Brain neurons have receptors for certain opiate drugs such as morphine and heroin. Two naturally occurring substances where discovered to use these receptors named Enkephalins and Endorphins. They have a potent analgesic effect 200% stronger than morphine. These are also called Opioid Peptides . It is thought that opioid peptides are the body’s natural painkillers. It is also thought that acupuncture increases the release is opioid peptides. Substance P , a neuropeptide, is released by neurons that transmit pain- related input from peripheral pain receptors into the CNS, enhancing the perception of pain. Enkephalin and endorphin suppress the release of substance P, thus decreasing the number of nerve impulses being relayed to the CNS for pain sensation. However, substance P has also been shown to counter the effects of certain nerve-damaging chemicals showing that it may be useful as a treatment for nerve degeneration.
Neural Circuits
The CNS contains billions of neurons organized into complicated networks called Neuronal Circuits. Neural circuits are functional groups of neurons that are responsible for processing specific types of information. Circuits are categorized according to how its neurons are organized. a) Simple Series Circuit : one presynaptic neuron stimulates only one postsynaptic cell. The second neuron then stimulates another, and again, etc. This is not common. b) Diverging Circuit: one presynaptic neuron stimulates several postsynaptic cells at the same time (postsynaptic neurons, muscles fibres, or glands). Sensory signals are arranged in diverging circuits allowing the impulse to be relayed to several areas of the brain. This amplifies the signal. c) Converging Circuit: one postsynaptic neuron receives input from several presynaptic cells providing for a more effective stimulation or inhibition of the postsynaptic neuron. d) Reverberating Circuit: Organized so that stimulation of the presynaptic cell causes the postsynaptic cell to transmit a series of nerve impulses. The incoming impulse stimulates the first neuron, which stimulates the second, which stimulates the third, and so on. Branches from later neurons synapse with earlier ones and the arrangement sends impulses back through the circuit again and again. Actions thought to be associated with this type of circuit are breathing, coordinated muscle activities, waking up, and short-term memory. e) Parallel after-discharge Circuit: one presynaptic cell stimulates a group of cells that all synapse with one postsynaptic cell. Thought to occur in precise activities such as math.
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