The Nervous system
I: Central Nervous System
     a) Brain
     b) Spinal Cord
II. Peripheral Nervous System
     a) Somatic (skeletal) nervous system:
     Voluntary behaviors
     b) Autonomic: Self-regulation of internal
     organs and glands.
         1. sympathetic NS: arousing
          Pupils dilate, HR, BP, respiration increase,
          and digestive processes slow down.
          Fight or flight response.
         2. parasympathetic NS: calming-opposite
         of sympathetic nervous system response.

                 Three types of Neurons
1. Sensory (afferent) neurons of the peripheral NS take incoming sensory information to the spinal cord and brain.
2. Motor (efferent) neurons take information from the spinal cord out to muscles and glands.
3. Interneurons are neurons in the central NS (brain & spinal cord). They communicate with each other and connect the sensory and motor neurons.

                       The Simple Reflex
A simple reflex involves afferent (sensory) neurons carrying sensory information to the spinal cord.  Interneurons connect the afferent neurons to the efferent (motor) neurons.  A reflex does not involve the brain.

                                   The Brain
Studying the Brain
Phineas Gage
Lesions: Destruction of brain tissue

 Studying the Brain (cont.)
EEG (electroencephalogram): amplified recordings of brain wave activity.
CT (computerized tomography) scan: X-ray photos of slices of the brain.  CT (or CAT) scans show structures within the brain but not functions of the brain.
PET (positron emission tomography): visual display of brain activity that detects where a radioactive form of glucose is being used while the brain performs certain tasks.
MRI (magnetic resonance imaging): technique that uses magnetic fields and radio waves to see structures within the brain.
fMRI (functional MRI): allows us to see where oxygen is being used in the brain while various tasks are being performed.

                 Structure and Function of the Brain
Brainstem: Oldest area of the brain. Also called the reptilian brain.
1. Medulla: the base of the brainstem; controls heartbeat and breathing.
2. Reticular Formation: A neural network within the brainstem; important in arousal including sleep.
Thalamus: Sits on top of the brainstem; received all incoming sensory information (except smell) and sends it to the appropriate part of the brain for further processing.
Cerebellum: The "little brain" attached to the back of the brainstem; it helps coordinate voluntary movement and balance.
The Limbic System: A doughnut-shaped structure between the brainstem and the cerebral hemispheres.  It is considered the "seat of emotion" and is also involved in motivated behavior like eating, drinking, and sex.

        
1. Amygdala: Involved in rage and fear as well as emotional memories.
2. Hippocampus: Involved in memory
3: Hypothalamus: Involved in eating, drinking, and sexual behavior.  It also controls the endocrine (hormonal system) via the pituitary gland.  It is sometimes referred to as "the pleasure center" of the brain.

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