Preparatory States & Processes: Proceedings of the Franco-American Conference, Ann Arbor, Michigan, August, 1982

By Sylvan Kornblum; Jean Requin | Go to book overview

14 Selective and Aselective Control of Spinal Motor Structures During Preparation for a Movement

C. H. M. Brunia Tilburg University The Netherlands

For a voluntary plantar flexion of the foot, motoneurons of the calf muscles have to be depolarized by a central command. Achilles tendon (T) reflexes evoked during the foreperiod of a reaction time (RT) experiment can be used to estimate the changes in excitability of these motoneurons, since the voluntary command and the reflex circuit share the same final common path. Bilateral T reflex recordings preceding a unilateral plantar flexion permit a comparison between changes in the excitability of motor structures which are involved or not involved in the movement. Similar recordings preceding a unilateral finger movement provide data about motor structures uninvolved in the response. These are localized at a different spinal level than that at which the response execution takes place. Bilateral T reflex recordings preceding a unilateral dorsiflexion of the foot provide data concerning motor structures not involved in the response, being localized at the same spinal level as the one at which the response execution takes place. Four experiments are discussed. They indicate that between the warning signal (WS) and the movement the three following processes take place. First, the WS causes a nonselective facilitation of the motor structures, irrespective of the kind of movement to be made. Second, in the remainder of the foreperiod a differential pattern in the changes in reflex amplitudes is found. Motor structures not involved in the response show an increase in excitability, whereas the agonist reflex arc shows a selective lack of increase. Third, after the response signal the differential pattern is reversed. Motor structures show a selective increase in excitability when they are agonist and an aselective increase to a lesser extent when they are not involved in the response.


INTRODUCTION

For a voluntary movement to be executed, the motoneurons innervating the agonist have to be depolarized to a critical value by a central command. A way of

-285-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited page

Bookmark this page
Preparatory States & Processes: Proceedings of the Franco-American Conference, Ann Arbor, Michigan, August, 1982
Table of contents

Table of contents

Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen
/ 386

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Author Advanced search

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.