Chapter 2 - Nervous System Fucntions Flashcards
1
Q
Evolution of Brain Size
and Human Behavior
A
• Human brain has optimized its overall size, (size and number of neurons, the number and length of connections, energy consumption) • Changing these features would compromise the others and neutralize any performance improvements
2
Q
The brain’s primary function is to produce
behavior. To do so, it must:
A
• Receive information about the world • Integrate information to create a sensory reality • Produce commands to control the movement of muscles
3
Q
The brain is plastic:
A
– Neural tissue has the capacity to adapt to the
world by changing how its functions are
organized
4
Q
Neuroplasticity
A
The nervous system’s potential for physical
or chemical change that enhances its
adaptability to environmental change and its
ability to compensate for injury
5
Q
Phenotypic Plasticity
A
An individual’s genotype (genetic makeup) interacts with the environment to elicit a specific phenotype from a large genetic repertoire of possibilities, a phenomenon that results from epigenetic influences
6
Q
Functional Organization of the Nervous
System (Recall)
A
• Brain and spinal cord together make up the central nervous system, and all the nerve fibers radiating out beyond the brain and spinal cord as well as all the neurons outside the brain and spinal cord form the peripheral nervous system
7
Q
Direction of Neural Information Flow is
Important
• Afferent
A
information is sensory information coming into the CNS (incoming information)
8
Q
Direction of Neural Information Flow is
Important
Efferent
A
information is
information leaving
the CNS (outgoing
information)
9
Q
• Many names for nervous-system structures
include information about anatomical
locations:
A
– with respect to other body parts of the animal
– with respect to their relative locations
– with respect to a viewer’s perspective
10
Q
“Brain–Body
Orientation”
A
illustrates brain-structure location from the frame of reference of the face
11
Q
“Spatial Orientation”
A
Illustrates Brain-Structure
Location in Relation to Other Body Parts
12
Q
“Anatomical
Orientation”
A
illustrates the direction of a cut, or section, through the brain (part A) from the perspective of a viewer (part B)
13
Q
Each hemisphere is
divided into four
lobes:
A
– frontal (executive function) – parietal (sensory integration) – temporal (auditory, taste, smell, memory) – occipital (visual)
14
Q
Cerebral
Cortex (Recall)
A
• The cerebral cortex is a thin sheet of nerve tissue folded many times to fit inside the skull • Your right fist can serve as a guide to the orientation of the brain’s left hemisphere and its lobes
15
Q
Surface Features of the Brain
• Meninges: Three layers of protective tissue
A
– Dura mater
• “hard mother”; tough outer layer of fibrous tissue
– Arachnoid layer
• “like a spider’s web”; thin sheet of delicate connective
tissue
– Pia mater
• “soft mother”; moderately tough inner layer that clings
to the brain’s surface
16
Q
Surface Features of the Brain
• Cerebrum
A
– Major structure of the forebrain, consisting of two virtually identical hemispheres (left and right)
17
Q
Surface Features of the Brain
• Cerebellum
A
\: “Little brain” – Involved in the coordination of motor and possibly other mental processes
18
Q
Gyrus (pl. gyri)
A
– A small protrusion or
bump formed by the
folding of the cerebral
cortex
19
Q
Sulcus (pl. sulci)
A
– A groove in brain matter,
usually found in the
neocortex or cerebellum
20
Q
Fissure
A
A very deep sulcus
21
Q
Brainstem
A
Central structures of the brain, including the
hindbrain, midbrain, thalamus, and
hypothalamus, responsible for most
unconscious behavior
22
Q
Surface Blood Vessels
A
– Anterior, middle, and posterior cerebral arteries
– Stroke
• Sudden appearance of neurological symptoms as a
result of severe interruption of blood flow
23
Q
Internal Features of the Brain
– Four Ventricles
A
(cavities in the brain that contain cerebrospinal fluid (CSF) • Two lateral ventricles (left and right) • Third ventricle • Fourth ventricle
24
Q
Internal Features of the Brain
• Cerebrospinal Fluid (CSF)
A
– Sodium chloride and other salts
– Fills the ventricles and circulates around the
brain and spinal cord in the subarachnoid space
(located between the arachnoid layer and the
pia mater)
– Cushions the brain
– Meningitis
• Infection of the meninges and CSF
25
Internal Features of the Brain: Macro
| • Gray Matter
– Areas of the nervous system predominately
| composed of cell bodies and blood vessels
26
Internal Features of the Brain: Macro
| White Matter
– Areas of the nervous system rich in fat-sheathed
| neural axons
27
Internal Features of the Brain: Macro
| • Corpus Callosum
– Fiber system connecting the two cerebral
| hemispheres
28
Internal Features of the Brain: Microscopic
| Two main types of cells:
• Neurons
– Carry out the brain’s major functions
– Approximately 80 billion
• Glial cells
– Aid and modulate neurons’ activities
– Approximately 100 billion
29
Internal Features of the Brain
| • Nucleus (pl. nuclei)
– A group of cells forming a cluster that can be
identified with special stains to form a functional
grouping
30
Internal Features of the Brain
| • Nerve
– Large collection of axons coursing together
| outside the central nervous system
31
Internal Features of the Brain
| • Tract
– Large collection of axons coursing together
| within the central nervous system
32
Evolutionary Development of the
| Nervous System
• Human brain is a complex mammalian
brain, yet it still retains most of the features
of other, less complex mammalian brains
• Most behaviors are not the product of a
single locus in the brain, but rather of many
brain areas and levels
33
Spinal Cord
```
• Controls most body movements
• Can act independently of the
brain
• Spinal reflex:
– Automatic movement
– Hard to prevent (brain cannot
inhibit)
– Example: Knee-jerk reflex (patellar
tendon)
```
34
Brainstem
```
• Begins where spinal cord enters the skull
• Receives afferent nerves coming from
senses and sends efferent nerves out to
control movements
• Three regions:
– Hindbrain
– Midbrain
– Diencephalon
Developed as simple animals
evolved a brain
```
35
Brainstem
```
Hindbrain integrates both voluntary and
involuntary body movement.
• Evolutionarily the oldest part of the brain
• Contains:
– Cerebellum
– Reticular Formation
– Pons
– Medulla
• Controls various motor functions ranging
from breathing to balance to fine
movements
```
36
The Brainstem:
Hindbrain
• Cerebellum
```
– Controls complex movements and cognitive
functions
– Size increases with the physical speed and
dexterity of a species
– Relatively large
cerebellums enable
fine, coordinated
movements such as
flight and landing in
birds and prey
catching in cats
– Slow-moving animals
such as the sloth
have smaller
cerebellums relative
to their brain size
```
37
The Brainstem:
Hindbrain
• Reticular Formation
– Reticular activating system
– Netlike mixture of neurons (gray matter) and
nerve fibers (white matter)
– Stimulates the forebrain:
• Regulation of sleep-wake behavior and behavioral
arousal
38
The Brainstem:
Hindbrain
• Pons (“bridge”)
– Connects cerebellum to the rest of the brain
| – Controls important movements of the body
39
The Brainstem:
| Hindbrain
– Rostral tip of spinal cord
– Vital functions:
• Control of breathing and heart rate
40
The Brainstem:
Midbrain
• Tectum (roof of midbrain)
– Sensory processing (visual and auditory)
– Produces orienting movements (e.g., turning
head to see source of sound)
41
The Brainstem:
Midbrain
• Tegmentum (floor of midbrain)
– Eye and limb movements
– Species-specific behaviors
– Perception of pain
42
The Brainstem:
| Diencephalon
```
• Integrates sensory and motor information
on its way to the cerebral cortex
• The two principal structures include:
1.the hypothalamus
2.the thalamus
```
43
Hypothalamus
```
– Hormone function
• Through connections with the pituitary gland
– Feeding
– Sexual behavior
– Sleeping
– Temperature regulation
– Emotional behavior
```
44
Thalamus
```
– Gateway for channeling sensory information
to the cortex
– Primary role is sensory processing
– Motor processing
– Integrative functions
```
45
The two principal structures include:
Hypothalamus: temperature regulation, eating, drinking,
and sexual behavior
Thalamus: information from all sensory systems is
integrated and projected into the appropriate region of the
neocortex
46
Forebrain
```
• Neocortex (cerebral cortex)
– Regulates various mental activities
• Basal Ganglia
– Control of voluntary movement
• Limbic System
– Regulates emotions and behaviors that create
and require memory
```
47
The Cortex Forebrain
```
• Neocortex (“new bark”)
– 6 layers of gray matter
– Creates and responds to a perceptual world
• Limbic Cortex
– Evolutionarily older
– 3 or 4 layers of gray matter
– Controlling motivational states
```
48
forebrain The Neocortical Lobes
```
• Occipital: Vision
• Parietal: Tactile functions
• Temporal: Visual, auditory, and gustatory
functions
• Frontal: Motor and executive functions
```
49
forebrain Neocortical Layers
• Different layers have different cell types
• Density of cells in each layer varies
• Differences in appearance relate to function
• Cytoarchitectonic Map
– Map of neocortex based on the organization,
structure, and distribution of the cells
50
Cytoarchitectonic Map
```
• Brodmann defined
areas by organization
and characteristics of
the cells
• The simplest sensory
perceptions of touch
(red), vision (purple),
and hearing (orange)
```
51
Forebrain
The Basal Ganglia
Basal Ganglia: control and coordination of
movement patterns rather than in activating the
muscles to move
• Collection of nuclei just below the white
matter of the neocortex
– 3 principal structures: caudate nucleus,
putamen, and globus pallidus
• Controls voluntary and involuntary movement
• Related disorders
– Parkinson’s disease and Tourette’s syndrome
52
Forebrain
| The Limbic System
```
• Group of structures between the neocortex
and brain stem
– Principal structures: amygdala, hippocampus,
and cingulate cortex
• Regulation of
– Emotional and sexual behaviors
– Memory
– Spatial navigation
```
53
Cranial Nerves
• Afferent functions, such as sensory inputs
to the brain from the eyes, ears, mouth,
and nose
• Efferent functions, such as motor control
of the facial muscles, tongue, and eyes
• Both functions, such as the modulation of
both sensation and movement in the face
54
Spinal Nerves
• Dermatome
– Area of the skin supplied with afferent nerve
fibers by a single spinal-cord dorsal root
• Spinal-cord segments are interconnected
so adjacent segments can operate
together to direct complex coordinated
movements
55
Spinal Nerves
```
• Dorsal fibers are
afferent: they carry
information from the
body’s sensory
receptors
• Ventral fibers are
efferent: they carry
information from the
spinal cord to the
muscles
```
56
The Autonomic Nervous System
• Sympathetic System
– Arouses the body for action (e.g., increase
heart rate and blood pressure)
– Mediates the “fight or flight” response
• Parasympathetic System
– Opposite of sympathetic: prepares the body to
“rest and digest”
– Reverses the “fight or flight” responses
57
Principle 1:
• The Nervous System Produces Movement
Within a Perceptual World the Brain
Creates
– Individual realities are rough approximations of
what is actually present
– The brain produces a reality that is adaptive
for that species to survive
– The behavior that the brain produces is
directly related to the world that the brain has
created
58
Principle 2:
• The Details of Nervous-System
Functioning Are Constantly Changing, an
Attribute Called Neuroplasticity
– Experience alters the brain’s organization,
and neuroplasticity is required for learning
and memory functions as well as for survival
– Information is stored in the nervous system
only if neural connections change
59
Principle 3:
• Many of the Brain’s Circuits Are Crossed
– Each hemisphere receives sensory
stimulation from the opposite (contralateral)
side of the body and controls muscles on
the contralateral side as well
60
Principle 4:
• The Central Nervous System Functions
on Multiple Levels
– Simple animals such as worms have a
spinal cord, more complex animals such as
fish have a brainstem as well, and yet more
complex animals have evolved a forebrain
– Each new addition to the CNS has added a
new level of behavioral complexity without
discarding previous levels of control
61
Principle 5:
• The Brain Is Both Symmetrical and
Asymmetrical
– The left and the right hemispheres look like
mirror images; they have some dissimilar
features
– Language is usually on the left side, and
spatial functions are usually on the right
62
Principle 6:
• Brain Systems Are Organized Both
Hierarchically and in Parallel
– CNS comprises multiple levels of function,
these levels must be extensively
interconnected to integrate their processing
and create unified perceptions or
movements
Subsystems of the brain are organized into
multiple parallel pathways. Yet our conscious
experiences are always unified
63
Principle 7:
• Sensory and Motor Divisions Exist
Throughout the Nervous System
– Sensory and motor divisions in the Somatic
Nervous System
– Sensory and motor divisions in the Central
Nervous System
64
Principle 8:
```
• Sensory Input to the Brain Is Divided for
Object Recognition and Motor Control
– Example: Dorsal and ventral processing
streams in the visual system
– Animals with complex brains evolved
separate systems for producing movement
toward objects and for recognizing them
```
65
Principle 9:
• Functions in the Brain Are Both
Localized and Distributed
– Damage to a small brain region produces
only focal symptoms
– Massive brain damage is required to
completely remove some functions
– A small injury could impair some aspect
of language functioning, but it would take
a widespread injury to completely remove
all language abilities
66
• Functions in the Brain Are Both
Localized and Distributed
– Damage to a small brain region produces
only focal symptoms
– Massive brain damage is required to
completely remove some functions
– A small injury could impair some aspect
of language functioning, but it would take
a widespread injury to completely remove
all language abilities
```
• The Nervous System Works by
Juxtaposing Excitation and Inhibition
– All neurons have a spontaneous rate of
activity that can be either increased
(excitation) or decreased (inhibition)
– Some neurons excite others, whereas other
neurons inhibit
```
