Functional connectivity in the retina at the resolution of photoreceptors

To understand a neural circuit requires knowledge of its connectivity. Here we report measurements of functional connectivity between the input and ouput layers of the macaque retina at single-cell resolution and the implications of these for colour vision. Multi-electrode technology was used to record simultaneously from complete populations of the retinal ganglion cell types (midget, parasol and small bistratified) that transmit high-resolution visual signals to the brain. Fine-grained visual stimulation was used to identify the location, type and strength of the functional input of each cone photoreceptor to each ganglion cell. The populations of ON and OFF midget and parasol cells each sampled the complete population of long- and middle-wavelength-sensitive cones. However, only OFF midget cells frequently received strong input from short-wavelength-sensitive cones. ON and OFF midget cells showed a small non-random tendency to selectively sample from either long- or middle-wavelength-sensitive cones to a degree not explained by clumping in the cone mosaic. These measurements reveal computations in a neural circuit at the elementary resolution of individual neurons.     

The 6-hydroxylation of tryptamines by microsomal preparations from human liver tissue obtained at routine autopsy

Riassunto I preparati di microsomi del fegato umano ottenuto all'autopsia hanno la capacitá di ossidare diverse triptamine. Gli enzimi implicati sono simili a quelli che processano le sostanze straniere e farmacologiche. Ció dimostra ch'é possibile utilizzare questi preparati negli studi sul metabolismo dei farmaci.

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This work was partially supported by a British Medical Association grant.