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In most right-handed people, language and motor functions are more reliant on systems of the left hemisphere while several non-linguistic visuo-spatial and attentional processes depend more on the right hemisphere. The rare exceptions to these rules provide important clues as to what functions co-lateralise, and are thus crucial for models of cereb...
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Limb apraxia is a neurological disorder of higher cognitive function characterized by an inability to perform purposeful skilled movements and not attributable to an elementary sensorimotor dysfunction or comprehension difficulty. Corticobasal Syndrome (CBS) is an akinetic rigid syndrome with asymmetric onset and progression with at least one basal...
Aspects of emotional facial expression (responsivity, appropriateness, intensity) were examined in brain-damaged adults with right or left hemisphere cerebrovascular lesions and in normal controls. Subjects were videotaped during experimental procedures designed to elicit emotional facial expression and non-emotional facial movement (paralysis, mob...
There exist few clinical assessments for limb apraxia, a disorder of learned, purposeful action, that enable clinicians to distinguish pathological from normal variance in limb praxis performance. We describe a theoretically motivated, comprehensive assessment battery for limb apraxia and present control comparison scores for 16 older healthy norma...
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... Due to the pronounced neuroanatomical connections, the infarcted thalamus can cause many neurological deficits. Typically, these include sensory and motor deficits, as well as disturbances of consciousness, but large cortical infarcts can also be mimicked [15,16]. Thalamic RSSIs thus represent a particular challenge for treating physicians in everyday clinical practice. ...
Diagnosing recent small subcortical infarcts (RSSIs) via early computed tomography (CT) remains challenging. This study aimed to assess CT attenuation values (Hounsfield Units (HU)) and net water uptake (NWU) in RSSI and explore a postprocessing algorithm’s potential to enhance thalamic RSSI detection. We examined non-contrast CT (NCCT) data from patients with confirmed thalamic RSSI on diffusion-weighted magnetic resonance imaging (DW-MRI) between January 2010 and October 2017. Co-registered DW-MRI and NCCT images enabled HU and NWU quantification in the infarct area compared to unaffected contralateral tissue. Results were categorized based on symptom onset to NCCT timing. Postprocessing using window optimization and frequency-selective non-linear blending (FSNLB) was applied, with interpretations by three blinded Neuroradiologists. The study included 34 patients (median age 70 years [IQR 63–76], 14 women). RSSI exhibited significantly reduced mean CT attenuation compared to unaffected thalamus (29.6 HU (±3.1) vs. 33.3 HU (±2.6); p < 0.01). Mean NWU in the infarct area increased from 6.4% (±7.2) at 0–6 h to 16.6% (±8.7) at 24–36 h post-symptom onset. Postprocessed NCCT using these HU values improved sensitivity for RSSI detection from 32% in unprocessed CT to 41% in FSNLB-optimized CT, with specificities ranging from 86% to 95%. In conclusion, CT attenuation values and NWU are discernible in thalamic RSSI up to 36 h post-symptom onset. Postprocessing techniques, particularly window optimization and FSNLB, moderately enhance RSSI detection.
... 28 Observations of the so-called nondominant hemisphere syndrome have been occasionally reported after left hemisphere damage. [29][30][31][32][33][34] The nondominant hemisphere syndrome is indeed classically reported in right hemisphere lesioned patients, and it typically comprises impairments in executive functions (lack of inhibition, loss of cognitive flexibility, attention disorders) and/or spatial neglect. ...
We report a case series of four patients operated on for a glioma in awake conditions and in whom task-based functional magnetic resonance imaging (fMRI) demonstrated right-dominant activity during a language production task. Language functional sites were identified intraoperatively by electrical stimulations only in the patient with a right-sided lesion. Furthermore, the pre- or postoperative cognitive evaluations in the three patients operated on for a left-sided glioma revealed right spatial neglect and dysexecutive syndrome, hence demonstrating that, in patients with right-dominant activity on language fMRI, the left hemisphere is implicated in spatial consciousness and cognitive control. This study supports the interest of presurgical task-based language fMRI to identify patients with a reversed lateralization of cognitive functions and to make an adequate selection of the battery of intraoperative cognitive tasks to be monitored in those rare outliers.
... The DMN is left lateralized, while the PDMN is bilateralized. Several previous studies mentioned the lateralized thalamic function and lateralized structural connections between the thalamus and cortical regions (Alkonyi et al. 2011;De Witte et al. 2011;Exner et al. 2001;Marchetti et al. 2005;Johnson et al. 2000;Oke et al. 1978), and functional lateralization of DMN ). However, there has been no general consensus on the mechanisms for the lateralization of the thalamic sub-regions of DMN, a topic which requires further investigation. ...
Various studies have indicated that the thalamus is involved in controlling both cortico-cortical information flow and cortical communication with the rest of the brain. Detailed anatomy and functional connectivity patterns of the thalamocortical system are essential to understanding the cortical organization and pathophysiology of a wide range of thalamus-related neurological and neuropsychiatric diseases. The current study used resting-state fMRI to investigate the topography of the human thalamocortical system from a functional perspective. The thalamus-related cortical networks were identified by performing independent component analysis on voxel-based thalamic functional connectivity maps across a large group of subjects. The resulting functional brain networks were very similar to well-established resting-state network maps. Using these brain network components in a spatial regression model with each thalamic voxel's functional connectivity map, we localized the thalamic subdivisions related to each brain network. For instance, the medial dorsal nucleus was shown to be associated with the default mode, the bilateral executive, the medial visual networks; and the pulvinar nucleus was involved in both the dorsal attention and the visual networks. These results revealed that a single nucleus may have functional connections with multiple cortical regions or even multiple functional networks, and may be potentially related to the function of mediation or modulation of multiple cortical networks. This observed organization of thalamocortical system provided a reference for studying the functions of thalamic sub-regions. The importance of intrinsic connectivity-based mapping of the thalamocortical relationship is discussed, as well as the applicability of the approach for future studies.
... Disturbances usually found in cases of right hemisphere lesions, such as visuospatial defects, but associated with left hemisphere lesions in right-handers [18] have also been reported [19][20][21][22]. Marchetti et al. [23], for example, described a patient with a left thalamic lesion who showed motor impersistence, visuospatial dysfunction, and poor comprehension of facial expressions. ...
A 74-year-old, left-handed man presented with a rapidly evolving loss of strength in his right leg associated with difficulty in walking. MR images disclosed an extensive left hemisphere tumor. A neuropsychological examination revealed that language was broadly normal but that the patient presented with severe nonlinguistic abnormalities, including hemineglect (both somatic and spatial), constructional defects, and general spatial disturbances; symptoms were usually associated with right hemisphere pathologies. No ideomotor apraxia was found. The implications of crossed-brain representations of verbal and nonverbal functions are analyzed.
... In the present study, MRJ-related metabolite differences were regionally specific to the lThal. Asymmetry in thalamic biochemical [37] and functional processing [38] has been previously established. Chronic MRJ use has been shown to interfere with verbal working memory [39], which is a cognitive process hypothesized to be lateralized to left hemispheric regions that includes the left thalamus [40]. ...
The effects of chronic marijuana (MRJ) use on neurochemistry are not well characterized. Previously, altered global myo-Inositol (mI) concentrations and distribution in white matter were associated with impulsivity and mood symptoms in young MRJ-dependent men. The objective of this study was to retrospectively examine previously collected data, to investigate the potential regional specificity of metabolite levels in brain regions densely packed with cannabinoid receptors. Spectra were acquired at 4.0 Tesla using 2D J-resolved proton magnetic resonance spectroscopic imaging (MRSI) to quantify the entire J-coupled spectral surface of metabolites from voxels in regions of interest. For the current regional spectral analyses, a 2D-JMRSI grid was positioned over the central axial slice and shifted in the x and y dimensions to optimally position voxels over regions containing thalamus, temporal lobe, and parieto-occipital cortex. MRJ users exhibited significantly reduced mI levels in the left thalamus (lThal), relative to non-using participants, which were associated with elevated cognitive impulsivity. Other regional analyses did not reveal any significant group differences. The current findings indicate that reduced mI levels are regionally specific to the lThal in MRJ users. Furthermore, findings suggest that mI and the lThal uniquely contribute to elevated impulsivity.
... Atualmente, as alterações comunicativas, bem como as cognitivas e as emocionais, resultantes de um acometimento neurológico no HD têm sido abordadas na literatura. Esse conjunto de sinais e sintomas decorrentes de LHD é denominado por alguns autores como "Síndrome do Hemisfério Direito -SHD" (Blake, Duffy, Tompkins, & Myers, 2003;Brookshire, 2003;Bryan, 1995;Kumral & Evyapan, 2000;Landau, Auerbach, Gross-Tsur, & Shalev, 2003;Marchetti, Carey, & Della Sala, 2005;Morin e cols., 2001;Myers, 2001;Pimental & Kingsbury, 1989). Uma das principais causas dessa síndrome é a lesão vascular (Tompkins, Fassbinder, Lehman-Blake, & Baumgaertner, 2002). ...
The present paper aims to outline an overview of national and international publications concerning research on the communicative, cognitive and behavioral impairments associated with a right hemisphere stroke. Research on LILACS and MEDLINE databases were done using keywords in Portuguese and in English: syndrome, hemisphere and right for the search on the right hemisphere impairments. Studies were selected taking into account inclusion criteria. Only few studies about these disorders were found, all of them international investigations. Cognitive disorders were the most frequently described. Sequelae including all cognitive functions, emotional and communicative processing are considered part of this set of right hemisphere impairments. More studies about the RHS are necessary to identify different clinical profiles and increase the efficiency of assessment and rehabilitation process.
Keywords: neuropsychology; cognition; right hemisphere; CVA.
... Similarly, there is general consensus that visuospatial abilities rely heavily upon the right hemisphere in people with conventional dominance. 25 Castro-Caldas, et al. 26 have proposed the existence of "clusters" of functions, which could be located in either the left or the right hemisphere, depending on the individual's genetic predisposition. They suggested that some basic physiological or psychological processes as well as functions may presumably be divided into three clusters as follows: 1) handedness and limb praxis; 2) language and oral praxis; and 3) those mechanisms whose disorders result in visual neglect and other visual perceptive disorders. ...
... Several reported cases, however, challenged this hypothes. 25,27,28 In our study, only case 1 met all three cluster definitions. She was right-handed and had right brain damage, normal limb praxis, aphasia with oral apraxia, and impaired visuospatial functions, including left visual neglect. ...
The lateralization of cognitive functions in crossed aphasia in dextrals (CAD) has been explored and compared mainly with cases of aphasia with left hemisphere damage. However, comparing the neuropsychological aspects of CAD and aphasia after right brain damage in left-handers (ARL) could potentially provide more insights into the effect of a shift in the laterality of handedness or language on other cognitive organization. Thus, this case study compared two cases of CAD and one case of ARL.
The following neuropsychological measures were obtained from three aphasic patients with right brain damage (two cases of CAD and one case of ARL); language, oral and limb praxis, and nonverbal cognitive functions (visuospatial neglect and visuospatial construction).
All three patients showed impaired visuoconstructional abilities, whereas each patient showed a different level of performances for oral and limb praxis, and visuospatial neglect.
Based on the analysis of these three aphasic patients' performances, we highlighted the lateralization of language, handedness, oral and limb praxis, visuospatial neglect and visuospatial constructive ability in aphasic patients with right brain damage.
... As a result, our review data suggest that: 1) a left hemisphere specialisation for language skills holds at the thalamic level for right-handed adults, and 2) typical non-dominant hemisphere functions do not seem lateralised at the thalamic level. Consequently, these findings support the idea of a 'lateralised linguistic thalamus' but restate the issue of 'a lateralised neurocognitive thalamus' as several authors have advocated (Bogousslavsky et al., 1986a(Bogousslavsky et al., , 1986bBaumgartner and Regard, 1993;Van Der Werf et al., 1999;Exner et al., 2001;Marchetti et al., 2005). ...
During the last decades, many studies have shown that the thalamus is crucially involved in language and cognition. We critically reviewed a study corpus of 465 patients with vascular thalamic lesions published in the literature since 1980. 42 out of 465 (9%) cases with isolated thalamic lesions allowed further neurocognitive analysis. On the neurolinguistic level, fluent output (=31/33; 93.9%), normal to mild impairment of repetition (=33/35; 94.3%), mild dysarthria (=8/9; 88.9%) and normal to mild impairment of auditory comprehension (=27/34; 79.4%) were most commonly found in the group of patients with left and bilateral thalamic lesions. The taxonomic label of thalamic aphasia applied to the majority of the patients with left thalamic damage (=7/11; 63.6%) and to one patient with bithalamic lesions (=1/1). On the neuropsychological level, almost 90% of the left thalamic and bithalamic patient group presented with amnestic problems, executive dysfunctions and behaviour and/or mood alterations. In addition, two thirds (2/3) of the patients with bilateral thalamic damage presented with a typical cluster of neurocognitive disturbances consisting of constructional apraxia, anosognosia, desorientation, global intellectual dysfunctioning, amnesia, and executive dysfunctions associated with behaviour and/or mood alterations. Our study supports the long-standing view of a 'lateralised linguistic thalamus' but restates the issue of a 'lateralised cognitive thalamus'. In addition, critical analysis of the available literature supports the view that aphasia following left or bithalamic damage constitutes a prototypical linguistic syndrome.
... However, there remains no inclusive basic-processing characterization of human olfaction after thalamic lesions. The scope of such a characterization is doubled in light asymmetries in thalamic structural (Eidelberg and Galaburda, 1982;Amunts, 2008), biochemical (Jayasundar, 2002), and functional (Ojemann and Van Buren, 1967;Ojemann, 1977;Mateer, 1978;Schuurman et al., 2002;Whelan et al., 2002;Marchetti et al., 2005) processing. ...
Olfactory information reaches olfactory cortex without a thalamic relay. This neuroanatomical substrate has combined with functional findings to suggest that, in olfaction, the typical thalamic role in sensory processing has shifted to the olfactory bulb or olfactory cortex. With this in mind, we set out to ask whether the thalamus at all plays a significant functional role in human olfaction. We tested olfactory function in 17 patients with unilateral focal thalamic lesions and in age-matched healthy controls. We found that thalamic lesions did not significantly influence olfactory detection but significantly impaired olfactory identification, and only right lesions altered olfactory hedonics by reducing the pleasantness of pleasant odors. An auditory control revealed that this shift in pleasantness was olfactory specific. These olfactory impairments were evident in explicit measures of perception, as well as in patterns of sniffing. Whereas healthy subjects modulated their sniffs in accordance with odorant content, thalamic patients did not. We conclude that, although the thalamus is not in the path of olfactory information from periphery to cortex, it nevertheless plays a significant functional role in human olfaction.
... This is because lesions causing aphasia (or neglect of one side of the body) do not always correspond to the avowed (behavioral) handedness of subjects. These irregularities include crossed aphasia, 3,4 crossed non-aphasia 5 and crossed right hemisphere syndromes, 6 which are exceptions to the law of "constant conjunction" of speech and handedness. ...
... The anosognosia and right-left disorientation were attributed to the lesion of the left hemisphere, assumed to be the major hemisphere in this patient. According to the new understanding, however, this case is an example of "crossed right hemisphere syndrome" reviewed by Marchetti et al. 6 with aphasia and transient cortical blindness due to the lesion in the right hemisphere and anosognosia and left-right disorientation caused by the lesion in the minor left hemisphere. Similar cases of cortical blindness associated with unilateral occipital lobe lesions from angiographic contrast injection have been described. ...
... According to one-way callosal traffic circuitry, this was an exceptional case in which a neural left hander had the characteristics of a right-handed person, and in whom the left hemisphere was the minor. 5,6 This resulted in the bilateral loss of somatosensory evoked potential after stimulating the patient's nondominant side (i.e. right median nerve). ...
