Language

Language (the generation and understanding of written, spoken, and gestural communication) has survival value, and is very important in social relationships

The Brain Structures of Language

Broca's Area is responsible for the production of language.

 Broca's aphasia is characterized by:

Non‑fluent speech

Anomia (Trouble finding the right words)

Difficulty with articulation

Agrammatic speech

 Wernicke's Area is responsible for language comprehension, both in  production and reception

Speech is fluent but meaningless 

Patient is unaware that anything is wrong

Structures involved in reading and writing

Disruptions to pathways in the angular gyrus can produce alexia (the inability to read)

and agraphia (the inability to write)

Dyslexia (a reading impairment) can be acquired through damage, although it is more commonly developmental.

There are 2 forms of dyslexia:

Visual‑perceptual difficulties

Read words backwards, trouble focusing on printed words, etc.

Phonological

difficulty distinguishing frequency and amplitude variations in speech

difficulty translating written words into auditory form

The magnocellular hypothesis is that dyslexia involves problems in the visual system

that detects rapidly moving stimuli and monitors eye movements

 In dyslexics the planum temporale is often smaller on the left than in controls

neurons are disordered

The Wernicke‑Geschwind Model

demonstrates how Broca's area and Wernicke's area interact to produce language.

 Overall, this model is too simple

 In answering an orally presented question, information flows from the auditory cortex to

 Wernicke's area, to Broca's area

Writing a response to an orally presented question involves progression from the auditory cortex to

 Wernicke's area, to the angular gyrus, where a visual pattern is elicited

In reading aloud, visual information is translated into auditory form by the angular gyrus, then

sent to Wernicke's area where a response is formed, then to Broca's area

Recovery from Aphasia

Appears to involve right‑hemisphere

compensation if the damage occurs before age 5

Left‑hemisphere - compensation if damage occurs later

Language Generating Mechanism

Innate Brain Specializations suggest such a mechanism

Although there is not a single center, over 90% of right‑handed individuals

and 67% of left handers have their primary speech control in the left hemisphere

In the majority of cases, Broca's area is larger and the lateral fissure and planum temporale

are longer in the left than in the right hemisphere

Location of Other Languages

 Sign language activates the same left‑hemisphere areas as spoken language, and left hemisphere damage causes significant, enduring impairments in sign language

The right hemisphere's involvement in sign language is probably due to the language's spatial characteristics

Language in Non‑Humans presents us with an interesting opportunity to trace the evolution of language

Chimpanzee Language Research has not resolved the issue of non‑human language

Lateralization in Animal Brains

Certain animals respond better when meaningful auditory stimuli are presented to their left hemisphere

Animal research suggests that we share similar brain structures with other animals, which may have provided the foundation for our own language development