QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online December 22, 2003
Journal of Experimental Biology 207, 535-544 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00789

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schriefer, J. E. Articles by Hale, M. E. Search for Related Content PubMed PubMed Citation Articles by Schriefer, J. E. Articles by Hale, M. E.

Strikes and startles of northern pike (Esox lucius): a comparison of muscle activity and kinematics between S-start behaviors

Julie E. Schriefer¹ and Melina E. Hale^1,2,3,*

¹ Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA
² Committee on Neurobiology, University of Chicago, Chicago, IL 60637, USA
³ Committee on Computational Neurobiology, University of Chicago, Chicago, IL 60637, USA

View larger version (6K): [in a new window]   Fig. 1. Electrode placement. Northern pike (Esox lucius) were implanted with seven electrodes to measure white epaxial muscle activity: one in the left jaw and bilaterally in anterior, midbody and posterior positions in the middle of the epaxial white muscle. Bars represent approximate range in the positions of electrodes among the fish. The asterisk indicates the center of mass (CM).

View larger version (65K): [in a new window]   Fig. 2. Movements of a strike and a startle of the northern pike (Esox lucius). The feeding strike (A–G) is characterized by isolated caudal movement (C–E) followed by a forward lunge accompanied by the opening of the jaw (F,G). The startle response (H–N) is characterized by an initial S-shaped bend (J) followed by a stronger bend (L-bend; K) and a propulsive tail stroke (L–N) with no jaw opening. A comparison of the feeding strike and escape startle demonstrates that initial movement is restricted to the caudal region of the body during the feeding strike (C–E) while the startle involves significant rostral and caudal movement (I–K). Scale bar, 10 cm.

View larger version (12K): [in a new window]   Fig. 3. The angle of head movement during behavioral stages of strike and startle responses. Values are means ± S.E.M.. The angles of head movement during the S-bend and from the maximum S-bend to the maximum L-bend are significantly greater for the startle than for the strike. There was no significant difference in the angle of head movement in stage 2 of strike and startle behaviors.

View larger version (14K): [in a new window]   Fig. 4. Durations of kinematics stages of S-start behaviors for the northern pike (Esox lucius). Values are means ± S.E.M.. The durations of the combined stages 1 and 2 movements, the S-bend and stage 1 were significantly greater for strikes than for startles. By contrast, there was no significant difference in L-bend or stage 2 durations between strikes and startles.

View larger version (11K): [in a new window]   Fig. 5. Mean peak center of mass velocity (A) and acceleration (B) of S-start behaviors for the northern pike (Esox lucius). Values are means ± S.E.M.. Mean peak linear velocity and linear acceleration were measured during the propulsive movement in stage 2. Neither velocity nor acceleration was significantly different between strike and startle behaviors.

View larger version (29K): [in a new window]   Fig. 6. Examples of electromyogram (EMG) patterns from S-start strike and startle behaviors. EMGs from rostral, midbody and caudal axial white muscle on both sides of the body and from left side jaw adductor muscle are shown. S, L and End indicate the end of the S-bend, L-bend and stage 2, respectively. The y-axis for jaw adductor EMGs of strikes and startles and for left caudal activity of the strike range from –1.0 mV to 1.0 mV while all other graphs range from –0.6 mV to 0.6 mV.Traces are aligned to first onset of activity with a vertical broken line. During the strike, caudal muscle activity (right side) occurs prior to more rostral activity; during the startle, there is near simultaneous activity of rostral and midbody muscle on one side of the body, in this case the left, with caudal muscle on the opposite side. During the strike, jaw muscle activity onset is considerably delayed from first onset of axial activity, while during the startle the jaw muscle is active from initiation of axial muscle activity.

View larger version (15K): [in a new window]   Fig. 7. Summary of the electromyographic recordings of S-start strike and startle muscle activity. The left margin of each bar is mean onset of activity and the right side is mean offset. Trials were aligned by setting the first onset of muscle activity to zero. Error bars represent the standard error of onset time (left) and duration (right). There is no standard error for initial caudal activity during the strike because this activity was, without exception, the first activity recorded for the strike. During the strike, initial caudal activity is followed by rostral and midbody activity on both sides of the body. Jaw adductor muscle activity is delayed relative to axial activity. During the startle response, jaw muscle is coactive with contralateral caudal muscle on one side of the body and rostral and midbody ipsilateral muscle on the opposite side. The initial activity is immediately followed by ipsilateral caudal muscle and stage 2 contralateral activity.

View larger version (11K): [in a new window]   Fig. 8. Frequency distributions of adductor muscle electromyogram (EMG) onset times. There were non-overlapping distributions of adductor muscle onset time between strike and S-start escape behaviors. Onset of adductor muscle activity during the startle took place within 5 ms of the initiation of axial activity while during the strike the delay between axial and cranial activity was longer and more variable.

View larger version (13K): [in a new window]   Fig. 9. Diagram of motor control and function of fast-start behaviors, modified from fig. 5 of Domenici and Blake (1997). The designations of whole-body S-start versus caudal S-start reflect the differences in rostral bending during the initial movements of strike and startle behaviors. This work confirms the role of an independent S-start behavior that functions as a startle and demonstrates differences in the motor control of strike and startle behaviors. While there are indications that these behaviors are controlled by different, but possibly overlapping, neural circuits, neural mechanisms have yet to be identified.