Unit Eleven: The Nervous System: C. Motor and

Integrative Neurophysiology

Chapter 57: Cerebral Cortex, IntellectualFunctions of the Brain, Learning, and

Memory

Guyton and Hall, Textbook of Medical Physiology, 12 edition

Physiologic Anatomy of the Cerebral Cortex

• Three Types of Neurons

a. Granular (stellate)1. Short axons2. Function as interneurons3. Excitatory with glutamate as neurotransmitter4. Inhibitory with GABA as neurotransmitter5. Found in the sensory areas of the cortex6. Found in association areas between sensory

and motor areas

Physiologic Anatomy of the Cerebral Cortex

• Three Types of Neurons

b. Fusiform and Pyramidal

1. Give rise to almost all output fibers from the cortex2. Pyramidal are larger and more numerous than

fusiform3. Pyramidal-source of nerve fibers that go all the way

to the spinal cord

Physiologic Anatomy of the Cerebral Cortex

Fig. 57.1 Structure of the cerebral cortex, showing: I, molecular layer; II, external granular layer; III, pyramidal layer; IV, internal granular layer; V, large pyramidal cell layer; VI, layer of fusiform or poly- morphic cells

Physiologic Anatomy of the Cerebral Cortex

• Anatomical and Functional Relations of the Cerebral Cortex to the Thalamus and OtherLower Centers

Fig. 57.2 Areas of the cerebral cortex that connect with specific portions of the thalamus

Functions of Specific Cortical Areas

Fig. 57.3 Functional areas of the human cerebral cortex as determined by electrical stimulation during neurological surgery or examination

Functions of Specific Cortical Areas

• Association Areas (see Fig. 57.4)

a. Parieto-occipitotemporal association area

1. Analysis of the spatial coordinates of the body2. Wernicke’s Area-important for language

comprehension3. Angular gyrus area-needed for reading4. Area for naming objects

Functions of Specific Cortical Areas

• Association Areas (see Fig. 57.4)

b. Pre-frontal association area

1. Broca’s area-neural circuitary for word formation

c. Limbic association area-behavior, emotions, andmotivation

d. Area for recognition of faces

Functions of Specific Cortical Areas

Fig. 57.6

Functions of Specific Cortical Areas

• Comprehensive Interpretative Function of Wernicke’sArea

Fig. 57.7

Functions of Specific Cortical Areas

• Comprehensive Interpretative Function of Wernicke’sArea

a. Angular gyrus-interpretation of visual information

• Concept of the Dominant Hemisphere

• Role of Language in the Function of Wernicke’s Area

• Functions of the Parieto-occipitotemporal Cortex inthe Nondominate Hemisphere

Functions of Specific Cortical Areas

• Higher Intellectual Functions of the Prefrontal Association Areas

a. Decreased aggressiveness and inappropriate socialbehavior

b. Inability to progress toward goals or carry throughsequential thoughts

c. Elaboration of thought-concept of a “working memory”

1. Functions of a working memory

Function of the Corpus Callosum

• Cutting the Corpus Callosum:

a. Blocks transfer of information from the dominanthemisphere to the motor cortex on the opposite side

b. Prevents transfer of somatic and visual info from the right to left hemisphere

c. Person would have two entirely separate consciousportions of the brain

Thoughts, Consciousness, and Memory

• Memory-Roles of Synaptic Facilitation and SynapticInhibition

a. Positive and negative memory—sensitization or habituation of synaptic transmission

b. Classification of memories

1. Declarative2. Skill

Thoughts, Consciousness, and Memory

• Declarative Memory- memory of the various details of integrated thought (i.e. memory of surroundings, time relationships, causes of experiences, meaningof an experience)

• Skill Memory- associated with motor activities basedon previous learning (i.e. hitting a tennis ball)

Thoughts, Consciousness, and Memory

• Short-Term Memory

• Intermediate Long-Term Memory

a. Memory based on chemical changes in the presynapticterminal or postsynaptic neuronal membrane

Fig. 57.9

Thoughts, Consciousness, and Memory

• Molecular Mechanism of Intermediate Memory

a. Mechanism of habituation-role of calcium channels

b. Mechanism of facilitation-role of serotonin releaseand cAMP activity

Thoughts, Consciousness, and Memory

• Long-Term Memory

a. Structural changes in synapses during the developmentof long-term memory

1. Increase in vesicle release site for secretion of transmitters

2. Increase in number of transmitter vesicles released3. Increase in the number of presynaptic terminals4. Changes in the structure of dendritic spines that

permit transmission of stronger signals

Thoughts, Consciousness, and Memory

• Long-Term Memory

b. Number of neurons and their connectivities change duringlearning

• Consolidation of Memory

a. Rehearsal enhances the transference of short-term memory into long-term memory

b. New memories are codified during consolidation

Thoughts, Consciousness, and Memory

• Consolidation of Memory

c. Roles of specific parts of the brain in the memory process

1. Hippocampus promotes storage of memories2. Hippocampi not important in reflexive learning