Precisely correlated firing in cells of the lateral geniculate nucleus.
Simple cells within layer IV of the cat primary visual cortex are selective for lines of a specific orientation. It has been proposed that their receptive-field properties are established by the pattern of connections that they receive from the lateral geniculate nucleus (LGN) of the thalamus. Thalamic inputs, however, represent only a small proportion of the synapses made onto simple cells, and others have argued that corticocortical connections are likely to be important in shaping simple-cell response properties. Here we describe a mechanism that might be involved in selectively strengthening the effect of thalamic inputs. We show that neighbouring geniculate neurons with overlapping receptive fields of the same type (on-centre or off-centre) often fire spikes that are synchronized to within 1 millisecond. Moreover, these neurons often project to a common cortical target neuron where synchronous spikes are more effective in evoking a postsynaptic response. We propose that precisely correlated firing within a group of geniculate neurons could serve to reinforce the thalamic input to cortical simple cells.
Alonso
J M
JM
Laboratory of Neurobiology, The Rockefeller University, New York 10021, USA. jma@rockvax.rockefeller.edu
Usrey
W M
WM
Reid
R C
RC
D000200:Action Potentials; D000818:Animals; D002415:Cats; D005829:Geniculate Bodies / Q000166:cytology / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D013788:Thalamus / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology