A link between role of two prefrontal areas in immediate memory and in long-term memory consolidation.
The dorsolateral and medial prefrontal cortex are critical for immediate memory processing. The possibility has been raised that those two areas may also contribute to long-term memory formation. Here, we studied the role of specific receptors in dorsolateral and medial prefrontal cortex in immediate and in long-term memory formation of one-trial inhibitory avoidance. Four different specific receptor ligands were infused into these two areas: the dopamine D1 receptor antagonist, SCH23390, the GABA(A) receptor agonist, muscimol, the AMPA glutamatergic receptor antagonist, ciano-nitro-quinoxaline-dione (CNQX), and the NMDA glutamatergic receptor antagonist, aminophosphonovaleric acid (AP5). In all cases the doses used had been previously shown to affect immediate or long-term memory. In the experiments on immediate memory the drugs were given 5 min before training and the animals were tested 3s post-training. These animals were then also tested 24h later for long-term memory. The effect of the treatments on long-term memory was studied by their infusion 0, 90, 180 or 270 min post-training, testing the animals 24h after training. Immediate memory was inhibited by SCH23390, muscimol and CNQX, but not by AP5, given into any of the two subregions. Long-term memory formation was inhibited by SCH23390, muscimol and CNQX, but not by AP5, given pre-training or 0, 90 or 180 but not 270 min post-training into the dorsolateral region; or 90 but not 0 or 180 min post-training into the medial region. Thus, there is a time- and receptor-dependent correlation in the two areas between their role in immediate and in long-term memory processing. Both roles require intact glutamate AMPA and dopamine D1 receptors, are inhibited by GABAergic synapses, and are unaffected by AP5. In the dorsolateral prefrontal cortex the link between immediate and long-term memory appears to be direct; in the medial area the link suffers a 90 min delay.
Izquierdo
Luciana A
LA
Centro de Memoria, Instituto de Pesquisas Biológicas, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Av. Ipiranga 6690, 2nd Floor, R90610-000, Porto Alegre, RS, Brazil.
Barros
Daniela M
DM
da Costa
Jaderson Costa
JC
Furini
Cristiane
C
Zinn
Carolina
C
Cammarota
Martin
M
Bevilaqua
Lia R
LR
Izquierdo
Ivan
I
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D008568:Memory / Q000187:drug effects; D008570:Memory, Short-Term / Q000187:drug effects*; D009118:Muscimol / Q000494:pharmacology*; D017397:Prefrontal Cortex / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D018091:Receptors, AMPA / Q000187:drug effects; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors; D018079:Receptors, GABA / Q000187:drug effects; D017470:Receptors, Glutamate / Q000187:drug effects; D012153:Retention, Psychology / Q000187:drug effects*; D013997:Time Factors
D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D017447:Receptors, Dopamine D1; D018079:Receptors, GABA; D017470:Receptors, Glutamate; D009118:Muscimol; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione