Spinal animal and Thalamic animal
Spinal animal
Spinal animal is prepared either transecting at the spinomedullary junction or by ligating both carotid arteries and the mid-vertebral artery to arrest the brain activities.
Frog’s head behind the tympanic membrane is transected to separate spinal cord from the brain. Transection is to be done below the foramen magnum. In these preparation when frog is palced on its back there is no spontaneous movement due to complete paralysis of the movement.
When a portion of a skin is pricked with the needle no withdrawal reflex is noticed. This is known as “Spinal shock depression of the spinal function and is reversible.
Spinal shock is removed in few minutes in a frog and few hours in a dog. Regaining from the spinal shock certain reflex activity are seen.
When one of the limb is pulled down it is quickly drawn up. Withdrawal of the limb is noticed on pinching. (flexor reflex)
If one of the limb is stimulated with the greater force all the limbs are flexed. However, respiratory movement voluntary movement righting reflexes are absent (they can’t swim when they place in the water). Except basic stretch reflex and supporting reactions all the other reflexes are absent.
Thalamic animal
Cerebral cortex, white matter some portion of the basal ganglia are removed. Thalamus and hypothalamus with the caudal portion of the basal ganglia remain intact.
These animals show righting reflexes and temperature regulation. Reflexes associated with emotional states fight and anger are present .
Tonic labyrinth and tonic neck reflexes and other righting reflexes are present. Propriokinesthetic, righting reflexes placing reactions and hopping reflexes are absent.