Two types of thalamic reticular cells in relation to the two visual thalamocortical systems in the rat.
We found in urethane-anesthetized rats that thalamic reticular (TR) cells responding to an electrical stimulus of the optic tract (OT) can be further subdivided into two types, viz. S- and L-type cells. S-type cells, which were selectively excited from area 17 of the visual cortex, were characterized by short latency responses (2.3-6.1 ms) to OT stimulation. TR cells activated antidromically from the dorsal lateral geniculate nucleus were all classified as S-type. Long OT latencies (5.2-15.3 ms) and selective excitation from area 18a were peculiar to L-type cells, which showed antidromic responses to the lateral posterior nucleus stimulation. Mapping studies documented that cells belonging to each type were segregated in the thalamic reticular nucleus; L-type cells were located in the most posterior part. It is suggested that S- and L-type cells are inhibitory interneurons modulating activity of geniculocortical and extrageniculocortical projection cells, respectively.
Sumitomo
I
I
Laboratory of Biological Science, Osaka Keizai University, Japan.
Hsiao
C F
CF
Fukuda
Y
Y
D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials; D005829:Geniculate Bodies / Q000502:physiology; D051381:Rats; D013238:Stereotaxic Techniques; D013788:Thalamus / Q000166:cytology / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*