Pergamon J. Ncwrt~/in~utsr~c~. Vol. 8. No. 2, pp. 135-148. 1994

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SPEECH AUTOMATISM PRODUCTION IN APHASIA

CHRIS CODE

School of Commumcation Disorders, Faculty of Health Sciences, University of Sydney, Lidcombe, NSW 2141, Australia

Abstract-This paper argues that explanations for the origins of lexical and non lexical (recurring utterances) aphasic speech automatisms must take into account: (a) both neurophysiological as well as environmental factors; (b) initial and subsequent productions of the utterance. A preliminary model is

proposed which accounts for initial and subsequent productions and provides the basis for further investigation into the neurogenesis of different subtypes of speech automatism. The model acknowledges the lack of straight linguistic input, it reflects the apparent holistic preparation and the invariance of production and it distinguishes between the two major types (lexical and non lexical).

INTRODUCTION

IN 1861, BROCA [ 1 ] presented the brain of his aphasic patient Leborgne to the French Anthropological Society in Paris, an event which is usually considered to have ushered in the very beginnings of the modern era of neuropsychology. Leborgne has come down in history with the name “Tan” as this was the apparently meaningless utterance that he produced most of the times he attempted speech. While this is often cited as the first example in the literature of an aphasic speech automatism, LEBRUN [2] cites a patient with the expletive “Sacre nom

de Dieu” described by Aubertin just one week before Broca’s case at a meeting of the same French Anthropological Society. Interestingly, the French poet Charles Baudelaire could say only “crk nom nom>‘, which was probably a debased form of the same expletive “Sacre nom

de Dieu” [2] The patient with such a speech automatism, like Leborgne, is often described as severely,

often globally, aphasic in all modalities [ 3,4] , although recent evidence [ 51 shows that some patients may have significantly preserved areas of ability. Nonetheless, these utterances are associated with severe “motor” aphasia, Broca’s aphasia in classical terminology, or severe apraxia of speech and aphasia, and they do not occur in the fluent types of aphasia. The utterance is not an occasional one for most patients. For some it is the only utterance they can produce [ 41.

HUGHLINGS JACKSON [ 6,7] was the first to write extensively about speech automatisms, and a number of terms have been used to describe them. JACKSON [6] himself called them “recurrent utterances” and “recurring utterances”, while “verbal stereotypy” [2,3], “speech automatism” [ 8,9] and “neologistic automatisms” [ lo] are also in current use. CODE [4]

used the terms “real word recurrent utterances” and “non meaningful recurrent utterances” to distinguish the two main types and MARSHALL [ 1 l] captures their essence with the contemporary term “pre-packed” speech. In recent years there has been some success in clearing up the terminological confusion [see 12-141 and in contemporary research speech automatism is the general term used for stereotyped and inappropriate utterances, whether lexical or non lexical utterances, whereas recurring utterance is used to refer to the non

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lexical variety made up of concatenated CV syllables. This paper examines linguistic research on speech automatisms, moves on to say something

about the neural mechanisms which may underlie them, and examines the apparent relation- ships between the different kinds of speech automatisms with reference to the notion of propositionality in language. Finally, a model is outlined which attempts to account for their production.

THE LINGUISTIC STATUS OF SPEECH AUTOMATISMS

Table 1 (from CODE [4]) shows a large collection of British-English lexical speech automatisms. While this is still the largest corpus of such utterances in English, it was collected by survey and there are inherent problems of reliability with survey research. Although many do not appear to fall easily into classifications, common identifiable subtypes are expletives, proper names, yes/no and serial numbers. Interestingly, all the expletives in this collection were produced by males and all the proper names were relatives of the patient in question. These types are predictable and have been described in the past. However, the most common subtype observed in this study was the pronoun + verb type (14 examples), a previously undescribed variety. Here a pronoun is combined with an auxiliary or modal verb, and sometimes. one or two other words. Additionally, and intriguingly, the most common word in the collection was “I”, occurring 13 times. These utterances appear as very personal and emotional expressions, often executed with great feeling and frustration. Often they are functionally as well as syntactically incomplete, although of those speech automatisms which did make complete, if simple, sentences, the pronoun + verb subtype was the most common. An interesting fact is that in this study 3 separate patients from 3 separate clinical settings produced the same utterance (“I want to. “) and the probability of this happening purely by chance would appear to be very low indeed. This subtype in particular illustrates the very

Table 1. A large selection of lexical speech automattsms from Coot [4]

alrtght away away away BBC because Bill Bill Billy Billy bloody hell Bloody hell bugger down I’m a stone I bin to town fuck fuck fuck fuck off fucking fucking fucking hell

COT blimey funny thing funny thing goody goody I can’t 1 can’t I can talk I can try I can talk and I try I did not hear 1 told you

1 thmk one two 1 said It’s a ptty pity pit> I want to I want to I want to one two one two I try one two and 1 can’t

and 1 want to John milk money no no now Walt a minute wait a

minute wait a minute Off

oh boy oh you bugger oil factory policeman on the corner paper and pencil

pardon for jou Parrot (proper name) piano Wednesday Percy’s died slbter sl\ter bibter so and \I) \o 50 hetter better snnewhere somewhere three three time a time tingalmg todaY two two two washing machine sewing machme well I know

YeP thing thingy Yes yes ye\ you can’t

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restricted semantic range utilised in lexical speech automatisms. Lexical speech automatisms are syntactically correct structures in the overwhelming majority

of cases. The utterances do not break the syntactic rules of English. With few exceptions the initial words are syntactically stressed content words. Although it is not possible to be sure of the syntactic function of words in the sample, or even if the words have a syntactic function, taking the words at their face value reveals that 43 (from 68) initial words are either nouns, pronouns or verbs. In normal conversational speech these are contentive lexical words, high in referential meaning and many of the initial words in the sample would normally be stressed.

In the most severely aphasic individuals, the impression the observer gets is that the patient makes no attempt to suppress the utterance, and is apparently completely unaware of the inappropriateness of the utterance. Less severe patients suggest by their behaviour and response to testing that they are clearly aware that the utterance is being produced, without their intention, in place of an intended utterance. For such patients the utterance appears to be produced with great struggle and frustration in an effort to suppress the emergence of the utterance. ALAJOUANINE [ 31 considered an impairment of awareness to be a significant factor in patients with speech automatisms. He suggested that, for those patients who do make recovery, there are four stages leading to that recovery, the end point of which is agrammatic but propositional speech. For Alajouanine it is the re-emergence of awareness, shown by the patient’s attempts to check the utterance, which is essential for recovery to occur. Recent developments in the neuropsychology of consciousness [ 15, 161 highlight the importance of a balance in automaticity and flexibility in normal mental activity and behaviour. The central impairment in some neurological conditions is one of conscious awareness, where a monitoring system is disconnected. Flexibility in mental activity is what conscious reflection is and the individual restricted to automatic processing only is berefted of flexibility. Automatic aspects of behaviour are outside of conscious awareness and can be dissociated in neurological disease. For KINSBOURNE [ 151 a distinction is necessary between “whether we experience something and whether we are aware of whether we are experiencing something” (p. 241). In conditions like unilateral neglect and cortical blindness the patient has lost a kind of meta-awareness. While they are conscious in the everyday sense, their problems with awareness may be due to a failure of a meta-awareness. For aphasic individuals who are unaware that they are producing inappropriate utterances, the same may be the case. ALAJOUANINE’S [ 31 observations on the quality of awareness in patients with speech automatisms have never been experimentally tested.

A problem which arises when approaching the linguistic nature of lexical speech automatisms is the degree to which we can analyse what is a “frozen” utterance-not language at all in the full linguistic sense. CODE [4] compared his collection with word frequency counts in English which showed that (with the exception of expletives and proper names which do not appear in frequency counts of normal conversational English) the words which make up these utterances are all high frequency. Although made up of recognisable words, the lexical speech automatism has no apparent referential or contextual connection with the patient’s world; the utterance appears to be phonologically, syntactically and semantically identical each time it is produced [41. However, this is not true of the proper names that occur as speech automatisms. These were all names which were traceable to relatives of the patients.

While many automatisms are single, often repeated, lexical items there are some syntactically complete sentences, for instance now wait a minute, and I bin to town. The pronoun + modallaux. utterances may fail to complete because of an inadequate lexical specification of the main verb of an intended utterance, but many of the utterances observed that do make up

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complete sentences are of this subtype. CODE [ 41 examined the frequency and distribution of the speech sounds which make up the

words of speech automatisms. The phones making up the words were compared to the phoneme counts which have been conducted on normal conversational English [ 171 There was a high correlation between the frequency of occurrence of phonemes in conversational English and phones in lexical speech automatisms. There is also a greater, but statistically insignificant, use of vowel articulations in the utterances than in conversational English: the ratio of consonants to vowels is 62.54% to 37.46%, respectively, in normal English, but in real-word speech automatisms it was found to be 56% to 46%.

The distribution of consonants by voice, place of articulation and manner of articulation (e.g. fricatives, plosives, nasals, etc.) was compared to the normal English distribution [ 171 and showed that although the distribution by voice and place in these fragments is similar to conversational English, the manner of articulation compared to normal English shows some deviation with plosives accounting for 40.25 % of consonant productions in speech automatisms (normal English = 29.21%), fricatives for 16.01% (normal English = 28.01%), nasals for 25.10% (normal English = 18.46%) and sonorants for 16.45% (normal English = 19.42%). This pattern suggests an increase in use of the motorically “easier”, and unmarked articulations and a reduction of articulations which are motorically more complex and marked.

Where the frequency of phones used in the lexical variety correlates highly with normal English phoneme counts, for non lexical recurring utterances the frequency of occurrence does not reflect normal usage. Where lni and it/ are the most common phonemes in normal English [ 171 and the lexical type, in recurring utterances iii, schwa, ibi and id/ are the most popular. There is also a marked increase in vowel articulations in the CV type: the ratio of consonants to vowels in recurring utterances was found to be 47% to 53%) (normal English = 62.54% to 37.46%). Where lexical utterances used 40 of the available 44 phonemes of English, the non lexical type used only 21, significantly less.

The distribution of consonants by voice and place in non lexical recurring utterances is similar to conversational English. However, again, the manner of articulation in recurring utterances shows plosives accounting for over 62 % of consonant productions (normal English = 29.21%), fricatives for over 22% (normal English = 28.01%), nasals for 7.5% (normal English = 18.46%) and sonorants for 7.5% (normal English = 19.42%). In the non lexical type, therefore, there’s an even more marked increase in the use of the motorically simpler articulations with a corresponding reduction in motorically more complex and more marked articulations.

Although it has been traditionally held that patients with both types of speech auto- matisms are able to use normal intonation with their utterance to signify meaning, instrumental research has not been carried out to examine this question. Perceptual investigation, however, suggests a very restricted ability to vary intonation linguistically for patients with automatisms [18,19].

Most patients with speech automatisms are severely aphasic. These patients have severe deficits in their ability to utilise syntax, semantics and phonology in expression or compre- hension in any modality. We might therefore reasonably conclude that the lesion has effectively destroyed most of the language system. However. recent evidence shows retention of certain language skills in some patients. There are indications that certain processes, mainly basic writing skills in the reported cases, can be partially preserved in some individuals with CV type recurrent utterances [ 20-223

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RELATED AUTOMATIC AND REITERATIVE UTTERANCES

A range of automatic, reiterated speech is observed in neurological conditions other than aphasia, and some seem to be closely associated with aphasic speech automatisms. In anterior temporal lobe epilepsy, several types of language disturbance can occur during focal epileptic seizures. Ictal speech automatisms (ISA) are made up of recognisable words which appear to be linguistically correct. The patient is amnesic for the utterance following the attack. Several types are observed [23,24], the most interesting of which are recurrent utterances, where the patient produces a repeated phrase over and over (e.g. “that is right, that is right”, “I must go, I must go”). More abnormal EEG wave patterns have been found over the right hemisphere than the left during the production of these utterances [24-281.

Usually delayed auditory feedback (DAF) causes an “artificial stuttering” in a subject (increased amplitude and pitch, reduced rate of utterance, disfluency) which is taken to indicate closed-loop auditory feedback control of speech [ 291. CHASE et al. [ 301 examined the effects of DAF on a temporal-lobe epileptic during the production of his ISA. None of the usual effects were observed, indicating that production of the automatism was under open-loop control: the automatism was produced as a single whole rather than segmentally.

In people with Gille de la Tourette Syndrome we observe probably the only example of spontaneous, involuntary speech produced by a conscious individual. The coprolalic nature of the utterance (coprolalia refers to obscene and sexual utterances) has parallels with expletive speech automatisms. Although individuals with Tourette’s syndrome appear unable to suppress the emergence of the utterance, they are aware that they are producing the utterance. It may be that the utterances emerge during stressful episodes which appears to reduce the individuals powers to suppress the utterance [ 3 1 ] . Why it is the foulest of expletives which should emerge in Tourette’s is unknown, but the disorder presents with clear limbic features [32,33], and basal ganglia involvement have been suggested [33-351.

Although ISAs and coprolalia are involuntary, they appear to be invariantly and holistically produced. Speech automatisms are also reiterative. A patient will often repeat the utterance over and over again with some limited variation in intonation in the absence, as it were, of newly generated speech. Like in aphasic speech automatisms, the major features of the coprolalia of Tourette’s syndrome and the ISAs of epilepsy, are apparent invariance and nonpropositionality with each production being linguistically the same.

NONPROPOSITIONAL AND AUTOMATIC SPEECH

It is well recognised that much of our general behaviour is routine and automatically produced [ 15, 16,361. All of our mental and motor activity is not under conscious control and guidance. There is much that is automatic and routine in speech production, despite the originality and creativity of human language [37]. LENNEBERG [38] pointed out over 25 years ago that thousands of muscular contractions take place during every second of speech, and these involve complex muscular activity at respiratory, articulatory, laryngeal and pharyngeal levels. Much of our speech activity is not under ongoing, moment-to-moment control, with each segment being individually planned and sequentially executed. It would be physiologically impossible for us to produce speech with the rapidity and the proficiency that we are able to if we had to plan and perform each segment individually. Speech appears to be under a mixture of closed- loop and open-loop control [39]. In closed-loop control, speech is feedback-controlled, segmentally planned and executed. Under open-loop control whole chunks are holistically

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planned and automatically produced. The speed and fluency of normal speech production from a neuromuscular system under physiological and mechanico-inertial constraints, means that a significant amount of automaticity is required for speech to proceed.

JACKSON [7], who derived his general evolutionary views which formed the basis of his model of the nervous system from the evolutionary ideas proposed by the highly influential philosopher Herbert Spencer (1820-1903), saw aphasic speech automatisms as primitive and automatic behaviour and the expression of levels lower down the neural hierarchy which have been released from higher level inhibition. It was his observations of aphasic speech auto- matisms which led him to propose the idea of propositionality in language. Nonpropositional speech appears to be produced, by definition, automatically and the individual syntactic, morphological and phonological elements are not newly or individually generated. This is distinguished from propositional speech where original ideas are being encoded into novel utterances. JACKSON [ 61 also introduced the idea that the left hemisphere was responsible for processing propositional language whereas both right and left were involved in the processing

of nonpropositional language. Jackson’s notion of the propositionality dimension in language is still only on the periphery

of linguistic and psycholinguistic study, although it was formulated over 100 hundred years ago. It has been argued [4, 8,40-421 that nonpropositional, holistically processed, formulaic language does not entail straight linguistic. unit-and-rule analysis and synthesis. Propositionality appears to be a feature of natural language use, although it is not a variable which can be easily manipulated in the psycholinguistics laboratory

Invariance of production and automaticity are the hallmarks of nonpropositional language. Verbal activities like recitation, counting, listing the days of the week and the months of the year and rote repetition of arithmetic tables are low in propositionality; they do not involve the generation and process of new ideas and their conversion into original utterances. Everyday phrases, idioms and “fillers” like “Nice day”, “How are you?” and “Sort of” are examples of English usage which is low in propositionality. Probably these expressions do not engage modules of a generative grammar. So separate productions of these kinds of formulaic utter- ances do not use a new and separate syntactic, morphological and phonological specification. Such regularly used idioms as “Good to see you” and “By the way” are most probably processed as single lexical items, as a complete holistic package. The main features of more nonpropositional and automatic language then are invariance of production and a non segmental and holistic construction.

Notwithstanding, it would be a mistake to view all such language as devoid of meaning; expressions of pain, emotion and feeling, for instance, are high in expressive significance. Many nonpropositional communications, such as social greetings, have a major pragmatic function. Although automatic, therefore, the degree of “propositionality” inherent in auto- matically produced language must be variable and situation-specific. Much nonpropositional language may therefore be seen as evolutionally pre-linguistic. It is concerned with social and emotional aspects of communication and expression which pre-exist the capacity in human beings to generate fully predicative propositional language.

Extensive evidence has accumulated in recent years which supports Jackson’s original notion that the right hemisphere has at least equal involvement in the processing of automatic and nonpropositional aspects of language. Prosody, emotional language, automatic language, idioms, metaphors, and other features which do not engage straight linguistics processes, appear to be processed with significant right hemisphere involvement (see [ 13,431 for review).

SPEECH AUTOMATISM PRODUCTION 141

THE ORIGINS OF SPEECH AUTOMATISMS

While the foregoing appears to support the view that aphasic speech automatisms do not function fully as language, we can ask whether an automatism was language in a fuller sense when first uttered and whether its frozen linguistic form can provide clues to the state of the language system at its origin, or clues to the nature of the language system’s adaptation.

Over the years some have considered that an individual’s automatism had some particular connection with the actual moment of brain damage. Jackson stated “I believe them to represent what was, or to represent part of what was, the last proposition the patient uttered, or was about to utter, when taken ill” (JACKSON [7], p. 178). One of Jackson’s famous examples is the lexicographer who had just finished preparing a dictionary when he had a stroke and was left with the automatism “List complete”. CRITCHLEY [44] favours Jackson’s view and lists some outlandish anecdotal examples. The patient with the utterance “on the booze” had apparently had his stroke during what Critchley describes as “a taproom brawl”. Another patient whose utterance was “I want protection” sustained brain damage during a street fight, and an attractive young woman following a cerebral haemorrhage could say nothing but the words “Not tonight, I’m tired”. Yet another patient, according to Critchley, is said to have sustained a CVA while making love in the early hours and was left with the automatism “good morning” (p. 207).

Jackson’s explanation emphasises an illocutionary connection between the utterance and an activity being pursued at the time of onset of brain damage, and assumes that the utterance has its origin at this moment. There are problems with these kinds of accounts especially as patients can have more than one utterance. None of the utterances collected by CODE [4] resemble those reported by Critchley. Fourteen subjects (from 75) in the corpus presented with more than one utterance. In more than half of the 14 there was a clear phonological, syntactic or semantic relationship between the two or more utterances the patient produced. In some cases, especially with recovery, individuals can develop a second and subsequent utterances, and in six of the cases there was evidence that one utterance existed independently before a second or third was added to the repertoire. These subsequent utterances cannot be accounted for by Jackson’s explanations: they clearly emerged following the original neurological incident. Further, it is unlikely that the emergence of a second or third utterance is linked to another neurological incident, as the emergence of additional utterances, as suggested by ALAJOUANINE [3], is seen as part of a picture of improvement and as a positive prognostic sign. The emergence of additional utterances is probably linked to some recovery of the underlying impairment where the individual can gain sufficient control to allow some variation in the single utterance they have been left with, and this is why subsequent utterances are commonly linguistically similar to the original. As discussed in an earlier section, a large proportion of these utterances come from a remarkably restricted semantic range. For this reason the common pronountverb type, in particular, is unlikely to have had its origin at the time of the stroke. The odds on 3 separate individuals engaged in identical activities and all about to say “I want to..” at the moment of their stroke is unlikely, to say the least. It seems improbable that an individual’s unexpressed or just about to be expressed thought at the precise time of the CVA should fall within the limited semantic range expressed by these utterances.

A further possible explanation is that the utterance originates at the time of the insult, not through cognitive-behavioural activities in operation before or during the CVA but as a result of the neuro-chemical activity accompanying the CVA. Thus, expletive utterances may have their origin following a sudden release of limbic mechanisms from the normal neural balance. Clinicians often report patients who were not in the habit of swearing before their CVA, like

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the Minister of the church who could produce only expletives, anecdotally supporting this idea that expletives may result from release of inhibition of limbic structures.

I have argued that speech automatisms have a range of origins. Apart from the two possible explanations for the origin of speech automatisms outlined above, many speech automatisms could have their origin during the very early recovery of the patient [ 45 ] Automatisms like “BBC”, “sister, sister” and the serial-number subtype can be accounted for as originating in response to stimuli since the stroke. They may be (a) related to the first utterance the patient attempted to produce post-onset or (b) the first utterance the patient heard post-onset.

Therapeutic intervention from therapists, nursing or medical staff and relatives might account for some automatisms. It is possible that the serial-number type could originate during the initial interview with the therapist. It is common practice for the therapist on first seeing a severe patient to attempt to deblock speech impairment through serial speech tasks, and it is often the only kind of speech severe patients can produce. Residual abilities are often drilled by ward staff and relatives. Many of the emotionally charged pronoun + verb types could be linked to initial frustration post-onset. Some automatisms may result from the first thing the patient heard following their stroke. For instance, the automatism “BBC” may have been a radio or TV announcement, “it’s a pity” might have been expressed by a sympathetic nurse or relative, “sister, sister” (two examples from CODE [4] ) is commonly heard in hospital wards and ‘&wee” is a common euphemism used with elderly patients in the United Kingdom.

These are not arbitrary, randomly selected, expressions; the restricted semantic range of the utterances confirms that. It seems improbable, therefore, that the majority of utterances have a connection with pre-CVA factors.

NEUROGENIC MECHANISMS UNDERLYING SPEECH AUTOMATISMS

Can we formulate hypotheses concerning the possible neurogenic mechanisms which underlie the origin of speech automatisms and perpetuate their production’? A range of studies have examined their neuropathology. Large anterior lesions have been found in globally aphasic patients with non lexical types [46] , whereas globally affected patients without automatisms had a more posterior pattern of damage. Non lexical types may therefore occur more often with lesions of the greater Broca’s area, and are associated with severe aphasia and apraxia of speech. Subcortical and limbic structures have been implicated in automatism production. and the basal ganglia have received particular attention. The structure is seen as the site of a motor program generator [34,47], and damage here has been implicated in the production of recurring utterances, speech automatisms, coprolalia and pallilalia [ 33, 341

BRUNNER et ul.‘s [48] results suggest that basal ganglia damage is essential for the production of speech automatisms. Using CT they examined 26 patients with basal ganglia involvement of whom 12 had either lexical or non lexical utterances. Neither type of utterance occurred in the patients without basal ganglia damage but automatisms did not occur in patients who had on131 subcortical (including basal ganglia) damage. In other words, a large left hemisphere lesion incorporating both the cortex and basal ganglia appears to be required in patients with automatisms. Of the 12 patients with automatisms, 9 had both anterior and posterior damage involving the basal ganglia and 3 had only anterior damage involving the basal ganglia.

POECK er al. [ 191 were unable to confirm the importance of the basal ganglia in their CT study of 8 patients with exclusively non lexical recurring utterances. They also found no significant differences in lesion patterns for global patients with and without automatisms.

SPEECH ~uTohwnsM PRODUCTION 143

However, HAAS et al. [ 101 have pointed out that POECK et al. [42] designated as damaged structures where more than 30% was included in the CT scan. In addition, patients of less than 2 months onset were included in the POECK et al. [ 191 study who must be considered unstabilised.

HAAS et al.‘s [ lo] CT study involved 49 subjects with damage including more than 2% of forebrain volume who were more than 4 months post-onset. Sixteen had non lexical and 2 had lexical automatisms and all 18 had lesions in the deep fronto-parietal white matter of the left hemisphere. A relationship between automatism production and structures in the depth of the area of supply of the middle cerebral artery was found. Automatisms were also associated with older patients suggesting that they may perhaps be associated with continuing left lateralisation [ 491, degenerative processes associated with advancing age not visible to the CT scan, or some

diffuse and progressive vascular pathology. Apart from the possible roles of subcortical structures and the right hemisphere alluded to

earlier, it has been hypothesised that some lexical speech automatisms fit well with what we know of right hemisphere-limbic interactions [ 81 The limbic forebrain makes a large contribution to human communication [ 321. In all mammals the phylogenically ancient limbic system is centrally involved in the expression of emotional and affective signals of rage, fear, surprise and social expressions of dominance, submission and aggression, as well as inter- gender and mother-child relationships. The right hemisphere may have a unique and specific relationship with the affective subsystems of the limbic system, a relationship that the left hemisphere does not have. The limbic system is “the obvious candidate for the level of brain activity likely to be responsible for the bulk of nonpropositional human communication” (LAMANDELLA [ 321; p. 159). In temporal lobe epilepsy it is areas of the limbic system which “trigger” the seizure which produces an ISAs and, as already alluded to, Tourette’s syndrome presents with clear limbic features [ 331

The emotionally charged pronoun + verb subtype of speech automatism and the expletive subtype are obvious candidates for central limbic involvement, being holistically produced without formal linguistic input. I have suggested elsewhere that “assuming that the limbic system has no linguistic or phonetic programming capability, but is simply the motivational force behind the utterance, then the right hemisphere, through its capacity to provide a motor Gestalt, controls the actual motor speech activity of the phono-articulatory mechanisms” (CODE [S] , p. 73). Similar arguments can be made for coprolalia and ISAs. For these utterances, too, the fragment of emotionally charged, holistically structured and invariantly produced speech could implicate a limbic-right hemisphere interaction. WALLESCH [ 141 has made the point that lexical speech automatisms might be emotionally charged or neutral (e.g. piano, washing machine).

Non lexical speech automatisms are clearly nonpropositional but have minimal linguistic structure to implicate affective-emotional processing. They are not arbitrary syllables, as has been suggested [44], but, as shown earlier, concatenated CV syllables governed by phono- tactic constraints. The non lexical utterances appear to reflect articulatory simplification where only high frequency and motorically unmarked articulations taken from the phonetic inventory of the speaker’s language are produced to conform to phonotactic rules. The fact that the non lexical type do not break phonotactic constraints may suggest that they access a phonological output module the first time they are produced. For these reasons the initial production of a non lexical recurring utterance may be by a severely damaged left hemisphere phonological system which does not have access to limbic-right hemisphere input.

KURTHEN et al. [.50] recently reported on a small proportion of left dominant epileptic

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subjects (5 out of 148) undergoing Wada investigation who perseverated on counting while the left hemisphere was anaesthetised. They suggest that this surprising finding is best explained as a continuation by the right hemisphere of a programme origination in the left hemisphere.

A PRELIMINARY MODEL

A preliminary model of speech automatism production must accommodate a number of features: first, it should acknowledge the lack of formal, “straight”, linguistic input; second, it should acknowledge the apparent holistic preparation and production of the utterance and the invariance of production; fourth, it should deal with (a) the initial production and (b) the subsequent productions of the utterance.

Figure 1 shows a model which acknowledges the lack of linguistic input, reflects the apparent holistic preparation and the invariance of production of the utterance, distinguishes between the two major types and accounts for (a) the initial production and (b) the subsequent productions of the utterance. The model assumes, as the evidence suggests [ 4, 121, that most of the language production system is severely damaged for most patients. The model therefore attempts to capture what remains of the language system that can account for speech auto- matisms. The first components of the model are labelled inrention ro communicate and expression of srate. An utterance may be formulated as either a result of an intention to communicate or as an expression of internal state, where for the latter the utterer has no intention to communicate to another party. The model assumes that for an initial production of either type of utterance an intention to communicate or an expression of state is generated and a speech act (e.g. question, command, statement, etc.) is formulated by the component labelled speech act formulation. This component determines the essential message of the utterance. In the case of lexical speech automatisms. the form of the utterance is then generated by an holistic speech lexicon and passed to an articulatory bufer [ 121 before final production.

Formulation I

Holistic Speech

,: I!,

Articulatorq LWiCOtl Formulation (Lexical) (Nonlexical)

Artwlatory Buffer I

SPEECH AUTOMATISM PRODUCTION 145

Initial non lexical recurring utterances are generated by an articulatoty formulation module which inputs the articulatory buffer before final production. For these non lexical utterances, however, it is the most unmarked and higher frequency phones that are selected for production. For subsequent productions of both types of utterance, shown by the thick arrow, an intention

to communicate or an expression of state inputs to speech act formulation and then directly into the articulatory buffer before expression an as utterance.

Some identifiable subtypes, expletives and pronoun + modal/auxiliary for instance, may have originated initially as expressions of internal state, while subsequent productions may occur as a result of either expression of state or an intention to communicate. While some variation in intonation is possible, the available evidence alluded to earlier suggests that patients with automatisms are not able to vary intonation normally, which is contrary to traditional belief. There may be individual variability and for such patients who are unable to vary intonation there may be an impairment at the level of speech act formulation.

The holistic speech lexicon is seen as a store of holistic-automatic schemas [ 361 which holds the representations of lexical speech automatisms like expletives, serial speech, pronoun + verb. An assumption of the model is that a non lexical utterance will ensue at initial attempts to speak if the route through the holistic lexicon is blocked by extensive neural damage. The lack of semantic range observed in many lexical automatisms could be a reflection of the holistic lexicon’s responsibility for very restricted and automatic output.

The model includes an articulatory buffer after BLANKEN [ 121 which, it is proposed, could be the locus of continued production. The buffer is responsible for temporary storage of the phonetic plan of an utterance which becomes necessary for most models of speech production to cope with the probability that the neural planning of an utterance is a lot faster than the ability of the phonoarticulatory mechanism to actually realise it. The buffer stores prepared utterances for short time durations. Neural damage may prevent changing the program within the buffer so that input into the buffer causes it to generate the same stored utterance each time. BLANKEN [ 121 has argued that because evidence suggests fairly strongly that the rest of the language production system above the buffer is severely impaired and written automatisms do not occur, then for non lexical CV speech automatisms the locus of the continuing production is within the articulatory buffer. Whether there may also exist comparable “automatisms” of language comprehension is a matter for speculation.

The model does not attempt to account for the unclassifiable utterances in Table 1. Nor does it differentiate between different subtypes of lexical automatism, but different subtypes would probably entail different routes to realisation. Neither does the model consider non-aphasic pathological reiterative utterances, such as coprolalia or ISAs. Some features, like the failure of the patient with Tourette’s syndrome to inhibit coprolalia, may be accounted for by the model. The Tourette patient may be unable to inhibit an expression of limbic state which inputs the model at the level of the speech act. However, why a patient would develop an expletive rather than a pronoun + modal type, for instance, can be a matter only for speculation with current understanding. Two possible explanations were considered earlier. One places the origins of a lexical automatism external to the individual, in the environment. The older explanations considered the utterance was actually produced or about to be produced, so already at some stage of production between intention to communicate or expression of state and the acoustic signal. We also considered the evidence for explanations which focused on interactions between the patient and environmental factors post-stroke and some speculations were considered which went some way to differentiate between subtypes. A further class of explanation which may differentiate between subtypes is internal to the patient; the neuro-

146 CHRIS CODE

physiological explanation which was discussed. Thus the origins of different subtypes may lie in the disturbance of or disruption to electrical or neurotransmitter activity during or immediately following the CVA.

CONCLUSIONS

Lexical speech automatisms may originate as holistically created products of a subcortical right hemisphere-limbic system mechanism. If they do then the linguistic system of the left hemisphere is not engaged during their genesis. In the case of the non lexical variety, almost by default as they show little evidence of right hemisphere language structure, I have suggested that they might be the product of severely compromised left hemisphere mechanisms dis- connected from subcortical and right hemisphere mechanisms. This might suggest that access to the phonology was so impaired that only very primitive CV syllables (usually one repeated syllable) are produced. The continuing failure on the part of the individual to produce more than the automatism is frustrated by an almost total apraxia of phonoarticulatory mechanisms.

The lexical variety have an adequate. if limited, syntactic structure. Some, like proper names, carry a restricted semantic reference while most appear to have no apparent reference to objects or experience in the individual’s world. This could suggest that, despite the similarities that they share, different processing mechanisms may be responsible for the production of different subtypes. It may be, for instance, that expletives. pronoun + modal auxiliaries, real name subtypes, etc., all have different underlying mechanisms. The invariant nature of both types of automatism implies no access to linguistic components at all, at least following the first utterance of the expression, although research suggests individual variability in severity. Detailed investigation of small groups shows a variety of retained and rudimentary expressive and receptive abilities in some patients.

What we may be observing is the fractionated output of different subsystems reflecting contributions from neuronal structures and mechanisms at different organisational and representational levels throughout the brain. In speech automatisms we see. especially in the case of automatically reiterated CV syllables, perhaps the most primitive capability of the fragmented expressive speech mechanism.

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