Do retinal bipolar cells receive direct input from retinal horizontal cells?, retinal neurons, horizontal cells, bipolar cells Options

[ReTina]

Please provide me with some references if possible.
Thanks!

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I'm not a native English speaker, forgive me for my strange expression.

[Paul King]

Most written summaries of the retina circuit seem to suggest that horizontal cells provide inhibitory GABAergic feedback only to photoreceptors, and that bipolar cells get their feedforward input only from the glutamatergic photoreceptors.

For bipolar cells to receive input from horizontal cells, they would need to have GABA receptors on their dendrites. Many papers assert that no GABA receptors exist on the dendrites of bipolar cells, for example:
http://jn.physiology.org/cgi/content/abstract/76/3/2005

However other papers find evidence for dendritic GABA receptors on bipolar cells mediating a feedfoward horizontal cell to bipolar cell signaling pathway. For example:
http://www.jneurosci.org/cgi/reprint/20/20/7657
http://www.springerlink.com/content/w15t4g6r48v5r174/
http://www.pnas.org/cgi/content/abstract/88/8/3310

This research page depicts a photoreceptor - horizontal cell - bipolar cell circuit diagram showing direct GABAergic communication from horizontal cells to bipolar cells:
http://retina.anatomy.upenn.edu/~noga/noga.html

Given that horizontal cells are releasing GABA in the vicinity of bipolar cell dendrites, it would seem strange if biology wouldn't have found some way for the bipolar cells to make use of that signal.