Language

Language

Principal method of human communication, consisting of words used in a structured & conventional way - conveyed by speech, writing, or gesture

• Language is complex:

  • Communication system based on symbols

  • Symbols are words or signs that represent objects or concepts

  • Symbols are derived from social agreement & are learned by people who share that language

Language vs. Speech

• Language is more than speech

• Speech is just one manifestation of the way humans use language

  • Written language + nonverbal communication = other manifestations

Language Development

Infants use visual, auditory, & motor input (listening to speech, watching faces, interacting with those around them) to regulate their actions in response to input (co-regulation)

Theories of Language

• Early theories described sequential processing of language

  • Broca’s & Wernicke’s areas connected by arcuate fasciculus discovered

• Contemporary theories postulate that language processing is more widely distributed

  • Believe that language is processed parallelly by different areas - rather than serial processing, by one center after another

  • Still accept some localization and that Broca’s & Wernicke’s areas are very important

• Language is complex - more areas are involved than previously suspected!

Hemispheres and Language

1. Left: understanding & producing language (for most people)

2. Right: rudimentary language skills

• Emotional / nonverbal part of language (prosody)

• Music

• Jokes

• Nonliteral part of language

• Understanding space

• Visual patterns (facial recognition)

Individual variation in the CNS - hemispheric differences (borders may vary)

Prosody

• Right (nondominant) part of brain = important for this aspect of speech

• Melodious part of speech (prose)

• Includes rhythm, sound, inflection, pitch, timbre

• Helps communicate emotion

Neurological Components of Language

• Broca’s area

• Wernicke’s area

• Other temporal / parietal structures

  • Supramarginal gyrus

  • Angular gyrus

• Arcuate fasciculus

• Limbic system contributions

Broca’s Area

Language production

• More recently, language production has been ascribed to a larger area - Broca’s territory

• Usually in the Left hemisphere

Wernicke’s Area

Language comprehension

• Encompasses larger area than previously thought - Wernicke’s Territory

  • Includes: middle & superior temporal gyri, part of inferior parietal lobe, etc.

Other Temporal/Parietal Regions

1. Supramarginal Gyrus: involved in phonological & articulatory processing of words (breaking down sounds)

2. Angular Gyrus: contributes to semantic processing & understanding of metaphors

Together, these areas receive multimodal info from auditory, visual, & somatosensory systems

Arcuate Fasciculus

• White matter pathway interconnecting Broca’s & Wernicke’s areas

• Critical for language - from spontaneous speech & word retrieval to repetition & comprehension

Limbic System + Language

• Initiation of language

  • Damage to limbic system can lead to mutism

• Emotionally charged language

  • Some people w aphasia may see improvement in speech when emotionally upset

  • OR see preservation of emotionally charged speech (i.e. swear words)

Speech and Language Disorders

• Aphasia: disorder of language

  • Broca’s/expressive/non-fluent

  • Wernicke’s/receptive/fluent

  • Conduction

  • Global (mixed expressive & receptive)

• Dysarthria: difficulty with articulation

• Apraxia: motor output of speech impaired

Among others, SLPs diagnose these!**

Expressive Aphasia

Broca’s / non-fluent

• Can understand much of language (spoken &/or written)

• Usually aware of language difficulties (frustrating)

• Often writing also impaired

Receptive Aphasia

Wernicke’s / fluent

• Interferes with ability to comprehend language (ASL too)

• Impairments with reading & ability to write meaningful words

• Can also develop Paraphasia - use of unintended words or phrases

• Appear unaware of disorder

Conduction Aphasia

• Damage to neurons that connect Broca’s & Wernicke’s areas - arcuate fasciculus

• Ability to read & understand language is normal

• In severe cases - speech & writing are meaningless

• In mild cases - may have paraphasia

Global Aphasia

• Large infarct damages Wernicke’s & Broca’s areas in addition to others (both cortical & subcortical)

• Severe language deficit

• Unable to use language in any form (listening/comprehending, reading, speaking, writing)

Dysarthria

• Speech deficit

• Difficulty with motor control of speech musculature due to weakness

• No problems with comprehension (written/spoken language)

  • Able to write w/o deficits

• Can be very difficult to understand speech

Verbal Apraxia

• Deficit w coordinating components of producing speech - including correct sequencing (motor planning)

• Can be developmental (diagnosed in childhood) or acquired

• Not due to weakness

• Symptoms can include: sound distortion, inconsistent errors in speech, groping for sounds, errors in prosody