Sensory and Motor Systems

Sensory Cortex & Brain Areas

  • Different brain areas have specific functions (e.g., Broca's area).

  • Larger groupings of brain areas play roles in brain function.

Limbic System: The Emotional Brain

  • The limbic system processes emotions.

  • It is not a single structure but a network of brain parts.

Components of the Limbic System

  • Cingulate Gyrus: Located near the corpus callosum (part of the cerebrum).

  • Parahippocampal Gyrus: Associated with the hippocampus.

Significance of Emotions

  • Emotions are crucial for survival.

    • Example: Fear helps avoid dangerous situations.

  • Emotions enrich experiences.

  • Animals also experience emotions to some extent.

Hippocampus and Memory

  • The hippocampus is involved in both memory and emotion.

  • Long-term memories often have emotional associations.

  • Emotions can trigger memories, and memories can trigger emotions due to the relationship between these brain areas.

Smell and Emotion

  • The area processing smell is closely linked to the emotional center.

  • Smells can elicit emotions.

    • Example: Smelling brownies evokes fond memories of one's grandmother.

Amygdala (Amygdaloid Body)

  • The amygdala is involved in emotion and emotional memory, especially fear.

  • Olfactory bulbs (smell processing) are part of the limbic system, which is why odors can trigger emotions.

Reticular Formation and Reticular Activating System (RAS)

  • The reticular formation is gray matter inside the brainstem.

  • It has both motor and sensory components.

    • Motor component: Helps control movement.

    • Sensory component (RAS): Processes sensory information and sends signals to the cerebral cortex to promote alertness.

  • The RAS helps arouse you from sleep through sensory input (e.g., alarm sound).

Motor Component of Reticular Formation

  • Assists in autonomic functions (functions beyond conscious control).

    • Example: Breathing is usually controlled automatically.

Reticular Formation Components

  • Motor and Sensory components.

Higher Mental Functions

  • Human brains enable higher mental functions that set us apart from other organisms.

Examples of Human Cognitive Abilities

  • Abstract thought, learning, memory.

  • Art, music, and complex problem-solving.

Cognition and the Frontal Lobe

  • Cognition includes thinking, awareness, knowledge, learning, memory, perception, and judgment.

  • Association areas of the cerebrum are responsible for personality, motor control, memory, and response to stimuli.

  • The frontal lobe is important for personality.

    • Example: Phineas Gage's personality change due to frontal lobe damage.

Cognition and the Cerebrum

  • Cognition primarily occurs in the cerebrum, the largest part of the brain.

Brain Development and Complexity

  • Brain size and complexity increase with development.

  • More complex brains lead to greater mental capacity.

  • Brain growth is rapid in early childhood (95% complete by age five).

  • Processing becomes more complex and refined beyond early childhood.

  • New neural connections are made, and some are pruned.

  • Proper nutrition is important for brain development in children.

CNS Neuron Regeneration

  • Some CNS neurons can regenerate after damage.

Memory Formation

Stages of Memory

  • Sensory Memory: Initial memory lasting milliseconds to one second.

  • Short-Term Memory: Memory lasting a minute or less if attention is paid.

  • Long-Term Memory: Memory formed through encoding by repeatedly thinking about something.

Maintaining Long-Term Memories

  • Long-term memories require periodic recall to reinforce them.

Example of Long-Term Memory

  • Remembering a childhood phone number.

Electroencephalogram (EEG)

  • EEG measures electrical activity in the brain using electrodes.

  • Brain waves with different patterns are observed.

  • Changes in patterns indicate sleep depth and other brain states.

Brain Activity During Sleep

  • Brain activity decreases during sleep, but the brain doesn't stop working.

  • The brainstem remains active for essential functions (breathing, blood pressure regulation).

Stages of Sleep

  • Non-REM sleep and REM sleep.

  • Most memorable dreams occur during REM sleep.

Cranial Nerves

  • Information processed by the brain moves to/from the spinal cord.

  • Spinal nerves transmit signals to the body.

  • Cranial nerves originate from the brain and send information to structures within the head.

  • There are 12 cranial nerves, numbered anterior to posterior.

  • Cranial nerve function will be tested in the lab.

Olfactory Nerve

  • Cranial nerve number one.

Facial Nerve Damage

  • Damage can lead to dry eyes due to decreased tear production from the lacrimal gland.

Abducens Nerve

  • Cranial nerve six.

  • Purely a motor nerve.

  • Controls the lateral rectus muscle, which abducts the eye (turns it outward).

Oculomotor Nerve

  • Controls most extrinsic eye muscles.

  • Cranial nerve number three.

  • Controls muscles that lift the eyelid, change pupil diameter, and change lens shape for focusing.

Vagus Nerve

  • Cranial nerve number 10.

  • A mixed nerve controlling muscles in the throat and voice box.

  • Carries sensation from abdominal organs to the brain.

  • Major controller for the parasympathetic nervous system.

Olfactory Nerve Location

  • Branches of the olfactory nerve pass through the cribriform plate of the ethmoid bone in the roof of the nasal cavity.

Facial Nerve Damage Conditions

  • Bell's Palsy can be caused, look in content PowerPoint for demonstration.

Vestibulocochlear Nerve

  • The nerve is cranial nerve eight and the cell bodies for this nerve are located within the vestibular ganglia.

Spinal Cord and Spinal Nerves

  • The spinal cord and spinal nerves link the brain to the rest of the body.

  • The brain stem is continuous with the spinal cord.

  • Spinal nerves extend from the spinal cord.

  • Main passageway for communication between the brain and the rest of the body.

Spinal Cord Regions

  • Same as the vertebral column: cervical, thoracic, lumbar, sacral, coccygeal.

Spinal Cord Length

  • Shorter than the vertebral column.

  • Lumbar part of the spinal cord is closer to the thoracic part of the vertebral column.

  • Spinal nerves extend down through the rest of the vertebral column.

Spinal Nerves and Vertebrae

  • There are eight cervical spinal nerves but only seven cervical vertebrae.

  • Spinal nerves are named based on the region of the spinal cord from which they originate (e.g., thoracic one, thoracic two).

Spinal Cord Dimensions

  • Typical adult spinal cord is 16-18 inches long (about a foot and a half).

  • About three-fourths of an inch in diameter.

Spinal Nerves

  • Have both sensory and motor neurons.

  • Carry information to and from the brain.

Spinal Nerve Structure

  • Rootlets come off the spinal cord directly.

  • Rootlets form the root of the spinal nerve.

  • The spinal nerve contains both motor and sensory neurons.

  • Posterior part of the spinal cord (posterior root): sensory neurons.

  • Anterior part of the spinal cord (anterior root): motor neurons.

Number of Spinal Nerves

  • 31 pairs.

The brain is protected by three layers of membranes known as the meninges, which include:

  1. Dura Mater

    • Outermost layer, tough and durable.

    • Provides a protective barrier against physical impacts.

  2. Arachnoid Mater

    • Middle layer, web-like structure.

    • Provides cushioning and contains cerebrospinal fluid (CSF).

  3. Pia Mater

    • Innermost layer, delicate and closely adheres to the surface of the brain.

    • Supplies blood to the brain and contains blood vessels.

Cerebrospinal Fluid (CSF)

  • Clear fluid that surrounds and cushions the brain and spinal cord.

  • Provides mechanical protection, chemical stability, and removes waste products.

  • Plays a critical role in maintaining intracranial pressure and supplying nutrients to the nervous system.

The brain is protected by three layers of membranes known as the meninges:

  1. Dura Mater

    • Outermost layer, tough and durable.

    • Provides a protective barrier against physical impacts.

  2. Arachnoid Mater

    • Middle layer, web-like structure.

    • Provides cushioning and contains cerebrospinal fluid (CSF).

  3. Pia Mater

    • Innermost layer, delicate and closely adheres to the surface of the brain.

    • Supplies blood to the brain and contains blood vessels.

The epidural space is located between the dura mater and the vertebrae. It houses adipose connective tissue, areolar connective tissue, and blood vessels. This space plays a crucial role in protecting the spinal cord and providing cushioning.

The epidural space is located between the dura mater and the vertebrae. It houses the following components:

  • Adipose Connective Tissue: Provides cushioning and insulation for the spinal cord, helping to absorb mechanical shocks.

  • Areolar Connective Tissue: Offers support and elasticity, allowing the spine to maintain flexibility while securing the spinal cord within the vertebral column.

  • Blood Vessels: Supply nutrients to the surrounding areas of the spinal nerves and spinal cord and assist in waste removal.
    This space plays a crucial role in protecting the spinal cord and providing a buffer against external forces, making it essential for maintaining the integrity and functionality of the central nervous system (CNS). Additionally, during medical procedures such as epidural injections, this space is accessed to deliver medication that can relieve pain or anesthesia.