Action potentials of single perigeniculate (PGN)
cells and relay cells of the dorsal lateral geniculate
nucleus (dLGN) with topographically matched or at least
partially overlapping receptive fields (RF) were simultaneously
recorded in the anesthetized and paralyzed cat during visual
stimulation with moving gratings or flashing light spots
of different size. In many cases, PGN cells showed an activity
pattern which appeared like a mirror image of distinct
periods of dLGN activity. Flashing spots evoked transient
volleys of activity in PGN cells which increased in strength
and shortened in latency with increasing size of the stimulus.
These responses were temporally matched with inhibitory
phases in the early part of visual responses in the dLGN.
The spatio-temporal properties of the RFs were established
by reverse correlation of the spike activity with the spatially
random presentation of bright and dark spots within an
array of 20 × 20 positions. Anticorrelated firing
patterns of such kind could also be elicited as interocular
inhibition with stimulation of the perigeniculate RF in
the nondominant eye. Inversely correlated changes in spontaneous
and visually induced activity were also visible during
spontaneous changes in EEG pattern. With increasing synchronization
of the EEG (predominance of delta-waves) the strength of
geniculate visual responses declined while maintained perigeniculate
activity increased. A weakened interocular and monocular
inhibition of dLGN relay cells during visual stimulation
of PGN RFs could be achieved with local reversible inactivation
of PGN areas topographically matched with the dLGN recording
sites. The results indicate that the PGN contributes to
the state-dependent control of retino-geniculate transmission
and to the monocular and interocular inhibitory processes
that shape the visual responses in the dLGN.