Very slow oscillatory activities in lateral geniculate neurons of freely moving and anesthetized rats

In urethane anesthetized rats many lateral geniculate neurons display a str ong very slow oscillatory behavior in the range of 0.025-0.01 Hz. One of th e aims of the present study was to determine whether very slow oscillatory activity in this range can also be obtained in barbiturate anesthetized and in awake animals, respectively. Although very slow oscillations were found in geniculate neurons both during awakeness and during anesthesia, signifi cant differences in peak frequencies of oscillations under the three experi mental conditions (barbiturate, urethane, awake) were demonstrated. In addi tion, we have tested the influence of glutamate antagonists and GABA agonis ts as well as antagonists on the very slow oscillatory activity in urethane anesthetized rats. Very slow oscillatory activity which could be blocked b y the continuous illumination of the eyes was re-induced by iontophoresis o f NMDA and non-NMDA glutamate antagonists. GABA, as well as GABA, agonists also caused a significant re-induction of very slow oscillatory activity un der light conditions. In the dark, muscimol, a GABAA agonist, significantly enhanced the very slow oscillatory activity, i.e, muscimol either induced it or reduced the frequency of very slow oscillations. For the whole sample , GABA antagonists did not have a significant influence on the very slow os cillatory activity. Autocorrelation analysis based on the spike interval hi stograms and determination of the spectrum of autocorrelograms revealed the significance of periodicity. (C) 1998 Elsevier Science Ireland Ltd. Ail ri ghts reserved.