GABA(B)-ergic modulation of burst rate and intersegmental coordination in lamprey: experiments and simulations.
Neuromodulators which influence the operation of neural networks act as a rule via several cellular and synaptic mechanisms. Activation of GABA(B)-receptors in the lamprey spinal cord reduce both calcium currents and the peak amplitude of the post-spike afterhyperpolarization (AHP). Activation of GABA(B)-receptors reduce the segmental alternation rate and modifies the intersegmental coordination when the spinal locomotor circuits are activated by NMDA. Using physiological experiments we find that a reduced AHP is not sufficient to account for the observed reduction of the burst rate. Computer simulations revealed that either a reduced AHP or calcium current could alter the phase coordination between the segments similar to earlier experiments.
Tegnér
J
J
Department of Neuroscience, Karolinska Institutet, S-171 77, Stockholm, Sweden. jespert@nada.kth.se
Grillner
S
S
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018755:GABA Agonists / Q000494:pharmacology; D007798:Lampreys / Q000033:anatomy & histology* / Q000502:physiology*; D008959:Models, Neurological; D016202:N-Methylaspartate / Q000494:pharmacology; D009415:Nerve Net / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D018080:Receptors, GABA-B / Q000187:drug effects / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D015220:Calcium Channels; D018690:Excitatory Amino Acid Agonists; D018755:GABA Agonists; D015221:Potassium Channels; D018080:Receptors, GABA-B; D016194:Receptors, N-Methyl-D-Aspartate; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D001418:Baclofen