(Introduction To) Language History and Use 1

(Introduction to) Language History and Use 1 Aphasia Rachael-Anne Knight Aphasia

Introduction Aphasia literally means 'without speech' and refers to the disruption of language abilities after trauma to the brain. Such trauma is most often caused by a stroke but may also be caused by surgery, a blow to the head or a missile wound.

1 Early descriptions of aphasia In the mid-19th century doctors began to investigate patients with various speech difficulties. Broca (1865) and Wernicke (1874) both found areas of the left hemisphere that seemed to be damaged in their patients. What came to be known as Broca's area is found in the left frontal lobe whilst Wernicke's area is in the superior temporal gyrus (further back in the brain). Theory at the time was that Broca's area was responsible for memories for the phonological form of words whilst Wernicke's are was responsible for semantics. The classical names for two very different types of aphasia still hold at least in the clinical environment today.

Figure 1 Anatomy of the brain

1.1 Broca's aphasia An example of speech from a patient diagnosed with Broca's aphasia trying to describe the 'cookie theft' picture. Cookie jar …fall over…chair…water…empty Broca's aphasics are traditionally described as having slow, laborious speech, dysprosody (little intonation), apraxia (articulation difficulties) and difficulties in ordering words. In addition it is clear that grammatical elements are produced seldom, if ever.

1.2 Wernicke's aphasia An example of speech from a patient describing the 'cookie theft' picture: Well this is … mother is away here working her work out o' here to get her better, but when she's looking, the two boys looking in the other part. One their small tile into here time here. She's working another time because she's getting to. So two boys work together and one is sneakin' around here, making his work an' his further funnas his time he had. (Introduction to) Language History and Use 2 Aphasia Rachael-Anne Knight

Wernicke's aphasics are traditionally described as having fluent but often meaningless speech containing well-formed sentences with lots of grammatical elements. They have normal prosody but poor comprehension. They suffer word-finding difficulties and often make substitutions and neologisms.

Figure 2 The Cookie Theft Picture

1.3 More Recent terms for aphasia In the more recent (especially non-clinical) literature, the terms Broca's and Wernicke's aphasia are largely abandoned. More often individual patients' language difficulties are classed according to 2 factors; how well they comprehend speech and how fluent their speech is in production. Thus the traditional Broca's patient is non-fluent but with spared comprehension whilst the typical Wernicke's patient is fluent with impaired comprehension. Many other terms are found in the literature and this can be confusing. Below is a summary of the main terms found and how they can be roughly divided between the two traditional classifications.

Broca's Type Wernicke's type Non-Fluent Fluent Good comprehension Poor comprehension Expressive Receptive Motor Sensory Agrammatic Neologistic/ Jargonistic (Introduction to) Language History and Use 3 Aphasia Rachael-Anne Knight

2 Agrammatism

2.1 Introduction Agrammatism is considered to be the grammatical deficit experienced by Broca's type patients. Patients diagnosed with agrammatism (usually) suffer with 3 separate components:

2.1.1 Sentence construction deficit Agrammatic patients have difficult ordering words and putting them together in a sentence.

2.1.2 Selective impairment of grammatical elements Whilst content words are relatively spared, agrammatic patients have difficulty producing function words and bound morphemes.

2.1.3 Syntactic comprehension deficit Although a traditional distinction would classify agrammatic / Broca's type aphasics as having intact comprehension, detailed testing reveals that comprehension is not completely spared especially when there are no semantic cues. For example if asked to choose who is the 'pusher' in the following 2 sentences they would usually be right for sentence a but would perform at chance level (suggesting that they are guessing) for sentence b. a. The girl pushed the boy b. The boy was pushed by the girl

2.2 The agrammatism debate There are complex issues surrounding agrammatism. The main issue in the debate concerns whether agrammatism is a syndrome or not. A syndrome is defined as a set of symptoms that co-occur often enough to suggest a single cause. Crucial issues then concern whether patients actually have the same symptoms and if so whether these symptoms always cluster together. This debate has important consequences for both experimental methodology and theory.

2.2.1 Implications for methodology There is a crucial debate in cognitive neuroscience concerning how experimental research into aphasia should be conducted. The choice of method is between group studies or single case studies and the debate hinges on whether or not agrammatism is a syndrome.

2.2.1.1 Group-studies In most scientific research groups of subjects are tested so that the results may be generalised to a larger population. The assumption behind such studies is that the group is homogenous, i.e. that all normal people are similar enough to make their results comparable. If however, agrammatism is not a syndrome then it is pointless to combine clinically defined groups of sufferers as they may actually be suffering from different symptoms caused by different things (Introduction to) Language History and Use 4 Aphasia Rachael-Anne Knight 2.2.1.2 Single case studies Single case studies are the obvious answer to the problems of group studies. If each patient is different and aphasia is not a syndrome then it makes sense to only look at the detailed profile of individual cases. However there are many problems with this method. It is difficult to see why any results are useful to theory if they cannot be generalised to a wider population and it is difficult to see how results can be proved as valid if they cannot be replicated.

2.2.2 Implications for theory If agrammatism is a syndrome then any theoretical explanation should be able to explain all 3 components. If it is not a syndrome then different explanations can be used to for each of the three components.

2.2.3 The evidence

2.2.3.1 Quantitative differences between patients The first set of evidence concerns whether or not agrammatic patients actually have the same symptoms

2.2.3.1.1 Sentence construction deficit There are many differences between the output of patients. One study compared 5 agrammatic patients description of a picture of a girl giving flowers to a woman. a. The young…the girl…the…little girl is …the flower b. The girl is flower the woman c. The girl is…going to flowers d. The girl is giving…giving the teacher…giving it teacher e. The girl is…is roses. The girl is rosin'. Subjects vary in terms of how fluent they are, whether or not main verbs are used, whether there are word finding difficulties etc.

2.2.3.1.2 Impairment of grammatical elements One study showed that different types of grammatical elements may be more or less impaired in different individuals. For example one patient omitted 83% of prepositions but only 23% of definite articles whilst another omitted only 19% of prepositions but 64% of definite articles.

2.2.3.2 Qualitative differences Not every patient suffers from all three of the components which make up agrammatism. In particular there are reports of some patients (from single-case studies) who are impaired in production but not in comprehension suggesting that these elements may be dissociated.

2.2.3.3 Conclusion Quantitative differences are, as the name implies merely differences in the exact details of impairment. If we concentrate on what is different between patient's speech then we will always be able to find some difference in quantity. Even if the exact details are different all the patients described do have problems constructing sentences and difficulty in using grammatical elements. The differences can perhaps be explained as being (Introduction to) Language History and Use 5 Aphasia Rachael-Anne Knight due to the severity of the condition, additional impairments or different adaptations to the same common problem. Qualitative differences create a more serious problem for agrammatism as a syndrome as it seems certain elements can be dissociated. Dissociation is used in cognitive neuropsychology to indicate that two processes can be separately disrupted. This would indicate that problems with production and comprehension of syntax could be due to different causes and therefore not part of an agrammatic syndrome. However, there are very few patients who show this pattern of dissociation and the vast majority of patients with one symptom suffer from all of them. These exception cases may perhaps have subtly different lesion locations. It is also worth noting that the obscure term 'often enough' in the definition of a syndrome is problematic in itself and makes it harder to decide one way or the other. There is still no definitive answer in the agrammatism debate. Both single-case and group studies are still conducted and both types of explanations are still put forward although most explanations cannot explain all three aspects of agrammatism.

2.2.4 Explanations of agrammatism Although we know that agrammatism results from damage to Broca's area of the left-hemisphere this does not explain how exactly language is damaged. We must consider specifically what abilities or processes are affected in order to produce agrammatic symptoms. Most theories cannot explain all three elements of agrammatism.

2.2.4.1 Grodzinsky's trace-deletion hypothesis Grodzinsky suggests that agrammatics patients' syntactic comprehension problems occur because they have a limitation in constructing syntactic representations of sentences. This theory is rooted in Government and Binding theory. In GB theory there are two levels of syntactic representation D (deep) and S (surface) structure which are related by movement rules. When a NP is moved it leaves a trace behind in the surface structure. So, in sentence 2.1.3.b above a trace (marked by ) has been left behind because the NP 'the boy' has been moved to form the passive. The boy was pushed by the girl.

When a normal person comes to assign thematic roles (such as agent) to a sentence, NPs that have been moved do not receive their role directly. Instead, the trace receives the role and the moved NP receives it only indirectly. Grodzinsky argues that agrammatic patients cannot represent traces and are therefore unable to assign thematic rules to any NP that has been moved. NPs that cannot be assigned a thematic role grammatically have their role assigned by an agent-first strategy. Therefore if a sentence has a thematically unspecified NP agrammatic patients assume the first NP in a sentence ('the boy' in this case) is the agent.

This can lead to sentences being assigned 2 agents. The first is assigned by the normal grammatical strategy, using the by-phrase and the second is assigned by the non-grammatical, agent -first strategy. Therefore the patient has to guess which one of the two is really the agent leading to their random performance.

This theory cannot explain all three components of agrammatism. Originally conceived to expalin syntactic deficits in comprehension and production it is now only said to expain the comprehension deficit. In addition (Introduction to) Language History and Use 6 Aphasia Rachael-Anne Knight it can't even explain all the problems agrammatics have in comprehension as not all involve sentences in which NPs have been moved.

2.2.4.2 Kean's Phonological Deficit Hypothesis Kean posited that agrammatics production deficits were due to damage to the phonological system whilst the rest of the language system remained intact. In this theory agrammatics omit items that are unstressed resulting in content words being spared and grammatical elements lost. This can possibly explain the difficulties producing function words and bound morphemes but is not sufficient t explain the sentence construction deficit.

2.2.4.3 Schwartz Schwartz related agrammatism to Garrets model of normal speech production. She suggested that agrammatics are unable to translate from the functional to the positional level of representation. Therefore a frame would not be constructed for the sentence and the grammatical elements would not be retrieved. This goes some way to explaining the sentence construction deficit and the selective impairment of grammatical elements. It does not, however, explain the syntactic comprehension problems of agrammatic patients, as the Garrett model is specifically a model of production. (Introduction to) Language History and Use 7 Aphasia Rachael-Anne Knight

3 Jargon Aphasia Jargon aphasia is an extreme version of fluent aphasia and would thus be classically classified as Wernike's type aphasia. People with jargon aphasia are often unaware that there is anything wrong with their speech. Unlike agrammatic patients, people with jargon aphasia have relatively normal syntactic abilities. Their problems lie in their content-word finding difficulties. Their semantic abilities seem generally good as most patients perform well on picture matching tasks, for example.

3.1 Types of errors in word finding

3.1.1 Content word substitutions or paraphasias Unrelated paraphasias thermometer  typewriter Semantic paraphasias scroll  letters Formal paraphasias pencil  pepper Phonemic Paraphasias swan  swam

3.1.2 Made up words or neologisms These are words that are not found in the dictionary and that the patient has seeming made up. Phonemic Distortions of the intended target whistle  swizl Abstruse Distortions ?  kwailai

3.2 Support for Garrets Model from jargon aphasia People with jargon aphasia generally produce appropriate function words in their speech. In addition they are observed to produce syntactically appropriate affixes attached to their neologisms. This supports the claim that content and function words are processed separately.

3.3 Explanations of jargon aphasia Explanations normally focus on the processes that cause the patient to produce neologisms

3.3.1 Failure of phonological form retrieval Butterworth is one of the main proponents of this explanation and has suggested that neologisms and other errors are accentuated normal speech errors. In particular errors are seen as normal lemma retrieval but failure of phonological retrieval. If no phonology can be retrieved the patient uses a random generator to produce sound. There are several strands of evidence for this view drawn from a single case study of the patient KC  Hesitations are more likely to occur before errors than real words  The (iconic) gestures in these hesitations are the same as those for normal speakers  There are a high number of word blend errors in KC's speech (Introduction to) Language History and Use 8 Aphasia Rachael-Anne Knight 3.3.2 Failure of the scan copier device Shattuck-Hufnagel extended Garrets' model of speech production to include a scan copier, which copies the phonemes of a word from the lexicon and outputs them into the syntactic frame. Errors in this device have been used to explain normal errors such as phoneme addition, substitution or deletion. Buckingham has suggested that in people with jargon aphasia this device malfunctions most of the time causing muddling up of phonemes or generating random syllables and causing neologisms.

Reading Harley, T. (2001) The Psychology of Language, Hove: Psychology Press. Ch. 12 p.376 onwards

Kolb, B. and Wishaw I.Q. (1980), Fundamentals of Cognitive Neuropsychology, New York: Freeman, Ch. 17

Parkin, A.J. (1996) Explorations in Cognitive Neuropsychology, Oxford:Blackwell, Chs.1 and 7

Lesser, R., and Milroy, L. (1993) Linguistics and Aphasia: Psycholinguistic and Pragmatic Aspects of Intervention, London: Longman, Chs. 1-5 depending on interest

Sarno, M.T. (1998) Acquired Aphasia, London: Academic Press (Third Edition), Especially Chs. 1, 2, 5, 6 and 7 but others if interested

Zurif, E.B. and Swinney, D.A (1994) "The neuropsychology of language" in M.A. Gernsbacher (Ed.), Handbook of Psycholinguistics, London: Academic Press, 1055-1074

All except Lesser and Milroy and Sarno are available on overnight loan at the MML library.