Phonological Working Memory limitations and Agrammatism: Is there a causal relationship between the two?

Introduction Syntactic processing in sentence comprehension requires some form of Working Memory (WM) resources. However, the nature of the relation between WM and sentence comprehension is controversial. One of the questions is whether WM for language is a single resource, or, alternatively, it consists of different components, each entrusted with a different linguistic function (Caplan & Waters, 1999). The aim of the study is to investigate the nature of the relation between WM and sentence comprehension by comparing sentence comprehension abilities with performance on WM tasks of four Greek-speaking patients with Broca’s aphasia. The experimental hypothesis is that patients with different performance patterns in sentence comprehension will present with different verbal WM capacity. Methods Two Greek-speaking patients with agrammatic aphasia (with impaired comprehension of syntactically complex reversible sentences) and two Greek-speaking patients with non-agrammatic Broca’s aphasia (with intact comprehension of syntactically complex sentences) participated in the study (for patients' language data see Varkanitsa et al. 2013). To assess patients’ WM capacity, we adapted Friedmann and Gvion's (2003) battery. The battery included tests that assess phonological WM: (i) two word span tests, one with short words (two syllables) and one with longer words (four syllables), (ii) a nonword span test, (iii) a forward digit span test, (iv) a backward digit span test, which requires not only storage but also manipulation of stored information, and, finally (v) a digit-ordering task that has been claimed to share some key features with sentence processing (MacDonald et al. 2001). The performance of each individual patient in the WM tasks was compared to a control group of 10, age and education-matched non-brain-damaged adults, using Crawford and Howell’s (1998) t-test. Results All patients with Broca’s aphasia presented with some kind of WM limitations (see table 1). The agrammatic patients performed significantly worse than controls in both word span tests and in the nonword span tests. The non-agrammatic patients performed significantly worse than controls in the 2-syllable word span test. All patients’ performance in the forward digit span test was indistinguishable from controls. One agrammatic and one non-agrammatic patient performed significantly worse in the backward digit span test, In the digit-ordering task, both the agrammatic and the non-agrammatic patients presented with significantly worse performance compared to controls. Discussion These results are inconsistent with theories assuming a single WM capacity that deals with all types of linguistic information. Rather, this study provides evidence that syntactic parsing relies on different resources from what is typically measured in verbal WM tasks. The four patients with Broca’s aphasia that participated in this study presented with similar phonological WM limitations with only quantitative differences in some tasks, despite the fact that only two of them also had sentence comprehension difficulties. The results also suggest that the agrammatic patients suffer from a specific WM deficit, linked to processing syntactic dependencies, which is not tapped by phonological WM tests

Common Neuroanatomical Substrate of Cholinergic Pathways and Language-Related Brain Regions as an Explanatory Framework for Evaluating the Efficacy of Cholinergic Pharmacotherapy in Post-Stroke Aphasia: A Review

Despite the relative scarcity of studies focusing on pharmacotherapy in aphasia, there is evidence in the literature indicating that remediation of language disorders via pharmaceutical agents could be a promising aphasia treatment option. Among the various agents used to treat chronic aphasic deficits, cholinergic drugs have provided meaningful results. In the current review, we focused on published reports investigating the impact of acetylcholine on language and other cognitive disturbances. It has been suggested that acetylcholine plays an important role in neuroplasticity and is related to several aspects of cognition, such as memory and attention. Moreover, cholinergic input is diffused to a wide network of cortical areas, which have been associated with language sub-processes. This could be a possible explanation for the positive reported outcomes of cholinergic drugs in aphasia recovery, and specifically in distinct language processes, such as naming and comprehension, as well as overall communication competence. However, evidence with regard to functional alterations in specific brain areas after pharmacotherapy is rather limited. Finally, despite the positive results derived from the relevant studies, cholinergic pharmacotherapy treatment in post-stroke aphasia has not been widely implemented. The present review aims to provide an overview of the existing literature in the common neuroanatomical substrate of cholinergic pathways and language related brain areas as a framework for interpreting the efficacy of cholinergic pharmacotherapy interventions in post-stroke aphasia, following an integrated approach by converging evidence from neuroanatomy, neurophysiology, and neuropsychology

Verbal Comprehension Ability in Aphasia: Demographic and Lexical Knowledge Effects

Background. Assessment of sentence-level auditory comprehension can be performed with a variety of tests varying in response requirements. A brief and easy to administer measure, not requiring an overt verbal or a complex motor response, is essential in any test battery for aphasia. Objective. The present study examines the clinical utility of receptive language indices for individuals with aphasia based on the Comprehension of Instructions in Greek (CIG), a variant of the Token Test, and the Greek version of PPVT-R. Methods. Normative data from a large community sample of Greek adults aged 46-80 years was available on both measures. A word-level-independent measure of auditory comprehension was computed as the standard score difference between the two tests and used to compare patients with and without comprehension deficits as indicated by their Boston Diagnostic Aphasia Examination profile. Results and Conclusions. Indices of internal consistency and test-retest reliability were very good. Education and age effects on performance were significant, with the former being stronger. The potential clinical utility of differential ability indices (contrasting sentence-and word-level auditory comprehension tests) is discussed

Is There a Role of Inferior Frontal Cortex in Motor Timing? A Study of Paced Finger Tapping in Patients with Non-Fluent Aphasia

The aim of the present study was to investigate the deficits in timing reproduction in individuals with non-fluent aphasia after a left hemisphere lesion including the inferior frontal gyrus, in which Broca’s region is traditionally localised. Eighteen stroke patients with non-fluent aphasia and twenty-two healthy controls were recruited. We used a finger-tapping Test, which consisted of the synchronisation and the continuation phase with three fixed intervals (450 ms, 650 ms and 850 ms). Participants firstly had to tap simultaneously with the device’s auditory stimuli (clips) (synchronisation phase) and then continue their tapping in the same pace when the stimuli were absent (continuation phase). Patients with aphasia demonstrated less accuracy and greater variability during reproduction in both phases, compared to healthy participants. More specifically, in the continuation phase, individuals with aphasia reproduced longer intervals than the targets, whereas healthy participants displayed accelerated responses. Moreover, patients’ timing variability was greater in the absence of the auditory stimuli. This could possibly be attributed to deficient mental representation of intervals and not experiencing motor difficulties (due to left hemisphere stroke), as the two groups did not differ in tapping reproduction with either hand. Given that previous findings suggest a potential link between the IFG, timing and working memory, we argue that patients’ extra-linguistic cognitive impairments should be accounted for, as possible contributing factors to timing disturbances

Frequency of Impulsive-Compulsive Behavior and Associated Psychological Factors in Parkinson’s Disease: Lack of Control or Too Much of It?

Background and Objectives: Impulse Control Disorders (ICDs) including pathological gambling, hypersexuality, compulsive eating, compulsive buying, and other related behaviors are well-known distinct non-motor symptoms in Parkinson’s Disease (PD). Some large-scale studies present a prevalence of at least 10%, however, there are other reports providing much higher rates. The majority of the conducted studies investigating ICDs focus mainly on pharmacological factors, however, from a psychological perspective, there is yet enough room for investigation. In order to address the above issues, we designed a two-part study. Materials and Methods: First, we aimed to identify the incidence of ICD and related behaviors in a cohort of 892 Greek PD patients. Second, we administered a comprehensive battery of psychometric tools to assess psychological factors such as personality dimensions, quality of life, defenses, coherence, and resilience as well as to screen general cognitive capacity in PD patients with ICD manifestations. Results: With regard to the first part, we identified ICD manifestations in 12.4% of the patients. Preliminary findings from the second part indicate elevated activity, rather than impulsivity, as well as interrelations between several variables, including measures of activity, coping mechanisms, and quality of life. Conclusions: We present a working hypothesis for the contribution of high activity channeled to specific behavioral patterns through specific coping mechanisms, concerning the emergence of ICDs and related behaviors in PD, and further stress the importance of compulsivity rather than impulsivity in this process

Moyamoya Disease: Clinical and Radiological Characteristics in Adult Greek Patients

Background and purpose: The aim of our study is to present, for the first time, the clinical, radiological, and neurocognitive characteristics of Greek adult patients with Moyamoya disease (MMD). Methods: We analyzed prospectively collected data of 12 patients referred to our department from 2004 to 2019. All patients underwent a thorough diagnostic work up, including extensive clinical, neuroradiological, and neurocognitive assessment. Results: Our study population consisted of 7 females and the median age at the time of the diagnosis was 43.5 years. No patient had a positive family history of the disease and roughly 50% were hypertensives. Ten patients presented with transient or permanent cerebrovascular ischemia and two patients suffered from hemorrhagic complications. The median NIHSS was 7.5 (0–23) and clinical status remained stable during follow-up with conservative treatment in most of the patients. The majority (83.3%) had bilateral disease confirmed by DSA. All lesions exclusively affected the anterior circulation, with 50% of patients presenting with stenoocclusive changes. No aneurysm or AVM were revealed. The most common neurocognitive deficits were in the executive and language domains. Conclusions: Our MMD patients had a later onset of the disease and an absence of familial occurrence. The most common manifestation was ischemia, transient or permanent, and all lesions affected the anterior circulation, whereas no vascular malformations (AVM, aneurysms) were demonstrated in brain imaging. These findings in Greek patients imply a probable different, Mediterranean phenotype