Shrinkage of X cells in the lateral geniculate nucleus after monocular deprivation revealed by FoxP2 labeling.
The parallel processing of visual features by distinct neuron populations is a central characteristic of the mammalian visual system. In the A laminae of the cat dorsal lateral geniculate nucleus (dLGN), parallel processing streams originate from two principal neuron types, called X and Y cells. Disruption of visual experience early in life by monocular deprivation has been shown to alter the structure and function of Y cells, but the extent to which deprivation influences X cells remains less clear. A transcription factor, FoxP2, has recently been shown to selectively label X cells in the ferret dLGN and thus provides an opportunity to examine whether monocular deprivation alters the soma size of X cells. In this study, FoxP2 labeling was examined in the dLGN of normal and monocularly deprived cats. The characteristics of neurons labeled for FoxP2 were consistent with FoxP2 being a marker for X cells in the cat dLGN. Monocular deprivation for either a short (7 days) or long (7 weeks) duration did not alter the density of FoxP2-positive neurons between nondeprived and deprived dLGN layers. However, for each deprived animal examined, measurement of the cross-sectional area of FoxP2-positive neurons (X cells) revealed that within deprived layers, X cells were smaller by approximately 20% after 7 days of deprivation, and by approximately 28% after 7 weeks of deprivation. The observed alteration to the cross-sectional area of X cells indicates that perturbation of this major pathway contributes to the functional impairments that develop from monocular deprivation.
Department of Psychology and Neuroscience,Dalhousie University,Life Sciences Center,Halifax,Nova Scotia,Canada.
Kevin R
KR
Duffy
Department of Psychology and Neuroscience,Dalhousie University,Life Sciences Center,Halifax,Nova Scotia,Canada.
Kaitlyn D
KD
Holman
Department of Psychology and Neuroscience,Dalhousie University,Life Sciences Center,Halifax,Nova Scotia,Canada.
Donald E
DE
Mitchell
D000818:Animals; D000831:Animals, Newborn; D002415:Cats; D002452:Cell Count; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D007839:Functional Laterality / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D005829:Geniculate Bodies / Q000473:pathology*; D009474:Neurons / Q000378:metabolism* / Q000473:pathology*; D012683:Sensory Deprivation
D051858:Forkhead Transcription Factors