A Theoretical Analysis of the Electrical Properties of a X-Cell in the Cat's LGN
Electron microscope studies of relay cells in the lateral geniculate nucleus of the CAT have shown that the retinal input of X-cells is associated with a special synaptic circuitry, termed the spine-triad complex. The retinal afferents make an asymmetrical synapse with both a dendritic appenda...
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| Language: | en_US |
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2004
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| Online Access: | http://hdl.handle.net/1721.1/6410 |
| _version_ | 1811077695117721600 |
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| author | Koch, Christof |
| author_facet | Koch, Christof |
| author_sort | Koch, Christof |
| collection | MIT |
| description | Electron microscope studies of relay cells in the lateral geniculate nucleus of the CAT have shown that the retinal input of X-cells is associated with a special synaptic circuitry, termed the spine-triad complex. The retinal afferents make an asymmetrical synapse with both a dendritic appendage of the X-cell and a geniculate interneuron. The interneuron contacts in turn the same dendritic appendage with a symmetrical synaptic profile. The retinal input to geniculate Y-cells is predominately found on dendritic shafts without any triadic arrangement. We explore the integrative properties of X- and Y-cells resulting from this striking dichotomy in synaptic architecture. The basis of our analysis is the solution of the cable equation for a branched dendritic tree with a known somatic input resistance. Under the assumption that the geniculate interneuron mediates a shunting inhibition, activation of the interneuron reduces very efficiently the excitatory post-synaptic potential induced by the retinal afferent without affecting the electrical activity in the rest of the cell. Therefore, the spine-triad circuit implements the analogy of an AND-NOT gate, unique to the X-system. Functionally, this corresponds to a presynaptic, feed-forward type of inhibition of the optic tract terminal. Since Y-cells lack this structure, inhibition acts globally, reducing the general electrical activity of the cell. We propose that geniculate interneurons gate the flow of visual information into the X-system as a function of the behavioral state of the animal, enhancing the center-surround antagonism and possibly mediating reciprocal lateral inhibition, eye-movement related suppression and selective visual attention. |
| first_indexed | 2024-09-23T10:47:05Z |
| id | mit-1721.1/6410 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T10:47:05Z |
| publishDate | 2004 |
| record_format | dspace |
| spelling | mit-1721.1/64102019-04-12T08:30:35Z A Theoretical Analysis of the Electrical Properties of a X-Cell in the Cat's LGN Koch, Christof Electron microscope studies of relay cells in the lateral geniculate nucleus of the CAT have shown that the retinal input of X-cells is associated with a special synaptic circuitry, termed the spine-triad complex. The retinal afferents make an asymmetrical synapse with both a dendritic appendage of the X-cell and a geniculate interneuron. The interneuron contacts in turn the same dendritic appendage with a symmetrical synaptic profile. The retinal input to geniculate Y-cells is predominately found on dendritic shafts without any triadic arrangement. We explore the integrative properties of X- and Y-cells resulting from this striking dichotomy in synaptic architecture. The basis of our analysis is the solution of the cable equation for a branched dendritic tree with a known somatic input resistance. Under the assumption that the geniculate interneuron mediates a shunting inhibition, activation of the interneuron reduces very efficiently the excitatory post-synaptic potential induced by the retinal afferent without affecting the electrical activity in the rest of the cell. Therefore, the spine-triad circuit implements the analogy of an AND-NOT gate, unique to the X-system. Functionally, this corresponds to a presynaptic, feed-forward type of inhibition of the optic tract terminal. Since Y-cells lack this structure, inhibition acts globally, reducing the general electrical activity of the cell. We propose that geniculate interneurons gate the flow of visual information into the X-system as a function of the behavioral state of the animal, enhancing the center-surround antagonism and possibly mediating reciprocal lateral inhibition, eye-movement related suppression and selective visual attention. 2004-10-04T14:55:31Z 2004-10-04T14:55:31Z 1984-03-01 AIM-787 http://hdl.handle.net/1721.1/6410 en_US AIM-787 8025534 bytes 6306024 bytes application/postscript application/pdf application/postscript application/pdf |
| spellingShingle | Koch, Christof A Theoretical Analysis of the Electrical Properties of a X-Cell in the Cat's LGN |
| title | A Theoretical Analysis of the Electrical Properties of a X-Cell in the Cat's LGN |
| title_full | A Theoretical Analysis of the Electrical Properties of a X-Cell in the Cat's LGN |
| title_fullStr | A Theoretical Analysis of the Electrical Properties of a X-Cell in the Cat's LGN |
| title_full_unstemmed | A Theoretical Analysis of the Electrical Properties of a X-Cell in the Cat's LGN |
| title_short | A Theoretical Analysis of the Electrical Properties of a X-Cell in the Cat's LGN |
| title_sort | theoretical analysis of the electrical properties of a x cell in the cat s lgn |
| url | http://hdl.handle.net/1721.1/6410 |
| work_keys_str_mv | AT kochchristof atheoreticalanalysisoftheelectricalpropertiesofaxcellinthecatslgn AT kochchristof theoreticalanalysisoftheelectricalpropertiesofaxcellinthecatslgn |