TY - JOUR
T1 - The morphoelectrotonic transform
T2 - A graphical approach to dendritic function
AU - Zador, Anthony M.
AU - Agmon-Snir, Hagai
AU - Segev, Idan
PY - 1995/3
Y1 - 1995/3
N2 - Electrotonic structure of dendrites plays a critical role in neuronal computation and plasticity. In this article we develop two novel measures of electrotonic structure that describe intraneuronal signaling in dendrites of arbitrary geometry. The log-attenuation L(ij) measures the efficacy, and the propagation delay P(ij) the speed, of signal transfer between any two points i and j. These measures are additive, in the sense that if j lies between i and k, the total distance L(ik) is just the sum of the partial distances: L(ik) = L(ij) + L(jk), and similarly P(ik) = P(ij) + P(jk). This property serves as the basis for the morphoelectrotonic transform (MET), a graphical mapping from morphological into electrotonic space. In a MET, either P(ij) or L(ij) replace anatomical distance as the fundamental unit and so provide direct functional measures of intraneuronal signaling. The analysis holds for arbitrary transient signals, even those generated by nonlinear conductance changes underlying both synaptic and action potentials. Depending on input location and the measure of interest, a single neuron admits many METs, each emphasizing different functional consequences of the dendritic electrotonic structure. Using a single layer 5 cortical pyramidal neuron, we illustrate a collection of METs that lead to a deeper understanding of the electrical behavior of its dendritic tree. We then compare this cortical cell to representative neurons from other brain regions (cortical layer 2/3 pyramidal, region CA1 hippocampal pyramidal, and cerebellar Purkinje). Finally, we apply the MET to electrical signaling in dendritic spines, and extend this analysis to calcium signaling within spines. Our results demonstrate that the MET provides a powerful tool for obtaining a rapid and intuitive grasp of the functional properties of dendritic trees.
AB - Electrotonic structure of dendrites plays a critical role in neuronal computation and plasticity. In this article we develop two novel measures of electrotonic structure that describe intraneuronal signaling in dendrites of arbitrary geometry. The log-attenuation L(ij) measures the efficacy, and the propagation delay P(ij) the speed, of signal transfer between any two points i and j. These measures are additive, in the sense that if j lies between i and k, the total distance L(ik) is just the sum of the partial distances: L(ik) = L(ij) + L(jk), and similarly P(ik) = P(ij) + P(jk). This property serves as the basis for the morphoelectrotonic transform (MET), a graphical mapping from morphological into electrotonic space. In a MET, either P(ij) or L(ij) replace anatomical distance as the fundamental unit and so provide direct functional measures of intraneuronal signaling. The analysis holds for arbitrary transient signals, even those generated by nonlinear conductance changes underlying both synaptic and action potentials. Depending on input location and the measure of interest, a single neuron admits many METs, each emphasizing different functional consequences of the dendritic electrotonic structure. Using a single layer 5 cortical pyramidal neuron, we illustrate a collection of METs that lead to a deeper understanding of the electrical behavior of its dendritic tree. We then compare this cortical cell to representative neurons from other brain regions (cortical layer 2/3 pyramidal, region CA1 hippocampal pyramidal, and cerebellar Purkinje). Finally, we apply the MET to electrical signaling in dendritic spines, and extend this analysis to calcium signaling within spines. Our results demonstrate that the MET provides a powerful tool for obtaining a rapid and intuitive grasp of the functional properties of dendritic trees.
KW - cable theory
KW - calcium dynamics
KW - computer models
KW - dendritic computation
KW - dendritic morphology
KW - dendritic spines
KW - electrotonic structure
KW - neuronal simulation
UR - http://www.scopus.com/inward/record.url?scp=0028970280&partnerID=8YFLogxK
U2 - 10.1523/jneurosci.15-03-01669.1995
DO - 10.1523/jneurosci.15-03-01669.1995
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C2 - 7891127
AN - SCOPUS:0028970280
SN - 0270-6474
VL - 15
SP - 1669
EP - 1682
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 3 I
ER -