Higher Cortical functions

Define:

• Aphasia: 

• Paraphasia: 

• Neologism 

• Prosody 

• Anomia 

Definitions:

• Aphasia: 

  • acquired disturbance of language function resulting from damage to CNS

• Paraphasia: 

  • production of incorrect word 

    • via substitution of phonemes or words w/ correct word

• Neologism 

  • paraphasic error where a novel word is produced

• Prosody 

  • melodic contour of speech

• Anomia 

  • difficulty in accessing names of objects

• Describe the relationship between Language Dominance vs Hand dominance:

• Anatomical Proof?

• Laboratory Proof?

• Language Dominance vs Hand dominance:

  • Right handed: 99% Left Hemi Dominance

  • Left Handed: 70% Left Hemi Dominance

• Anatomical Proof:

  • Seen in size differences the two Planum temporale

• Laboratory Proof:

  • Wada Procedure:

    • Sodium amytal injection into 1 (R or L) carotid artery -> put hemisphere to sleep

    • Test Pts. Language capabilities 

      • Which ever hemisphere provoke language difficulties = language dominance

      • Also, Which ever hemisphere provokes Contralateral paralysis/sensory loss

List the Neurological Locations of Language and Function

Neurological Locations of Language:

• Perisylvian structures

  • Broca's area

    • motor speech 

  • Wernicke's area

    • language comprehension

  • arcuate fasciculus

    • Links the two 

  • Angular Gyrus:

    • Involve in comprehension of Written speech

      • Info transferred from visual cortex

Draw out the Wernicke-Lichtheim Schema

1. List the Exact Locations of  language implementation

   • Broca’s

   • Wernicke's 

   • Other

2. List the Neural Substrates for conceptual knowledge

   • What is Conceptual Knowledge:

   • Locations that mediate language implementation/conceptual systems:

Exact Locations of  language implementation :

• Broca’s:

  • Inferior frontal operculum 

  • BA 45, 44

• Wernicke's 

  • left posterior superior temporal gyrus 

  • BA 22 (posterior)

• Other regions in Left Perisylvian 

  • Inferior parietal lobule

  • insula 

  • subadjacent white matter

    • arcuate fasciculus

---

Neural Substrates for conceptual knowledge

• What is Conceptual Knowledge:

  • Association of word forms w/ meaning

• Locations that mediate language implementation/conceptual systems:

  • Posterior sensory association cortices, 

  • left prefrontal cortex,

  • inferotemporal region

  • temporal pole

What are the 3 factors for determining aphasias:

3 factors for determining aphasias:

• Fluency

• Comprehension

• Verbatim repetition

Describe Expressive Aphasia (Broca's aphasia)

• Symptoms

• Areas Invovled

Expressive Aphasia (Broca's aphasia)

• Symptoms:

  • Impaired speech production (fluency) + repetition

    • Decreased and labored output

  • Intact auditory comprehension

  • Pts aware of disability + frustrated -> use inappropriate or vulgar language

  • Agraphia 

  • Understanding complex instructions

  • Hemiparesis + upper motor neuron signs (facial weakness)

• Areas involved:

  • Broca's area (BA 44/45)

  • left frontal operculum, 

  • underlying white matter

  • anterior insula.

Describe Receptive Aphasia (Wernicke's aphasia)

• Symptoms

• Locations

Receptive Aphasia (Wernicke's aphasia)

Symptoms:

• impaired auditory comprehension, naming, and repetition

  • “Everyone seems to mumble”

• Fluent speech w/ paraphasia + neologisms 

• Alexia

• Agraphia

• Less aware of deficit -> not as frustrated 

• Contralateral homonymous hemianopia (or quadrantanopia)

  • Via lesions of Meyer’s loop + Optic Radiation

---

Locations:

• Wernicke's area

• nearby regions in temporal and lower parietal cortices

Describe Conduction aphasia 

• Symptoms

• Locations

Conduction aphasia 

• Symptoms:

  • Impaired naming and repetition w/ intact comprehension

  • Fluent paraphasic speech

• Locations:

  • Arcuate Fasciculus

  • Damage to either supramarginal gyrus (BA 40) in inferior parietal lobe or to primary auditory cortices with extension into insular cortex and subadjacent white matter

Describe Global aphasia 

• Symptoms

• Locations

Describe Transcortical aphasia:

• What causes/spares impaired repetition?

• Describe Transcortical Motor/Sensory Aphasia

Global aphasia 

• Symptoms:

  • all major functions of language are impaired

    • Poor recovery 

• Location:

  • Extensive destruction of left perisylvian region

---

Transcortical aphasia:

• What causes Impaired repetition:

  • Impaired repetition: damage to perisylvian region

  • Repetition spared:  Damage anterior to Broca's area or posterior to Wernicke's area

• Transcortical Motor Aphasia

  • Resembles Broca's aphasia but repeat verbatim ability is preserved

• Transcortical Sensory Aphasia

  • Resembles Wernicke's aphasia but verbatim repetition is spared 

    • Damage to temporal-occiptal-parietal junction — angular gyrus

Describe Anomic Aphasia

• What is it?

• Location

List the Verb/Noun retrieval Locations:

List the specific noun locations:

• Proper

• Common

  • Animal?

  • Tools?

Anomic Aphasia

• What is it?

  • impairment of confrontation naming (anomia)

• Location:

  • Left inferotemporal or anterior temporal regions

---

Noun/Verb retrieval Locations:

• Verb: 

  • left premotor/prefrontal region

• Noun:

  • left inferior and anterolateral temporal regions

---

Specific Noun Locations:

• Proper nouns (names)

  • left temporal polar region (BA 38)

• Common nouns

  • inferotemporal region (BA 20/21; anterior 37)

    • Animal Names: Ant. Left

    • Tools: Post. Left

Describe Aprosadia

• What is it?

• Symptoms?

• Location?

Aprosadia

• What is it?

  • Prosody w/o aphasia

    • Motor or Sensory

• Symptoms:

  • Monotone voice, 

  • inability to express emotion in speech (anger, distress, etc)

  • Inability to understand prosody of speech, e.g., "You're going home?"

• Location:

  • right hemisphere in areas corresponding to language areas of the dominant hemisphere

Broca’s

Wernicke’s

Conduction Aphasia

Global Aphasia

Red = transcortical motor aphasia

blue = transcortical sensory aphasia

Blue = verb retrieval

red = proper nouns

yellow = common nouns

Describe Alexia + Agraphia:

• Location

Describe Alexia w/o agraphia

• What is it?

• Location?

Alexia + Agraphia:

• Location:

  • Dominant Angular Gyrus

---

Alexia w/o agraphia

• What is it?

  • Pure word blindness

  • Writing = normal, but pt cannot read it.

    • disconnection between bilateral visual system and unilateral language system (angular gyrus)

  • Right hemianopia

  • color agnosia

• Location:

  • Left visual cortex and splenium of corpus callosum

Alexia + agraphia

Alexia w/o agraphia

Describe the Magnocellular Stream

• Pathway

• Function?

• Lesions Symptoms

• Blindsight?

Magnocellular Stream

• Pathway:

  • Involves lateral geniculate +  pulvinar.

  • Info from RGCs (mostly rods) w/ large receptive fields

• Function:

  • "where" objects are

    • position, 

    • Motion (objects moving + perception of body moving) 

      • Moving edges detection 

      • Appreciation of motion

    • depth, and other spatial information.

    • Higher level processing:

      • Navigation

      • Directing eye movement

      • Motion perception

    • Suppression of vision during saccades

• Lesions Symptoms:

  • Cannot appreciate object motion

    • “not being able to cross the street because cars seemed at first far away and then suddenly very near.

    • People in a room would also suddenly appear in different places.

• Blindsight:

  • In pts w/ qeniculostriate pathways lesions 

  • Lose all conscious vision but can demonstrate perception of movements or changes in light

Describe the P stream

• Pathway

• Function

• Lesions/Locations:

  • Prosopagnosia

  • cerebral achromatopsia

The P stream (parvocellular, X, blob zone) 

• Pathway:

  • Parvocellular (Cone) area of LGN -> V2 -> V4 (A19) -> inferior temporal region -> A 20, 21, 37 of temporal cortex

• Function:

  • “What”

    • color 

    • Shape 

      • (high) resolution aspects of form

  • @ higher levels:

    • Face Recognition 

      • (inferior temporal lobe)

• Lesions/Locations:

  • Bilat lesions of Inferior temporal + fusiform:

    • Prosopagnosia

      • Inability of facial recognition

      • May be associated w/ autism

  • V4 lesions + adj. Area (occipitotemporal gyrus; fusiform gyrus)

    • cerebral achromatopsia

      • World = shades of gray

      • May affect quadrants (upper), Hemi field, or complete Field

      • Associated w/ visual field defects or prosopagnosia

Prosopagnosia

cerebral achromatopsia

Describe Balint syndrome

• Cause

• Symptoms

Balint syndrome

• Cause:

  • Bilat lesions involving parieto-occipital junction

• Symptom: triad:

  • optic apraxia 

    • poor control of eye movements

  • optic ataxia

    • poor visually guided movement

      • ability to point to or reach for an object

  • Simultapnosia

    • inability to perceive visual field as a whole

Describe Non dominant Parietal Lesions

• Function/ Lesion -

• Symptoms

Non dominant Parietal Lesions

• Function:

  • Dominant in directing attentive processing

    • Lesion = disruption of spatial relationships and selective attention

• Symptoms:

  • contralateral neglect  (left spatial/visual field) svndrome

    • unaware of objects/events in left half of his surrounding space, including own body (asomatoapnosia)

    • dressing apraxia

      • “staff get the ‘other person" out of the bed

    • Constructional apraxia

      • Inability to successfully manipulate objects in space or to duplicate a simple block construction

Note:

• Dom. parietal = language

Describe Prefrontal Cortex lesions

• Function

• dx difficulty

• Old ways to treat?

• Specific locations/functions:

  • Dorsolateral prefrontal region

  • Ventral medial Region (includes? )

  • Superior mesial region (includes? )

• Frontal Lobe and emotion:

  • Left vs right lobes

  • Clinical Associations:

Prefrontal Cortex lesions

• Function:

  • human intellectual traits

    • Judgment. Foresight, purpose, responsibility, social propriety

• Diagnosis difficulty:

  • Subtle lesions hard to detect

• Old ways to treat:

  • Prefrontal lobotomy

    • Ice pick procedure

---

Specific locations/functions:

• Dorsolateral prefrontal region

  • Working memory; 

  • intellectual capacities;

  • creative, flexible thinking; 

  • fluency: 

  • L — verbal, R - nonverbal

• Ventral medial Region (includes medial orbitofrontal cortex)

  • Judgment, 

  • planning, 

  • decision making,

  • social conduct

• Superior mesial region (includes anterior cingulate gyrus)

  • emotional behavior 

  • Basic drive states 

    • associated w/ motivation and arousal

---

Frontal Lobe and emotion:

• Left vs right lobes

  • Left = positive affects; 

  • Right = Negative affects

• Clinical Associations:

  • Depression incidence + severity = higher in pts w/ left anterior lobe lesion

  • Right lesion = inappropriately cheerful

Blue: Dorsolateral prefrontal region

Yellow: Ventral medial Region (includes medial orbitofrontal cortex)

Green: Superior mesial region (includes anterior cingulate gyrus)

Describe Function in Split Brain patients

• Stereognosis ability

• R vs L Visual Fields

Function in Split Brain patients

• Stereognosis ability

  • Right Hand:

    • Pt can name object

  • Left Hand:

    • Can indicate object’s use 

• Right vs Left Visual field

  • Right:

    • Read word or ID picture verbally

  • Left:

    • Show emotional response to humorous object