Behavioral Neuroscience, Leech Circuitry
Neurocircuitry of the Leech, subclass Hirudinea back to Behavior Lecture
Hirudinea Nervous System:
1) Segmental Organization
Similar in segmented functional compartments to all vertebrates
1.5) Chain of ganblia
2) ganglion
3) Electrical Synapses
4) Identified Neurons
left = anterior Dorsal View (left figure) Ventral View (right figure)
T cells = touch mechanoreceptors
![Somatosensory cells](Tcells.JPG)
![](LeechganglionTPNAE.jpg)
![](TPNactionpotentials.jpg)
P cells = pressure mechanoreceptors
![Pressure cells](Pcells.JPG)
N cells = Nociception = Pain cells
![Pain Receptors](Ncells.JPG)
![](Ncellsdorsal.JPG)
Ventral View (left figure) Dorsal View (right figure)
S cells = interneurons
![interneurons](Scells.JPG)
Retzius Cells
![](77Lent_Retzius_cell_diagram_1_pair.jpg)
Motor Neurons = L cells efferent ACh neurons ending at neuromuscular junctions
![motor neurons](motor L neurons.JPG)
Action Potenial
5) Ding Vm = membrane potential
![](APVm.jpg)
Na+ in first, then K+ out
![Na current can be augmented by Ca](APK+out.JPG)
Afterhypolarization
![](Afterhyperpolarization.JPG)