Chapter 3: Neuroanatomy and Neurophysiology of Language
Learning Outcomes:
2. Identify the major structures and functions of the human brain.
4. Describe major concepts related to neurophysiological and neuroanatomical sensitive
periods.
I. What are Neuroanatomy and Neurophysiology?
A. Neuroscience is a branch of science that focuses on the anatomy and physiology of the
nervous system, or the neuroanatomy and neurophysiology, respectively.
B. The human nervous system includes the central nervous system (CNS) and the
peripheral nervous system (PNS).
C. 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).
D. Technologies such as magnetic resonance imaging (MRI), positron emission
tomography (PET), computerized tomography (CT) scanning, and
G. Linguistics is a broad field concerned specifically with language as a developmental and
ecological phenomenon, whereas psycholinguistics is a more focused field dealing with
the cognitive processes involved in developing, processing, and producing human
language.
H. Terminology
1. Nervous System Axes
a. The human nervous system is organized along two axes: the horizontal axis and
the vertical axis.
b. Together, these aces compose the T-shaped neuraxis.
c. The horizontal axis runs from the anterior (frontal) pole of the brain to the
posterior (occipital) pole.
d. The vertical axis extends from the superior portion of the brain downward along
2. Directional and Positional Terms
a. Proximal refers to structures relatively close to a site of reference, whereas distal
refers to structures relatively far from a site of reference.
b. Other common terms are anterior (toward the front) and posterior (toward the
back), superior (toward the top) and inferior (toward the bottom), external
(toward the outside) and internal (toward the inside), and efferent (away from the
I. Neuroscience Basics
1. Neurons
a. The billions of highly specialized cells that compose the nervous system are
called neurons.
b. The cell body is the center of the neuron, containing its nucleus; the nucleus
contains DNA material (genes, chromosomes) and proteins.
corresponds with the dendritic extension of another neuron.
i. Dendrites are the afferent extensions of a neuron, meaning they bring nerve
impulses into the cell body from the axonal projections of other neurons.
j. A single cell body contains a number of dendritic extensions; many dendrites are
studded with small protuberances (called spines), which increase the surface area
p. White matter is the tissue that carries information among gray matter tissues.
q. Neurons are sheathed in a coating called myelin.
r. The myelin sheath contributes to the rapid relay of impulses, particularly within
white matter and also helps protect the neuron.
s. Myelinization refers to the growth of the myelin sheath, a slow process that is not
2. Nervous System Divisions
a. Innervate is the term in neuroscience that means “to supply nerves” to a
particular region or part of the body.
b. The 12 pairs of nerves that emerge from the brain are the cranial nerves.
c. The 31 pairs of nerves that emerge from the spinal cord are called spinal nerves.
d. Central Nervous System
• The CNS consists of the brain and spinal cord.
• The first protective shield is bone.
• The skull covers the brain, and the vertebral column covers the spinal cord.
• The second shield is a series of layered membranes; these meninges, which
comprise three layers, completely encase the CNS.
• These are sometimes called the meningeal envelope.
• The inside layer of membrane, called the pia mater, tightly wraps around the
• The third shield is a layer of fluid called cerebrospinal fluid (CSF).
• CSF circulates between the two innermost layers of the meninges – the pia
mater and the arachnoid mater – within the subarachnoid space.
• CSF carries chemicals important to metabolic processes, but it is also an
important buffer against jolts to the CNS.
e. Peripheral Nervous System
• The PNS is the system of nerves connected to the brainstem and the spinal
cord.
• The 12 pairs of cranial nerves run between the brainstem and the facial and
neck regions and are particularly important for speech, language, and hearing.
• The cranial nerves transmit information concerning four of the five senses
(vision, hearing, smell, and taste) to the brain.
o Facial (VII): Taste sensation; facial movements, including smiling
o Acoustic (VIII): Hearing and balance
o Glossopharyngeal (IX): Tongue sensation; palatal and pharyngeal
movement, including gagging
• The 31 pairs of spinal nerves run between the spinal cord and all peripheral
areas of the human body, including the arms and the legs.
• These nerves mediate reflexes, sensory activity, and conscious (volitional)
motor activity.
II. What are the Major Structures and Functions of the Human Brain?
A. The human brain – and its capacity for abstract thought and language – differentiates
humans most significantly from other species.
B. Proportionally, the relative size of the human brain and its sheer demand for energy
(consuming one-fifth of the metabolic resources of the body) far exceed those of any
other mammal.
C. The neocortex controls most of the functions that exemplify human thought and
language, including speech, language, reasoning, planning, and problem solving.
D. Cerebrum
1. The cerebrum, or cerebral cortex, is the location of the most unique human qualities:
reasoning, problem solving, planning, and hypothesizing, to name only a few.
3. The cerebrum includes both the allocortex and the neocortex; the former comprises
4. Cerebral Hemispheres
a. The cerebrum consists of two mirror-image hemispheres, aptly named the right
5. Cerebral Lobes
a. Frontal Lobe
• The frontal lobe is the largest lobe of the human brain; it resides in the most
anterior part of the brain.
• Two key functions of the frontal lobe are activating and controlling both fine
• This part of the brain is involved with the affective aspects of sensations,
including gloom, elation, calmness, and friendliness; it thus serves as a
“regulator of the depth of feeling.”
• Also located in the frontal lobe are the primary motor cortex and the
premotor cortex, both important for human speech, as well as other motor
• Located on both the left and right sides of the frontal lobe, the connections
that run from the motor strip in the brain to the motor functions they control
throughout the body are contralateral.
• The motor cortex of the left frontal lobe is also home to Broca’s area, an
especially important region of the brain for spoken communication.
• It is responsible for the fine coordination of speech output.
b. Occipital Lobe
• The occipital lobe comprises the posterior portion of the brain.
• This lobe is functionally specialized for visual reception and processing.
c. Parietal Lobes
• The two parietal lobes reside posterior to the frontal lobe on the left and right
sides (above the ears).
• Processing of sensory information occurs mainly in the primary
somatosensory cortex and the sensory association cortex, both of which
complex system that permits individuals to hold in memory certain
information while executing a given task, such as a seven-digit phone number
while dialing on the phone.
d. Temporal Lobes
• The two temporal lobes also sit posterior to the frontal lobe but inferior to the
auditory stimuli, but cannot understand spoken words.
• The left temporal lobe also contains Wernicke’s area, sometimes called the
receptive speech area, which is a critical site for language comprehension.
• It is located in the superior portion of the left temporal lobe near the
intersection of the parietal, occipital, and temporal lobes.
typically exhibit significant difficulty with processing and producing coherent
language in both spoken and written form, called Wernicke’s aphasia.
• Although persons with Wernicke’s aphasia may produce relatively fluent and
intelligible speech, their spoken language may not make any sense because it
E. Brainstem
1. The brainstem sits directly on top of the spinal cord and serves as a conduit between
the rest of the brain and the spinal cord.
3. The brainstem is a key transmitter of sensory information to the brain and of motor
information away from the brain.
5. The brainstem structures and functions are associated with metabolism and arousal.
6. Three major reflex centers are located in the brainstem: the cardiac center, which
controls the heart; the vasomotor center, which controls the blood vessels; and the
respiratory center, which controls breathing.
F. Cerebellum
2. The cerebellum is primarily responsible for regulating motor and muscular activity,
and has little to do with the rational part of the brain that involves conscious planning
and responses.
III. How Does the Human Brain Process and Produce Language?
A. Current perspectives on the anatomical and physiological organization of the brain rely
on connectionist models.
B. Connectionist models attempt to represent the computational architecture of the brain as
C. The structures of the brain are not necessarily hard-wired for a given role, as was long
believed.
D. Most contemporary perspectives of how the brain works is that most higher-level
cognitive functions, including that of language, involve numerous brain areas in their
execution.
E. Connectionist models emphasize that the connectivity among units is critical to
understanding how information is processed.
F. Although research results suggest that particular regions of the brain correspond to
certain aspects of language processing or speech production, many basic language
processes (e.g., word retrieval) are distributed throughout the sensory and motor cortices
of the brain and not confined to a single structure.
G. Semantics
1. Semantic knowledge is a distributed modality
a. Word storage involves distributed neural networks transcending the frontal and
2. Semantic knowledge is left-lateralized
3. Some aspects of semantic knowledge involve right-hemisphere processing
H. Syntax and Morphology
1. An individual’s ability to rapidly and automatically process the rules of syntax and
2. The possibility of a distinct morphosyntactic brain module is supported by at least
three lines of research.
4. Second, the likelihood of a specialized morphosyntactic processor is supported by
5. Third, the results of a number of studies of morphosyntactic processing showed
6. Likewise, the results of studies involving attempts to isolate semantic processing
showed distinct neuroanatomical correlates for processing complex syntax.
7. Morphosyntactic processing might best be conceived as a complex cognitive ability
I. Phonology
1. Processing speech sounds is qualitatively and quantitatively different from processing
2. Some experts contend that the human brain has evolved a specialized processor,
3. The phonetic segments of spoken language are channeled through the human ears
4. Rapid analysis of the temporal characteristics of the speech sounds occurs in the
6. Neuroimaging data confirm historical neuroanatomical models in which phonological
7. Heschl’s gyrus, Wernicke’s area, and Broca’s area of the left hemisphere are
connected by a series of anatomical pathways.
9. Researchers have failed to identify a single structure or location in the brain
specialized solely for speech processing.
J. Pragmatics
1. Pragmatic ability draws primarily on frontal lobe functions.
3. The results of brain-imaging studies indicate that many human executive functions
4. Willful attention is what people use to maintain attention to a give task when
competing stimuli are present.
5. Both parietal and frontal lobe regions are involved in willful attention.
IV. What are Neurophysiological and Neuroanatomical Sensitive Periods?
A. Sensitive Periods Defined
1. As applied to the development of the human brain, a sensitive period is a time frame
2. Sensitive periods have the following three features:
a. Sensitive periods correspond to a time of active neuroanatomical and
neurophysiological change.
b. Sensitive periods are a phase not only of opportunity but also of risk.
B. Neuroanatomical and Neurophysiological Concepts Related to Sensitive Periods
2. At about the end of the first year, the infant’s brain contains approximately twice as
3. Neural plasticity is a term pertaining to the malleability of the CNS, and it relates
4. Plasticity relates to sensitive periods because the plasticity of the brain for
5. Experience-expectant plasticity refers to the ongoing sculpting of brain structures
that occur as a result of normal experiences.
6. As the infant develops, multitudes of synapses are present in the brain, expectantly
8. Once the sensitive period for a given experience-expectant brain function has passed,
9. Acquisition of language grammar occurs as a function of experience-expectant
plasticity.
10. Experience-dependent plasticity is unique to a given individual; this type of
11. Learning new information (whether it is novel information or information that must
12. Experience-dependent plasticity is a brain capacity available independent of age
because, through time, the human brain retains most of its capacity to learn through
experience and to adapt to change.
C. Sensitive Periods and Language Acquisition
1. Linguistic Isolation
a. Linguistic isolation occurs when a child develops with little or no exposure to a
2. Second Language Learners
a. Accents seem to be governed by a sensitive period, in that those with later ages of
arrival (AOAs) were associated with stronger foreign accents; however, this was
not the case with syntax.
3. Plasticity and Language
a. Evidence on sensitive periods for language acquisition suggests that researchers
must consider both experience-expectant and experience-dependent plasticity to
researchers’ inability to identify a putative end point to the sensitive period for
Beyond the Book:
1. There are a number of commercial programs on the Internet that claim to boost brain
functioning, including computer games and even vitamins. Search the Internet to find a
few such examples. How convincing are the claims for each of the commercial programs
that the brain will actually improve?
2. International adoption rates have decreased in the last few years in the United States.
3. A classic study by Hubel and Wiesel in 1970 involving kittens was instrumental in
improving our understanding of neural plasticity. What can you find out about this study?
How was the research conducted, and what did it tell us about the brain’s plasticity? In
your opinion, is this work worthy of the Nobel Prize the authors received?
4. The frontal lobe is responsible for executive functions. In small groups, discuss the
5. The Bucharest Early Intervention Project involved the random assignment of children to
remain in institutionalized care or to be placed in foster care. Discuss the ethical issues of
research of this type and why, in your opinion, random assignment of children to such
conditions is appropriate or not.
Discussion Points:
• What additional technological advances might improve scientists’ understanding of the
capacity of the brain for language?
• To further explore the concepts of efferent and afferent pathways with in the CNS, raise
your right arm above your head and identify the types of information carried toward and
away from the brain during this act.
• The CNS is not totally impervious to injury. What types of accidents or illnesses pose the
most risk to the CNS?