Reflexes – Pathological, conditioned, conditioned reflex
Pathologic reflexes occur with nerve or brain damage. The best-known pathological reflex is the Babinski reflex, which leads to extension of the big toe and flexion of all other toes when the sole of the foot is stroked. It is one of the early childhood reflexes and can normally no longer be triggered after the 12th month of life.
Babinski reflex in severe brain damage
In the case of massive brain damage, such as can occur after a cerebral hemorrhage  or a stroke  , a positive Babinski reflex indicates severe damage to the cerebrum. The reflex response is always evaluated in a side comparison – i.e. on both arms or legs: A different reflex response, eg a one-sided weakening or reflex strengthening, indicates nerve damage.
muscle reflexes in old age
In addition, with advancing age, many reflexes often weaken, which then occur on both sides and are not limited to one organ or muscle.
An increase mainly in the muscle reflexes is often seen in paralyzed muscles after a stroke – the extreme form is the so-called clonus, a rhythmic inexhaustible twitching of a muscle on a single stimulus. Clonus occurs when there is damage to the nerves coming from the cerebrum that excite muscles.
What is a conditioned or conditioned reflex?
Reflex body reactions that are learned or acquired are differentiated from the innate reactions mentioned above. The best known in this context is certainly Pavlov’s dog experiment, with which it was possible to prove that dogs, after coupling food with the sound of a bell, also reacted to the sound of the bell alone by producing saliva.
In the case of an acquired reflex, an innate reflex ( salivation  when food is expected) is coupled with another stimulus (here bell tone) until conditioning is achieved so that the first stimulus (food) can be omitted. This process, which we are not consciously aware of, influences our behavioral development, the learning of content and also the adaptation to our environment.
Therapeutically, the coupling is used in the field of psychotherapy for desensitization, in which a repeated pairing of a fear  -triggering stimulus is produced with a pleasant situation: the connection of positive emotion with the negative stimulus leads to the latter gradually losing its effect.
