Those who read my blog post a couple days ago (“Information that Moves from the Eyeball to the Brain“) will recall that I was not happy with the paper I reviewed. It seemed to me to represent a lot of work and presented no new ideas or findings. Then I noticed that another paper was published back-to-back in the same issue of the Journal of Neuroscience on the same topic. Would this paper enlighten me and show me the error of my earlier reading?
The paper titled “Recoding of Sensory Information across the Retinothalamic Synapse” published October 13, 2010 in the Journal of Neuroscience was by a different research team. While the experimental techniques were mostly the same as in the other paper, the analysis and discussion were quite different and, I thought, provided some useful new information. Interestingly, this paper clearly stood on the shoulders of a 1998 paper from the principle investigator that produced the paper I reviewed a couple of days ago.
This paper asks if pairs of spikes in retinal ganglion cells separated by certain time spans (between about 2.5 to 30 milliseconds) together carry information not carried by the individual spikes alone. If yes, is that information encoded and represented in single spikes in the receiving thalamic neurons. Their answer was yes to both questions.
Note: Those who need basic background on the visual system should consult my previous post “Information that Moves from the Eyeball to the Brain.”
They conclude that their “work provides a first biological example of the transformation of a correlation code into an independent code across a synapse through which sensory information flows from the periphery to the brain.” Their unique contribution was a joint encoding model that enabled them to show that thalamic neurons inherited selectivity for the spatial features encoded by their retinal inputs but gained sensitivity to different temporal features.
I found this paper satisfying because they looked at how information distributed in spikes in the retina was re-presented in the thalamus. They also provided evidence for synaptic integration underlying the transformation between retinal ganglion cells and thalamic neurons.
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