Aims: 

The goal of the present study was to examine the basic properties of sensory gating in this brain region in freely moving rats.

Methods: 

We developed special equipment for startle reflex measuring (3D-accelerometer on preamplifier recording head movements). We used a prepulse inhibition paradigm with 160 ms interval between startle stimulus (40 ms, 120 dB white noise) and prepulse stimulus (20 ms, 75 dB white noise). In the medial prefrontal cortex we recorded both single unit, local field and evoked potentials (64-channel low voltage converter, Noted Bt., Hungary) by means of chronically implanted tetrodes during startle stimulus alone (SA), prepulse stimulus alone (PA), and prepulse inhibition paradigm (PPI).

Results: 

We observed different types of inhibition and excitation during SA, PPI and PA. Our results showed that during PPI the single unit inhibition was shorter and amplitude of inhibition was smaller than during SA. On the other hand, we demonstrated that single unit excitation was shorter and excitation was higher during PPI than during SA. We investigated evoked potential of auditory sensory gating, too. Evoked potentials recorded during SA were absent or their amplitudes were smaller after the startle stimulus onset of PPI. However, evoked potentials could generally be recording during PA and PPI showing distinct role of prepulse stimulus in generating evoked responses.

Conclusion: 

These data support the possible role of medial prefrontal cortex in inhibitory processes and mechanisms of sensory gating.

Support: 

NKTH-OTKA K68431, SROP-4.2.1.B-10/2/KONV-2010-0002, HAS