multiplexing: one construct, many systems

In telecommunications, multiplexing combines several independent signals onto one shared transmission medium so they travel together and can be separated again at the far end, whether by giving each a different time slot, a different frequency band, or a different code. Bennett's 1941 Time division multiplex systems laid out the interleaving of multiple channels into recurring time slots on a single line. The referent is the packing of many independent streams into one shared carrier so a single resource serves many users at once, the same construct that neuroscientists read into shared neural pathways and that molecular biologists realise in a single reaction tube.[1]

Unit

The number of independent streams carried on one shared channel

Recovery means

Not applicable

Measured by

Characterised by the channel count, the separation scheme (time, frequency, or code), and the crosstalk between combined streams

In neuroscience, multiplexing is the idea that a single population of neurons or a shared pathway conveys more than one stream of information at the same time, with different messages separated by distinct oscillatory frequencies or timescales that a downstream reader can selectively decode. Akam and Kullmann's 2014 Oscillatory multiplexing of population codes for selective communication in the mammalian brain develops this as a routing scheme for selective communication. It is the same shared-channel construct as telecom multiplexing, here realised in neural circuits and measured by how distinct codes ride one pathway.[2]

Unit

The number of distinct information streams carried on one neural pathway

Recovery means

Not applicable

Measured by

Inferred from frequency- or phase-separated components of population activity and the selective decodability of each stream

In molecular biology, multiplexing runs several reactions in a single vessel at once: multiplex PCR amplifies many distinct DNA targets in one tube by including multiple primer pairs, each yielding a distinguishable product. Chamberlain and colleagues' 1988 Deletion screening of the Duchenne muscular dystrophy locus via multiplex DNA amplification introduced the approach to screen many sites in parallel. It is the same shared-resource construct as a multiplexed channel, transposed to a reaction tube and measured by how many targets are co-amplified and resolved without interference.[3]

Unit

The number of distinct targets assayed together in one reaction

Recovery means

Not applicable

Measured by

Assessed by the number of co-amplified targets, product resolvability, and the absence of primer interference or dropout