Transcript SPHS 4050, Neurological bases, PP 01

SPHS 4050
Neurological Bases of Speech
and Hearing Sciences
Scope of practice in
speech-language pathology and
audiology
• Communication…of any and all
types!
• Swallowing
The role of the neurological
system in communication and
swallowing
• Carries motor, efferent
signals in the direction away
from the brain (rostral CNS
to distal PNS)
• Carries sensory, afferent
signals in the direction
toward the brain (distal PNS
to rostral CNS)
The process of communication
depends on the neurological
system
Expressive communication uses
efferent neurological pathways
Receptive communication uses
afferent neurological pathways
Neurological system supports variety of communicative functions
Efferent
modality +
afferent
modality
Efferent (motor) neural
pathways for expressive
communication
BRAIN PLANS AND
INITIATES
Afferent (sensory) neural
pathways for receptive
communication
BRAIN RECEIVES AND
INTERPRETS
Verbal +
auditory
(talking +
listening)
Spoken language (system of
sounds/words/syntax/discourse);
speech (articulation);
prosody (pitch, timing, loudness)
Hearing and interpretation: sounds
and sound localization, words, word
order, discourse, prosody, metaphor
Writing +
reading
Production of written language,
symbols, pictures (manual or
digital)
Reception and interpretation of
written language, symbols or
pictures **
Motor +
tactile
e.g. move to touch person
e.g. making a braille message
e.g. handing person an object
e.g. feel touch of others
e.g. feel braille bumps **
e.g. feel shape of object **
Motor +
visual
e.g. movement for posturing,
gesturing, sign language, facial
expression
e.g. vision**: visual scanning, and
interpretation of the posture,
gesture sign, facial expression
** Note that the message receiver has to MOVE (eyes or hands) to
successfully receive message; both afferent and efferent systems involved
Neurological system also supports the
pragmatics of communication, no matter
what the modality…..
• Expressive:
– Planning and using the “right” communication for
the given context
• e.g. changing one’s talking style for a close friend vs.
one’s boss
• e.g.deciding when and where to use certain gestures
• Receptive:
– Figuring out appropriateness and “deeper meaning”
of communication, for the given context
• e.g. We could figure out what he really meant by that
comment… He wasn’t really complimenting her….
• e.g. Why did he/she use that intonation in his/her “Oh” ?
Pragmatics applies across all the efferent and afferent modalities
Pragmatics applies to all the modalities,
both efferent and afferent. How so?
Efferent
modality +
afferent
modality
Efferent (motor) neural
pathways for expressive
communication
BRAIN PLANS AND INITIATES
Afferent (sensory) neural
pathways for receptive
communication
BRAIN RECEIVES AND
INTERPRETS
Verbal +
auditory
(talking +
listening)
Spoken language (system of
sounds/words/syntax/discourse);spe
ech (articulation);
prosody (pitch, timing, loudness)
Hearing and interpretation:
sounds and sound localization,
words, word order, discourse,
prosody, metaphor
Writing +
reading
Production of written language,
Reception and interpretation of
symbols, pictures (manual or digital) written language, symbols or
pictures
Motor + tactile
e.g. move to touch person
e.g. making a braille message
e.g. handing person an object
e.g. feel touch of others
e.g. feel braille bumps
e.g. feel shape of object
Motor + visual
e.g. movement for posturing,
gesturing, sign language, facial
expression
e.g. vision, visual scanning, and
interpretation of posture, gesture,
sign, facial expression
Pragmatics Planning and use of the “right”
communication content in a given
context
Figuring out appropriateness and
“deeper meaning” of the
communication in a given context
The process of swallowing
depends on the neurological
system
Swallowing uses both efferent
and afferent neurological
pathways
• Movement (efferent)
• Sensation (afferent)
NOTE: Smell and taste are integral for
eating, too!
Phases of
swallow
require
the use of
both:
• Efferent
•
(motor)
neural
pathways
Afferent
(sensory)
neural
pathways
Why Neurosciences for Specialists
in Communication and Swallowing
(like Speech-Language
Pathologists and Audiologists)?
Well, sometimes a client has loss of a communicative
function (clinical sign or symptom), which is related to
disease or damage in the neurological system
(neuropathology)
Efferent
modality +
afferent
modality
Efferent (motor) neural
pathways for expressive
communication
BRAIN PLANS AND
INITIATES
Afferent (sensory) neural
pathways for receptive
communication
BRAIN RECEIVES AND
INTERPRETS
Verbal +
auditory
(talking and
listening)
Language (system of sounds/
words/syntax/discourse);
speech (articulation); prosody
(pitch, timing, loudness)
Hearing and interpretation: sounds
and sound localization, words, word
order, discourse, prosody, metaphor
Can’t hear Acoustic
in one ear neuroma
Can’t hear high
freq.
Damage to
high freq. hair
cells in cochlea
Can’t interpret
prosody
(receptive
aprosodia)
Damage to
right
hemisphere of
brain
• Clinicopathologic method
Can’t interpret
prosody
(receptive
aprosodia)
Damage to
right
hemisphere of
brain
– Relation between:
• the behavioral functions that are
lost or modified (as seen in the
clinic), and
• the site of a lesion (neurological
damage, pathology)
– Tools:
• Careful documentation of client’s
abilities
PLUS
• Neurodiagnostic techniques (as in
Chapter 20)
• Clinicopathologic method is used in the field of behavioral
neurology: “Study of how client’s behaviors/abilities are
related to or supported by the neurological system”
• Examples from the fields of speech-language pathology
and audiology, that we’ll encounter in this class
Dysarthria (speech motor disorder)
Damage to brain stem or cranial
nerves, as might happen with M.S.
Aphasia (acquired language disorder)
Damage to left hemisphere of
cerebrum
Cognitive-communicative disorders
associated with memory and
attention problems
Traumatic brain injury (diffuse injury
to brain)
Meniere’s disease
Meniere’s disease (associated with
damage to hair cells in the cochlea)
Dysphagia (swallowing disorder)
Damage to specific cranial nerves
Cortical blindness
Damage to vision centers of brain
Anosmia (inability to smell)
Damage to nerve receptor endings in
nasal epithelium
Some examples
from the book
(Table 1-2) of
clinical signs
symptoms
associated with
various
neurological
diseases/pathology.
This again
illustrates
clinicopathologic
method.
Need for this knowledge/understanding
of behavioral neurology
• Variety of work settings
–
–
–
–
Schools
Hospitals
Medical centers
University and private clinics
• Increasingly interdisciplinary work settings
need workers with specialized knowledge,
who can also interpret work of other
disciplines
• e.g. IMT (interdisciplinary management team)
• e.g., multidisciplinary school IEP meetings
Basic Principles of the Organization
of the Nervous System
Basic Principles:
Why Study These?
• They give us clue about how the nervous
system is organized
– Our understanding of these principles affects
how we study and investigate the brain
– These principles are based on
clinicopathologic evidence of how the brain
works
#1: Interconnectivity in the Brain
• All functionally
discrete/separate
regions of the
brain are
connected, either
– Directly
– Indirectly
• Multiple areas
interact, e.g., for
language,
memory,
attention
See pp. 73-77 for
discussion of the three
types of connecting
fibers!
#2: Centrality of Central
Nervous System (CNS)
• Role of Central nervous system (brain
and spinal cord)
– Integrate impulses: Bring information in
and make sense of it
– Generate impulses: Typically accomplished
through movement
• CNS “Collaborates” with peripheral
•
nervous system PNS (outside of brain
and spinal cord)
Info entering and leaving the CNS are
carried by different pathways
– Information going (up) to the CNS from
the PNS is sensory or afferent.
– Information coming (down) from the CNS
to the PNS is motor or efferent.
#3a Hierarchy of Neuraxial
organization: Lower to Higher
• Lower levels perform more basic
•
functions, higher levels perform more
complex functions
For example (going from simple/basic to
more complex)
− Spinal cord responsible for reflexes
(no cognitive involvement)
− Brain stem responsible for more
complex tasks such as body
functions (breathing, heart beat)
− Brain’s cortex is responsible for
complex integration and higher
mental functions, like language,
memory, and attention
#3b Hierarchy of Organization:
Inside to Outside
• Structures at deeper level of brain:
More basic/primal/older
– e.g. limbic system (in color): Basic
emotions such as fear, as linked to
memory
• Structures closer to surface: “Newer”
structures develop on top of older
structures
– E.g., neocortex (in brown) is laid on
top of the (older) limbic system,
and allows us to “think about,”
interpret, analyze, plan, based on
memories and emotions associated
with them
#4a Bilateral Anatomic Symmetry
(throughout NS)
• Both sides of CNS
essentially
structural mirror
images of each
other
• This principle is
used in medical
diagnosis
#4b Unilateral functional asymmetry
• Generally thought that the
both sides of the nervous
system are functionally the
same at birth
• Experience allows for some
functions to become
associated with one side of
the brain or the other
– Language associated with
left cerebral hemisphere
– Pragmatics associated with
right cerebral hemisphere
Careful: This does not mean that
we don’t use right hemisphere
when we’re using language. The
two hemisphere do communicate.
#4c Contralateral Sensorimotor Control
(esp. for body sensation and mvmnt)
• Most sensory (afferent) and motor
•
•
(efferent) fibers decussate (cross)
the midline of the body
– A touch at the right hand
crosses midline over to the left
– Movement of right is controlled
by the left
Some information (i.e. hearing)
may cross midline more than once
Some systems (e.g., speech motor
system) have both ipsilateral and
contralateral control
#5a Structure/Function Relationship
• If two NS structures have differing
morphologies (different shapes), then they
probably also have different functions (Fx)
– Different morphologies reflect different
processing times and processing
abilities
• e.g., long nerve cells with thick
insulation are designed to carry
nerve impulses long distances, as
opposed to short cells with little
insulation, designed for short
distance
• E.g., different areas of the cortex
covering the brain surface have
different cellular composition and
perform different functions
#5b Functional networking
• Many different locations are
networked together to fill
complex functions
– E.g. reading aloud
– E.g. Thinking about what
someone said and responding
appropriately
– E.g. someone taps you on the
shoulder, and you respond to it
#6 Topographical Organization
of Function
• Functions can be
strongly
associated with
certain
anatomical
locations
• E.g. Motor
homunculus (“little
man”) in primary
motor cortex
NOTE: EACH side of the
brain has BOTH a sensory
and a motor homunculus.
(Motor is in front of the
sensory on each side.)
#7 Plasticity in the Brain
• Brain is able to reorganize functions if needed
– Particularly true in younger children
– Seem to lose some of this ability as we age
• PNS may better able to reorganize than CNS
•
after trauma, but our understanding of CNS
recovery is improving
Plasticity
– Learning
– Recovery following
trauma, through
rehabilitation
#8 Culturally neutral brain
• Brain potential-independent of gender,
color, or cultural variations
• Notable variations in brain size, shape, or
weight
–Functionally unimportant normal
variations