Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Dendritic Trees

 

Dendritic trees with plasticity of synaptic connections

Thousands of synapses on the spines of each neuron’s dendritic tree provide a virtual infinity of connections space for the 10¹² neurons of the brain’s neural network.  The plasticity of synaptic connections permits the synaptic strength to be continually refined and updated with new experience, and with memory consolidation in sleep and dreaming.

The thousands of synapses in each neuron’s dendritic tree offer the potential for shaping patterned efficacy of synapse response both in terms of spatial distribution and temporal correlations in input spike patterns.  The following recent article describes research and a continuing attempt to understand the effects of patterned responses in neuron’s dendritic trees.

Integrative properties of dendritic trees. (Llinás; Cerebellum, 256)

Adaptive changes in individual neurons in the nervous system take from seconds to hours. (Holland; Hidden Order, 9)

 

Dendrites and dendritic spines

Surface area of dendrites is one to two orders of magnitude larger than that of the soma, (Douglas; Neocortex, 494)

One of most prominent features of cortical neurons is that dendritic spines, (Douglas; Neocortex, 497)

Because excitatory synapses and some inhibitory synapses terminate on dendrites, the physiology and biophysics of synaptic transmission is complicated by the properties of dendrites. (Johnston; Hippocampus, 439)

Recent advances in imaging techniques make it possible to measure calcium dynamics in individual spines, (Douglas; Neocortex, 497)

Most of the synaptic current injected into the spine head reaches the trunk dendrite via the spine neck, (Douglas; Neocortex, 497)

Resistance to current flow through the neck is high, on the order of 100 MΩ or more, (Douglas; Neocortex, 497)

Neck resistance could be used to control the efficacy of the synapse and thus to provide a basis for a synaptic plasticity, (Douglas; Neocortex, 497)

Twitching spine hypothesis -- Francis Crick (1982) proposed that a change in spine length could be achieved quickly, by calcium activation of myosin and actin localized in the spine neck, (Douglas; Neocortex, 497)

 

Research study — Spine Stabilization and Synaptic Enhancement

Research study — Dendritic Encoding of Sensory Stimuli by Cortical Interneurons

 

 

Shape of the dendritic tree may affect spike output pattern

Theoretical work has suggested that the shape of the dendritic tree is a major factor in controlling the pattern of spike output from neurons, (Douglas; Neocortex, 465)

 

 

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