Monday, August 13, 2012

Activation of specific interneurons improves V1 feature selectivity and visual perception.

Lee, SH. Kwan, AC. Zhang, S. Phoumthipphavong, V. Flannery, JG. Masmanidis, SC. Taniguchi, H. Huang, ZJ. Zhang, F. Boyden, ES. Deisseroth, K. Dan, Y. (2012) Activation of specific interneurons improves V1 feature selectivity and visual perception. Nature.

ChR2 targeted to PV, SOM, VIP, CAMKII-Arch. Multichannel probe for recording all layers. Drifting grating.

Activation of PV caused decrease in tuning bandwidth, and increase in direction selectivity. Preferred orientation remained relatively constant. They record whole-cell, inject current to get F-I response and find that PV activation is additive, while SOM activation is multiplicative. (This is the opposite effects of what the other papers say about the roles of PV and SOM).

They next had an orientation discrimination task with mice and activated the PV cells. They found that activating the PV cells can actually improve discriminability (d') of the Go, No-Go task. They claim that this is because PV increases the orientation selectivity of neurons, making the task easier. (I'm skeptical of this, decreasing the tuning width is likely to remove information of the orientation from the system, it definitely does not add any information.)

They address Bass's result saying: Bass's study shows "PV activation only moderately affects the tuning of V1 neurons. This is probably caused by the relatively low level of PV activation compared with our study". So, this could mean the difference is explained by them over-activating PV cells and getting some iceberg effect.

1 comment:

  1. This study is also injecting current to get the input-output response. Perhaps injecting current directly into the soma, vs current coming into the soma from the dendrites is the difference. In this case, its possible that the inhibition (also at the soma) is not appropriately acting like a voltage divider.