Archives pour l'étiquette frequency coding

Introduction of Temporal and rate decoding in spiking neurons with dendrites

ULTIMATELY understanding the role of dendrites in neural computation requires a theory. This theory must identify the benefits of having dendrites and reveal the basic principles used to provide these benefits” [1]. In the conclusion of the book entitled “Dendrites”, the editors Nelson Spruston, Greg Stuart and Michael Häusser wrote:

“Despite this tremendous progress, the most exciting times in dendrite research lie ahead of us. Much of the knowledge we have accumulated to date has been descriptive […] Two key questions that now need addressing are:

  1. What computations does each neuron perform within its neuronal network?
  2. And, which features of dendrites are most relevant to how neurons perform these computations? [2]

Concerning neuronal functions, a first element was given by Rieke et al in 1999 [3]:

“When we see, we are not interpreting the pattern of light intensity that falls on our retina; we are interpreting the pattern of spikes that the million cells of our optic nerve send to the brain. […] Spike sequences are the language for which the brain is listening, the language the brain uses for its internal musings, and the language it speaks as it talks to the outside world.”

There is also much evidence showing that biological neurons are able to interpret firing rate [4] and temporal codes [5]. Here we show that the addition of a single dendrite to a point neuron model considerably extends its possible range of functions, in particular, enabling it to detect a precise spatio-temporal pattern of spikes or, conversely, to have an undifferentiated response to precise spike timing but to react to average firing rate. We also show that these two distinct types of behavior characterized either by spatio-temporal or frequency sensitivity depend solely on the morphology of the « synapse-dendrite » system and in particular on the position of synapses on the dendrite. These findings provide an additional element necessary to our global understanding of the features required by dendrites that enable biological neurons to perform these computations.