chapter 46: the mammalian nervous system: structure and higher functions chapter 46 the mammalian...

Chapter 46: The Mammalian Nervous System: Structure and Higher Functions

CHAPTER 46The Mammalian Nervous

System: Structure and Higher Functions


Chapter 46: The Mammalian Nervous System: Structure and Higher FunctionsThe Nervous System: Structure, FunctionThe Nervous System: Structure, Function, and Information Flow, and Information Flow

Functional Subsystems of the Nervous SFunctional Subsystems of the Nervous Systemystem


Chapter 46: The Mammalian Nervous System: Structure and Higher FunctionsInformation Processing by Neuronal CircInformation Processing by Neuronal Circuitsuits

Understanding Higher Brain Functions in Understanding Higher Brain Functions in Cellular TermsCellular Terms


The Nervous System: Structure, Function, and Information Flow• Brain and spinal cord make up the Brain and spinal cord make up the

central nervous system. central nervous system. • Cranial and spinal nerves make up the Cranial and spinal nerves make up the

peripheral nervous system. peripheral nervous system. • A nerve is a bundle of many axons A nerve is a bundle of many axons

carrying information to and from the carrying information to and from the central nervous system. central nervous system.

Review Figure Review Figure 46.146.1

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Figure 46.1

Figure 46.1Figure 46.1

figure 46-01.jpg


The Nervous System: Structure, Function, and Information Flow • The nervous system can be modeled The nervous system can be modeled

conceptually in terms of direction of conceptually in terms of direction of information flow and whether or not information flow and whether or not we are conscious of the information. we are conscious of the information.


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Figure 46.2


figure 46-02.jpg


The Nervous System: Structure, Function, and Information Flow • The vertebrate nervous system develops The vertebrate nervous system develops

from a hollow dorsal neural tube. from a hollow dorsal neural tube. • The brain forms from three swellings at The brain forms from three swellings at

its anterior end, which become the:its anterior end, which become the: hindbrain, hindbrain, midbrain, and midbrain, and forebrain. forebrain.


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Figure 46.3 – Part 1

Figure 46.3 – Part 1Figure 46.3 – Part 1

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figure 46-03b.jpg




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The Nervous System: Structure, Function, and Information Flow • The forebrain develops into the The forebrain develops into the

cerebral hemispheres and the cerebral hemispheres and the underlying thalamus and underlying thalamus and hypothalamus. hypothalamus.

• The midbrain and hindbrain develop The midbrain and hindbrain develop into the brain stem. into the brain stem.

• More primitive and autonomic More primitive and autonomic functions are localized in the brain functions are localized in the brain stem, and conscious experience stem, and conscious experience depends on the cerebrum.depends on the cerebrum.

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Functional Subsystems of the Nervous System• The nervous system is composed of The nervous system is composed of

many subsystems functioning many subsystems functioning simultaneously. simultaneously.

• Some important ones are the spinal Some important ones are the spinal cord, reticular system, limbic system, cord, reticular system, limbic system, and cerebrum.and cerebrum.

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Functional Subsystems of the Nervous System • The spinal cord communicates The spinal cord communicates

information between brain and body. information between brain and body. • It processes and integrates much It processes and integrates much

information, and can issue some information, and can issue some commands to the body without brain commands to the body without brain input. input.


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Figure 46.4


figure 46-04.jpg


Functional Subsystems of the Nervous System • The reticular system of the brain stem is The reticular system of the brain stem is

a complex network that directs a complex network that directs incoming information to appropriate incoming information to appropriate brain stem nuclei brain stem nuclei

• They control autonomic functions, as They control autonomic functions, as well as transmitting the information to well as transmitting the information to the forebrain resulting in conscious the forebrain resulting in conscious sensation. sensation.

• The reticular system controls level of The reticular system controls level of nervous system arousal. nervous system arousal.


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Figure 46.5


figure 46-05.jpg


Functional Subsystems of the Nervous System • The limbic system is an evolutionarily The limbic system is an evolutionarily

primitive part of the forebrain involved primitive part of the forebrain involved in:in: emotions emotions physiological drivesphysiological drives instincts instincts memory. memory.


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Figure 46.6


figure 46-06.jpg


Functional Subsystems of the Nervous System • The cerebral hemispheres are the The cerebral hemispheres are the

dominant structures of the human dominant structures of the human brain. brain.

• Their surfaces consist of a layer of Their surfaces consist of a layer of neurons called the cerebral cortex.neurons called the cerebral cortex.

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Functional Subsystems of the Nervous System • Most of the cerebral cortex is involved Most of the cerebral cortex is involved

in higher-order information processing, in higher-order information processing, and these areas are generally called and these areas are generally called association cortex.association cortex.

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Functional Subsystems of the Nervous System • The cerebral hemispheres can be divided into The cerebral hemispheres can be divided into

temporal, frontal, parietal, and occipital temporal, frontal, parietal, and occipital lobes. lobes.

• Many motor functions are localized in the Many motor functions are localized in the frontal lobefrontal lobe

• Information from many receptors around the Information from many receptors around the body projects to the parietal lobebody projects to the parietal lobe

• Visual information projects to the occipital Visual information projects to the occipital lobelobe

• Auditory information projects to the temporal Auditory information projects to the temporal lobe. lobe.

Review Figures Review Figures 46.746.7, , 46.846.8, , 46.946.9, , 46.1046.10

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figure 46-07a.jpg




figure 46-07b.jpg


Figure 46.8


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Figure 46.9


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Figure 46.10


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Information Processing by Neuronal Circuits• The functions of the nervous system The functions of the nervous system

are beginning to be understood in are beginning to be understood in terms of the properties of cells terms of the properties of cells organized in neuronal circuits.organized in neuronal circuits.

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Information Processing by Neuronal Circuits • The autonomic nervous system The autonomic nervous system

consists of efferent pathways that consists of efferent pathways that control the body’s organs and organ control the body’s organs and organ systems. systems.

• Its sympathetic and parasympathetic Its sympathetic and parasympathetic divisions normally work in opposition. divisions normally work in opposition.

• They are characterized by their They are characterized by their anatomy, neurotransmitters, and anatomy, neurotransmitters, and effects on target tissues. effects on target tissues.





figure 46-11a.jpg




figure 46-11b.jpg


Information Processing by Neuronal Circuits • Neuronal circuits in the occipital cortex Neuronal circuits in the occipital cortex

integrate visual information. integrate visual information. • Receptive field responses of retinal Receptive field responses of retinal

ganglion cells are communicated to ganglion cells are communicated to the brain in optic nerves. the brain in optic nerves.

• This information is projected to the This information is projected to the visual cortex so as to create receptive visual cortex so as to create receptive fields for cortical cells.fields for cortical cells.

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Information Processing by Neuronal Circuits • A simple cell is stimulated by a bar of A simple cell is stimulated by a bar of

light with a specific orientation falling light with a specific orientation falling at a specific location on the retina. at a specific location on the retina.

• A complex cell is maximally stimulated A complex cell is maximally stimulated by such a stimulus moving across the by such a stimulus moving across the retina. retina.

• The visual cortex seems to assemble a The visual cortex seems to assemble a mental image of the visual world by mental image of the visual world by analyzing edges of patterns of light. analyzing edges of patterns of light.



Figure 46.12


figure 46-12.jpg


Information Processing by Neuronal Circuits • Binocular vision results from circuits Binocular vision results from circuits

that communicate information from that communicate information from both eyes to binocular cells in the both eyes to binocular cells in the visual cortex. visual cortex.

• These cells interpret distance by These cells interpret distance by measuring the disparity between measuring the disparity between where the same stimulus falls on the where the same stimulus falls on the two retinas. two retinas.


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Figure 46.13


figure 46-13.jpg


Understanding Higher Brain Functions in Cellular Terms• Humans have a daily cycle of sleep Humans have a daily cycle of sleep

and waking. and waking. • Sleep can be divided into slow-wave Sleep can be divided into slow-wave

and rapid-eye-movement sleep. and rapid-eye-movement sleep. • Human non-REM sleep is divided into Human non-REM sleep is divided into

four stages of increasing depth. four stages of increasing depth.


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Figure 46.14


figure 46-14.jpg


Understanding Higher Brain Functions in Cellular Terms • Some learning and memory processes Some learning and memory processes

have been localized to specific brain have been localized to specific brain areas. areas.

• Repeated activations of identified Repeated activations of identified circuits in brain regions have revealed circuits in brain regions have revealed long-lasting changes in synaptic long-lasting changes in synaptic properties referred to as long-term properties referred to as long-term potentiation and long-term depressionpotentiation and long-term depression

• These may be involved in learning and These may be involved in learning and memory. memory.


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figure 46-15a.jpg




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Understanding Higher Brain Functions in Cellular Terms • Complex memories can be elicited by Complex memories can be elicited by

stimulating small regions of stimulating small regions of association cortex. association cortex.

• Damage to the hippocampus can Damage to the hippocampus can destroy the ability to form long-term destroy the ability to form long-term memories.memories.

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Understanding Higher Brain Functions in Cellular Terms • Language abilities are localized mostly Language abilities are localized mostly

in the left cerebral hemisphere, a in the left cerebral hemisphere, a phenomenon known as lateralization.phenomenon known as lateralization.

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Understanding Higher Brain Functions in Cellular Terms • When the corpus callosum is cut, When the corpus callosum is cut,

communication between left and right communication between left and right cerebral hemispheres is eliminated.cerebral hemispheres is eliminated.

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Understanding Higher Brain Functions in Cellular Terms • Different areas of the left hemisphereDifferent areas of the left hemisphere

—including Broca’s area, Wernicke’s —including Broca’s area, Wernicke’s area, and the angular gyrus—are area, and the angular gyrus—are responsible for different aspects of responsible for different aspects of language. language.


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Figure 46.16


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chapter 46: the mammalian nervous system: structure and higher functions chapter 46 the mammalian...

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