Neural Circuits

Neural Circuits

  Neural Circuits have different and unique tasks that process different information and are organized and arranged in specific ways. In addition, they control our senses, moods, movement, etc. The connection format is what distinguishes the circuits. These connections are made of thick lumps of dendrites and axons and glia, which are known as neuropil.

    
    Although different, many have the same characteristics and similar ways processes are carried out. Preeminent is the direction and way that information travels in all circuits. The direction information flows is key to the distinction of the circuit.The 2 types of preeminent is afferent and efferent. Neurons that carry information from the Peripheral nervous system (PNS)(check my post about peripheral nervous system and central nervous system here for more information here) to the central nervous system are called afferent neurons, but those who carry information away from the CNS to the PNS branches, are classified as  efferent neurons. And there are 

    Interneurons (local circuit neurons) which only participate in short-distance routes which their axons extend.

    An example of a neural circuit is the myotatic spinal reflex, also known as knee-jerk reflex. Afferent and efferent play the role of the reflex. When you get your reflexes tested, you get a hammer tap test. This is what, if you have normal reflexes, triggers the knee-jerk reflex.

    So, here is how it works. The process begins after the hammer has tapped your knee. This stretches your tendon which then stretches the sensory receptors in your extensor muscles (the sensory receptor is the pink little dot on the extensor muscles in this diagram). You can see a blue line, a sensory axon, which is afferent. This axon carries the message of the hammer tap to the purple interneuron and the red motor axon. Now, the interneuron stops the yellow flexor muscle motor axon from moving the flexor muscle. Instead, the flexor muscle relaxes.

    Now, the red extensor muscles axon carries the message to the extensor muscles, which then contracts the muscle. Finally, the leg extends.
Credits: Neuroscience 4th edition