SPHS 4050SPHS 4050Neurological Bases of Neurological Bases of Speech and Hearing Speech and Hearing

SciencesSciences

Scope of practice in Scope of practice in speech-language pathology speech-language pathology

and audiologyand audiology

•Communication…of any Communication…of any and all types!and all types!

•SwallowingSwallowing

The role of the neurological The role of the neurological system in communication system in communication and swallowing and swallowing

• Carries motor, efferent Carries motor, efferent signals signals in the direction in the direction away from away from the brain the brain (rostral CNS to distal PNS) (rostral CNS to distal PNS)

• Carries Carries sensory, afferent sensory, afferent signals signals in the direction in the direction towardtoward the brain (distal the brain (distal PNS to rostral CNS)PNS to rostral CNS)

The process of The process of communicationcommunication depends on depends on the neurological system the neurological system

Expressive communication Expressive communication uses efferent neurological uses efferent neurological pathwayspathways

Receptive communication Receptive communication uses afferent neurological uses afferent neurological pathwayspathways

Neurological system supports variety of communicative Neurological system supports variety of communicative functionsfunctionsEfferent modality + afferent modality

Efferent (motor) neural pathways for expressive communicationBRAIN PLANS AND INITIATES

Afferent (sensory) neural pathways for receptive communicationBRAIN 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 persone.g. making a braille messagee.g. handing person an object

e.g. feel touch of otherse.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 Neurological system also supports the pragmaticspragmatics of communication, no of communication, no matter what the modality…..matter what the modality…..

• Expressive:Expressive:– Planning and using the “right” communication Planning and using the “right” communication for the for the

given contextgiven context•e.g. changing one’s talking style for a close friend vs. one’s boss 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 e.g.deciding when and where to use certain gestures

• Receptive:Receptive:– Figuring out appropriateness and “deeper meaning” of Figuring out appropriateness and “deeper meaning” of

communication, communication, for the given contextfor the given context•e.g. We could figure out what he e.g. We could figure out what he reallyreally meant by that meant by that

comment… He wasn’t really complimenting her….comment… He wasn’t really complimenting her….

•e.g. Why did he/she use e.g. Why did he/she use thatthat intonation in his/her “Oh” ? intonation in his/her “Oh” ?

Pragmatics applies across all the efferent and afferent Pragmatics applies across all the efferent and afferent modalitiesmodalities

The process of The process of swallowingswallowing depends on the neurological depends on the neurological systemsystem

Swallowing uses both Swallowing uses both efferent and afferent efferent and afferent neurological pathways neurological pathways • Movement (efferent)Movement (efferent)

• Sensation (afferent) Sensation (afferent)

NOTE: Smell and taste are integral for eating, too!

Phases of Phases of swallow swallow require require the use the use of both:of both:

• Efferent Efferent (motor) (motor) neural neural pathwayspathways

• Afferent Afferent (sensory) (sensory) neural neural pathwayspathways

Why Neurosciences for Why Neurosciences for Specialists in Communication Specialists in Communication and Swallowing (like Speech-and Swallowing (like Speech-Language Pathologists and Language Pathologists and

Audiologists)?Audiologists)?

Well, sometimes a client has loss of a Well, sometimes a client has loss of a communicative function (communicative function (clinical sign or clinical sign or symptomsymptom), which is related to disease or ), which is related to disease or damage in the neurological system damage in the neurological system ((neuropathologyneuropathology))Efferent modality + afferent modality

Efferent (motor) neural pathways for expressive communicationBRAIN PLANS AND INITIATES

Afferent (sensory) neural pathways for receptive communicationBRAIN 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

• Clinicopathologic methodClinicopathologic method – Relation between: Relation between:

•the behavioral functions that are the behavioral functions that are lost or modified (as seen in the lost or modified (as seen in the clinicclinic), and ), and

•the site of a lesion (neurological the site of a lesion (neurological damage, damage, pathologypathology))

– Tools: Tools: •Careful documentation of client’s Careful documentation of client’s

abilities abilities

PLUSPLUS

•Neurodiagnostic techniques (as in Neurodiagnostic techniques (as in Chapter 20)Chapter 20)

• Clinicopathologic method is used in the field of Clinicopathologic method is used in the field of behavioral neurologybehavioral neurology: “Study of how client’s : “Study of how client’s behaviorsbehaviors/abilities are related to or supported by /abilities are related to or supported by the neurological system” the neurological system”

• Examples from the fields of speech-language Examples from the fields of speech-language pathology and audiology, that we’ll encounter in pathology and audiology, that we’ll encounter in this classthis 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 Need for this knowledge/understanding of knowledge/understanding of

behavioral neurologybehavioral neurology• Variety of work settingsVariety of work settings

– SchoolsSchools– HospitalsHospitals– Medical centersMedical centers– University and private clinicsUniversity and private clinics

• Increasingly interdisciplinary work Increasingly interdisciplinary work settings need workers with specialized settings need workers with specialized knowledge, who can also interpret knowledge, who can also interpret work of other disciplineswork of other disciplines

•e.g. IMT (interdisciplinary management team)e.g. IMT (interdisciplinary management team)

•e.g., multidisciplinary school IEP meetingse.g., multidisciplinary school IEP meetings

Basic Principles of the Basic Principles of the Organization of the Nervous Organization of the Nervous

SystemSystem

Basic Principles: Basic Principles: Why Study These? Why Study These?

• They give us clue about how the They give us clue about how the nervous system is organizednervous system is organized– Our understanding of these principles Our understanding of these principles

affects how we study and investigate affects how we study and investigate the brainthe brain

– These principles are based on These principles are based on clinicopathologic evidence of how the clinicopathologic evidence of how the brain worksbrain works

#1: Interconnectivity in the #1: Interconnectivity in the BrainBrain• All functionally All functionally

discrete/separatdiscrete/separate regions of the e regions of the brain are brain are connected, connected, eithereither

– DirectlyDirectly– IndirectlyIndirectly

• Multiple areas Multiple areas interact, e.g., interact, e.g., for language, for language, memory, memory, attentionattention

See pp. 73-77 for discussion of the

three types of connecting fibers!

#2: Centrality of Central #2: Centrality of Central Nervous System (CNS)Nervous System (CNS)

• Role of Central nervous system Role of Central nervous system (brain and spinal cord)(brain and spinal cord)– Integrate impulses: Bring information Integrate impulses: Bring information

in and make sense of itin and make sense of it– Generate impulses: Typically Generate impulses: Typically

accomplished through movementaccomplished through movement

• CNS “Collaborates” with CNS “Collaborates” with peripheral nervous system PNS peripheral nervous system PNS (outside of brain and spinal cord)(outside of brain and spinal cord)

• Info entering and leaving the CNS Info entering and leaving the CNS are carried by different pathwaysare carried by different pathways– Information going (up) to the CNS Information going (up) to the CNS

from the PNS is from the PNS is sensorysensory or or afferent.afferent.– Information coming (down) from the Information coming (down) from the

CNS to the PNS is CNS to the PNS is motor motor or or efferentefferent. .

#3a Hierarchy of Neuraxial #3a Hierarchy of Neuraxial organization: Lower to organization: Lower to HigherHigher• Lower levels perform more basic Lower levels perform more basic functions, higher levels perform functions, higher levels perform more complex functionsmore complex functions

• For example (going from For example (going from simple/basic to more complex)simple/basic to more complex)

− Spinal cord responsible for Spinal cord responsible for reflexes (no cognitive reflexes (no cognitive involvement)involvement)

− Brain stem responsible for more Brain stem responsible for more complex tasks such as body complex tasks such as body functions (breathing, heart beat)functions (breathing, heart beat)

− Brain’s cortex is responsible for Brain’s cortex is responsible for complex integration and higher complex integration and higher mental functions, like language, mental functions, like language, memory, and attentionmemory, and attention

#3b Hierarchy of Organization: #3b Hierarchy of Organization: Inside to OutsideInside to Outside

• Structures at deeper level of brain: Structures at deeper level of brain: More basic/primal/olderMore basic/primal/older– e.g. limbic system (in color): Basic e.g. limbic system (in color): Basic

emotionsemotions such as fear, as linked such as fear, as linked to to memorymemory

• Structures closer to surface: Structures closer to surface: “Newer” structures develop on top “Newer” structures develop on top of older structuresof older structures– E.g., neocortex (in brown) is laid E.g., neocortex (in brown) is laid

on top of the (older) limbic on top of the (older) limbic system, and allows us to system, and allows us to “think “think about,” interpret, analyze, planabout,” interpret, analyze, plan, , based on memories and emotions based on memories and emotions associated with themassociated with them

#4a Bilateral #4a Bilateral AnatomicAnatomic Symmetry (throughout NS)Symmetry (throughout NS)

• Both sides of Both sides of CNS essentially CNS essentially structural mirror structural mirror images of each images of each otherother

• This principle is This principle is used in medical used in medical diagnosisdiagnosis

#4b Unilateral #4b Unilateral functionalfunctional asymmetryasymmetry• Generally thought that the Generally thought that the

both sides of the nervous both sides of the nervous system are functionally the system are functionally the same at birthsame at birth

• Experience allows for some Experience allows for some functions to become functions to become associated with one side of associated with one side of the brain or the otherthe brain or the other– Language associated with Language associated with

left cerebral hemisphereleft cerebral hemisphere– Pragmatics associated with Pragmatics associated with

right cerebral hemisphereright cerebral hemisphereCareful: This does not mean

that we don’t use right hemisphere when we’re using

language. The two hemisphere do communicate.

#4c Contralateral Sensorimotor #4c Contralateral Sensorimotor Control (esp. for body sensation Control (esp. for body sensation and mvmnt)and mvmnt)• Most sensory (afferent) and motor Most sensory (afferent) and motor

(efferent) fibers (efferent) fibers decussatedecussate (cross) (cross) the midline of the bodythe midline of the body– A touch at the right hand crosses A touch at the right hand crosses

midline over to the left midline over to the left – Movement of right is controlled Movement of right is controlled

by the left by the left

• Some information (i.e. hearing) Some information (i.e. hearing) may cross midline more than oncemay cross midline more than once

• Some systems (e.g., speech motor Some systems (e.g., speech motor system) have both system) have both ipsilateral ipsilateral and and contralateralcontralateral control control

#5a Structure/Function #5a Structure/Function RelationshipRelationship• If two NS structures have differing If two NS structures have differing

morphologies morphologies (different shapes), then (different shapes), then they probably also have different they probably also have different functions (Fx)functions (Fx)– Different morphologies reflect Different morphologies reflect

different processing times and different processing times and processing abilities processing abilities

• e.g., long nerve cells with thick e.g., long nerve cells with thick insulation are designed to carry insulation are designed to carry nerve impulses long distances, as nerve impulses long distances, as opposed to short cells with little opposed to short cells with little insulation, designed for short insulation, designed for short distancedistance

•E.g., different areas of the E.g., different areas of the cortexcortex covering the brain surface have covering the brain surface have different cellular composition and different cellular composition and perform different functionsperform different functions

#5b Functional networking#5b Functional networking• Many different locations are Many different locations are

networked together to fill networked together to fill complex functionscomplex functions– E.g. reading aloudE.g. reading aloud– E.g. Thinking about what E.g. Thinking about what

someone said and responding someone said and responding appropriatelyappropriately

– E.g. someone taps you on the E.g. someone taps you on the shoulder, and you respond to shoulder, and you respond to itit

#6 Topographical #6 Topographical Organization of FunctionOrganization of Function

• Functions can Functions can be strongly be strongly associated associated with certain with certain anatomical anatomical locationslocations

• E.g. 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#7 Plasticity in the Brain• Brain is able to reorganize functions if neededBrain is able to reorganize functions if needed

– Particularly true in younger children Particularly true in younger children – Seem to lose some of this ability as we ageSeem to lose some of this ability as we age

• PNS may better able to reorganize than CNS PNS may better able to reorganize than CNS after trauma, but our understanding of CNS after trauma, but our understanding of CNS recovery is improvingrecovery is improving

• Plasticity Plasticity – LearningLearning– Recovery following Recovery following trauma, through trauma, through rehabilitationrehabilitation

#8 Culturally neutral brain#8 Culturally neutral brain

•Brain potential-independent of Brain potential-independent of gender, color, or cultural variationsgender, color, or cultural variations

•Notable variations in brain size, Notable variations in brain size, shape, or weight shape, or weight – Functionally unimportant normal Functionally unimportant normal

variationsvariations