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Investigation of burst generation by the electrically coupled cyberchron network in the snailHelisomausing a single‐electrode voltage clamp

 

作者: Michael Merickel,   Richard Gray,  

 

期刊: Journal of Neurobiology  (WILEY Available online 1980)
卷期: Volume 11, issue 1  

页码: 73-102

 

ISSN:0022-3034

 

年代: 1980

 

DOI:10.1002/neu.480110108

 

出版商: Wiley Subscription Services, Inc., A Wiley Company

 

数据来源: WILEY

 

摘要:

AbstractThis paper describes the results of investigating burst generation by the cyberchron network in the snailHelisoma. The cyberchron network is composed of approximately 20 electrically coupled neurons and controls the feeding behavior of the snail. The electrical coupling between network members has made it particularly difficult to distinguish between the importance and involvement of single‐cell and network properties in burst generation by this system. The present investigations utilized the new single‐electrode voltage clamp to examine the membrane properties and network interactions of the cyberchron neurons: (1) A slow outward current is activated by moderately large depolarizing commands (−40 to 0 mV) and does not undergo inactivation decay (i.e., decline in magnitude) during a command potential step maintained for 10 sec or more. The lack of inactivation of the outward current in cyberchron neurons appears to be due to the dominating role of a Ca‐dependent K current. (2) There are two functionally distinct classes of cyberchrons—current generator cyberchrons and follower cyberchrons. (3) Primary current generator cyberchrons have membrane properties similar to endogenous bursting neurons (e.g., persistent inward Ca current and negative resistance region inI–Vplot) and appear to provide the main driving and timing current for the rest of the network. (4) The vast majority of cyberchrons are secondary current generator cyberchrons with membrane properties which exhibit inward‐going rectification and appear to burst as a result of regenerative excitation with one another and the primary current generator cyberchrons. (5) The second class of cyberchrons are driven by the electrical synaptic input from the current generator cyberchrons, do not exhibit inward‐going rectification, and are called follower cyberchrons. (6) Burst termination is due to activation of a slow outward tail current in most cyberchrons during the burst (probably Ca‐activated K current) which causes a hyperpolarization in individual cyberchrons, terminating the burst. (7) Decay of the outward tail current causes the cyberchrons to depolarize, which activates the persistent inward Ca current in the primary current generator cyberchrons, starting the

 

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