Frequency potentiation in the medial cortex of young turtle brains in vitro.
Turtle brains have a relatively primitive cortex. Glutamate receptors in the cortex of turtles include N-methyl-D-aspartate (NMDA) and DL-alpha-amino-3-hydroxy-5-methylisoxazole-propionic acid (AMPA). Our aim was to determine whether the medial cortex in turtles, like the cortex and hippocampus in mammals exhibits frequency potentiation, a non-lasting form of synaptic plasticity, and, if so, to identify the involved receptors. Our results indicate that (1) the medial cortex exhibits this phenomenon with septal stimulation at 2 Hz, the frequency with maximum power spectral density in the electrocorticogram of turtles, showing an increase in both the excitatory postsynaptic potential and the evoked potential amplitudes; (2) the frequency potentiation of the medial cortex in turtles is mediated by AMPA type glutamate receptors; (3) the dynamics of frequency potentiation development in turtles show a number of differences from that in mammals. In summary, the cortex in this group of reptiles exhibits a functional trait of the cortex in mammals that is related to learning and memory; this trait, frequency potentiation, may have appeared as an independent specialization in both groups.
Muñoz
M D
MD
Neurología Experimental, Dpto. Investigación, Hospital Ramón y Cajal, Madrid, España. dolores.munoz@hrc.es
Magariños-Ascone
C
C
Gaztelu
J M
JM
García-Austt
E
E
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism*; D004558:Electric Stimulation; D005071:Evoked Potentials; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology; D016202:N-Methylaspartate / Q000378:metabolism*; D017966:Pyramidal Cells / Q000502:physiology; D012688:Septum Pellucidum / Q000378:metabolism; D014426:Turtles / Q000502:physiology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000378:metabolism*
D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid