6) neurological basis of the major acquired communication disorders

Neurological damage

Damage to central or peripheral nervous system

• Motor Speech Disorders (MSD)

• Acquired Language Disorders

What are the main anatomical regions of the brain

• Brainstem

• Cerebellum

• Cerebeal hemispheres

Brainstem

Controls vital funcrions such as breathing, heart rate, and reflexes

• cough reflex to clear trachea or breathing trube

• swallowing

Brainstem damage

Affects eating/drinking

• brainstem stroke

• requires long rehabilitation

Cerebellum

Manages balance and coordination

• primitive brain” provides the minimum brain power to survive

Cerebellum damage

Leads to ataxic dysarthria, affecting speech clarity

Cerebral Hemispheres

Controls speech, thinking, complex movements, and vision

Structure of the brain

Left and right hemisphere, each with four lobes

Four lobes of the brain

• Frontal

• Temporal

• Parietal

• Occipital

Frontal lobe

Higher-level cognition

• prefrontal cortex: cognitive dunctions; reasoning, abstract thought, decision-making, & pragmatic behaviour

• includes primary motor cortex

• broca’s area for spoken language

Temporal lobe

Processes auditory input & memory

• primary auditory cortex

• auditory association cortex

• Wernicke’s area for language comprehension

Damage to Wernicke’s area

Wernicke’s aphasia

• produces jargon: semantically empty speech

• speech is fluent, but not aware they weren;t making sense bc of absence of feedback loop

Parietal lobe

Integrates sensory information

Occipital lobe

Processes visual information relevant for reading and writing

Commissural fibers

enables the brain’s hemispheres to communicate with the body

• nerve bundles that cross from one hemisphere to the other, enabling contralateral control of the body (e.g. left hemisphere controls the right side of the body & vice versa)

Corpus callosum

Large bundle of nerve fibers that facilitates communication between the two hemispheres

Left hemisphere

Primarily responsible for (in most right-handed individuals)

• language

• logic

• speech

Left hemisphere stroke effects

Results in symptoms on the right side of the body due to contralateral control, such as right-sided weakness or paralysis

• impacts speech & language functions if left hemisphere is language dominant, which is common in right-handed individuals

Right hemisphere

Involved in:

• aspects of nonverbal communication: prosody & emotional tone

• imagination

• creativity

• spatial awareness

How does the brain communicate with the body in relation to speech?

• Through cranial nerves (for head & neck muscles) & spinal nerves (for limbs & trunk), which pass thru gaps in the spine

• Neurons connecting the CNS to muscles are known as lower motor neurons (LMN) & enable fast, complex speech motor movements

Processes of speech

• Plan on what you're going to say

• Producing sound

○ Initiation

○ Phonation

○ Articulation

§ Resonance

○ Prosody

• SLTs assess all these different processes to check which area has been impaired (can be at diff levels)