Biology of Behavior Part 1

Overview of Nervous System

  • The nervous system serves as the communication system within the body.

  • It is organized and operates quickly.

  • Two main divisions:

    • Central Nervous System (CNS): Comprises the brain and spinal cord.

    • Peripheral Nervous System (PNS): Connects the rest of the body’s nerves to the brain.

Divisions of the Nervous System

Peripheral Nervous System (PNS)

  • PNS has further divisions:

    • Somatic Nervous System:

      • Controls voluntary muscle movements connected to the skeletal system.

      • Example: Raising hand in class involves somatic muscles.

    • Autonomic Nervous System (ANS):

      • Involuntary system managing internal organs and glands.

      • Functions independently of conscious thought.

Autonomic Nervous System

  • Breaks down into:

    • Sympathetic Nervous System:

      • Engaged in emergencies (fight-or-flight response).

      • Prepares the body for action, increases energy use.

    • Parasympathetic Nervous System:

      • Responsible for rest and energy conservation.

      • Calms the body after stress and maintains homeostasis.

    • Sympathetic and parasympathetic systems work together to balance body functions.

Major Brain Structures

Brain Stem & Hindbrain

  • Medulla:

    • Controls heartbeat and breathing; essential for life.

  • Reticular Formation:

    • Regulates arousal and consciousness; keeps one awake and helps in sleep cycles.

  • Cerebellum:

    • Coordinates movement and balance; also involved in muscle memory (e.g., riding a bicycle).

Thalamus

  • Acts as the brain's relay station for sensory information.

  • Routes incoming sensory messages (e.g., visual information) to the appropriate processing areas (e.g., visual cortex).

Limbic System (Midbrain)

  • Involved in emotion and motivation; includes multiple structures:

    • Amygdala:

      • Significant in processing negative emotions (fear, anxiety).

    • Hypothalamus:

      • Regulates internal balance (homeostasis) including hormone release, body temperature, hunger, and thirst.

    • Hippocampus:

      • Engaged in processing memory, particularly in converting short-term memories into long-term ones.

Cerebral Cortex

  • The outer covering of the brain reminiscent of tree bark (cortex).

  • Contains convolutions allowing for greater surface area.

  • Divided into four lobes:

    • Frontal Lobe:

      • Involved in planning, judgment, speech, and personality.

    • Temporal Lobe:

      • Associated with auditory processing.

    • Parietal Lobe:

      • Houses sensory cortex and association areas at the top back of the brain.

    • Occipital Lobe:

      • Responsible for visual processing at the back of the brain.

  • Motor Cortex and Sensory Cortex:

    • Motor cortex governs movement, while sensory cortex is dedicated to touch sensation; both contain maps of the body’s sensory areas.

Hemispheres of the Brain

  • The brain is split into two hemispheres (left and right).

  • Connected by corpus callosum for inter-hemispheric communication.