A left basal ganglia case of dynamic aphasia or impairment of extra-language cognitive processes?

Abstract

We report the case of OTM who presented with dynamic aphasia following a stroke that occurred in the left basal ganglia. He showed drastically reduced spontaneous speech in the context of well preserved naming, repetition and comprehension skills. OTM was particularly impaired in generating words, sentences and phrases when cued by a stimulus allowing many response options. By contrast, when a single response was strongly suggested by a stimulus, he could generate verbal responses adequately. OTM's non-verbal response generation abilities varied across tasks. He performed in the normal range in a motor movement generation test and he produced as many figures as controls when tested on a figural fluency task. He showed, however, many perseverations on this test. Moreover in a random number generation task he produced more responses that were part of ascending and descending series of numbers. The patient's impairments are interpreted as a consequence of two deficits. The first of these consists of an inability to generate verbal responses particularly in situations of high competition and involves the function of left frontal regions. The second deficit is one of impaired novel thought generation as evidenced by perseverations. This second deficit has been proposed to be a function of basal ganglia damage.

Propositional speech in unselected stroke: The effect of genre and external support

“…This pattern of decreasing speech rate with overt visual cues available with different genre type is consistent with the external support findings discussed below. Finally, the LH deficit is consistent with investigations of dynamic aphasia that highlight crucial brain areas underpinning conceptual preparation processes for propositional language (e.g., left basal ganglia, Crescentini et al, 2008;left inferior frontal, Robinson et al, 1998left inferior frontal, Robinson et al, , 2005. However, at present it is unclear how this relates to studies that have demonstrated a role of the subthalamic nuclei in proposition speech (e.g., Castner et al, 2007Castner et al, , 2008.…”

“…Procedural tasks facilitate concept selection because task topics are often habitual events or actions and are verbally rehearsed (Bartels-Tobin & Hinckley, 2005). Familiarity of topic tasks minimises the need to construct a novel message, as demonstrated by patient OTM who presented with dynamic aphasia and intact procedural discourse (Crescentini et al, 2008;see below). At the same time, the need to organise steps may place greater demands on sequencing.…”

“…Thus far, studies focused on selection have employed single word (e.g., Crescentini, Shallice, Del Missier, & Macaluso, 2010) and sentence (e.g., Crescentini et al, 2008;Robinson et al, 2005;Robinson, Shallice, Bozzali, & Cipolotti, 2010) generation tasks (although for a recent exception, see Robinson, 2013). Studies investigating sequencing have involved patients with Parkinson's disease who demonstrate failure to select and inhibit competing motor (Mink, 1996) and lexical-semantic representations (Copland, Sefe, Ashley, Hudson, & Chenery, 2009).…”

“…Dynamic aphasia is a distinct language disorder characterised by reduced propositional speech despite well-preserved core language skills (i.e., repetition, reading, naming, comprehension; Luria, 1970Luria, , 1973. This disorder has been documented in both neurodegenerative conditions (e.g., Esmonde, Giles, Xuereb, & Hodges, 1996) and focal lesions (e.g., Bormann, Wallesch, & Blanken, 2008;Costello & Warrington, 1989;Raymer, Rowland, Haley, & Crosson, 2002), including individuals following stroke (e.g., Crescentini, Lunardelli, Mussoni, Zadini, & Shallice, 2008;Gold et al, 1997). Several accounts for dynamic aphasia have been proposed that suggest the disorder is due to a breakdown in the process of translating internal speech into overt speech (Luria, 1970(Luria, , 1973, a failure in verbal planning (Costello & Warrington, 1989), an inefficient semantic search strategy (Gold et al, 1997), an inability to generate verbal and non-verbal responses (Raymer et al, 2002), and an inability to select one idea from amongst multiple competing ideas (Robinson, Blair, & Cipolotti, 1998;Robinson, Shallice, & Cipolotti, 2005).…”

Basal ganglia structures differentially contribute to verbal fluency: Evidence from Human Immunodeficiency Virus (HIV)-infected adults

“…The BG is implicated in higher-level cognitive functions via five parallel frontal–subcortical circuits (i.e., skeletomotor, oculomotor, dorsolateral prefrontal, orbitofrontal, and anterior cingulate) (Alexander et al, 1986; Cummings, 1993). In primate models, retrograde labeling of neurons have demonstrated that 1/3 of BG output is directed to prefrontal areas (i.e., BA regions 9, 46, and lateral aspect of 12), including multiple areas of the prefrontal cortex (PFC) that are critical to functions such as language production (Crescentini, Lunardelli, Mussoni, Zadini, & Shallice, 2008). Understanding the neuroanatomical correlates of selective language functions is the first step to improving the assessment and identification of language disturbances that may arise from neurological insult to the basal ganglia (BG), or from diseases that preferentially target BG functions (e.g., Human Immunodeficiency Virus-Type 1 [HIV-1], Huntington’s, and Parkinson’s).…”