Dynamic aphasia and the generation of language

Gail Robinson* and Lisa Cipolotti

National Hospital for Neurology and Neurosurgery, London, WC1N 3BG, UK

Available online 23 July 2004

Severely reduced propositional speech in the context of intact

nominal language skills (i.e., repetition, naming, comprehension, and

reading) is the hallmark of dynamic aphasia (Luria, 1970). Recent

evidence suggests there may be different types of dynamic aphasia as

some patients do not produce any response on verbal generation

tasks, whilst others are able to perform normally on verbal genera-

tion tasks. For example, Robinson and colleagues (Robinson, Blair,

& Cipolotti, 1998; Robinson, Shallice, & Cipolotti, 2004) reported

two dynamic aphasics who failed to produce a verbal response when

many verbal response options were activated by a stimulus, but not

when a dominant response was available. By contrast, a dynamic

aphasic patient reported by Snowden, Griffiths, and Neary (1996)

was able to produce sentences and words on specific verbal gener-

ation tasks. We report a dynamic aphasic patient (KAS) who, sim-

ilarly to the patient reported by Snowden et al. performed flawlessly

on all verbal generation tasks, despite almost abolished propositional

speech.

Subjects

KAS, a patient with progressive supranuclear palsy, presented with

a severe verbal inertia. Spontaneous speech was virtually abolished in

the context of well-preserved repetition, naming, reading, and com-

prehension skills. This pattern can be classed as dynamic aphasia. MRI

brain scan revealed generalized cerebral atrophy, severe midbrain at-

rophy and white matter change in the frontal lobes bilaterally. Three

matched healthy controls were used.

Methods

KAS and controls were administered five verbal generation and

two narrative production tasks.

The verbal generation tasks consisted of 30 sentence frames, 30

phrases, 30 word pairs, 30 words, and 30 simple pictorial scenes (based

on Robinson et al., 1998, 2004). KAS was required to generate a word

or phrase to complete sentence frames and phrases, respectively, and to

generate a sentence from word pairs, single words, and pictorial scenes.

Number correct was recorded.

The narrative production tasks involved an interview and a

topic-based discussion. The interview was either unstructured with

minimal verbal prompting (duration = 16 min for KAS and a mean

of 14.2 min for controls) or highly structured and much shorter with

unlimited verbal prompting (duration = 8 min). For the topic-based

discussion, three topics were discussed: films, actresses, and stage

shows. There were two conditions for the source of the topic. The

topic was either externally driven in that the examiner selected an

example of the topic (familiarity with the topic was ensured) or

internally generated in that KAS selected her favorite example of a

topic. Subjects were given a maximum of 2 min for each topic for

both conditions. For both narrative production tasks, speech rate

(words per minute), and total number of words produced were

calculated.

Results

KAS was unimpaired on all verbal generation tasks. Despite al-

most abolished propositional speech, CK was able to generate 29/30

words to complete sentences, 30/30 phrases to complete phrases, 29/30

sentences from a single word, 30/30 sentences from word pairs, and 30/

30 sentences that described pictorial scenes.

In contrast, KAS was severely impaired on both narrative

production tasks. Both in the interviews and in the topic-based

discussions her speech rate and total number of words she was able

to produce was severely reduced. However, her difficulties were far

greater in the unstructured interview that contained minimal

prompting and in the discussion task when the source of the topic

was externally driven. In particular, in the unstructured interview

her speech rate was less than half than in the shorter structured

interview. Moreover, she produced much less words (speech rate,

No. of words produced: unstructured = 9.4, 149; structured = 21.4,

171; Controls—unstructured = 180.6, 2602; structured = 155.9,

1247).

Similarly in the topic-based discussion task her speech rate and total

number of words produced were more reduced when a topic was exter-

nally generated (speech rate, No. of words produced: externally gener-

ated = 9.2, 18.3; internally generated = 25.2, 50.3; Controls—externally

generated = 180.7, 361.3; internally generated = 183.7, 367.3).

Discussion

Despite almost abolished propositional speech, KAS performed

well on verbal generation tasks. Thus, similar to the dynamic

aphasic described by Snowden et al. (1996), KAS is able to produce

a verbal response on specific verbal generation tasks. Nevertheless,

KAS’s performance on narrative production tasks is severely im-

paired, especially when the task is unstructured or when the source

Brain and Language 91 (2004) 49–50

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*Corresponding author. Fax: +44-20-78132516.

E-mail address: g.robinson@ion.ucl.ac.uk (G. Robinson).

0093-934X/$ - see front matter � 2004 Elsevier Inc. All rights reserved.

doi:10.1016/j.bandl.2004.06.027

of the topic for discussion is externally generated. Interestingly, her

performance improved when verbal prompts were available and

when she generated the specific topic to be discussed. In terms of

Levelt’s model of speech production, we suggest that her severely

reduced propositional language skills arise from a breakdown in an

early stage, prior to the conceptual preparation process that is in-

volved in generating a message (i.e., conceptual structure). The

generation of a message is thought to involve a variety of knowl-

edge sources. A deficit prior to the conceptual preparation stage

would impair the ability of the speaker to generate any message

and, hence, result in little or abolished propositional speech. Certain

conditions, however, such as a verbal prompt or the generation of a

specific topic to be discussed, would activate or enable the con-

ceptual preparation processes and increase the likelihood that a

message is generated and speech is produced.

References

Levelt, W. J. M. (1999). Producing spoken language: A blueprint of the

speaker. In C. M. Brown & P. Hagoort (Eds.), The neurocognition

of language (pp. 83–122). Oxford, UK: Oxford University Press.

Luria, A. R. (1970). Traumatic aphasia. The Hague: Mouton.

Robinson, G., Blair, J., & Cipolotti, L. (1998). Dynamic aphasia: An

inability to select between competing verbal responses? Brain, 121,

77–89.

Robinson, G., Shallice, T., & Cipolotti, L. (2004). A failure of high

level verbal response selection in progressive dynamic aphasia.

Cognitive Neuropsychology (in press).

Snowden, J. S., Griffiths, H. L., & Neary, D. (1996). Progressive

language disorder associated with frontal lobe degeneration.

Neurocase, 2, 429–440.

50 Abstract / Brain and Language 91 (2004) 49–50