Early contributions to the reflex chain hypothesis

W T Clower1

  • 1Institute des Sciences Cognitive, Universite Claude Bernard, Lyon Cedex, France.

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Early Reflexes During Infancy

Early reflexes are automatic, involuntary responses to specific stimuli and provide information about neurological development during infancy. Some reflexes are present at birth or appear soon afterward. Known as primitive reflexes, they support early survival and adaptation.Primitive ReflexesPrimitive reflexes help newborns respond to their environment before voluntary motor control develops. The rooting reflex causes an infant to turn toward stimulation near the mouth, helping the infant...
Reflex Activity01:08

Reflex Activity

A reflex activity is an automatic, involuntary response to specific stimuli. It is a part of our survival mechanism, designed to protect us from potential harm. For example, when a bright light suddenly shines into our eyes, we instinctively close them or look away. This is a simple reflex activity orchestrated by the nervous system without conscious thought or effort.
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Somatic Spinal Reflexes

Somatic spinal reflexes are rapid, involuntary muscular responses to external stimuli that involve the somatic musculature and the spinal cord.
One of the most well-known somatic spinal reflexes is the stretch reflex, which is activated by the sudden stretching of a muscle. This reflex involves the activation of specialized sensory receptors called muscle spindles, which are located in the muscle tissue and detect changes in the length and speed of muscle contractions. When a muscle is suddenly...
Indirect Motor Pathways01:22

Indirect Motor Pathways

The indirect motor or extrapyramidal pathways originate in the brainstem, the lower portion of the brain that connects it to the spinal cord. They consist of several distinct tracts, each with specialized functions. The four main tracts of the indirect motor pathways are the vestibulospinal tract, the reticulospinal tract, the tectospinal tract, and the rubrospinal tract.
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Sensorimotor Stage I: Substages 1 to 3

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Action Potential

Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of neurotransmitters at axon terminals, thereby transmitting information to the nervous system. An action potential is a specific "all-or-none" change in membrane potential that results in a rapid spike in voltage.
Membrane potential in neurons
Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive...