Language. The Left Hemisphere plays a leading role in language processing

Language
Neural Organization of Language
Classical Neurological Conceptions
Broca’s aphasia
People with Broca’s aphasia have great difficulty producing words.
Their difficulty with speech output was not accompanied by motoric problems of the vocal musculature, such as paralysis.
Broca conceptualized the region of the brain as the area that is critical for programming speech output.
Telegraphic speech

Language
Neural Organization of Language
Classical Neurological Conceptions
Wernicke’s aphasia
Disrupted speech comprehension along with fluent (but nonsensical) speech output
Word salad (the words are combined in a way that makes little sense)

Language
Neural Organization of Language
Classical Neurological Conceptions
Conduction aphasia
Person can not repeat what was just heard, because sound images received by Wernicke’s area could not be conducted forward to Broca’s area to be produced
Conduction aphasia is a example of a disconnection syndrome
The deficit arises from an inability to relay information from one intact area to another intact area
Large nerve-fiber tract - arcuate fasciculus.

Language
Neural Organization of Language
Classical Neurological Conceptions
Lichtheim three-part model
The concept center is the place in the brain where meanings are stored and from whence they originate
Transcortical motor aphasia – people have deficits in initiation and maintenance of conversations, which results in reduced speech output.
Ideas can not translate into speech.
intact repetition

Language
Neural Organization of Language
Classical Neurological Conceptions
Lichtheim three-part model
Transcortical sensory aphasia – such a disconnection should prevent an individual from interpreting the meaning of words.
Patients have symptoms similar to those of patients with Wernicke’s aphasia, except that they can repeat words.

Language
Neural Organization of Language
Classical Neurological Conceptions
Global aphasia
People who had extensive damage to multiple parts of the system have neither the ability to comprehend language nor the ability to produce it.
This syndrome is associated with extensive left hemisphere damage that typically includes not only Wernicke’s and Broca’s areas, but the area between them as well

Language
Neural Organization of Language
Classical Neurological Conceptions
Table 9.2 lists the major aphasic syndromes observed clinically and their characteristics

Language
Neural Organization of Language
Classical Neurological Conceptions
Picture provides a summary schematic of the typical lesion locations for each type of aphasia

Language
Luria’s classification of aphasias
I. Efferent aphasias
Efferent motor aphasia
Dynamic aphasia
II. Afferent aphasias
Sensory aphasia
Acoustic-mnestic aphasia
Semantic aphasia
Afferent motor aphasia

Language
Luria’s classification of aphasias
Efferent motor aphasia
Brain localization- Broca’s area.
The primary defect is the breakdown of the word articulatory programme
In severe cases, patients who are able to imitate individual movements of the tongue and lips and repeat isolated sounds are unable to pronounce a serially organised set of articulations that make up a word.

Language
Luria’s classification of aphasias
Dynamic aphasia
Brain localization- prefrontal cortex near to Broca’s area.
Luria hypothesised that patients with this form of aphasia were suffering from an impairment of the inner schema of an utterance, as a result of which general thought could not get embodied in an inner speech schema and thus could not serve as the basis for constructing a narrative
Motor aspect of speech is not impaired.
In severe cases, a patient cannot and does not attempt to initiate speech

Language
Luria’s classification of aphasias
Sensory aphasia
Brain localization- posterior third of the upper-temporal gyrus of the left hemisphere.
Mechanism of sensory aphasia
is a deficit of phonemic hearing in the absence of elementary hearing deficits.
Symptoms
Impaired understanding
Patients can repeat (imitate) the pronunciation of a word, but cannot understand its meaning
In severe cases, patients perceive other people’s speech as inarticulate noise
In mild cases, patients have difficulty only in recognizing “oppositional” phonemes: (b-p)

Language
Luria’s classification of aphasias
Semantic aphasia
Brain localization- lesion of the juncture of parietal-temporal-occipital areas of the left cerebral hemisphere
Mechanism
Luria has hypothesised that the mechanism underlying the semantic form of aphasia involves simultaneous synthesis defect
Symptoms
Difficulties in understanding of logical-grammatical constructions (for example, a patient understands the meanings of the words “father” and “brother,” but the meaning of “father’s brother” is beyond him).