Language and Lateralization

Communication

The movement of information from one place to another

Language

rule-bound arrangement of symbols (can be spoken, written, signed, etc.) which is used to convey a vast range of thoughts, actions, and concepts.

Dynamic

It changes over time

Arbitrary

There is no inherent relationship between a word and its meaning

Grammatical

Follows a series of rules that dictate structure and usage

Phonemes

The most basic sounds of speech

Morphemes

The most basic unit of meaning. In some languages, most morphemes are words. In other languages, morphemes can include distinct, stand-alone words and things like prefixes and suffixes

Words

Distinct, meaningful units of language, made of at least one morpheme. There is not widespread agreement about a definition of “word” that applies to all languages

Lexicon

The full set of words belonging to a given language

Grammar

The system of rules that governs how words are used

Syntax

Rules about the organization of words into sentences

Semantics

The method by which we draw meaning from groups of Morphemes and words

BF Skinner’s Explanation

Reinforcement. Parents and other caregivers provide feedback in response to vocalizations. If that feedback is positively reinforcing, that vocalization reoccurs

Noam Chomsky’s Explanation

Innate Grammar. There exists in many languages a fundamental structure that is determined by universal rules. Thus, the brain comes into the world already knowing what to look for, thus facilitating acquisition of a given language.

What percentage of humans speak more than one language?

40-50% of humans

Evidence for Chomsky’s explanation

Babbling is likely a natural developmental process during which the babies practice phoneme formation with their mouth and vocal cords.

Critical Period

The time window that constrains language learning and development

Genie

• Individual word meaning, particularly complex descriptors (Colors,

Numbers)

• Some grammatical rules (Plurality)

• Conceptual Interrogatives (How, Why, When)

Neglect and abuse for 13 years of her life:

• More complex grammatical rules (tense)

• Syntax (sentence structure)

The FOXP2 Gene

A rare mutation in this gene caused developmental verbal dyspraxia (DVD)across multiple generations of an English family (KE Family)

planum temporale

part of the superior surface of the temporal lobe (which contains an important language center), is larger in the left hemisphere

Wada test

involves delivery of a fast, briefly acting anesthetic to one hemisphere via injection directly into one carotid artery

corpus callosum

iber tract connecting the cerebral hemispheres

split-brain syndrome

corpus callosum is severed

What is something a person with split-brain syndrome would experience?

A patient with this syndrome will not verbally report a word presented in the left visual field

(which is processed by the right, not the left, side of the brain)

Broca’s Area

located on the left inferior frontal gyrus

Broca’s aphasia

which involves difficulty expressing language, but not understanding it (also called ‘nonfluent

aphasia’). Patients seem to have insight into their symptoms

agrammatism

difficulty producing grammatical speech

anomia

difficulty finding the correct word

Wernicke’s Area

is located on the left superior temporal lobe

What does damage to the Wernicke’s Area do?

causes Wernicke’s aphasia, which involves difficulty understanding language (also called ‘fluent aphasia’)

Symptoms of Wernick’s aphasia

include fluid, meaningless speech. Complete, grammatical sentences are expressed easily, but words are used in a way that lacks meaning. Many patients seem to lack insight into the issues they are experiencing. This is the inability to respond to spoken language (word deafness) and inability to respond to written language (word blindness)

Global Aphasia

Total loss of language function; Very poor prognosis with limited recovery

arcuate fasiculus

is a tract of axons that interconnects Broca’s and Wernicke’s areas, allowing the two regions to communicate (connects two processes of language comprehension and production)

Compensatory Plasticity

Following destruction of one brain area, other regions may compensate for the loss of function. This process can replace lost function and lead to total recovery, though in many cases deficits remain