Behavioral Neuroscience, Leech Circuitry
USD Department of Biology
Behavioral Neuroscience
Leech Shortening
Sensory Stimulation of Shortening
S&R Sensitization
Motor Efferents
Neuromuscular Function
Leech figures
Shortening Neurocircuitry
end     Acronyms/Abbreviations
Neurocircuitry of the Leech, subclass Hirudinea    back to Behavior Lecture

Hirudinea Nervous System:
1) Segmental Organization
Comparison of Leech and Human Nervous Systems

Similar in segmented functional compartments to all vertebrates
1.5) Chain of ganblia

2) ganglion
Leech segmental ganglion

3) Electrical Synapses

4) Identified Neurons
Each Neuron is identified for a specific purpose Ventral Aspect T, P, N, R, S labelled

left = anterior Dorsal View (left figure)                                                               Ventral View (right figure)

T cells = touch mechanoreceptors
Somatosensory cells

P cells = pressure mechanoreceptors
Pressure cells

N cells = Nociception = Pain cells
Pain Receptors

                       Ventral View (left figure)                                                               Dorsal View (right figure)

S cells = interneurons

Retzius Cells
large 5-HT cells

Motor Neurons = L cells efferent ACh neurons ending at neuromuscular junctions
motor neurons

Action Potenial

5) Ding Vm = membrane potential

Na+ in first, then K+ out
Na current can be augmented by Ca