Topic 12: Neuropsychology of Language Flashcards
Phonemes
The fundamental language sounds (“p; b; sh”) - do not need to be words; they are sounds that makeup words
Morphemes
Smallest meaningful units of words (“dog” “unbreakable”) - “unbreakable” can be broken up into smaller units, which are separate morphemes
Lexicon
Collection of all the words in a language (vocabulary)
Syntax
Rules of grammar
Semantics
Meaning of words and sentences
Prosody
Vocal intonations; changing the inflection of your voice, which will have different meanings based on how you say something
Discourse
Stringing sentences together to form a meaningful narrative
Wernicke-Geshwind Model
- Language processing involves interconnected regions in the brain.
- These regions include the primary auditory cortex, Wernicke’s area, the arcuate fasciculus, Broca’s area, and the motor cortex.
- These regions are involved in different aspects of language processing, including speech perception, language comprehension, language production, and articulation.
- Language processing begins with perceiving speech sounds in the primary auditory cortex.
- Information is then transmitted to Wernicke’s area, where it is processed and assigned meaning.
- Information is then transmitted via the arcuate fasciculus to Broca’s area.
- Broca’s area is responsible for the planning and execution of speech movements.
- The motor cortex carries out speech movements.
According to the model, language processing involves a series of interconnected regions in the brain, including the primary auditory cortex, Wernicke’s area, the arcuate fasciculus, Broca’s area, and the motor cortex. These regions are involved in different aspects of language processing, such as speech perception, language comprehension, language production, and articulation.
In the Wernicke-Geschwind model, language processing begins with the perception of speech sounds in the primary auditory cortex. This information is then transmitted to Wernicke’s area in the posterior part of the left temporal lobe, where it is processed and assigned meaning. From there, the information is transmitted via the arcuate fasciculus, a neural pathway that connects Wernicke’s area with Broca’s area in the posterior part of the left frontal lobe. Broca’s area is responsible for the planning and execution of speech movements, which are then carried out by the motor cortex.
Aphasia
- Complete loss of language (dysphasia is more common, where certain aspects of language are lost.
- 85% result from cerebrovascular strokes (a consequence of stroke)
Absence of sensory impairments (i.e., need to rule out other impairments when diagnosing):
- Perceptual (agnosia) (e.g., reading)
- Motor (apraxia)
- Thought (autism, dementia etc.) = Sometimes, with certain types of aphasia, people lose the ability to comprehend language but can fluently produce it, so sometimes their language can sound jumbled and not make sense.
The breakdown between thought & language
There is the need to rule out perceptual impairments such as agnosia (difficulty recognizing objects or stimuli) that could interfere with language comprehension, as well as motor impairments such as apraxia (difficulty with voluntary movement) that could affect speech production.
The author also notes that certain types of aphasia can result in what is known as fluent aphasia, in which a person can produce language fluently but may struggle to comprehend it. In these cases, it is important to rule out thought-related impairments such as autism or dementia, which could be contributing to the language difficulties.
Sensory (Fluent) Aphasia
- Also called Wernicke’s or receptive aphasia (i.e., because there is a deficit in receiving information and comprehending the reception of information in a formal way).
- Prominent deficits in language comprehension
Speech production is normal (i.e., normal rate, prosody, rhythm, applying syntax and grammar), but they have:
- Production errors - especially phoneme & syllabic repetition errors & neologisms (made-up words): described as a ‘word salad.’
- They lose the ability to comprehend language, incoming and their own language and speech; they lose comprehension of what they say as they speak (losing the ability to track the meaning of what they are saying)
- Production sometimes becomes excessive: ‘press of speech’ or ‘logorrhea.’ they don’t know when to stop, or they don’t know how to get to their point
- Speech can be semantically empty (e.g., When asked where he lived, “I came there before here and returned there.”)
This passage describes a type of language impairment known as sensory aphasia, which is also referred to as Wernicke’s or receptive aphasia. Individuals with sensory aphasia typically experience significant difficulties with language comprehension, even though their speech production appears to be normal. Specifically, they may produce speech at a normal rate, with appropriate prosody (intonation and stress), and with a normal rhythm.
However, individuals with sensory aphasia may make errors in their speech production, such as phoneme and syllabic repetition errors, or they may use neologisms, which are made-up words. These errors can contribute to speech that sounds jumbled or nonsensical, leading some clinicians to describe it as a “word salad.” Additionally, some individuals with sensory aphasia may experience a “press of speech” or “logorrhea,” meaning they speak excessively, often with little regard for the conversational norms of turn-taking and listening.
Importantly, the primary deficit in sensory aphasia is in language comprehension. Individuals with this type of aphasia may struggle to understand spoken or written language, and their speech may be semantically empty or lack meaning. For example, when asked a question about where they live, they may respond with a string of words that do not convey the intended meaning, such as “I came there before here and returned there.”
Production (Motor) Aphasia
Also called Broca’s, expressive or nonfluent aphasia (i.e., because people are having trouble producing language or expressing through language; or called nonfluent because now words are not freely coming out)
- Main symptom: prominent deficit in production; struggling to get words out; in the example image, there is a great amount of time passing between the words
- Frustrating because they conceptually have what they want to say but cannot get it out
- Need to make sure this is not a motor issue (e.g., moving mouth, moving hand)
- Since this is the frontal lobe region, therefore the production of language may be affected regardless of the type of output
Symptoms range from inability to speak to laborious speech: Morphology & syntax are often also disrupted, with patients frequently using unaffixed word forms
- As well as eliminating adjectives, articles, and adverbs. Described as - ‘telegraphic speech = wanted to just get out the key words
- Rely on content words (nouns & verbs) (e.g., “I would like a cup of juice right now” verses “JUICE NOW!”)
Sensory (Fluent) Aphasia: which area in the brain is affected?
Also called Wernicke’s or receptive aphasia (i.e., because there is a deficit in receiving information and formally comprehending the reception of information).
Production (Motor) Aphasia: which area in the brain is affected?
Also called Broca’s, expressive or nonfluent aphasia (i.e., because people are having trouble producing language or expressing through language; or called nonfluent because now words are not freely coming out)
- comprehension is intact
- see some premotor cortex impacted as well
Bilingualism: Functional Organization
Studied bilingual participants who had acquired a second language late in life, Looking at brain functioning in Brocas and Wernickes
- Used fMRI to “image” a working brain while performing tasks in both languages (English & French)
- Native language: English
- 2nd language learned: French
- We saw a development of the surrounding area that is now dedicated to the production and syntax of a second language, which has been created with experience and practice (i.e., two separate “foci” in the front regions of the brain, Broca’s area?)
- So there is a commonality regardless of how the person is taking in the information regardless of language, but when it comes to the production of language, the syntax can be very different between two languages, so we see different foci areas
- those who are bilingual early in life have no separation though
- because there are two foci points, damage may affect one and not the other
Challenges to the Broca Aphasia Model
Syntactic complexity affects comprehension in production aphasics (i.e., the challenge is, the person may struggle with production, and we say that for the most part, their comprehension is intact, but when you make the requirement of comprehensive more complex, then we see in deficits in comprehension)
E.g., Match phrase with appropriate picture:
“the dog was chased by the cat”
“the cat chased the dog” (most simple)
“The boy the apple is eating is tall” (they can be interpreted in two ways grammatically)
Syntax versus semantics?
conduction aphasia
A type of language impairment known as conduction aphasia is caused by damage to the association fibres that connect the Wernicke’s and Broca’s areas in the brain, resulting in impaired repetition abilities & severe disruption in the repetition of non-meaningful words or sequences.
- You can have a conversation will them and bypass the conduction by using other regions in the brain (i.e., cannot see a deficit in normal conversation)
- CANNOT repeat things verbatim, which requires a carbon copy sent from Wernickes to Brocas Area (therefore like Broca’s, where there is an issue with production)
- Attempt to correct
- Aware of the disorder
- Harder for non-concrete words (proud)
- Association fibre damage
- Disconnection syndrome
Hear, “bicycle” – access visual imagery system, therefore, can reach the concept.
Hear, “balachhs” (i.e., nonsensical) or abstract terms “proud” – no idea
This passage describes a type of language impairment known as conduction aphasia, caused by damage to the association fibres that connect the Wernicke’s and Broca’s areas in the brain. Individuals with conduction aphasia typically have impaired repetition abilities, meaning they have difficulty repeating or sequences of words. This difficulty is particularly severe with non-meaningful words or sequences. However, unlike other types of aphasia, such as Wernicke’s aphasia, individuals with conduction aphasia are aware of their language disorder and may attempt to correct themselves.
Like Broca’s aphasia, individuals with conduction aphasia may find it harder to produce non-concrete words, such as abstract concepts like “proud.” This is because the damage to the association fibres disrupts the ability to access the appropriate semantic information for these words.
The disruption in the association fibres also leads to disconnection syndrome, meaning that the affected individual may have difficulty integrating information from different brain areas. For example, when hearing the word “bicycle,” they may be able to access the visual imagery system and mentally picture a bicycle. Still, when hearing a non-word like “balayage,” they have no idea what it means and may struggle to create a mental image or understand the meaning.
How Language Breaks Down (Lichtheim Model)
Arrow up: input of language (i.e., speech, reading)
C = comprehension of language, Wernicke’s area
1= arcuate fasciculus, a neural pathway that connects Wernicke’s area with Broca’s area in the posterior part of the left frontal lobe
B = Broca’s area
Arrow Down: output (i.e., speech)
Higher order regions:
A = higher order concepts, they can involve parietal and frontal lobe regions
2 = connections from Wernickes; routes through parietal lobe
3 = connections from higher-order regions to Broca’s for production of language
- when higher-order areas are damaged, we can see aphasic symptoms
Transcortical Sensory Aphasia
- Similar to Wernicke’s, but symptoms are much more severe in terms of the deficits in comprehension
- Main feature: A deficit in accessing (thinking about or remembering) meanings of words; and comprehension severely impaired.
- Damage thought to be in the connection from Wernickes to those higher-order concepts; the main feature of Transcortical Sensory Aphasia is difficulty accessing words’ meanings.
- The patient cannot read or write
- Severe difficulty word finding
- Can repeat words & non-words (because the arcuate fasciculus is intact)
- Phonology is intact
Transcortical Sensory Aphasia is a type of language disorder that affects the patient’s ability to access and comprehend the meaning of words. This condition is similar to Wernicke’s Aphasia, but the main feature of Transcortical Sensory Aphasia is difficulty accessing words’ meanings. Patients with this condition have severely impaired comprehension and may struggle to read or write. Additionally, they often have severe difficulty in word-finding and may repeat words and non-words. However, their phonology, which refers to the sound structure of words, remains intact. Overall, Transcortical Sensory Aphasia is characterized by the inability to understand and produce meaningful language while retaining the ability to repeat words and phrases.
Transcortical Motor Aphasia
Broca’s-like nonfluent aphasia: characterized by nonfluent speech production, impaired writing skills, and intact repetition abilities.
- Damage more on route to Broca’s area, therefore comprehension is intact, and we still see access to higher order concepts, but production is impaired (particularly in creative or spontaneous speech, they can’t just come up with things)
- Can usually only utter a few syllables.
- Often impaired writing
- Often right-side motor problems
- Can fluently repeat words & phrases (output intact, different from Broca’s… because the arcuate fasciculus is intact)
Transcortical Motor Aphasia is a type of language disorder that affects a person’s ability to produce fluent speech. It is similar to Broca’s Aphasia, which is another type of nonfluent aphasia. Patients with Transcortical Motor Aphasia have difficulty with spontaneous and creative speech and can usually only utter a few syllables. They may also have impaired writing skills and often have right side motor problems. However, they can usually repeat words and phrases fluently, which is different from Broca’s Aphasia where repetition abilities are impaired. Overall, Transcortical Motor Aphasia is characterized by nonfluent speech production, impaired writing skills, and intact repetition abilities.
Mixed Transcortical Aphasia
- Also called ‘isolation of speech area’ as it may only apply to right hemisphere language function.
- Patients have no apparent language functions at all
- Cannot understand or produce speech spontaneously
- Can repeat words & often do (echolalia) - because the arcuate fasciculus is intact
- This may only apply to the right hemisphere language function
Mixed transcortical aphasia is a rare type of aphasia that results from damage to the brain’s language centers, which causes severe disruption to all aspects of language function. Patients with mixed transcortical aphasia have no apparent language function at all and cannot understand or produce speech spontaneously. However, unlike other types of aphasia, they can still repeat words and phrases, a phenomenon known as echolalia. The term “mixed” refers to the fact that this type of aphasia is a combination of features seen in other types of aphasia. It is also sometimes called “isolation of speech area,” as it may only apply to right hemisphere language function.
Double dissociation?
Alexia without agraphia – suggests a visual perception disorder.
Agraphia without alexia – suggests motor planning? The person can read but cannot write
