SLP 665 Study Guide Exam 1

Central Nervous System and Peripheral Nervous System

Central Nervous System and Peripheral Nervous System

2 parts of Nervous System

12 pairs of cranial nerves and 31 pairs of spinal nerves

How many cranial and spinal nerves in PNS?

Cerebrum

What structure is…

• The largest structure of the nervous system

• Two cerebral hemispheres

• Wrapped by three meningeal linings

• Cerebrospinal Fluid (CSF) and ventricular system

• Landmarks: Cerebral longitudinal fissure, lateral sulcus (a.k.a. Sylvian fissure), central sulcus (the Rolandic sulcus/fissure)

Cerebral Cortex (aka grey matter)

• Outermost layered neural tissue of the cerebrum

• Darker color, consisting of neuron cell bodies

• Divided into 5 lobes

Frontal lobe

What lobe?

• Voluntary movement and cognitive function

Primary Motor Cortex

• Important for the initiation of voluntary motor movement

• In frontal lobe

Prefrontal cortex

• Important for attention, working memory, and executive function (such as judgment, problem solving, etc.)

• In frontal lobe

Broca’s Area

• Important for verbal expression (production of fluent, well-articulated speech)

• Nearby areas: Planning and organizing speech movements

• In frontal lobe

Parietal lobe

What lobe?

• Somatic (body) sense

Primary somatosensory cortex (postcentral gyrus)

• The primary reception site of somatosensory input

• In parietal lobe

Sensory association area

• Integrating information related to \n vision (from occipital lobe), audition (from temporal lobe), and somatic sense

• In parietal lobe

Angular Gyrus

• Important for the comprehension of written material

• in dominant hemisphere

• in parietal lobe

supramarginal syrus

• Involved in language perception and processing

• in dominant hemisphere

• in parietal lobe

Temporal lobe

What lobe?

• Hearing, analysis of auditory signals, and memory formation

middle temporal gyrus

• Important for higher-level information processing and forming new memory

• In temporal lobe

Primary auditory cortex

• Organized according to the frequency of sounds

• in temporal lobe

Wernicke’s area

• important for language comprehension (processing speech and language decoding)

• in temporal lobe

occipital lobe

What lobe?

• Vision and higher-lever visual processing

• Marked by imaginary lines rather than prominent sulci

• Different regions of the occipital lobes process different aspects of visual information

Insular lobe

What lobe?

Involve in consciousness and regulation of emotion and homeostasis

Folded deep within the lateral sulcus

in the dominant hemisphere: Facilitate the production of well-articulated, fluent speech

Anterior Language Region

• Planning and organizing speech action \n – Responsible for controlling the muscles used in speech production \n • The heart of the this region: Broca’s area

In left frontal lobe

Posterior language region

• Language comprehension and formulating linguistic messages with appropriate syntax and semantic content

– Storage and retrieval of words

– Retrieval of grammatical and linguistic rules

• The heart of this region: Wernicke’s area

In left temporal and parietal lobes

Myelinated fibers (white matter)

• Make up the communication link between neurons

• 3 types: projection, association, commissural

Projection fiber

What fiber?

• Connect the cortex with the distant locations

• The tracts running to the cortex and from the cortex to the brainstem and the spinal cord, e.g. corona radiata

Association fiber

What fiber?

Provide communication between regions of the same hemisphere

• Short ___ fibers (within the same lobe)

• Long ___ fibers (between lobes), e.g. arcuate fasciculus

Commissural fiber

What fiber?

Connect one location of a hemisphere to the corresponding location of the other hemisphere, e.g. corpus callosum

Subcortex

A collection of gray matter inferior to the cerebral cortex

Basal ganglia

Control of movement and movement patterns

• subcortex

Limbic system

Mediate long-term memory, feelings, emotion, the desire to produce language

• subcortex

Thalamus

The largest structure of the diencephalon

• The final relay for nearly all sensory (except olfaction) information to the cerebral cortex

• Integrating and transmitting information

• Important role in consciousness, attention, and memory

The Carotid System

After joining the circle of Willis, the internal carotid artery divides to form the anterior cerebral artery (ACA) and middle cerebral artery (MCA)

The Vertebral-Basilar System

- Two vertebral arteries merge to form a basilar artery • After joining the circle of Willis, basilar artery forms the posterior cerebral artery (PCA)

Circle of willis

Connects the carotid system with the vertebrobasilar system

Stroke (cerebrovascular accident CVA)

– Brain damage caused by vascular disruptions

• Affects the arteries leading to and within the brain

2 types: ischemic and hemorrhagic

Ischemic stroke

Type of stroke?

• Occurs when a blood vessel that supplies blood to the brain is blocked

– Often results from atherosclerosis (a thicken artery wall causes narrowing of the arterial lumen)

Thrombosis

A clot may form in an artery that is already very narrow (thrombus)

Thrombotic stroke

Type of stroke?

When thrombus completely blocks the artery

Embolic stroke

Type of stroke?

• A clot may break off from somewhere (embolus) and travel up to the brain to block a smaller artery

Transient Ischemic Attack (TIA)

-an episode in which a person has stroke-like symptoms.

– Symptoms, are similar or the same as a stroke, begin suddenly, last only a short time (from a few minutes to an hour), and disappear completely

• TIA is a temporary interruption of blood supply to the brain

– Results in a sudden, brief decrease in brain function – It is caused by mechanisms that interfere with blood supply to the brain

Hemorrhagic stroke

Type of stroke?

• Occurs when a blood vessel in part of the brain becomes weak and bursts open, causing blood to leak into the brain

– The flow of blood damages the brain

• Possible Causes

– Weakness of a vessel wall, traumatic injury to a vessel, or extreme fluctuations in blood pressure (rare)

Intracerebral hemorrhagic stroke

Occurs when a diseased blood vessel within the brain bursts, allowing blood to leak inside the brain

• Common sites: Thalamus, basal ganglia, brainstem, and cerebellum

Extracerebral hemorrhagic stroke

subarachnoid hemorrhages is the most common and often caused by cerebral aneurysms

• Aneurysms are weak or thin spot on a blood vessel in the brain that balloons out and fills with blood

• The blood vessel wall becomes weak and prone to rupture \n

Acute therapy

Stroke treatment

– To protect and improve blood flow to the region of infraction during early stage of stroke

– Emergency treatment with medications (clot-busting drugs)

• Example: Tissue plasminogen activator (t-PA). Must be given within 3 hours after the onset of an ischemic stroke

Chronic Therapy

Stroke treatment

– Rehabilitation begins as soon as possible when the patient is medically stable (May begin within 48 hours after the stroke)

• To improve function so that the stroke survivor can become as independent as possible

Aphasia

• An acquired communication disorder caused by brain damage, characterized by an impairment of language modalities: speaking, listening, reading, and writing.

• results from damage to the parts of the brain that contain language

• may cause difficulties in speaking, listening, reading, and writing, but does not affect intelligence.

1. Neurogenic

2. Acquired

3. Involves language problems

4. May also have other problems like dysarthria, apraxia or dysphagia

Aphasia (4 characteristics)

• stroke (most common)

• head injury

• Cerebral tumors

• infection/ inflammation

• Any brain tissue damage that occurs in the language center of the brain

Etiology of aphasia

Neuroplasticity

• Brain’s ability to modify, change, and adapt both structure and function throughout life and in response to experience.

• The ability of the nervous system to respond to intrinsic or extrinsic stimuli by reorganizing its structure, function and connections.

Behavioral changes

• Neuroplasticity drives __ ____. __ ____ drive brain plasticity.

diaschisis

a sudden loss of function in a portion of the brain connected to, but at a remote distance away from, a damaged area

Injury-Induced Neuroplasticity

• The brain compensates for damage by reorganizing and forming new connections between intact neurons • Requires stimulation and opportunities for learning

stimulation and opportunities for learning

What is required for injury-induced neuroplasticity?

Rerouting

• re-establishing an existing nervous connection via an alternative neural pathway.

• new neural connections are made between a neuron and other active neurons

Sprouting

growth of new axon or dendrite fibers to enable new \n neural connections to be formed.

Rerouting and sprouting

Adaptive plasticity is achieved vis 2 primary mechanisms:

stimulation

__________ is needed for neural “reconnection” and “reorganization”

Recruitment of different or remote neural circuits \n allows a given behavior to occur in a different way \n • As learning takes place, new neural pathways are \n generated \n • New pathways allow the brain to perform lost \n functions in a new and different way

Pros for neuroplasticity

This reorganization may inhibit the potential for \n restoration of the damaged neural circuits

Cons for neuroplasticity

Recovery

Perform previously impaired task in the same manner as before the injury

Compensation

• Use of a new strategy to perform the same task.

• Focus on independence NOT impairment.

• Different neural tissues take over the lost function

6-8 weeks

Spontaneous recovery happens during the first ______ after a stroke depending on the etiology, size & location of the lesion.

• RH can take over SOME linguistic functions after a LH stroke. \n • Therapy induced recovery involves both hemispheres.

Better recovery requires LH reorganization of language skills following a temporary increasing RH activity. \n ➡New left hemisphere regions not previously involved in language function may be recruited (Fridriksson et al., 2012). Domain-general networks not specifically related to language in LH may play a role in supporting recovery from aphasia

Role of right hemisphere during recovery

• Site of lesion

• Lesion size

• Severity

• Time Post-onset

• Personal factors

• Psychosocial factors

Factors Related to Recovery-Type of Impairment

Verbal (auditory) comprehension deficits

• Compromised ability to comprehend the verbal language

• Auditory comp involves self monitoring and self-correction.

• Poor comp—> compromised self-monitoring—> not aware of their own speech errors (e.g., Wernicke’s & Global aphasia: do not self correct)

Anomia

• Greater than normal word retrieval problems.

• Problems with recalling words or names or to find the appropriate word to identify an object or person

Circumlocation

• know what intended word but cannot find the word.

• Indirect, roundabout language to describe a word or concept

Paraphasia

speech disturbances resulting from brain damage in which words are jumbled and sentences meaningless

Phonemic/ Literal paraphasia

• Speech errors are unrelated to motor deficits but linked to higher language-level deficits associated with aphasia.

• Syllables, words, or phrases produced unintentionally by an individual with aphasia

• Substitution, insertion, deletion, or transposition of phonemes (usually with at least 50% overlap of phonemes between error production and target, but definitions differ).

• Error production may be a word (telephone —> television) or non-word (e.g., I drove home in my lar).

Semantic/ verbal paraphasia

• Have a clear semantic relationship to the desired word and represent the same part of speech (Goodglass, 1993).

• Identified based on whether there is a semantic relationship between the error and the intended word.

• Self correction may or may not occur

• e.g., cup/glass, wife/husband, talk/hear, milk/juice, glass/water

Neologistic paraphasia/ neologism

• Non-word substitution for a target word (usually with less than 50% overlap of phonemes between error and target)

• Spoken words which cannot be identified as having come from the patient's language.

• e.g., planker/comb; pinwad/light; leoz/belt