This page describes the activities undertaken as part of a grant with the
above title, funded by EPSRC (GR/R12350/01).
Abstract. The abstract of the research proposal is available here.
Background. In this project we are interested in how spatial temporal
interactions within populations of synaptic inputs shape the output discharge
of a neurone. We have investigated this issue in detailed compartmental
models of motoneurones and CA3 pyramidal neurones. We characterise
spatial temporal interactions by studying the effects of introducing spatial
and temporal correlation into a sub set of the total synaptic input. Spatial
correlation refers to clustering of inputs in certain locations, temporal
correlation refers to the timing of individual spikes in the spike trains
driving the synaptic inputs.
First we establish the basic pattern of spatial temporal interactions within a neurone subjected to large scale synaptic input which lacks spatial or temporal correlation, i.e. synaptic inputs are uniformly distributed over the dendritic tree and all inputs are activated by random spike trains.
Local feedback in dendritic currents following individual inputs
Transfer function analysis of membrane potential fluctuations during large scale input
|Axial current reversal following synaptic input.
This figure illustrates the axial membrane current, ia, between a dendritic compartment and its proximal (left), and distal neighbours (right). Note the reversal of axial current after 0.9 ms, which only occurs in the distal current. The solid lines indicate the current in response to a single synaptic input applied in isolation, the dashed lines are the current due to a single input in the presence of large scale background activation of the cell.
Transfer function analysis of membrane potential
fluctuations during large scale input
We use a statistical signal processing framework to analyse the relationship between membrane potential fluctuations in different parts of the dendritic tree during large scale synaptic input, using the same notoneurone model as above. The figure below shows the axial membrane current and a time domain transfer function analysis of the membrane potential fluctuations. The synaptic input is uniformly distributed and all 996 inputs are activated by random spike trains, each with a mean rate of 32 spikes/sec.
|Analysis of membrane potential fluctuations
and axial current during large scale synaptic input. (Left) Section
of 100ms duration showing axial current between one dendritic compartment
and its proximal neighbour during large scale background activation of the
neurone. (Right) Estimate of time domain transfer function between the membrane
potential fluctuations at the mid point of one dendrite and those at the
soma for a 100 s record during large scale synaptic input.
Please note - this page is still under construction. Further results will
If you would like further details about the above work, the following publications provide details. Further publications will be added as they become available.
M. Griffin & D.M. Halliday (2003) "On the role of dendritic
feedback in synaptic integration", British Neurosci. Assoc. Abstr., vol17,
Abstract is available here. Poster presentation to the BNA meeting is available in three pages (jpg): page1 page2 page 3.
M. Griffin & D.M. Halliday (2003) "Axial current reversal promotes
synchronous correlation between dendritic membrane potentials during large
scale synaptic input." To be presented at the Computational Neuroscience
Pre-print (PDF) is available here.
This work was supported by (GR/R12350/01).
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