Pleural 9 Neuron
Pleural 9 is a neuron in Tritonia.
- The Pl 9 neuron type refers to one or two 70 micron cells located one or two cell layers below the dorsal surface of the pleural ganglion on each side of the brain.
- Pl 9 is situated close to the region where Pleural Nerve 1 enters the ganglion.
- Pl 9 is known to receive direct EPSPs from most or all of the ipsilateral S-cells and conversely, it produces fast IPSPs onto the entire S cell population.
- Pl 9 can be identified in an isolated brain preparation by first impaling one or more S-cells with a microelectrode and then probing the cells below with another microelectrode for a cell that receives monosynaptic EPSPs from the S-cells and produces one-for-one fast IPSPs onto the S-cells.
- Pleural 9 produces direct IPSPs onto the TR1, DRI and VSI-B interneurons.
- Pl 9 is known to play a role in mediating prepulse inhibition (PPI) in Tritonia. Intracellular stimulation of Pl 9 mimics the inhibitory effects of skin prepulses on the S cell activity. Pl 9 can block the swim motor program, partly due to the cell's ability to reduce the efficacy of the excitatory S cell synapse onto the interneurons that initiate the stereotypic Tritonia escape response.
Method for identifying Pl9
from Lee et al (2012)
- Place an intracellular electrode in an S-cell.
- With a second electrode blindly penetrate neurons one cell layer below the surface at the known location of Pl-9
- It can be identified by its production of 1-for-1, short and constant latency IPSPs onto the S-cell with each action potential, and its receipt of 1-for-1 short and constant latency EPSPs from ipsilateral S-cells.
- Frost WN, Tian LM, Hoppe TA, Mongeluzi DL, Wang J. A cellular mechanism for prepulse inhibition. Neuron. 2003 Dec 4;40(5):991-1001. PubMed ID: 14659097. 
- Lee AH, Megalou EV, Wang J, Frost WN. Axonal conduction block as a novel mechanism of prepulse inhibition. J Neurosci. 2012 Oct 31;32(44):15262-70.