BIO 210 Chapter 13 Supplement 3 The Central Nervous System PowerPoint by John McGill Supplemental Notes by Beth Wyatt

CEREBRUM Largest, Uppermost Division STRUCTURE CEREBRAL HEMISHPERES LOBES

CEREBRAL HEMISHPERES 2 Halves of the Cerebrum That are Joined

Sheep Brain: Cerebral Hemispheres

LOBES of the CEREBRUM LOBES Cerebrum is Divided into Lobes by Fissures Majority of Lobes Named After Bones FRONTAL LOBE PARIETAL LOBE TEMPORAL LOBE OCCIPITAL LOBE INSULA Lies Hidden in the Lateral Fissure

LOBES of the CEREBRUM: Insula Lies Hidden in the Lateral Fissure (a.k.a. lateral sulcus)

Insula Photos

Cerebral Fissures FISSURES (4 Major) LONGITUDINAL FISSURE (next slide) CENTRAL SULCUS (aka central fissure) LATERAL FISSURE PARIETALOCCIPITAL FISSURE

Cerebral Fissures: Longitudinal Deepest; Divides Cerebrum into 2 Hemispheres

Cerebral Fissures: Central Sulcus

Cerebral Fissures: Lateral Fissures

Cerebral Fissures: Parietaloccipital

CEREBRAL CORTEX CONVOLUTIONS (GYRI) are Folds SULCI are Grooves

Cerebrum vs. Cerebellum Cerebral Cortex has Convolutions and Sulci as Cerebellum, Both Larger in Cerebrum

Cerebral Tracts White Matter of the Cerebrum Lies Below the Cortex Cerebrum Has 3 Major Kinds of Tracts PROJECTION TRACTS ASSOCIATION TRACTS COMMISSURAL TRACTS

PROJECTION TRACTS are Extensions of Tracts of Spinal Cord & Brainstem, ascending & descending. Example of Ascending (Sensory) spinothalamic Example of Descending (Motor) corticospinal

Projection Tracts: Sensory/Ascending-spinothalamic

Projection Tracts: Motor/Descending-corticospinal

ASSOCIATION TRACTS Tracts That Extend From 1 Convolution to Another Convolution in the SAME Hemisphere Most Numerous

COMMISSURAL TRACTS Tracts That Extend From 1 Convolution to a Corresponding Convolution in the OPPOSITE Hemisphere Compose the Corpus Callosum

Additional Cerebral Structures CEREBRAL NUCLEI (BASAL GANGLIA) CORPUS CALLOSUM SEPTUM PELLUCIDUM

CEREBRAL NUCLEI (BASAL GANGLIA) Gray Matter Located Deep Within the Cerebrum’s White Matter

CEREBRAL NUCLEI (BASAL GANGLIA)

CORPUS CALLOSUM White Curved Structure That Joins the 2 Cerebral Hemispheres Composed of Commissural Tracts

SEPTUM PELLUCIDUM Membrane That Lies Below the Corpus Callosum Covers the Lateral Ventricles

FUNCTIONS OF THE CEREBRAL CORTEX Organized Into 3 Groups SENSORY, MOTOR, & INTEGRATIVE.

FUNCTIONS OF THE CEREBRAL CORTEX

SENSORY FUNCTIONS OF THE CEREBRAL CORTEX Cortex Involved in the Interpretation of Sensations

MAJOR SENSORY AREAS OF THE CEREBRAL CORTEX PRIMARY SOMATIC SENSORY AREA (POSTCENTRAL GYRUS): CONTAINS SOMATIC SENSORY MAP VISUAL CORTEX (OCCIPITAL LOBE) PRIMARY AUDITORY AREA (TRANSVERSE GYRUS) PRIMARY TASTE AREA

MAJOR SENSORY AREAS PRIMARY SOMATIC SENSORY AREA POSTCENTRAL GYRUS CONTAINS SOMATIC SENSORY MAP Major Area Involved in the Interpretation of General Sensations Located in the Postcentral Gyrus (Parietal Lobe) Contains a Somatic Sensory (General Sense) Map

VISUAL CORTEX (OCCIPITAL LOBE) Major Area Involved in the Interpretation of Vision Located in the Occipital Lobe

PRIMARY AUDITORY AREA (TRANSVERSE GYRUS) Major Area Involved in the Interpretation of Hearing Located in the Transverse Gyrus (Temporal Lobe)

PRIMARY TASTE AREA Major Area Involved in the Interpretation of Taste Located in the Postcentral Gyrus

ASSOCIATION AREAS Areas that Assist the Major Sensory Areas in the Interpretation of Sensations In Addition, Other Areas of the Brain are Also Involved in the Interpretation of Sensation (i.e., Mamillary Bodies, Corpora Quadrigemina, Thalamus)

MOTOR FUNCTIONS OF THE CEREBRAL CORTEX Cortex also Involved the Producing Normal Voluntary Movements of Skeletal Muscles

MOTOR FUNCTIONS OF THE CEREBRAL CORTEX Movements of Skeletal Muscles PRIMARY SOMATIC MOTOR AREA (PRECENTRAL GYRUS): CONTAINS SOMATIC MOTOR MAP Major Area Responsible for Producing Voluntary Movements (Nerve Impulses Begin Here) Located in the Precentral Gyrus (Frontal Lobe) Contains a Somatic Motor (Skeletal Muscle) Map

Sensory & Motor Maps

Motor Functions continued… PREMOTOR AREA Assists the Major Motor Area in Producing Voluntary Movements Located in the Frontal Lobe In Addition, Other Areas of the Brain are Also Involved in Producing Normal Voluntary Movements (i.e., Cerebellum, Cerebral Nuclei, Thalamus)

Integrative Functions 3 cerebral functions: Sensory Motor Integrative Integrative Functions Reticular Activating System-awareness Language-understanding & speech Limbic System-emotions Memory

INTEGRATIVE FUNCTIONS: Awareness CONSCIOUSNESS RETICULAR ACTIVATING SYSTEM Awareness of One's Self, the Environment, Others

INTEGRATIVE FUNCTIONS: Awareness Involves the Reticular Activating System (RAS) RAS = Neuron Pathways of the Reticular Formation, Brainstem, Hypothalamus, Thalamus, Areas of the Cerebral Cortex Mechanism: As NI are Continuously Conducted Over the RAS and Excite Key Areas of the Cerebral Cortex, Consciousness Results RAS Functions as the Arousal (Alerting) Mechanism

Integrative functions: LANGUAGE (SPEECH CENTERS) The 2 major Speech Centers Include: Wernicke's Area: Sensory Speech Area (Understanding Language) Broca's Area: Motor Speech Area (Use of Language) Speech Centers Are Usually Located in the Left Cerebral Hemisphere

Integrative functions: EMOTIONS (LIMBIC SYSTEM) Limbic System Structures Form a Curving Border Around the Corpus Callosum E.g. Cingulate gyrus & Hippocampus Involved in Both the Experience and the Expression of Emotions There Are Other Areas of the Cerebral Cortex Important in the Expression of Emotions

Integrative functions: Memory Considered a Major Function of the Cerebral Cortex Involves Many Areas of the Cerebral Cortex Also Appears to Involve the Limbic System

Memory Formation

Memory Involves Many Brain Areas Most activities involve multiple brain areas Consider hearing and then repeating words: impulses start in the ear and end in the precentral gyrus

GENERALIZATIONS ABOUT CEREBRAL FUNCTIONS LEFT AND RIGHT HEMISPHERES SPECIALIZE IN DIFFERENT FUNCTIONS Left: Language, Right: Nonlanguage (i.e., Images or Nonspeech Sounds) Both Hemispheres Work Together to Accomplish Functions

CEREBRAL ACTIVITY GOES ON AS LONG AS LIFE ITSELF (EEG) Cerebral Activity: Nerve Impulses (Measured as Brain Waves) Absence of Brain Waves = Death (Brain Death) Evidence Comes From EEG Electroencephalogram: Measures Brain Waves)

SENSORY PATHWAYS FOR THE CEREBRAL CORTEX TO PERFORM ITS SENSORY FUNCTIONS, IMPULSES MUST BE CONDUCTED TO ITS SENSORY AREAS ALONG SENSORY PATHWAYS Example: Spinothalamic Sensory Pathways: See Handout & Next Slide Sensory Pathways Are Crossed

SENSORY PATHWAYS

Motor Pathways FOR THE CEREBRAL CORTEX TO PERFORM ITS MOTOR FUNCTIONS, IMPULSES MUST BE CONDUCTED FROM ITS MOTOR AREAS TO SKELETAL MUSCLES ALONG SOMATIC MOTOR PATHWAYS Example: Corticospinal Somatic Motor Pathways: See Handout & Next Slide Most (Though Not All) Somatic Motor Pathways Are Crossed

Motor Pathways

LEFT BRAIN & RIGHT BRAIN LEFT AND RIGHT HEMISPHERES SPECIALIZE IN DIFFERENT FUNCTIONS due to ascending and descending pathways being crossed.