Laminar organization of receptive field properties in the dorsal lateral geniculate nucleus of the tree shrew (Tupaiaglis belangeri)

Academic Article

Abstract

  • A laminar analysis of the receptive field properties of relay cells in the binocular region of the tree shrew dorsal lateral geniculate nucleus (LGN) found three main subdivisions. Lamina 1 (receiving ipsilateral eye input) and lamina 2 (contralateral) comprise a pair of layers that contain only ON‐center neurons. Laminae 4 (contralateral) and 5 (ipsilateral) comprise a pair of layers with mostly OFF‐center cells (86%). Laminae 3 and 6 (both contralaterally innervated) also form a distinct pair, although lamina 3 contains a mixture of cells with ON‐centers (43%) or OFF‐centers (57%), and lamina 6 contains mostly cells with ON‐OFF centers and suppressive surrounds (81%). Cells located in the interlaminar zones resembled neurons in laminae 3 and 6. In comparison with the cells in the OFF‐center laminae 4 and 5, the ON‐center cells in laminae 1 and 2 had smaller, more elliptical receptive field centers with stronger responses to flashed visual stimuli. In addition, cells in the ipsilateral eye laminae 1 and 5 showed a greater change in center diameter, with eccentricity from the area centralis, than cells in the contralateral eye laminae 2 and 4. Principal components analysis using six receptive field properties (latency to optic chiasm stimulation, receptive field center diameter, maintained discharge rate, response onset latency, peak spike density, and phasic‐tonic index) suggested that the cells in laminae 3 and 6 and the interlaminar zones are W‐like. Principal components analysis of the same receptive field properties in laminae 1, 2, 4, and 5 did not reveal differences clearly related to X‐like (parvocellular) and Y‐like (magnocellular) categories. Ninety‐seven percent of the cells tested for linearity of spatial summation in laminae 1, 2, 4, and 5 were linear. We conclude that the dominant organizational features of the tree shrew LGN are the ON‐center, OFF‐mter, and W pairs of layers that project to different regions within the striate cortex. © 1995 Wiley‐Liss, Inc. Copyright © 1995 Wiley‐Liss, Inc.
  • Authors

    Published In

    Digital Object Identifier (doi)

    Author List

  • Holdefer RN; Norton TT
  • Start Page

  • 401
  • End Page

  • 413
  • Volume

  • 358
  • Issue

  • 3