Language and Communication

Communication in Lower Animals

Beas have complex sign language for direction of food

Singing birds share same gene FOXP2 expressed in basal ganglia of human.

Do Apes Have Language?

Apes can learn limited signs, understand and speak

Great apes have similar brain area like human to support language

Learning to Speak

The Development of Language: A Critical Period in Humans

A critical period for learning language is shown by the decline in language ability (fluency) of non-native speakers of English as a function of their age upon arrival in the United States

Brain as hollow organ : Nemesius (circa 320), Nature of Man

The cerebral ventricles were supposed to be responsible for mental operationsLanguage was not represented

Language area in Phrenology

19th century, Franz Joseph Gall and J. G. Spurzheim The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular

Aggregate field view of the brain (Flourens 1820) Experimental psychologist

‘a large section of the cerebral lobes can be removed without loss of function. As more is removed, all functions weaken and gradually disappear. Thus the cerebral lobes operate in unison for the full exercise of their functions ... The cerebral cortex functioned as an indivisible whole ... [housing] an ‘‘essentially single faculty’’ of perception, judgement and will ... the last refuge of the soul’ (Flourens, cited by Changeux, p. 17, [7] ).

Broca’s Aphasia

Autopsy of a patient who could understand, with normal speech apparatus but could not speak or write a sentence.

Only articulate sound he could make was “tan”

After autopsying eight similar patient with lesion in the left frontal lobe

He made a famous statement that “we speak with the left hemisphere”

First time identified the language center on the left frontal lobe

Paul Broca 1861

Wernicke’s Aphasia

Ten years later, Carl Wernicke, a German neurologist, discovered

another part of the brain, this one involved in understanding language, in

the posterior portion of the left temporal lobe.

People who had a lesion at this location could speak, but their speech

was often incoherent and made no sense.

Wernicke - Geshwind model:

Cortical mapping of the language areas in the left cerebral cortex during neurosurgery

(A) Location of the classical language areas. (B) Evidence for the variability of language representation among individuals. This diagram summarizes data from 117 patients whose language areas were electrically mapped at the time of surgery. The number in each circle indicates the percentage of the patients who showed interference with language in response to stimulation at that site. Note also that many of the sites that elicited interference fall outside the classic language areas. (B after Ojemann et al., 1989.)

Broca’s Area

Area 44 (the posterior part of the inferior frontal gyrus) : phonological processing and in language production as such; this role would be facilitated by its position close to the motor centres for the mouth and the tongue.

Area 45 (the anterior part of the inferior frontal gyrus) seems more involved in the semantic aspects of language. Though not directly involved in accessing meaning, Broca’s area therefore plays a role in verbal memory (selecting and manipulating semantic elements).

Wernicke’s Area

WA lies superior temporal gyrus, in the superior portion of Brodmann area 22 has 3 subdivision

The first responds to spoken words (including the individual’s own) and other sounds.

The second responds only to words spoken by someone else but is also activated when the individual recalls a list of words.

The third sub-area seems more closely associated with producing speech than with perceiving it

Language-related areas in the human brain: Damasio

The implementation system is made up of several regions located around the left sylvian fissure. It includes the classical language areas (B = Broca's area; W = Wernicke's area) and the adjoining supramarginal gyrus (Sm), angular gyrus (AG), auditory cortex (A), motor cortex (M), and somatosensory cortex (Ss). The posterior and anterior components of the implementation system, respectively Wernicke's area and Broca's area, are interconnected by the arcuate fasciculusThe mediational system surrounds the implementation system like a belt (blue areas). The regions identified so far are located in the left temporal pole (TP), left inferotemporal cortex (It), and left prefrontal cortex (Pf). The left basal ganglia complex (not pictured) is an integral part of the language implementation system

H. Damasio

Marsel Mesulam Model of Language 1980

Simple language task like rhyming year, days of week require Motor and Premotor area Hearing a word primary unimodel auditory cortex superior and anterior temporal lobe Unimodel area send to

Paralimbic system, for long term memory and emotional system.

Posteriorsuperior temporal sulcus for meaning.

The triangular and orbital portions of the inferior frontal gyrus also play a role in

semantic processing. Two classical epicenters (B+W) still work for semantic processing

Language Related area of Left Brain PET

PET Speaking Task (Naming)

Geschwind’s territory

the inferior parietal lobule is connected by large bundles of nerve fibres to both Broca’s area and Wernicke’s area.

Information might therefore travel between these last two areas either directly, via the arcuate fasciculus, or by a second, parallel route that passes through the inferior parietal lobule.

The inferior parietal lobule is one of the last structures of the human brain to have developed in the course of evolution

Inferior Parietal Lobule and Language

The supramarginal gyrus seems to be involved in phonological and articulatory processing of words, whereas the angular gyrus (together with the posterior cingulate gyrus) seems more involved in semantic processing. The right angular gyrus appears to be active as well as the left, thus revealing that the right hemisphere also contributes to semantic processing of language.

Insula is important for planning or coordinating the articulatory movements

A. Lesions of 25 patients with deficits in planning articulatory movements were computer-reconstructed and overlapped. All patients had lesions that included a small section of the insula, an area of cortex underneath the frontal, temporal, and parietal lobes. The area of infarction shared by all patients is depicted here in dark purple.

B. The lesions of 19 patients without a deficit in planning articulatory movements were also reconstructed and overlapped. Their lesions completely spare the precise area that was infarcted in the patients with the articulatory deficit.

Area 24: Initiation and maintenance of speech

They are also important to attention and emotion and thus can influence many higher

functions. Damage to these areas does not cause an aphasia in the proper sense but impairs the initiation of movement (akinesia) and causes mutism, the complete absence of speech. Mutism is a rarity in aphasic patients and is seen only during the very early stages of the condition. Patients with akinesia and mutism fail to communicate by words, gestures, or facial expression. They have an impairment of the drive to communicate, rather than aphasia.

Handedness and Language

Lateralization of Language: Wada Test

Spit Brain Experiment

The brain’s anatomical asymmetry

Manual “babbling” in deaf infants raised by deaf, signing parents compared to manual babble in hearing infants

Babbling was judged by scoring hand positions and shapes that showed some resemblance to the components of American Sign Language. In deaf infants, meaningful hand shapes increase as a percentage of manual activity between ages 10 and 14 months. Hearing children raised by hearing, speaking parents do not produce similar hand shapes

Sign Language

Signing deficits in congenitally deaf individuals who had learned sign language from birth and later suffered lesions of the language areas in the left hemisphereLeft hemisphere damage produced signing problems in these patients analogous to the aphasias seen after comparable lesions in hearing, speaking patients

The Right Cerebral Hemisphere Is Important for Prosody and Pragmatics

• Prosody refers to the intonation

and stress with which the

phonemes of a language are

pronounced

• Understand organization of

discourse: Signs that establish

the context for a communication,

• To understand non literal

language, irony or metaphors

Woman deciding whether orNot certain words rhyme.

Women and Language

Females’ speech is more fluid: they can pronounce more words or sentences in

a given amount of time

Women have the reputation of being able to talk and listen while doing all sorts

of things at the same time,

Men supposedly prefer to talk or hear about various things in succession rather

than simultaneously.

Women language is more widespread in both hemisphere while in men more left

lateralized (Brain scan studies)

Women also have more nerve fibres connecting the two hemispheres of their

brains, which also suggests that more information is exchanged between them.

The males’ higher levels of testosterone, which delays the development of the

left hemisphere

4 times more boys than girls suffer from stuttering, dyslexia, and autism.

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