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DR NILESH KATE MBBS,MD ASSOCIATE PROF ESIC MEDICAL COLLEGE, GULBARGA. DEPT. OF PHYSIOLOGY HIGHER FUNCTIONS OF BRAIN. LANGUAGE & SPEECH

Higher functions of brain language speech

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Page 1: Higher functions of brain language speech

DR NILESH KATE

MBBS,MD

ASSOCIATE PROF

ESIC MEDICAL COLLEGE, GULBARGA.

DEPT. OF PHYSIOLOGY

HIGHER FUNCTIONS OF

BRAIN.LANGUAGE &

SPEECH

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OBJECTIVES Language & speech Learning & memory Higher intellectual

functions of prefrontal association cortex.

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LANGUAGE & SPEECH

Neurophysiology of language & speech.

Speech disorders.

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NEUROPHYSIOLOGY OF LANGUAGE & SPEECH.

Components of sound based language. Wernicke’s theory of language. Development of speech. Mechanism of speech & speech centers.

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Language Faculty of nervous system which enables the

humans to understand the spoken & printed words & to express ideas in the form of speech & writing.

It keeps the Humans much above the animals. Sensory aspect includes – visual, auditory &

Proprioceptive. Motor includes – spoken & written language.

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COMPONENTS OF SOUND BASED LANGUAGE.

Phonemes. – fundamental sounds in a language whose linking together in particular order forms Morphemes.

Morphemes – smallest meaningful units of words.

Words – made up of syllables which includes consonants & vowels.

Lexicon – collection of all words in a given language.

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COMPONENTS OF SOUND BASED LANGUAGE.

Syntax – linking together of different words by use of verbs & verb tense. i. e making a sentence.

Semantic – understanding the meaning of lexicons & syntaxes.

Discourse – linking together of sentences to form meaningful narrative.

Progody – Rise & fall of pitch of the voice in speaking so as to modify literal meaning of words & sentences.

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WERNICKE’S THEORY OF LANGUAGE.

Theory of language production in the brain is put forward by Wernicke’s later on revived by Gestwind.

Based on defects in language observed in patients with lesions of different parts of cortex.

‘Utterence’ arises in Wernicke’s area – pass to Broca’s area via arcuate Fasciculus – sentence is formulated in Broca’s area – transferred to Motor area – articulation is programmed by activation of appropriate muscle in mouth & face.

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DEVELOPMENT OF SPEECH.

Involves coordinated activity of 3 areas.

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DEVELOPMENT OF SPEECH.

First stage. Association of words

with visual, tactile, auditory & other sensations stored in memory.

Second stage. Establishment of new

neuronal circuits. When meaning is attached

pathway between auditory & motor area for speech articulation established.

Child attempts to formulate & pronounce words what learnt.

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MECHANISM OF SPEECH & SPEECH CENTERS.

Spoken speech. Involves both

understanding & expression of ideas in the form of spoken words.

Written speech. Involves both

understanding & expression of ideas in the form of written words.

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Mechanism of speech

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MECHANISM OF SPEECH & SPEECH CENTERS.

Understanding of speech.

Sensory aspect of communication.

Expression of speech.

Motor aspect of communication.

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UNDERSTANDING OF SPEECH. Spoken

Hearing of spoken words.

Recognition & understanding.

Interpretation & comprehension of speech ideas.

Written. Perception of written

words. Interpretation of

written speech. Visual association areas.

Generation of thought /ideas in response to written speech.

Dejerine areas.

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EXPRESSION OF SPEECH. Expression in the form

of spoken speech. Wernicke's, Dejerine &

Broca’s , motor areas involved.

Expression in the form of written speech.

Wernicke's, Dejerine & Broca’s , Exner’s (motor writing centre) areas involved.

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CONCEPT OF DOMINANT HEMISPHERE IN LANGUAGE.

Interpretive functions of Wernicke’s area, Angular gyrus & Frontal motor speech area – more developed in Dominant hemisphere.

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CONCEPT OF DOMINANT HEMISPHERE IN LANGUAGE.

95% left hemisphere is dominant. Motor area for hand movement is

associate with speech area so right handedness in 90%.

Wernicke’s area in Non-dominant is concerned with emotional content, intonation of spoken language, understanding & interpreting non-verbal, visual & auditory experiences as interpretation of Music.

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CONCEPT OF CATEGORICAL & REPRESENTATIONAL HEMISPHERE.

Functions allotted to left hemisphere in right handed person.

Right hand control. Spoken language. Written language. Mathematical skills. Scientific skills. Reasoning.

Functions allotted to right hemisphere in right handed person.

Left hand control. Music awareness. Three dimensional awareness. Art awareness. Insight. Imagination.

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SPEECH DISORDERS. Dysarthria. Difficulty in articulation of

words but comprehension is not affected.

Cause – Paresis or in coordination of muscle for speech.

Seen in – lesions of pyramidal tract, cranial nerves, cerebellum, basal ganglia.

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Aphasia. Def – Inability to

understand & express spoken & written speech with no mental confusion & motor deficit.

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Types. Sensory/Wernicke’s Site of lesion – Wernicke’s

area. C/F – Difficulty in

understanding meaning of speech.

Motor speech intact (Fluent Aphasia) but associated with Anomia, neologism, paraphasias.

Impairment in reading & writing (word Blindness)

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Types.

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Motor (Broca’s) Lesion – Broca’s area.44 C/F – comprehension of

written & spoken speech good.

Difficulty in speaking. Speech is Non-fluent. Agraphia (inability to

write)

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Types. Global Total inability to use

language Communication. Lesion – both areas

Wernicke’s & Broca’s. Common cause –

thrombosis or embolism of artery of dominant hemisphere.

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Thank You