Voltage-sensitive Conductances of Bushy Cells of the Mammalian Ventral Cochlear Nucleus

1. Voltage-sensitive Conductances of Bushy Cells of the Mammalian Ventral Cochlear Nucleus Xiao-Jie Cao, ShaliniShatadal, and DonataOertel

2. Anatomy: Characteristic of Bushy Cells Class Notes Paper

3. Physiology: Characteristic of bushy cells Two groups?

4. Methods – Slice preparation Exact location Controlled environment Drugs Patch Clamp Simultaneous stimulation & recording Caudal VCN

5. Goal • Using the slice preparation technique, can the authors provide further evidence that there are two groups of bushy cells? • In vitro patch clamp experiments • Current clamp • # APs • Voltage clamp • Voltage sensitivity of conductances

6. N = 30 Results – Depolarizing Current Steps Current Steps

7. N = 40 Results – Hyperpolarizing Current Steps Current Steps

8. Currentclamp to Voltage clamp!

9. Results – Low voltage K+conductance Voltage Clamp Current defined by blocker

10. Results – High voltage K+ conductance and mixed conductance High-voltage activated K+ conductance • Blocked by 10 mM TEA Hyperpolarization activated conductances • Blocked by 50 M ZD7288

11. Two separate groups? Faster Depolarizations

12. Major Findings Low threshold K+ conductance Multi AP BCs Conductance variance for ‘two groups’

13. Conclusions

14. Considerations • Did they accomplish the following goal: [evidence that there are two groups of bushy cells] • Why two BC groups important? • Histological staining show three groups • Differ in size and projection patterns • Mouse vs. gerbil • Lack of low frequency hearing & MSO • In vitro vs. in vivo • Direct comparisons possible? • Slice preparation • Advantages and Disadvantages Approx. range (Hz) Species

16. Bushy Cells! • Encode fine timing • Project to SOC • Two projections = two cell types? • MSO  receives projections from small BCs • LSO  receives projections from large BCs

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