The field of non-invasive stimulation of the cerebellum is quickly expanding. The anatomical structure of the cerebellum with a high density of neurons in the superficial layer, its electrical properties, and its participation in numerous closed-loop circuits involved in motor, cognitive, and affective operations both in children and in adults make of the cerebellum a target with very high potential for neuromodulation of both cerebellar and extra-cerebellar disorders, in neurology, psychiatry, and neurosurgery. A common research effort is required to extract the optimal parameters of stimulation and to identify how non-invasive stimulation of the cerebellum modifies cerebellar plasticity and functional connectivity in remote cortical and subcortical areas. A patient stratification should be considered.

In the majority of cases published between 1907 and 2014, FAS is due to a neurogenic etiology. Only a few reports about FAS with an assumed psychogenic origin have been published. The present article discusses the findings of a careful database search on psychogenic FAS. This review may be particularly relevant as it is the first to analyze the salient features of psychogenic FAS cases to date. This article hopes to pave the way for the view that psychogenic FAS is a cognate of neurogenic FAS. It is felt that this variant of FAS may have been underreported, as most of the psychogenic cases have been published after the turn of the century. This review may improve the diagnosis of the syndrome in clinical practice and highlights the importance of recognizing psychogenic FAS as an independent taxonomic entity.

This paper presents the case of a 17-year-old right-handed Belgian boy with developmental FAS and comorbid developmental apraxia of speech (DAS). Extensive neuropsychological and neurolinguistic investigations demonstrated a normal IQ but impaired planning (visuo-constructional dyspraxia). A Tc-99m-ECD SPECT revealed a significant hypoperfusion in the prefrontal and medial frontal regions, as well as in the lateral temporal regions. Hypoperfusion in the right cerebellum almost reached significance. It is hypothesized that these clinical findings support the view that FAS and DAS are related phenomena following impairment of the cerebro-cerebellar network.

Foreign accent syndrome is a rare motor speech disorder that causes patients to speak their language with a non-native accent. In the neurogenic condition, the disorder develops after lesions in the language dominant hemisphere, often affecting Broca's area, the insula, the supplementary motor area and the primary motor cortex. Here, we present two new cases of FAS after posterior fossa lesions. The first case is a 44-year-old, right-handed, Dutch-speaking man who suffered motor speech disturbances and a left hemiplegia after a pontine infarction. Quantified SPECT showed a bilateral hypoperfusion in the inferior lateral prefrontal and medial inferior frontal regions as well as a significant left cerebellar hypoperfusion. Further clinical investigations led to an additional diagnosis of brainstem cognitive affective syndrome which closely relates to Schmahmann's syndrome. The second patient was a 72-year-old right-handed polyglot English man who suffered a stroke in the vascular territory of the left posterior inferior cerebellar artery (PICA) and developed a foreign accent in his mother tongue (English) and in a later learnt language (Dutch). In this paper, we discuss how the occurrence of this peculiar motor speech disorder can be related to a lesion affecting the posterior fossa structures.

Research has shown that linguistic functions in the bilingual brain are subserved by similar neural circuits as in monolinguals, but with extra-activity associated with cognitive and attentional control. Although a role for the right cerebellum in multilingual language processing has recently been acknowledged, a potential role of the left cerebellum remains largely unexplored. This paper reports the clinical and fMRI findings in a strongly right-handed (late) multilingual patient who developed differential polyglot aphasia, ataxic dysarthria and a selective decrease in executive function due to an ischemic stroke in the left cerebellum. fMRI revealed that lexical-semantic retrieval in the unaffected L1 was predominantly associated with activations in the left cortical areas (left prefrontal area and left postcentral gyrus), while naming in two affected non-native languages recruited a significantly larger bilateral functional network, including the cerebellum. It is hypothesized that the left cerebellar insult resulted in decreased right prefrontal hemisphere functioning due to a loss of cerebellar impulses through the cerebello-cerebral pathways.

A variety of tDCS approaches has been used to investigate the potential of tDCS to improve language outcomes, or slow down the decay of language competences caused by Primary Progressive Aphasia (PPA). The employed stimulation protocols and study designs in PPA are generally speaking similar to those deployed in post-stroke aphasic populations. These two etiologies of aphasia however differ substantially in their pathophysiology, and for both conditions the optimal stimulation paradigm still needs to be established. A systematic review was done and after applying inclusion and exclusion criteria, 15 articles were analyzed focusing on differences and similarities across studies especially focusing on PPA patient characteristics (age, PPA variant, language background), tDCS stimulation protocols (intensity, frequency, combined therapy, electrode configuration) and study design as recent reviews and group outcomes for individual studies suggest tDCS is an effective tool to improve language outcomes, while methodological approach and patient characteristics are mentioned as moderators that may influence treatment effects. We found that studies of tDCS in PPA have clinical and methodological and heterogeneity regarding patient populations, stimulation protocols and study design. While positive group results are usually found irrespective of these differences, the magnitude, duration and generalization of these outcomes differ when comparing stimulation locations, and when results are stratified according to the clinical variant of PPA. We interpret the results of included studies in light of patient characteristics and methodological decisions. Further, we highlight the role neuroimaging can play in study protocols and interpreting results and make recommendations for future work.

Publications on FAS were identified by means of searches in electronic databases (Medline, PsycINFO, Current Contents, Web of Science). In addition, the bibliographies of all obtained articles were scrutinized to identify additional references. Only first source information was analyzed; second-or third-line references to original contributions were not considered. This resulted in a survey of 172 FAS cases in total.The quality of the collected data was variable as to the degree of reported details. Inclusion and exclusion criteria were applied to narrow down the corpus for further analysis. Inclusion criteria were defined as (i) the description of a patient in whom a change of accent was observed, and (ii) for whom there was a clear description of the associated etiology in order to avoid misinterpretation of the data. In order to improve the readability of this paper, we have avoided listing cases in the text to which particular statements apply. Rather, we have used single numbers between square brackets to represent series of FAS cases: the association of these numbers and the FAS cases they refer to can be found in table 8.1 in section 8 of this article (list A). The alphabetically ordered list B of table 8.1 enables the reader to identify the paper in which each FAS case is described. A full summary description of individual FAS patients can be consulted in the supplementary materials.Regarding the exclusion criteria, it was decided to exclude cases reported in poster or oral presentations, conference proceedings [1] 1 and unpublished theses [2] 2 . Furthermore, cases were excluded if (i) there was an explicit statement that the etiology was unclear or could not unambiguously be identified as organic or as functional in the above-mentioned meaning by the authors [3], (ii) the etiology was not mentioned [4], (iii) there was doubt about the origin ('suggestive') [5]. Due to linguistic limitations, only articles published in English, Spanish, Norwegian, German or Portuguese were included. One case had to be excluded because a translation could not be obtained, i.e. Tokudo et al. (2015).It should also be mentioned that some of the cases have been reported more than once [6]. When a case occurs in several publications, this is indicated in the the supplementary materials. When considering only 'authentic' cases fulfilling the inclusion criteria, the number of cases amounted to 112 [7]: these were published between 1907 and October 2016. Parietal lobe (right) 36, 85 3 Corpus callosum 53 2Insular region (right) 11 2 Edwards et al. (2005) Case 1* 70/F/NI Traumatic hemorrhage Left parietal/basal ganglia/internal capsule acute: FAS: receded within 4 days (4 weeks follow-up), normal speech and articulation English  Welsh Confusion 43 Edwards et al. (2005) Case 2* 58/M/NI Hemorrhage Left basal ganglia acute: Normal speech and articulation, FAS persisted (1 year follow-up) English  Irish NI 44 Edwards et al. (2005) Case 3* 64/F/NI Infarction Left basal ganglia/internal capsule acute: impaired articulation, agrammatism...

This paper presents the case of a 33-year-old, right-handed, French-speaking Belgian lady who was involved in a car accident as a pedestrian. Six months after the incident she developed a German/Flemish-like accent. The patient's medical history, the onset of the FAS and the possible psychological causes of the accent change are analyzed. Relevant neuropsychological, neurolinguistic, and psychodiagnostic test results are presented and discussed. The psychodiagnostic interview and testing will receive special attention, because these have been underreported in previous FAS case reports. Furthermore, an accent rating experiment was carried out in order to assess the foreign quality of the patient's speech. Pre- and post-morbid spontaneous speech samples were analyzed phonetically to identify the pronunciation characteristics associated with this type of FAS. Several findings were considered essential in the diagnosis of psychogenic FAS: the psychological assessments as well as the clinical interview confirmed the presence of psychological problems, while neurological damage was excluded by means of repeated neuroimaging and neurological examinations. The type and nature of the speech symptoms and the accent fluctuations associated with the patient's psychological state cannot be explained by a neurological disorder. Moreover, the indifference of the patient toward her condition may also suggest a psychogenic etiology, as the opposite is usually observed in neurogenic FAS patients.