The human nervous system includes the central nervous system (CNS, comprising the brain and the spinal cord) and the peripheral nervous system (PNS, comprising the cranial and spinal nerves, which carry information inward to and outward from the brain and spinal cord)

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Neuroscientists study the anatomical structures of the nervous system (neuroanatomy), and examine how these structures work together as a complex unit and as separate, distinct biological units (neurophysiology)

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anatomists

Neuroscience is a focused branch of the more general disciplines of anatomy and physiology, which involve the study of body structures and the functions of these structures. More specifically, anatomists study the physical characteristics of body structures and examine how they relate to other structures to form anatomical systems

Physiologists

Physiologists study how body structures function, both individually
and in concert with other structures to form physiological systems.

Neuroscientists

Neuroscientists study the structures
and functions of the nervous system; their work has benefited tremendously from the rapid and remarkable advances in imaging technologies that allow researchers to study nervous system functions and structures at the level of the neuron.

magnetic resonance imaging

Technologies such as magnetic resonance imaging (MRI), positron emission to- mography (PET), computerized tomography (CT) scanning, and magnetoencepha- lography (MEG) provide detailed images of the anatomy and/or physiology of the nervous system

Although commonplace today, researchers only began using MRI
to examine the brain’s functioning in the early 1990s (Belliveau et al., 1990). Now, there are entire conferences and organizations devoted to sharing research findings that involve neuroimaging of the brain (e.g., the Organization for Human Brain Mapping). See Research Paradigms: fMRI Studies for information on a brain-imaging
technique that allows researchers to examine brain activity when an individual is engaged in a specific processing task.

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neurolinguists,

Neuroscience has several subdisciplines, including developmental neuro- science, cognitive neuroscience, neurology, neurosurgery, neuroanatomy, neurophysiology, neuropathology, and neurolinguistics. The foci for these various subdisciplines appear in Table 3.1. Of particular interest to the study of language acquisition is the work of neurolinguists, who study the structures and functions of the nervous system that relate to language. Some neurolinguists study the neu-
roanatomy of language to identify the nervous system structures involved with language processing. Other neurolinguists study the neurophysiology of language to identify the specific ways in which the nervous system functions, such as how the human brain processes language. Still, other neurolinguists study the neuropathol-
ogy of language to identify the ways in which diseases and injuries affect the functioning of the human nervous system; for example, some study how various brain structures reorganize and assume new language functions after injury.

Functional magnetic resonance imaging (

Functional magnetic resonance imaging (fMRI) is a
type of brain imaging that allows researchers and cli-
nicians to identify the brain structures involved in spe-
cific mental functions. fMRI is a noninvasive procedure
that maps neural activities (i.e., functions) to specific
neural regions (i.e., structures) according to changes
in blood oxygen levels that correspond to changes in
neural activity (Brown, Cheng, Haacke, Thompson, &
Venkatesan, 2014). fMRI uses MRI technology, which
provides structural scans of the brain (e.g., measure-
ments of anatomical regions of the brain). However,
fMRI differs from MRI in that it maps brain functioning
by examining brain activity when individuals are en-
gaged in a specific processing task (e.g., listening to
yes–no questions) or in a resting state. fMRI has signif-
icant benefits over other types of brain-imaging tech-
nologies, such as PET scans, because it requires no
injections of radioactive materials, images can be col-
lected relatively quickly (often with a single pass), and
the resultant images are of extremely high resolution.
An example of an image obtained by using fMRI is
presented in the figure accompanying this box.

One example of the potential for fMRI to improve
understanding of language functions in the brain is de-
scribed in a study by a team of scientists in the Nether-
lands (Groen et al., 2010). In Chapter 2, we noted that
children with autism spectrum disorder (ASD) exhibit
difficulties with social aspects of communication. One
such difficulty involves the ability to integrate informa-
tion that is important for communicating socially. For
instance, when communicating with others, we must
integrate our knowledge about the speaker with our
knowledge of what words to use to communicate ef-
fectively. This is called linguistic-context integration
(we must match our language to the context in which
we are communicating). When speaking to a 3-year-
old, we might choose to use the word “frog” rather than
“amphibian” because we understand a young child is
more likely to be familiar with the former than the latter.
Persons with ASD have difficulty integrating these and other types of information, which leads to difficulties with social communication.

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Few studies have sought to determine whether
there is a neural basis for this difficulty. That is, whether
differences exist in the brain functions of persons with
ASD compared to those without ASD that cause dif-
ficulties with social communication. Groen and col-
leagues sought to determine whether this was the
case by using fMRI to study the brain functions of 30
adolescents with ASD and 31 adolescents who were
typically developing (TD). The participants listened ei-
ther to sentences that involved integrating congruent
information (the integrated information made sense)
or incongruent information (the integrated informa-
tion didn’t make sense). For instance, the participants
heard the sentence “If only I looked like Britney Spears
in her latest video” as spoken by both a male and a
female (Groen et al., 2010, p. 1939). When spoken by
a female, the linguistic-context integration is congru-
ent; when spoken by a male, it is not. The research-
ers identified several regions of interest (ROIs) near
Broca’s area to examine brain functions while partic-
ipants heard these congruent and incongruent sen-
tences. They found adolescents with ASD showed less
activation in the ROIs when hearing linguistic-context
incongruent sentences than the TD participants. Ado-
lescents with ASD do not seem to process incongruent
information in the way their typical peers do, suggest-
ing that social-communication difficulties of persons
with ADS may have a neural basis.

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human brain processes language. Still, other neurolinguists study the neuropathology of language to identify the ways in which diseases and injuries affect the functioning of the human nervous system; for example, some study how various brain structures reorganize and assume new language functions after injury.

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Linguistics and psycholinguistics are additional disciplines that have yielded considerable advances in understanding language

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Linguistics

Linguistics is a broad field concerned specifically with language as a developmental and ecological phenomenon

psycholinguistics

psycholinguistics is a more focused field dealing with the cognitive processes involved in developing, processing, and producing human language

Psycholinguistics

Psycholinguistics is the study of the psychology of language, an integration of the fields of psychology and linguistics. It also involves studying the language and com- municative capacities of other species, such as nonhuman primate

Terminology
Students of language development require knowledge of the specific terminology, or nomenclature, to describe anatomy and physiology, as well as the neuroanatomy and neurophysiology of language. Much of this terminology has its roots in ancient Latin and Greek.

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Nervous System Axes
The human nervous system is organized along two axes: the horizontal axis and the vertical axis. Together, these axes compose the T-shaped neuraxis.

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The horizontal

The horizontal

axis runs from the anterior (frontal) pole of the brain to the posterior (occipital) pole

vertical axis

The vertical axis extends from the superior portion of the brain downward along the entire spinal cord. Figure 3.1 depicts the horizontal and vertical axes of the neuraxis.

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When experts describe specific nervous system structures, they often use the horizontal and vertical axes as reference points. They use four terms to specify locations on a specific axis: rostral, caudal, dorsal, and ventral.

rostral

On the
horizontal axis, rostral refers to the front of the brain,

caudal

whereas caudal refers to
the back of the brain

Dorsal

refers to the top of the brain,

ventral

refers
to the bottom of the brain

vertical axis,

On the vertical axis, rostral refers to the top of the
spinal cord (near the brain),

caudal refers

and caudal refers to the bottom of the spinal cord
(near the coccyx, or tailbone).

caudal

caudal refers to the bottom of the spinal cord
(near the coccyx, or tailbone).

Dorsal

Dorsal refers to the back of the spinal cord (the side nearest the back), whereas

ventral

whereas ventral refers to the front of the spinal cord (the
side nearest the belly).

Directional and Positional Terms

Directional and Positional Terms
Neuroscientists use several additional terms to discuss the directional and positional relationships among various anatomical and physiological structures.

Proximal

Proximal refers to structures relatively close to a site of reference

distal

distal refers to
structures relatively far from a site of reference.

anterior

Other common terms are anterior
(toward the front) an

posterior

posterior (toward the back

superior

superior (toward the top)

inferior

(toward the bottom

external

external (toward the outside)

internal

internal (toward
the inside

efferent

and efferent (away from the brain)

Efferent pathways (also called descending pathways) move away from the brain, carrying motor impulses from the central nervous system to more distal body structure

afferent

afferent (toward the brain).

Afferent pathways (also called ascending pathways) move toward
the brain, carrying sensory information from the distal body structures to the brain

and efferent (away from the brain) and afferent (toward the brain). The last two terms often describe the pathways of information as it moves to and from the brain

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Neuroscience Basics
The human nervous system, like that of many other species, is a complex anatomical and physiological structure that includes the brain, the spinal cord, and sets of nerves that carry information to and from the brain and spinal cord. The human nervous system mediates nearly all aspects of human behavior, with few exceptions

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