodulation of synaptic strength by a serotonergic interneuron. J Neurosci 29: 268-279.

3. E.S. Hill, A. Sakurai and P.S. Katz (2008) Transient enhancement of spike-evoked calcium signaling by a serotonergic interneuron. J Neurophysiol 100: 2919-2928.

4. S. Clemens, R.J. Calin-Jageman, A. Sakurai and P.S. Katz (2007) Altering cAMP levels within a central pattern generator modifies or disrupts rhythmic motor output. J Comp Physiol A 193:1265-1271.

5. A. Sakurai, R.J. Calin-Jageman and P.S. Katz (2007) The potentiation phase of spike timing dependent neuromodulation by a serotonergic interneuron involves an increase in the fraction of transmitter release. J Neurophysol 98: 1975-1987.

6. A. Sakurai (2007) Spike timing-dependent neuromodulation in the Tritonia swim central pattern generator. Jpn Soc Comp Physiol Biochem 24: 18-26.

7. A. Sakurai, N.R. Darghouth., R.J. Butera, and P.S. Katz (2006) Serotonergic enhancement of a 4-AP-sensitive current mediates the synaptic depression phase of spike timing-dependent neuromodulation. J Neurosci 26: 2010-2021.

8. P.S. Katz, A. Sakurai, S. Clemens, and D. Davis (2004) The cycle period of a network oscillator is independent of membrane potential and spiking activity in individual central pattern generator neurons. J Neurophysiol 92: 1904-1917.

9. A. Sakurai and P.S. Katz (2003) Spike timing-dependent serotonergic neuromodulation of synaptic strength intrinsic to a central pattern generator circuit. J. Neurosci 23: 10745-10755.

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