Classifying Neurons Neurotransmitter Type Cholinergic Acetylcholine Adrenergic

Classifying neurons neurotransmitter type cholinergic

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Classifying Neurons: Neurotransmitter Type Cholinergic Acetylcholine Adrenergic Adrenaline GABAergic Gamma-aminobutyric acid Glutamatergic Glutamate Dopaminergic Dopamine Serotonergic Serotonin BIO616 Neurons and Glia 59
Classifying Neurons: Effect Excitatory Inhibitory BIO616 Neurons and Glia 60
Neural Circuits Flow of information in NS Dictated by neuronal circuits Certain patterns of circuits are commonly used Variations allow a wide variety of control mechanisms Circuits are partially stimulated and inhibited at the same time Stimulation must reach the threshold level to fire neurons in a given circuit BIO616 Neurons and Glia 61
NEURON RESTRICTED NEURAL CIRCUIT (NEURAL ASSEMBLY) STRUCTURES NEURAL NETWORK (CIRCUIT) BEHAVIOR Neural Circuits BIO616 Neurons and Glia 62 Nervous system structure (bottom up approach) ... SYNAPSE
Simple circuit Synapse between sensory neurons & motor neurons, resulting in a simple reflex Complex circuit Such as those associated with most behaviors, involve integration by interneurons in the CNS Convergent circuits Divergent circuits Reverberating (oscillating) circuits (memory storage) Parallel after-discharge circuits BIO616 Neurons and Glia 63 Types of Neural Circuits
Types of Neural Circuits: Simple Reflex arc Reflexes are rapid automatic responses to stimuli Neural reflex involves sensory fibers to CNS and motor fibers to effectors BIO616 Neurons and Glia 64
Types of Neural Circuits Diverging circuit The signal diverge from one → many Amplifying type the imput signal is spread > 1 neuron per synapse E.g. a single pyramidal cell in the motor cortex is able to excite up to 10,000 muscle fibres (corticospinal tract) Divergence into multiple tracts the signal is deviated in at least 2 separate directions E.g. signals from dorsal columns follow two courses in the brain: into the cerebellum, and into the thalamus and eventually cerebral cortex (spinothalamic tract with branching afferents to inferior peduncles of cerebellum) BIO616 Neurons and Glia 65
Types of Neural Circuits Converging circuit Multiple inputs converge to a single neuron (many → one) From a single source multiple synaptic terminals from the presynaptic neuron communicate with a single postsynaptic neuron anatomical basis of spatial summation of multiple EPSPs, to finally excite the postsynatpic neuron BIO616 Neurons and Glia 66
Types of Neural Circuits Both reverberating and parallel-after- discharge neurons are prolonged (continuous) discharge from an efferent neuron even after stoppage of stimulation of the afferent nerves Reverberating (oscillating) circuit Stimulation of one synaptic neuron results in several postsynaptic impulses Allows extended coordinated muscle movements - breathing BIO616 Neurons and Glia 67
Types of Neural Circuits Reverberating (oscillating) circuit Examples Reticular activating system (RAS) Wakefulness depends upon the activity of RAS ( contains many reverberating circuits)

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