Biology 347 General Physiology Lab
Auditory and Visual Reflexes
Objectives
Introduction
During our
day-to-day lives we detect changes in the environment and react appropriately.
An external stimulus is detected by one or more neurons, which sends the
sensory information to the central nervous system, where it is processed. If a
motor response is initiated, it usually involves a series of action potentials
which produce a muscle contraction and a movement of one or more parts of the
body. A simple reflex is perhaps the easiest of this type of stimulus-response
reaction. A loud sound or something flying at your eye makes you blink, while a
tap on the tendon under the knee cap produces the knee-jerk (or myotactic)
reflex.
A simple reflex
like the myotactic reflex is produced via single synapses between sensory axons
and motor neurons. The required circuitry for this reflex is confined to the
spinal cord. Sensory information also ascends to higher centers, but the brain
is not necessary or required to perform the reflex. More complex reflexes
usually involve additional (inter-) neurons and more than one population of
motor neurons. Thus, more neurons and synapses are involved, which usually
results in a longer delay between stimulus and response and often a more
complex response. One example of such a complex response is the flexion
withdrawal reflex, where a noxious stimulus to one leg causes withdrawal of the
stimulated leg and extension of the other.
In this lab you
will study the time taken between a stimulus and the response. These reaction
time measurements will be made from an individual subjected to harmless visual
and sound stimuli. In addition, the effect of priming and prediction will be
examined.
Procedure: Equipment Set-up
1.
Start
the Labscribe software on your computer.
2.
Pull down the Settings menu.
First select Human Nerve then select the Auditory-VisualReflexes-LS2 settings
file.
3.
After a short time, LabScribe will appear on the
computerscreen as configured by the Auditory-VisualReflexes-LS2 settings.
4.
Plug the event marker into Channel 3 on
the iWorx unit.
Procedure: Reaction Time and Visual Cues
1.
Instruct the subject to:
€ Sit in a chair and face the computer screen.
€ Position a hand on the keyboard in a manner that enables
the subject to push the Enter key as quickly as possible.
€ Watch the right side of the computer screen and quickly
press the Enter key on the keyboard when the signal generated by the
event marker first appears.
2.
Out of sight of the subject, another
student should prepare to quietly press and release the button of the event
marker. In this exercise, the subject will perform ten trials.
3.
Type <Subject¹s Name> Visual
Cues in the Mark box that is to the right of the Mark button.
4.
Click on the Record button.
Instruct the subject to press the Enter key on the keyboard to mark the
recording as soon as he or she sees the visual cue on the right side of the
computer screen.
5.
Instruct the subject that the exercise
has begun and that a visual cue could appear on the screen at any time
6.
Use the event marker to deliver ten
visual cues to the subject. The cues should not be less than five seconds nor more
than ten seconds apart.
7.
After the tenth cue, click Stop to halt recording.
Save your recording.
Procedure: Data Analysis
1.
Scroll to the beginning of the data
recorded for Reaction Time a Visual Cues to display the first trial on the Main
window.
2.
Use the Display Time icons to
adjust the Display Time of the Main window to show both the
visual cue made with the event marker and the mark made by the subject¹s response
on the Main window.
3.
Click on the Analysis window icon
in the toolbar or select Analysis from the Windows menu to
transfer the data displayed in the Main window to the Analysis
window.
4.
Look at the Function Table that
is above the display of the Reaction Time channel displayed in the Analysis
window. The mathematical function, T2-T1, should appear in this table.
The value for T2-T1 is seen in the table across the top margin of the Reaction
Time channel.
5.
Use the mouse to click on and drag a
cursor to the onset of the signal used as the visual cue. Drag the other cursor
over the mark made by the subject responding to the visual cue.
6.
Once the cursors are placed in the
correct positions for determining the reaction time, record the value for T2-T1
in Table 1. Repeat this analysis for the remaining nine trails.
Procedure: Reaction Time and Auditory Cues
1.
Cover the computer screen with an
opaque piece of construction paper to prevent the subject from seeing any signal
on the screen as a visual cue.
2.
Instruct the subject to:
€ Sit in a chair in front of the computer keyboard.
€ Position a hand on the keyboard in a manner that enables the
subject to push the Enter key as quickly as possible.
€ Listen for the click (sound) of the event marker as the
other student presses the button and then press the Enter key as quickly
as possible.
3.
Out of sight of the subject, another
student should prepare to sharply tap the button of the event marker to create
a auditory cue that is also recorded as a signal on the Reaction Time
channel. In this exercise, the subject will perform ten trials.
4.
Type Auditory Cues in the Mark
box that is to the right of the Mark button.
5.
Click on the Record button.
Instruct the subject to press the Enter key on the keyboard to mark the
recording.
6.
Instruct the subject that the exercise
has begun and that an auditory cue could be heard at any time
7.
Use the event marker to deliver ten
auditory cues to the subject. The cues should not be less than five seconds nor
more than ten seconds apart.
8.
After the tenth cue, click Stop to
halt recording. Save the recording.
9.
Record the reaction time, using the
same procedure above in Data Analysis, in Table 2.
Procedure: Reaction Time and Prompted Auditory Cues
1.
Repeat the procedure for Reaction Time and Auditory
Cues, with an additional step. Before each auditory cue is delivered, tell the
subject to get ready to respond to the cue. It is best to use a one word cue
before immediately clicking the event marker button.
2.
Record the reaction times in Table 3.
Procedure: Reaction Time and Predictable Auditory Cues
1.
Repeat the procedure for Reaction Time and Auditory
Cues, with a predictable interval of five seconds between each auditory cue.
2.
Record the reaction times in Table 4.
Table 1: Reaction Time and Visual Cues
|
Trial
1 |
Trial
2 |
Trial
3 |
Trial
4 |
Trial
5 |
Trial
6 |
Trial
7 |
Trial
8 |
Trial
9 |
Trial
10 |
Reaction
Time (ms) |
|
|
|
|
|
|
|
|
|
|
Mean Reaction Time
of Subject to Visual Cues: _______________________
Table 2: Reaction Time and Auditory Cues
|
Trial
1 |
Trial
2 |
Trial
3 |
Trial
4 |
Trial
5 |
Trial
6 |
Trial
7 |
Trial
8 |
Trial
9 |
Trial
10 |
Reaction
Time (ms) |
|
|
|
|
|
|
|
|
|
|
Mean Reaction Time
of Subject to Auditory Cues: _______________________
Table 3: Reaction Time and Prompted Auditory Cues
|
Trial
1 |
Trial
2 |
Trial
3 |
Trial
4 |
Trial
5 |
Trial
6 |
Trial
7 |
Trial
8 |
Trial
9 |
Trial
10 |
Reaction
Time (ms) |
|
|
|
|
|
|
|
|
|
|
Mean Reaction Time
of Subject to Prompted Auditory Cues: _______________________
Table 4: Reaction Time and Predictable Auditory Cues
|
Trial
1 |
Trial
2 |
Trial
3 |
Trial
4 |
Trial
5 |
Trial
6 |
Trial
7 |
Trial
8 |
Trial
9 |
Trial
10 |
Reaction
Time (ms) |
|
|
|
|
|
|
|
|
|
|
Mean Reaction Time
of Subject to Predictable Auditory Cues: _______________________
Table 5: Class Data on Mean Reaction Times
|
Mean
Reaction Time (ms) |
|||||
Cue |
Group 1 |
Group 2 |
Group 3 |
Group 4 |
Group 5 |
Group 6 |
Visual |
|
|
|
|
|
|
Auditory |
|
|
|
|
|
|
Prompted Auditory |
|
|
|
|
|
|
Predictable Auditory |
|
|
|
|
|
|
Questions and Conclusions
1.
How does the subject¹s mean reaction
time to visual cues compare to his or her mean reaction time to auditory cues?
2.
What would cause a longer reaction time
to one type of cue as compared to another?
3.
How do your subject¹s mean reaction
times compare to those of other subjects?
4.
Do all subjects respond more quickly to
the same cue?
5.
To which auditory cue did your subject
respond most quickly?
6.
To which auditory cue did your subject
respond to most slowly? For what reasons?
7.
Did your subject respond more quickly
or more slowly to same auditory cue as the other members of the class?