Antonio Miozzo

Do subcortical structures control ‘language selection’ in polyglots? evidence from pathological language mixing

Abstract In the field of multilinguism, ‘switching’ defines a mechanism operating automatically when speakers shift among different languages. While the neural basis of this mechanism is unknown, recent studies of polyglot aphasia have suggested a possible role of subcortical structures. We report a case of subcortical polyglot aphasia which provides further evidence for a role of the basal ganglia in the switching mechanism. A polyglot female (Armenian-English-Italian), after a subcortical infarction in the language dominant hemisphere, developed a non-fluent aphasia characterized by pathological mixing among these languages in oral production tasks. This case confirms that damage to subcortical structures may result in different types of dysfunction in the mechanisms implicated in the selection of languages.

Pure anomia with spared action naming due to a left temporal lesion

We report the case of a patient who, after surgical ablation of an angioma in the depth of the left temporal lobe, developed a highly selective impairment of naming. A detailed investigation allowed to exclude a disorder of visual recognition or of semantic memory, and indicated the output lexicon as the most probable site of impairment. Grammatical class effects, with superior action naming, and a high consistency within and across output modalities further characterized the patients performance. Together with some other recently reported cases, this patient suggests a correlation between temporal lobe lesions outside Wernickes area and output lexicon disorders. A relatively spared action naming seems to be a characteristic feature of this pattern of impairment.

The representation of stress: Evidence from an aphasic patient

We report the case of an aphasic patient who, following an acquired lesion involving the left temporo-parietal cortex, produced many word stress errors in spontaneous speech, naming of objects and reading aloud. The stress impairment concerned exclusively words in which stress was unpredictable on the basis of syllabic structure, and was equally severe in naming and reading aloud. Errors were significantly more frequent in the cases of words with stress on the antepenultimate syllable, and of low frequency words. There was a high consistency between errors in naming and reading aloud. These findings suggest that stress representation can be selectively impaired after brain damage; we hypothesise that a partial disorder at the level of the form lexicon, involving the representation of lexical stress, can account for most of the features of the patients performance.

Anomia training and brain stimulation in chronic aphasia

Recent studies have reported enhanced performance on language tasks induced by non-invasive brain stimulation, i.e., repetitive transcranial magnetic stimulation (rTMS), or transcranial direct current stimulation (tDCS), in patients with aphasia due to stroke or Alzheimers disease (AD). The first part of this article reviews brain stimulation studies related to language recovery in aphasic patients. The second part reports results from a pilot study with three chronic stroke patients who had non-fluent aphasia, where real or placebo rTMS was immediately followed by 25 minutes of individualised speech therapy. Real rTMS consisted of high-frequency rTMS over the left dorsolateral prefrontal cortex (BA 8/9) for 25 minutes. Each patient underwent a total of four weeks of intervention. P1 underwent four weeks of real rTMS (5 days/week) where individualised speech therapy was provided for 25 minutes immediately following each rTMS session. P2 and P3 each underwent two weeks of placebo rTMS, followed immediately by individualised speech therapy; then two weeks of real rTMS, followed immediately by individualised speech therapy. Assessments took place at 2, 4, 12, 24 and 48 weeks post-entry/baseline testing. Relative to entry/baseline testing, a significant improvement in object naming was observed at all testing times, from two weeks post-intervention in real rTMS plus speech therapy, or placebo rTMS plus speech therapy. Our findings suggest beneficial effects of targeted behavioural training in combination with brain stimulation in chronic aphasic patients. However, further work is required in order to verify whether optimal combination parameters (rTMS alone or speech therapy alone) and length of rTMS treatment may be found.

Persistent post-traumatic retrograde amnesia: a neuropsychological and (18F)FDG PET study.

We report the case of a 48-year old woman who, after a severe closed head injury, developed a severe and persistent disruption of retrograde memory, associated with a mild impairment of learning abilities. The patients dense amnesia spared only the childhood period and included both explicit memory (autobiographical and semantic) and procedural skills. Because of her partially spared learning ability and intact language, intensive training by family members resulted in the reacquisition and retention of many autobiographical events and of some skills she had lost after the accident. Brain CT scan and MRI were normal; a PET study with (18F)FDG revealed a significant bilateral reduction of metabolism in the hippocampus and anterior cingulate cortex, suggesting a role for these structures in memory for past events.

Time Perception in Spatial Neglect: A Distorted Representation?

OBJECTIVE It has been proposed that time, space, and numbers share the same metrics and cortical network, the right parietal cortex. Several recent investigations have demonstrated that the mental number line representation is distorted in neglect patients. The aim of this study is to investigate the relationship between time and spatial configuration in neglect patients. METHOD Fourteen right-brain damaged patients (six with neglect and eight without neglect), as well as eight age-matched healthy controls, performed a time discrimination task. A standard tone (short: 700 ms and long: 1,700 ms) had to be confronted in duration to a test tone. Test tone differed of 100, 200, and 300 ms respect to the standard tone duration. RESULTS Neglect patients performed significantly worse than patients without neglect and healthy controls, irrespective of the duration of the standard tone. CONCLUSION These results support the hypothesis that mental representations of space and time both share, to some extent, a common cortical network. Besides, spatial neglect seems to distort the time representation, inducing an overestimation of time durations.

Confabulation and delusional misidentification: a four year follow-up study.

We describe a patient, AZ, who showed, in addition to an amnesic syndrome which eventually improved, longstanding confabulation and delusional misidentification following bilateral frontal and right temporal post-traumatic lesions. Confabulation appeared in personal recollections and on long-term verbal memory testing. Misidentification concerned mainly his wife and house. During the four year follow-up AZs confabulation progressively shrinked so as to become restricted to verbal memory tasks. By contrast, misidentification persisted. General semantic memory was unimpaired throughout, while performance on frontal tests was initially poor and partly improved in time. We argue that confabulation and misidentification, though often intermingled and occurring after similar lesion pattern, should be considered as different neuropsychological entities.

Prefrontal cortex rTMS enhances action naming in progressive non‐fluent aphasia

Background and purpose: Progressive non‐fluent aphasia (PNFA) is a neurodegenerative disorder that is characterized by non‐fluent speech with naming impairment and grammatical errors. It has been recently demonstrated that repetitive transcranial magnetic stimulation (rTMS) over the dorsolateral prefrontal cortex (DLPFC) improves action naming in healthy subjects and in subjects with Alzheimer’s disease.

Frequency and patterns of subclinical cognitive impairment in patients with ANCA-associated small vessel vasculitides.

We investigated the prevalence of disease-related cognitive impairment in patients with anti-neutrophil cytoplasmic antibodies (ANCA)-associated small vessel vasculitides (SVV). We studied 43 patients with ANCA-associated SVV (Wegeners granulomatosis (WG), Churg-Strauss syndrome (CSS) and microscopic polyangiitis (MP)), with no evidence of focal neurological deficits and dementia and in whom other potential causes of cognitive decline were carefully excluded. All patients underwent a detailed neuropsychological evaluation and their performances were compared with those of matched healthy controls. Patients were considered to be affected by subclinical cognitive impairment when they had abnormal results in at least two neuropsychological tests. Magnetic resonance imaging (MRI) scans of the brain were also obtained in 11 patients.The average neuropsychological test scores were not significantly different between the SVV patients and the control subjects. Thirteen patients had abnormal results in two tests (seven patients) or three or more tests (six patients). Most frequently, abnormal tests were the Rey Figure Recall (six cases), the Wisconsin Card Sorting Test (six cases), and the reaction times (eight cases). The frequency and extent of brain MRI abnormalities were higher in impaired than in unimpaired patients. This study demonstrates that 30% of clinically nondemented SVV patients can have a subclinical neuropsychological impairment, characterized by mild abstract reasoning loss, mental speed reduction and nonverbal memory impairment. MRI findings in impaired patients are consistent with the presence of an SVV-mediated subcortical damage of the brain.

The residual calculation abilities of a patient with severe aphasia: Evidence for a selective deficit of subtraction procedures

We report the case study of a severe fluent aphasic patient, who showed relatively preserved numerical abilities. A detailed investigation of number processing indicated good numerical comprehension and a relative sparing of addition and subtraction abilities; on the other hand, multiplication and division were severely impaired. A further study of multi-digit operations showed that the patients performance was characterized by a selective impairment of the borrowing procedure, in which she applied the so-called Smaller-from-Larger bug, typically observed in children learning to calculate. The present case provides further evidence for the dissociation between operations based on verbal sequences and on quantity manipulation, respectively impaired and preserved in patients with severe aphasia. Moreover, it provides evidence indicating that procedures may be dissociated from conceptual knowledge within a single arithmetical operation.