Selective responsiveness of medial prefrontal cortex neurons to the meaningful stimulus with a low probability of occurrence in rats.
Multi-unit neuronal activity was recorded in the medial prefrontal cortex (mPFC) of 13 chronically prepared male rats while they performed a two-tone discrimination task. Tones at 1000 and 2000 Hz were sequentially presented at intervals of 3-6 s. The duration of each tone was 0.8 s. Rats were trained to press a bar within 1.2 s after the cessation of the 1000 Hz tone (target), and not to press the bar when the other tone (non-target) was presented. Intracranial electrical stimulation (ICS) of the medial forebrain bundle was given as a reward immediately after the rats had correctly responded to the target tone. Probability of the target occurrence was either 30% or 70% in different sessions. When the target tone was presented on only 30% of the trials, the mPFC neurons in the majority of rats tested (10/13) exhibited phasic excitation about 100 ms after the onset of the target tone. However, when the target tone occurred on 70% of the trials, mPFC neurons in most of rats (11/13) did not show excitatory responses, and in some of them (5/13) were inhibited. No mPFC neurons exhibited significant responses to the non-target tone, regardless of its probability. These results suggest that the mPFC neurons selectively respond to meaningful events with a low probability of occurrence.
Jodo
E
E
Department of Physiology, Fukushima Medical University, School of Medicine, 1 Hikari-ga-oka, Fukushima, Japan. jodo1019@fmu.ac.jp
Suzuki
Y
Y
Kayama
Y
Y
D000161:Acoustic Stimulation; D000818:Animals; D001307:Auditory Perception / Q000502:physiology*; D003216:Conditioning, Operant / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology*; D004558:Electric Stimulation; D008297:Male; D008839:Microelectrodes; D009474:Neurons / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D011336:Probability; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward