Xiao-Jie Cao, Shalini Shatadal, and Donata Oertel Voltage-sensitive Conductances of Bushy Cells of the Mammalian Ventral Cochlear Nucleus Conductance – ability of material to pass ions Xiao-Jie Cao, Shalini Shatadal, and Donata Oertel

Anatomy: Characteristic of Bushy Cells Class Notes Paper

Physiology: Characteristic of bushy cells In vivo In vitro Two groups?

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

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

Results – Depolarizing Current Steps

Results – Hyperpolarizing Current Steps

Current clamp to Voltage clamp!

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

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

Two separate groups? Faster Depolarizations

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

Conclusions Possibility of two different BC groups BCs encode fine timing Low threshold K+ conductance Presence may play a role in BCs ability to encode fine timing Two groups may = two different timing functions

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 rat 200-76,000  mouse 1,000-91,000  gerbil 100-60,000 

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

Figure 2

Figure 7

Figure 8

Figure 9

Figure 10