M9

• Neurotransmitter


  Causes excitatory effects to neurons
• Clinical examples of neurotransmitters causing excitatory effects

  • Cocaine
  • Amphetamines
• Nerve


  Innervates the diaphragm
• How many spinal nerves are innervated in the spinal cord?

  
• Diencephalon


  Part responsible for homeostasis & sexual emotions
• Lobe of the brain


  Evaluates sensory input such as touch & pain

  
• Ascending Tracts


  Pathways that transmit information via action potentials from the periphery to various parts of brain

  
• Types of Ascending Tracts

  • Spinothalamic
  • Dorsal Column
  • Spinocerebellar
• Spinothalamic Tract


  Carries pain, temperature, light touch, pressure, tickle, itch sensation
• Dorsal Column Tract


  Carries proprioception, touch, deep pressure, vibration
• Spinocerebellar Tract


  Carries proprioception to the cerebellum
• Primary Sensory Areas


  Where ascending tracts project & sensations are perceived
• Association Areas


  Cortical areas adjacent to primary sensory area; involved in the process of recognition
• Primary Somatic Sensory Cortex / General Sensory Area


  Located in parietal lobe posterior to central sulcus; receives information directly from sensory fibers or from thalamic neurons

  
• Somatic Motor Functions


  Include involuntary (no conscious thought) and voluntary movements (consciously activated)
• Motor Neurons involved in Voluntary Movements

  • Upper Motor Neurons
  • Lower Motor Neurons
• Upper Motor Neurons


  Have cell bodies in cerebral cortex; their axons form descending tracts that connect to lower motor neurons

  
• Lower Motor Neurons


  Have cell bodies in anterior horn of spinal cord; their axons leave the CNS & extend through spinal or cranial nerves to skeletal muscles
• Primary Motor Cortex


  Located in posterior portion of frontal lobe, anterior to central sulcus; control voluntary motor movements

  
• Premotor Area


  Located at frontal lobe where motor functions are organized before initiation
• Prefrontal Area


  Region of association cortex which involves in motivation & regulation of emotional behavior and mood; accounts for foresight to plan and initiate movement

  
• Descending Tracts

  • Direct Pathway
  • Indirect Pathway
• Direct Pathway


  Extends directly from upper motor neurons in cerebral cortex to lower motor neurons in spinal cord and brainstem

  
• Lateral Corticospinal Tract


  Controls muscle tone & skilled movements (especially of hands)
• Anterior Corticospinal Tract


  Controls muscle tone & movement of trunk muscles
• Indirect Pathway


  No direct connection exists between the cortical & spinal neurons; from basal nuclei, cerebellum, or cerebral cortex through the brainstem to lower motor neurons in spinal cord
• Rubrospinal Tract


  Controls movement coordination
• Reticulospinal Tract


  Controls posture adjustment, especially during movement
• Vestibulospinal Tract


  Controls posture and balance
• Tectospinal Tract


  Controls movement in response to visual reflexes
• Basal Nuclei


  Group of functionally related nuclei; vital in planning, organizing, & coordinating motor movements & posture
• Feedback Loops / Circuits from Neural Circuits of Basal Nuclei

  1. Action potential from motor cortex travels to lower motor neurons in spinal cord

  2. Inform the cerebellum of the intended movement

  3. Lower motor neurons send action potential to skeletal muscle and contract

  4. Proprioceptive signals sent to cerebellum during contraction

  5. Cerebellum compares information from motor cortex with proprioceptive input

  6. Sends action potentials to motor cortex & spinal cord to correct the discrepancy once detected

  7. Smooth and coordinated movements

  
• Commissures


  Connections between two hemispheres intended to share the received sensory information
• Corpus Callosum


  The largest of commissures; a broad band of nerve tracts at the base of longitudinal fissure
• Right Cerebral Hemisphere


  Receives sensory input from and controls muscular activity in the left half of the body

  
• Left Cerebral Hemisphere


  Receives input from and controls muscular activity in the right half of the body
• Sensory Speech / Wernicke Area


  In parietal lobe; functions in understanding & formulating coherent speech

  
• Motor Speech / Broca Area

  In frontal lobe; controls movement necessary for speech

  
• To repeat a word you hear

  1. Action potentials from ear is perceived to primary auditory cortex

  2. Word recognition in auditory association area & comprehended in portions of Wernicke area

  3. Conduct action potentials through nerve tracts in speech areas

  4. Broca area determines the muscle activity needed to repeat the word

  5. Send to premotor area for programming the movement

  6. Action potentials conduct to primary motor cortex where specific movements are triggered

  
• To speak a written word

  1. Word from eyes enters visual cortex

  2. Visual association area for recognition

  3. Continues to Wernicke area where it is understood & formulated as it is to be spoken

  4. Conduct action potentials through nerve tracts in speech areas

  5. Broca area determines the muscle activity needed to repeat the word

  6. Send to premotor area for programming the movement

  7. Action potentials conduct to primary motor cortex where specific movements are triggered