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DOWNLOADABLE VIDEOS: MUSCLES, SENSE ORGANS AND BEHAVIOR

1) BUG STANDS UP - Audio channel is the Trochanteral Extensor Motoneuron (Ds) of the front (prothoracic) leg

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AUDIO CHANNEL

NEUROPHYSIOLOGICAL RECORDING

 Spontaneous Activity of the Trochanteral Extensor Muscle of the Front Leg in Postural Adjustments - The animal is standing at the start of the sequence, then raises his head and anterior body in a peering movement.  The audio track of this video is a recording of activities of the motoneuron (Ds) of the trochanteral extensor muscle. The motoneuron firing is greatly elevated and sustained during the peering movement.  The picture below is a view of the audio channel in Nero Wave Editor software.  The channel shows the motoneuron activity (recorded in both channels).   The transcription of the neurophysiological recording below shows the burst as the animal raises up (from DAT tape taken simultaneously) and the vertical position of the animal. The frequency of firing (at low and high resolution) and the change in body height are closely correlated. 

Note:  Right Clicking over the video link will allow you to save it to your computer.  You may need the divx codec (video compression-decompression utility)  to play this file.  It is available from http://www.divx.com and the divx 3.11 version is available as freeware from other sites (it will cause no harm).

2) SUPPORT OF BODY WEIGHT IN WALKING - Audio channel is the Trochanteral Extensor Motoneuron (Ds) of the front (prothoracic) leg

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NEUROPHYSIOLOGICAL RECORDING

 Activity of the front leg trochanteral extensor (Ds) in walking - The trochanteral extensor motoneuron (Ds) shows a pattern of activity in the front legs that is similar, but not identical, to that seen in the hind legs.  The extensor is active during most of the stance phase, but its firing is initiated in swing.  In the hind legs, this firing occurs immediately prior to foot placement and is thought to limit forward movement of the leg during swing .  In the front legs, Ds activity in swing is more prolonged and acts to lower the leg and press it toward the substrate (similar to the E1 phase of activity in vertebrates).  Activity of the extensor declines during the last part of the stance phase, after the adjacent middle leg is placed upon the substrate in support.
 

3) SUDDEN INCREASE IN BODY WEIGHT BY CURRENT APPLIED TO MAGNETIC COIL BELOW ARENA IN WALKING ANIMAL - Audio channel is the Trochanteral Extensor Motoneuron (Ds) of the middle (mesothoracic) leg
 

Activity  of the trochanteral extensor muscle is tuned to body load -  As the animal walks toward the left edge of the coil (indicated by the white square grid  below the arena) a current pulse is applied.  The pulse also causes activation ) after a slight dela) of a light emitting diode in the center of the field of view.  The current pulse causes an increase in the body weight and decrease in the body height (the animals body moves down toward the substrate)

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The traces on the left are from a  transcription of part of the recording from this sequence.  The lower trace shows the trochanteral extensor during three steps (the movements of the middle leg are indicate above in red in the traces labeled SWING/STANCE).  The upper traces show the change in height of the animal's body  above the substrate and velocity of vertical movement.  The vertical red line shows the time of onset of current to the coil (also see trace CURRENT).  The increase in body load produces a rapid increase in the rate of firing of the extensor (EXT TROCH FREQ).  The initial peak of motor firing occurs close to the time of the negative peak velocity of body movement.    The duration of the stance phase is also increased (small red arrow).