Receptive aphasia

Wernicke's aphasia, also known as receptive aphasia, sensory aphasia, fluent aphasia, or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language because of damage to a distributed network of brain regions involved in language comprehension rather than a single isolated area. Patients with Wernicke’s aphasia often have fluent speech, which is characterized by typical speech rate and effortless speech output, but the content may lack meaning or include incorrect or made-up words. Writing often reflects speech by lacking substantive content or meaning, and may contain paraphasias or neologisms, similar to how spoken language is affected. In most cases, motor deficits do not occur in individuals with Wernicke's aphasia. Therefore, they may produce a large amount of speech without much meaning. Individuals with Wernicke’s aphasia commonly show anosognosia, meaning they may be unaware of their errors in speech and may not realize that their spoken language lacks meaning. They typically remain unaware of even their most profound language deficits.
Like many acquired language disorders, Wernicke's aphasia can be experienced in many different ways and to many different degrees. Patients diagnosed with Wernicke's aphasia can show severe language comprehension deficits; however, this is dependent on the severity and extent of the lesion. Severity levels may range from being unable to understand even the simplest spoken and/or written information to missing minor details of a conversation. Many diagnosed with Wernicke's aphasia have difficulty with repetition in words and sentences and/or working memory.
Wernicke's aphasia was named after German physician Carl Wernicke, who is credited with discovering the area of the brain responsible for language comprehension and discovery of the condition which results from a lesion to this brain area. Although Wernicke's area is known as the language comprehension area of the brain, defining the exact region of the brain is a more complicated issue. A 2016 study asked neuroscientists what portion of the brain they consider to be Wernicke’s area, and results suggested that the classic “Wernicke–Lichtheim–Geschwind” model does not fully account for modern evidence about the distributed network of cortical and subcortical regions involved in language processing. This is because this model was created using an old understanding of human brain anatomy and does not take into consideration the cortical and subcortical structures responsible for language or the connectivity of brain areas necessary for production and comprehension of language. While there is no single, well-defined area solely responsible for language comprehension, Wernicke’s aphasia is a well-documented clinical condition in which individuals have difficulty understanding language due to damage in key parts of the language network.
A better way to describe aphasia is fluent or non-fluent rather than "expressive" or "receptive" given the typical presence of both expressive and receptive language deficits in all subtypes of aphasia.

Signs and symptoms

People with Wernicke’s aphasia often produce fluent but disorganized speech that may include made-up words or incorrect word substitutions. Although their speech sounds fluent, it can be difficult to follow because the content lacks meaning.
The following are common symptoms seen in patients with Wernicke's aphasia:

Impaired comprehension: deficits in understanding written and spoken language. This is because Wernicke's area is responsible for assigning meaning to the language that is heard, so if it is damaged, the brain cannot comprehend the information that is being received.
Poor word retrieval: ability to retrieve target words is impaired. This is also referred to as anomia, and it is often classified into the following subsets:
* Word-selection anomia: this type of anomia describes patients who know the function of a certain object, and can single out the target object from a larger group of objects, but they do not have the ability to name the object. For example when shown different clothes items and asked to select the one meant to keep their head warm, they will correctly select the hat, but will not be able to state the name of the object. In some patients this type of anomia is specific to certain categories like colors or animals.
* Semantic anomia: unlike patients with word-selection anomia, patients exhibiting semantic anomia also lose the ability to correctly distinguish the function or use of a given object, along with not being able to provide the name of it. Therefore, even provided with both the name and function of an object, these patients still would not be able to correctly select it out of a group.
* Disconnection anomia or modality-specific anomia: this subset of anomia affects patients' ability to name or distinguish objects if they are presented through a certain sensory modality, and is caused by a disconnect between the given sensory cortex and the language centers of the brain. For example, a patient may be able to distinguish an apple from a banana when presented with their given smells, but not when they are presented the objects through only touch.
* Phonemic substitution anomia: describes patients that exhibit paraphasia when trying to name objects. This can result in patients either selecting incorrect phonemes, such as saying 'bad' when shown an image of a 'bat', or they may simply try to use non-real words, or neologisms.
Neologisms: Neologism is a Greek-derived word meaning "new word". The term is used in this sense to mean invented non-words that have no relation to the target word.
* E.g. "dorflur" for "shoe"
Production of jargon: speech that lacks content, consists of typical intonation, and is structurally intact. Jargon can consist of a string of neologisms, as well as a combination of real words that do not make sense together in context. The jargon may include word salads.
Fluent speech: individuals with Wernicke's aphasia do not have difficulty with producing connected speech that flows. Although the connection of the words may be appropriate, the words they are using may not belong together or make sense. For example, a person might answer a simple question with a fluent but confusing sentence such as, ‘The dog of my chair went glimmering,’ illustrating intact speech flow but reduced meaningful content. Some patients with Wernicke's Aphasia experience logorrhea, which is also known as over fluency. These patients use an excessive amount of words when speaking or writing.
Awareness: Individuals with Wernicke's aphasia are often not aware of their incorrect productions, which would further explain why they do not correct themselves when they produce jargon, paraphasias, or neologisms. Additionally, patients may become irritated or frustrated because others cannot understand what they are saying, but they believe their speech is completely comprehensible.
Paraphasias:
* Phonemic ''paraphasia: Errors in selecting phonemes. Involves the substitution, addition, omission, or rearrangement of sounds so that an error can be defined as sounding like the target word. Often, half of the word is still intact which allows for easy comparison to the appropriate, original word. The more phonemic paraphasias in a word, the harder it is to understand, to the extent at which may become unidentifiable. Often, these unidentifiable words are known as neologisms.
* Semantic paraphasia: Failure to select the proper words with which to convey their ideas. The word used is always a real word, however it may not always be directly or closely related to the word the patient is trying to convey. Can result in saying a word that is related to the target word in meaning or category. Other times, semantic paraphasias can result in empty speech, or the use of overly generic words such as "thing" or "stuff" to stand in for the word they cannot come up with. This leads to speech that contains real words but lacks any substantial meaning.
Circumlocution: talking around the target word.
* E.g. "uhhh it's white... it's flat... you write on it..."
Pressured speech: Wernicke's patient's inclination to run on their speech. Often described as an overabundance of speech. Common in Wernicke's patients due to the ease at which they produce speech, circumlocution, and lack of self-monitoring.
* E.g. a clinician asks, "What do you do at a supermarket?" And the individual responds with "Well, the supermarket is a place. It is a place with a lot of food. My favorite food is Italian food. At a supermarket, I buy different kinds of food. There are carts and baskets. Supermarkets have lots of customers, and workers..."
Lack of hemiparesis: typically, no motor deficits are seen with a localized lesion in Wernicke's area.
Reduced retention span: reduced ability to retain information for extended periods of time.
Impairments in reading and writing: impairments can be seen in both reading and writing with differing severity levels.

Symptom	Patients with Wernicke's Aphasia
Comprehension of spoken material	Impaired
Segmental phonology	Impaired
Word selection	Impaired
Word semantics	Normal
Fluency	Normal or overly fluent
Production of writing	Normal
Use of function words	Normal
Grammaticality	Normal or mildly impaired
Repetition of what others say	Impaired
Controversial proficiency	Normal
Concern about impairment	Little to none
Concern about errors in language	Little to none
Short-term retention and recall of verbal materials	Impaired

Distinction from other types of aphasia/other conditions

Expressive aphasia : this is generally considered the second main categorization of aphasia, where individuals have great difficulty forming complete sentences with generally only basic content words. Unlike Wernicke's aphasia, which causes patients to speak fluently, but producing a jumbled mix of nonsensical words, people with Broca's aphasia speak slowly, and typically in small sentences, yet they are much more able to convey the intended meaning of the sentence. Additionally, while people with Wernicke's aphasia typically are unaware of their confusing language and may get frustrated with the listener for not understanding them, people with Broca's aphasia are completely aware of their language difficulties and can sometimes become frustrated with themselves.
Global aphasia: individuals have extreme difficulties with both expressive and receptive.
Anomic aphasia: the biggest hallmark is one's poor word-finding abilities; one's speech is fluent and appropriate, but full of circumlocutions.
Conduction aphasia: individuals can comprehend what is being said and are fluent in spontaneous speech, but they cannot repeat what is being said to them.
Transcortical sensory aphasia: individuals have impaired auditory comprehension with intact repetition and fluent speech.
Progressive confluent aphasia'': A form of frontotemporal dementia characterized by motor speech impairment, agrammatism, laborious speech, and apraxia of speech. It is understood that comprehension of speech and semantic memory are relatively preserved. Symptoms progress over time unlike many other aphasias where symptoms appear immediately after stroke.
Wernicke-Korsakoff Syndrome: A well described syndrome of neurological and cognitive problems that comprises both Wernicke's Encephalopathy and Korsakoff Syndrome. It is often characterized by impairment in memory formation and is caused by long term thiamine deficiency.