CH12 - Central Nervous System

List the four regions of an Adult Brain

1. Cerebral hemispheres (Cerebrum)

2. Diencephalon

3. Brain stem

   • Midbrain

   • Pons

   • Medulla

4. Cerebellum

Gray Matter vs White matter

• Gray matter

  • Short, non-myelinated neurons and cell bodies

• White matter

  • Myelinated and non-myelinated axons

Describe the basic pattern found in CNS in regards to brain regions and organization

• CNS (Brain & Spinal cord)

  • Central cavity surrounded by gray matter, white white matter external to gray matter

• Spinal cord

  • Exhibits this basic pattern → however pattern changes with ascent to brainstem

T/F: Most neuron cell bodies are located in PNS

→ False

• Most neuron cell bodies are located in CNS

  • Nuclei: clusters of neuron cell bodies in CNS

  • Ganglia: clusters of neuron cell bodies in PNS

Structural and Function of Ventricles

• STRUCTURE

  • Fluid-filled chambers that are continuous to one another and to central canal of spinal cord

    • Filled with cerebrospinal fluid (CSF)

    • Lined by ependymal cells (neuroglial cells)

      • Line the central cavities of the brain and spinal column

      • Produce cerebrospinal fluid (CSF)

  • Paired lateral ventricles (first and second) are large, C-shaped chambers located deep in each hemisphere

    • Pair is separated by membranous septum pellucidum

  • Third ventricle is in diencephalon

  • Fourth ventricle is between brain stem and connects with central canal of spinal cord

• FUNCTION

  • Produce and secrete cerebrospinal fluid to protect and maintain your central nervous system

  • CSF is constantly bathing the brain and spinal column, clearing out toxins and waste products released by nerve cells

• EXAMPLE

  • The waste product - Amyloid A-b peptide → increases the risk of Alzheimer’s disease if too much accumulates in the brain

Structural and Function of Cerebral Hemispheres (Cerebrum)

Regions of an Adult Brain (1/4)

• STRUCTURE

  • Left and right hemisphere

    • Accounts for 83% of brain mass

  • Separated by a groove, the longitudinal fissure

  • Each of these hemispheres has an outer layer of grey matter, the cerebral cortex

    • The cerebral cortex is supported by inner layer of white natter

  • The hemispheres are linked by the corpus callosum, a very large bundles of nerve fibers

• FUNCTION

  • Form superior part of brain

List the major lobes of the Cerebral Hemispheres (Cerebrum)

1. Frontal lobe

2. Parietal lobe

3. Temporal lobe

4. Occipital lobe

5. Insular lobe

   • Buried under portion of temporal, parietal and frontal lobes

Functions of Frontal Lobe

1. Executive functions

   • Planning, organizing, problem-solving, decision-making, attention, and self-control

2. Motor control

   • Initiating and coordinating voluntary movements

3. Langauge

   • Producing and understanding speech

4. Emotional regulation

   • Controlling emotions, such as anger, fear, and sadness

5. Personality

   • Expressing personality traits and social behavior

6. Working memory

   • Holding and manipulating information in the short term

7. Creativity and innovation

   • Generating new ideas and solutions

Functions of Parietal Lobe

1. Somatosensory perception

   • Processing sensations such as touch, pain, temperature, and proprioception (body awareness)

2. Spatial orientation

   • Understanding and interpreting the position and movement of objects in space

3. Attention and focus

   • Directing attention to specific stimuli and maintaining focus

4. Movement planning

   • Initiating and coordination voluntary movements

5. Language processing

   • Contributing to the understanding and production of language

6. Number and calculation

   • Processing numerical information and performing calculations

Functions of Temporal Lobe

1. Auditory Processing

   • The primary auditory cortex, which receives and processes auditory information

2. Language

   • Understanding and producing spoken language

3. Memory

   • Hippocampus, plays a vital role in forming and storing memories

4. Emotion

   • The amygdala processes and regulates emotions, including fear, pleasure, and anger

5. Visual Processing

   • Contributes to visual processing by aiding in object recognition, face recognition, and the integration of visual information with other sensory inputs

Functions of Occipital Lobe

1. Receiving visual information

   • Receives visual information from the retina via the thalamus

2. Mapping visual input

   • It helps with spatial reasoning and visual memory

3. Color determination

   • Helps determine the color of the items you see

4. Depth perception

   • It is involved in assessing distance, size, and depth

5. Object and face recognition

   • It plays a crucial role in identifying familiar faces and objects

6. Motion detection

   • The occipital lobe is also involved in processing motion

Functions of Insular Lobe

1. Interception

   • Integrates information about the internal state of the body, including pain, temperature, and visceral sensations

2. Taste

   • It’s involved in the perception and processing of taste sensations

3. Emotional Awareness

   • Experience and recognition of emotions, including happiness, sadness, fear, disgust, and empathy

4. Social Cognition

   • The insula contributes to social decision-making, trust, and other aspects of social behavior

5. Self-Awareness

   • The insula plays a role in our sense of our own body in space and our relationship to it, and awareness of self

6. Addiction

   • Implicated in the processes of addiction, including and reward-seeking behavior

Clinical - Explain Dementia

• Refers to a decline in cognitive function, including memory, thinking, and reasoning, to the point where it interferes with a person’s ability to perform daily activities

  • Dementia is not one specific disease, but rather a group of symptoms cause by various brain diseases

• While many diseases can cause dementia, Alzheimer’s disease is the most common

• Other causes include vascular dementia, Lewly body dementia, frontotemporal dementia, and Parkinson’s disease dementia

List and describe the Surface Markings on the Cerebral Hemispheres (Cerebrum)

1. Gyri

   • Ridges

2. Sulci

   • Shallow grooves

3. Fissures

   • Deep grooves

List the major Fissures of the Cerebral Hemispheres (Cereburm)

Fissure → deep grooves

1. Longitudinal fissure

   • Separates two hemispheres

2. Transverse cerebral fissure

   • Separates cerebrum and cerebellum

List the major Sucli that divide lobes

1. Central sulcus

   • Separates pre-central gyrus of frontal lobe and post-central gyrus of parietal lobe

2. Parieto-occipital sulcus

   • Separates occipital and parietal lobes

3. Lateral sulcus

   • Outlines temporal lobes

List the three basic regions of the Cerebral Hemisphere (Cerebrum)

1. Cerebral cortex of gray matter superficially

2. White matter internally

3. Basal nuclei deep within white matter

Structural and Function of Cerebral Cortex 

BASIC REGIONS of the Cerebral Hemisphere (Cerebrum) (1/3)

• STRUCTURE

  • Thin (2-4 mm) superficial layer of gray matter

  • Composed of neuron cell bodies, dendrites, glial cells, and blood vessels

  • 40% of mass of brain

• FUNCTION

  • Site of conscious mind

    1. Awareness

    2. Sensory perception

    3. Voluntary motor initiation

    4. Communication

    5. Memory storage

    6. Understanding

List the functional areas of the cerebral cortex 

BASIC REGIONS of the Cerebral Hemisphere (Cerebrum) (1/3)

No functional area of the cortex acts alone, and conscious bheavior involves the entire cortex in one way or another

1. Motor areas

   • Control voluntary movement

2. Sensory areas

   • Conscious awareness of sensation

3. Association areas

   • Integrate diverse information

     1. Visual areas

     2. Auditory areas

Responsible for complex processing that goes on between the arrival of sensory input cortices and the generation of behavior

T/F: All neurons in the cortex are interneurons

→ True

Explain Cerebral Cortex Domains

• Specific motor and sensory functions located in discrete cortical areas

• Higher functions are spread over many areas

• Shown on Functional imaging (PET and MRI)

Explain Contralateral vs Lateralization of cortical function 

1. EACH hemisphere is concerned with contralateral (opposite) side of body

2. Lateralization (specialization) of cortical function can occur in only ONE hemisphere

3. Conscious behavior involves entire cortex

Describe the location, function, structure of Motor Areas in Cerebral Cortex

Functional areas of the cerebral cortex (1/3)

• LOCATION

  • In frontal lobe

• FUNCTION

  • Motor areas act to control voluntary movement

• STUCTURE

  1. Primary motor cortex

  2. Premotor cortex

  3. Broca’s area

  4. Frontal eye field

List the components of Motor Area

Functional areas of the cerebral cortex (1/3)

Motor areas in Cerebral Cortex

1. Primary (somatic)Motor Cortex

   • LOCATION

     • In pre central gyrus of each frontal lobe

   • FUNCTION

     • Initiating voluntary movements

     • Somatotopy → All muscles of body can be mapped to area on primary motor crotex

     • Motor homunculi → Upside-down caricatures represent contralateral motor innervation of body regions

2. Premotor cortex

   • LOCATION

     • Anterior to the pre-central gyrus of each frontal lobe

   • FUNCTION

     • Helps to plan and coordinate complex movements

3. Broca’s area

   • LOCATION

     • Anterior to inferior premotor area

     • Present in one hemisphere (usually left)

   • FUNCTION

     • Motor speech area that directs muscles of speech production

     • Active in planning speech and voluntary motor activities

Clinical - Examples to damages to area Primary Motor Cortex

• Damage to areas of primary motor cortex, as seen in a stroke, paralyzes muscles controlled by those areas

• Paralysis occurs on opposite side of body from damage

• Only voluntary control is lost, however, as the muscles can still contract reflexively

Clinical - Examples to damages to area Premotor Area

• Muscle strength or ability to PERFORM discrete individual movements is not impaired; ONLY CONTROL over movements is lost

• EX: Damage to premotor area controlling movement of fingers would still alllow fingers to move, but voluntary control needed to type would be lost

  • Other premotor neurons can be reprogrammed to rake over skill of damaged neurons

  • Would require practice, just as the initial learning process did

Describe the location, function, structure of Sensory areas in Cerebral Cortex

Functional areas of the cerebral cortex (2/3)

• LOCATION

  • Occur in parietal, insular, temporal, and occipital lones

• FUNCTION

  • Areas of cortex concerned with conscious awareness of sensation

• STUCTURE

  • Primary somatosensory cortex

Location and function of Primary somatosensory cortex

Functional areas of the cerebral cortex (2/3)

Sensory areas in Cerebral Cortex

• LOCATION

  • In postcentral gyri of parietal lobe

• FUNCTION

  • Receives sensory information from skin and proprioceptors of skeletal muscle, joints, and tendons

  • Capable of spatial discrimination → identification of body region being stimulated

  • Somatosensory homunculus → upside-down caricatures represent contralateral sensory input from body regions

Describe the location, function, structure of Assoication areas in Cerebral Cortex

Functional areas of the cerebral cortex (3/3)

Visual association areas in Cerebral Cortex

• LOCATION

  • Surronds primary visual cortex

• FUNCTION

  • Uses past-visual experiences to interpret visual stimuli (color, form, or movement)

    • EX ability to recognize faces

  • Complex processing involves entire posterior half of cerebral hemispheres

• STRUCTURE

  • Primary visual (striate)

    • Cortex located on extreme posterior tip of occipital lobe

Auditory association areas in Cerebral Cortex

• LOCATION

  • Located posterior to primary auditory cortex

• FUNCTION

  • Stores memories of sounds and permits perception of sound stimulus

• STRUCTURE

  • Primary auditory cortex

    • Superior margin of temporal lobes

    • Interprets information from inner ear as pitch, loudness, and location

Clinical - Damage to the Primary Visual Cortex

• Primary visual cortex → results in blindness

• Visual association area → can see, but they do not comprehend what they are looking at

Describe the general structure function of the Cerebral White Matter

BASIC REGIONS of the Cerebral Hemisphere (Cerebrum) (2/3)

• STURCURE

  • Second of three basic regions of cerebral hemispheres

  • Consists of myelinated fibers bundled into large tracts

• FUNCTION

  • Responsible for communication between cerebral areas and between cortex and lower CNS

  • Classified according to direction they run”

    1. Association

    2. Commissural

    3. Projection fibers

Describe the general structure function of the basal nuclei (basal ganglia) 

BASIC REGIONS of the Cerebral Hemisphere (Cerebrum) (3/3)

• STRUCTURE

  • Third of the three basic regions of cerebrum

• FUNCTION

  • Influence muscle movements

  • Play role in cognition and emotion

  • Filter out incorrect/inappropriate responses

Clinical - Disorders of the basal nuclei

1. Parkinson’s disease

   • Brain disorder that causes unintended or uncontrollable movements, such as shaking, stiffness, and difficulty with balance and coordination

2. Huntington’s disease

   • An inherited disorder that causes nerve cells (neurons) in parts of the brain to gradually break down and die