Neurological bases of speech eamm 5

subcortical tracts associated w lang processing

dorsal pathway

ventral pathway

uncinate fasciculus

dorsal pathway

superior longitudinal fasciculus

arcuate fasciculus

ventral pathway

inferior longitudinal fasciculus

early auditory processing

activation of the superior temporal gyri bilaterally

• left posterior superior temporal sulcus- familiar auditory patterns

superior temporal gyrus is responsible for

early auditory processing

semantic processing terms

meaningful speech

semantic access

semantic retrieval

sentence comprehension

meaningful speech (anatomy)

left middle and inferior temporal cortex

semantic access (anatomy)

left posterior superior, middle and inferior temporal gyri

semantic retrieval (anatomy)

left angular gyrus and pars orbitalis

sentence comprehension (anatomy)

superior temporal sulci bilaterally

semantic control

-word retrieval and selection: left inferior frontal gyrus

-uncinate fasciculus

-inferior longitudinal fasciculus

speech production steps

speech planning

speech initiation and execution

speech planning anatomy

left anterior insula

speech initiation and execution anatomy

left putamen

presupplementary motor area

supplementary motor area

motor cortex

speech monitoring: response suppression (anatomy)

anterior cingulate

bilateral head of caudate nuclei

speech monitoring: response suppression (what it is)

we monitor the speech we produce and correct errors

language function among older adults

rely on support networks outside traditional core lang networks, extending to right homologous counterparts

bilateral involvement

two types of brain measures

static

dynamic

static measure

structural changes or abnormalities

dynamic measure

metabolic changes during task

static measure goods

typically good for detailed pics of brain anatomy and large lesions

static measure not so good

dont provide info on fuctioning or info on the blood flow

dynamic measure good

provide info on how brain is functioning with respect to blood flow, metabolism and response to stimulation

dynamic measure not so good

not very complex with relatively poor anatomical benefits

static brain measures (tests)

computed tomography scant (CT scan)

magnetic resonance imaging (MRI)

cerebral angiography

computed tomography scan: procedure

x-ray generator rotates around head

scan for tissue density

computer analyzes images

present anatomical structure

what does computed tomography scan show

shows in grey, ventricles, csf, and air 

CT scans can be applied to (limbs)

chest, pelvis, and extremities

CT scan identifies _____ structural changes

large

CT scan identifies large structural changes such as

bone fractures

tumors

tissue displacement

hematoma or hemorrhage

enlarged ventricles (CSF

CT scan advantages

non-invasive

inexpensive

detect large structural changes

CT scan disadvantages

radiation

MRI w better resolution

MRI procedure

provide an anatomical view of the brain using radio waves in a magnetic field

• head placed in magnetic field

• nuclei align w magnetic field which sends electromagnetic pulse

• alignment is disrupted and nuclei swing back into alignment

• nuclei send electromagnetic signal that’s analyzed

MRI advantages (2)

better resolution than CT

no radiation

MRI disadvantages

expensive

take a longer scanning time

cannot use with patients with metallic devices, uncooperative patients, or patiences who are claustrophobic

CT scan vs MRI

both non invasive

MRI: detects small lesions, tumor, infarct

MRI diffusion tensor imaging

used more commonly to study brain fiber tracts

look at white fiber tracts

MRI: DTI measures

the directionality of water molecular movements affects by tissue barriers in the body

MRI: DTI identifies

intact vs impaired myelination axonal tracts (white matter)

• multiple sclerosis

• Alzheimer disease

• aphasia

• alexia

• autism

• schizophrenia

cerebral angiography provide..

visual presentation of cerebral blood vessels

cerebral angiography detects

vascular disorders:

• thrombosis (blood clot)

• hemorrhage (bleeding)

• aneurysm

• malformations of arteries and veins

CA procedure

a catheter is inserted into a large artery (common femoral artery in the groin) → up through the carotid artery

a radiopaque contrast agent (radioactive dye) is inserted into the catheter and images (radiographs) are taken

Cerebral angiography (invasive/ non invasive)

invasive: radioactive contrast material injected into arteries

• series of xrays

• stroke risk (rare)

• little info beyond the blockage point

dynamic brain measures (tests)

positron emission tomography (PET)
functional magnetic resonance imaging (fMRI)

Positron emission tomography procedure

-inject glucose or water molecules with radioactive (positron-emitting) isotope into the bloodstream

-changes in glucose and oxygen in neurons and cerebral blood flow

-computer analyzes metabolism

• represented by colors on computer image

• low metabolism implies structural and or functional problems

PET (downsides)

invasive

research-oriented and expensive

structural boundaries- difficult to identify

functional magnetic resonance imaging (mri vs fmri)

same apparatus as MRI but analyzes changes in blood oxygen levels

blood oxygenation level dependent (BOLD ) imaging

When a neuronal activity ____, there is an ______ demand for O2 so there is an _____ demand for blood flow. Since blood oxygenation varies according to the levels of neuronal activity, these differences can be used to detect levels of brain activity

increases

increased

increased

fMRI shows

-both an anatomical and a functional view of the brain

-changes in oxygenation overlaid onto MRI structural ‘map’ => indicate precise areas of activity

fMRI advantages

-produce high resolution images

-present images of blood flow in the brain as it is occurring

• more specific than PET or CT

-produce images of brain activity in <3 sec

• PET takes >40 sec

Neuroplasticity

neurons have the capacity to alter and adapt their structure and function in response to internal and external pressures (eg learning, behavioral training)

Hebbian learning

learning stems from changes in neural connections at the level of the synapse

hebbian learning: cells that fire together wire together meaning

2 separate and disconnected neurons becomes simultaneously activated during a repetitive and persistent stimulation of both neurons (or a network of neurons)

brain reorganization healthy

learning involves changes in synapses, neurons and neuronal networks in specific regions

brain reorganization injured

development of compensation strategies to preform daily activities.

reorganization of remaining tissue in the damaged brain

• axonal spouting

axonal sprouting

brain attempts to overcome damage: healthy neurons send out new projections that will reestablish some of the connections lost or damaged to the injury and form new ones resulting in partial recovery

if rehabilitation can change ____, it can change the ____

behavior

brain

a group of injured neurons may become ____ if they are activated at the same time

reconnected

SLPs work on facilitating the “____ __ ____ ___ after the brain injury through rehabilitation”

reconstruction of behavioral functioning

principles of experience- dependent neural plasticity- planning matters

1. specificity

2. salience

3. interference

4. time

5. age

1.Specificity

the nature of the training experience dictates that nature of the plasticity. provide tx tasks that mirror real world experience

make stimuli and context as similar to target task as possible

2.Salience matters

the training experience must be sufficiently salient to produce plasticity. Use target tasks and behaviors that are relevant and meaningful to the user

3.Interference

plasticity in response to one experience can interfere with the acquisition of others

during initial acquisition training, be sure that training does not address multiple, salient targets simultaneously

4.Time

difference forms of plasticity occur at different times during training

Tx should be provided as early as possible (eg during acute post-injury period)

5.Age

training-induced plasticity occurs more readily in younger brains

whereas younger brains may have a great ability to substitute function they have fewer established pathways to support learned behaviors

Principles of experience- dependent neural plasticity- Practice Matters

1. use it or lose it

2. use it and improve it

3. repetition

4. intensity

5. transference

1.Use it or lose it

failure to drive a specific brain function can lead to functional degradation

2.Use it and improve it

training that drives a specific brain function can lead to an enhancement of that function

3.Repetition matters

induction of plasticity requires high amount of practice

provide high amounts of practice

4.Intensity matters

induction of plasticity requires sufficient training intensity

provide intensive practice during initial target acquisition

5.Transference (generalization)

plasticity in response to one training experience can enhance the acquisition of similar behaviors

generalization is more likely to occur to a lang behavior that is similar to the trained lang behavior

The brains metabolic needs are important in regulation of ___ ___

blood flow

____ blood pressure forces blood through brain

• elasticity of ____ wall

arterial

interruption of blood flow after 1 min

neuronal activity stops

interruption of blood flow after 4-6 mins

irreversible damage

2 main circulation systems

vertebral arteries

carotid arteries

• external carotid

• internal carotid

vertebral arterial system

basilar artery

basilar artery joins ___ arteries at ____

vertebral

pons

basilar artery eventually connects into ___ ___ ___

posterior cerebral arteries

basilar artery supplies

posterior regions of brain

brainstem

cerebellum

spinal cord and posterior spinal nerve roots

common carotid artery parts

external carotid

internal carotid

external carotid artery supplies

face, oral and nasal cavities

internal carotid is a major source of …

blood to the brain

internal carotid supplies

anterior portions of the brain

parts of internal carotid artery system

anterior cerebral artery

middle cerebral artery

anterior communicating artery

posterior communicating artery

each internal carotid artery devides into ___ and ____

MCA
ACA

MCA is a direct continuation of ____

ICA

AComm connects 2 ___

ACA

PComm connects ___ with the ____

ICA
PCA

Anterior cerebral artery (abreviation)

ACA

Anterior cerebral artery branches off from ____

ICA

Anterior cerebral artery connects with the ____

AComm

anterior cerebral artery supplies

medial and upper lateral surface of brain

• upper/anterior of frontal lobes

• top of motor/sensory strip

• portions of corpus callosum

• internal capsule

• other deep structures

ACA impairment

contralateral hemiplegia of legs and feet

present prefrontal symptoms

largest artery

MCA

middle cerebral artery supplies

entire lateral surface of brain (except that supplied by ACA and PCA)

• frontal, parietal, and temporal lobes

• all sensory and motor regions other than leg

MCA impairment

contralateral hemiplegia (motor disorders other than leg)

impaired sensory function

aphasia, apraxia

MCA Striate Arteries

supply insula, internal capsule, basal ganglia

common site of CVAs related to hypertension, especially hemorrhages

MCA stands for

middle cerebral artery

PComm stands for

posterior communicating artery