Attentional activation of the visual thalamic reticular nucleus depends on 'top-down' inputs from the primary visual cortex via corticogeniculate pathways

Brain Res. 2000 May 2;864(1):95-104. doi: 10.1016/s0006-8993(00)02182-x.


This study is concerned with corticothalamic neural mechanisms underlying attentional phenomena. Previous results from this laboratory demonstrated that the visual sector of the GABAergic thalamic reticular nucleus is activated by attention in rats. Here it is demonstrated that Fos-detected activation of the visual reticular sector in rats, induced by attentive exploration of a novel-complex environment, is dependent on 'top-down' cortical inputs from the primary visual cortex, on the basis (a) that activation of the visual reticular sector is drastically diminished after ibotenate lesions mostly restricted to layer 6 of the primary visual cortex, which gives origin to the corticogeniculate pathway that innervates both the visual reticular sector and the dorsal lateral geniculate nucleus; and (b) the lesions did not induce retrograde degeneration nor diminution of Fos label in the geniculate. The results are consistent with the previously proposed hypothesis that a focus of attention in V1 generates a column of increased thalamocortical transmission in LGN by means of monosynaptic glutamatergic corticogeniculate inputs, and decreased transmission of surrounding regions by disynaptic cortico-reticulo-geniculate (ultimately GABAergic) inputs. The results also suggest that attentional modulation of thalamocortical transmission is a main function of corticothalamic pathways to sensory relay nuclei.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Action Potentials / drug effects
  • Action Potentials / physiology
  • Animals
  • Attention / physiology*
  • Denervation
  • Excitatory Amino Acid Agonists
  • Functional Laterality / physiology
  • Geniculate Bodies / cytology
  • Geniculate Bodies / physiology*
  • Ibotenic Acid / pharmacology
  • Immunohistochemistry
  • Male
  • Nerve Degeneration / chemically induced
  • Nerve Degeneration / physiopathology
  • Photic Stimulation / methods
  • Proto-Oncogene Proteins c-fos / analysis
  • Proto-Oncogene Proteins c-fos / metabolism
  • Psychomotor Performance / physiology
  • Rats
  • Rats, Long-Evans
  • Visual Cortex / cytology
  • Visual Cortex / physiology*
  • Visual Pathways / cytology
  • Visual Pathways / physiology*


  • Excitatory Amino Acid Agonists
  • Proto-Oncogene Proteins c-fos
  • Ibotenic Acid