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Brain, continued

Brain, continued. Midbrain and hindbrain- relay centers for sensory and motor pathways Midbrain visual and auditory reflexes connects with cerebrum and cerebellum (motor reflexes) Dopaminergic neurons: some required for motor coordination Others part of mesolimbic system

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Brain, continued

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  1. Brain, continued

  2. Midbrain and hindbrain- relay centers for sensory and motor pathways Midbrain visual and auditory reflexes connects with cerebrum and cerebellum (motor reflexes) Dopaminergic neurons: some required for motor coordination Others part of mesolimbic system stimulated by drugs: heroin and morphine- production cocaine and amphetamines- prevent reuptake

  3. See Table 8.3 Stimulants opiates stimulate opioid receptors cocaine inhibits dopamine reuptake amphetamines stimulate dopamine release and so on

  4. Hindbrain Metencephalon pons (“bridge”)- cranial nerve tracts respiratory control cerebellum- motor coordination motor learning- ataxia caused by damage to this area trained voluntary activity

  5. Myencephalon Medulla oblongata- brain stem- everything must pass through it Many crossed tracts (pyramids) relay sensory information cardiovascular responses breathing RAS- nonspecific activation (wakefulness)

  6. Spinal cord tracts Ascending- send sensory information to brain Descending- motor pyramidal- from precentral gyrus (in cerebrum; motor cortex) (corticospinal tracts) directly into spinal cord other cells in cortex also contribute many fibers cross over fine motor activity

  7. Extrapyramidal Originate in midbrain and brain stem many synapses Reticulospinal tracts- many originate in RAS other tracts activated

  8. Cranial and spinal nerves 12 pairs of cranial nerves most are mixed nerves except for those that detect special senses (sensory only) 31 pairs of spinal nerves- mixed nerves but separate at ganglion dorsal root- sensory ventral root- motor Cell bodies of some autonomic neurons in ganglia outside of spinal cord

  9. Reflex arc- involuntary response to a stimulus May consist of a single synapse May not directly involve the brain at all Some are much more complicated

  10. Spinal reflexes Withdrawal Postural Emptying (urination, etc.) Can be overridden by higher brain centers Some local responses are not controlled by nerves or hormones (blood vessel dilation, inflammatory response, etc.)

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