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1. Nervous Physiology DECEREBRATED FROG
2. Introduction O The forebrain, which contains the olfactory
bulb and cerebrum, has activities that include processing of
olfactory input (smells), regulation of sleep, learning, and any
complex processing. The midbrain, located centrally in the brain,
coordinates routing of sensory input. The hindbrain, part of which
forms the cerebellum, controls involuntary activities, such as
blood circulation, and coordinates motor activities, such as
locomotion. - Campbell et. al., Biology, Tenth Ed. p. 1085
(2014)
3. Hypotheses O Null Hypothesis: The decerebrated frog will not
respond to the stimuli. O Alternative Hypothesis: The decerebrated
frog will respond to the stimuli.
4. Procedure 1. Make the frog sleep using Chloroform (CHCl3).
2. Open the frog of the mouth. 3. Cut the upper portion of the head
from just behind the eyes (between the eyes and tympanum). 4.
Expose the frog to the different stimuli.
5. Touch O With forceps, pinch the hind toe gently, then
firmly. O Response: The frog pulled back from the forceps
6. Electric Shock O Apply the electrodes from the secondary
coil of an induction coil (adjusted for a light shock) to the hind
foot and then close the switch key for an instant. O Response: The
frog jerked.
7. Heat O Bring a hot iron rod (such as a soldering iron) close
to some part of the trunk or a limb. O Reaction: After a while, the
frog tried to flip over.
8. Chemical O Moisten a small disc of filter paper in 10%
acetic acid and apply it to different parts of the body (abdomen,
back, arm, hind leg, toe). After each test, wash the skin well with
water. O Reaction: After a while, the frog tried to flip over.
9. Righting the Body O Turn the frog on its back and see
whether the animal can regain its normal position. O Reaction: The
frog tried to move back to its normal position.
10. Compensatory movement O Place the frog in a petri dish,
then rotate the dish, first clockwise, then counter clockwise; also
tilt the dish from side to side. O Reaction: The frog tried to
right itself.
11. Summary of Responses: Stimuli Response (+/-) Touch +
(delayed) Electric shock + Heat + (delayed) Chemical + (delayed)
Righting the body + Compensatory movement + Overall +
12. Conclusion & Discussion O The decerebrated frog reacted
to the different stimuli despite not having a forebrain. This is so
because the part of the brain that controls locomotion, the
cerebellum, remains intact.