#14092 - Speech And Language - Neuroscience 1

SPEECH and LANGUAGE

-Hearing is crucial for vocal learning and production

-In song birds-deafnesss early in life prevent song learning and production

Areas of brain involved in speech

Wernicke’s area: Understanding written and spoken language

-Traditionally it is Brodmann area 22, found on posterior section of superior temporal gyrus in the dominant cerebral hemisphere (left hemisphere in 95% of right handed individuals and 60% of left handed individuals)

-Area encircles the auditory cortex on sylvian fissure

-Lesion in Wernicke’s area- sensory A PHASIA- person will be able to connect words but will lack meaning

Broca’s Area:

-Region of the frontal lobe of one hemisphere (usually left) with functions linked to speech production

-Brodmann’s area 44, 45

-Motor aphasia: Able to comprehend words and sentences but are unable to generate fluent speech, other problems: fluency, articulation, word-finding, word repetition

Hemispheric specialisation

Left hemisphere: in charge of language functions and logical thought; speech, song, writing

Right hemisphere: controlled by left hemisphere and is responsible for perception of rhythm, spatial-relation skills

-Wada test: injection of sodium pentothal to the blood supply of each hemisphere- if injected on the left side and ask them to read some text and they continue to read but if injected into right and they can’t read- then patient has reversed laterality

All those who answered this question wrote well informed essays; many were quite outstanding with

unexpected evidence of which I was unaware, such as recent evidence for the role of Broca’s area in

linguistic short term memory. I was sad that so many thought that FMRI activations showing where

processing takes place are sufficient to explain how speech is understood or produced. How the named

areas cooperate in a network was hardly discussed, nor was the relationship of language to gesture.

Production of speech

-Speech is produced as a sequence of sounds – 3 stages

-Conceptulisation- speech begins as a pre-verbal message

-Formulation- pre verbal message is converted into linguistic form

-Lexicalaisation: though converted into appropriate words

-Synaptic planning: Words arranged in the right way

-Articulation: Sound be produced

Vocal cords

-pair of vibrating membranes that lie within the larynx- responsible for vocalisation-these are attached to the arytenoids cartilages and can be separated/ brought together by the action of vocal muscles

The interior wall of the larynx has two folds on each side that stretch from the thyroid cartilage at the front to the arytenoids cartilage at the back. The superior pair are the vestibular folds which close the glottis during swallowing.

The inferior pair, the vocal cords (or vocal folds) produce sound when air passes between them. Air forced between the vocal cords vibrates them producing a high pitched sound when the cords are relatively taut and a lower pitched sound when they are more relaxed. Loudness is determined by the force of the air passing between the vocal cords. The pharynx, oral cavity, tongue and lips form the crude sounds of the vocal cords into words.

Making a sound

-During phonation, larynx produces a...