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Neuroscience 162 (2009) 827–835

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UANTIFICATION OF GRAY MATTER CHANGES IN THE CEREBRALORTEX AFTER ISOLATED CEREBELLAR DAMAGE: A VOXEL-BASED

ORPHOMETRY STUDY

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. CLAUSI,a,b M. BOZZALI,b* M. G. LEGGIO,a,c

. DI PAOLA,b G. E. HAGBERG,b C. CALTAGIRONEd,e

ND M. MOLINARIa

Ataxia Laboratory, Santa Lucia Foundation, IRCCS, Via Ardeatina06, 00179 Rome, Italy

Neuroimaging Laboratory, Santa Lucia Foundation, IRCCS, Viardeatina 306, 00179 Rome, Italy

Department of Psychology, University “La Sapienza,” Via dei Marsi8, 00185 Rome, Italy

Department of Clinical and Behavioural Neurology, Santa Luciaoundation, IRCCS, Via Ardeatina 306, 00179 Rome, Italy

Department of Neuroscience, University of Rome “Tor Vergata,” Viaont Pelier 1, 00133-Rome, Italy

bstract—There is growing evidence based on behavioral andunctional imaging studies about the cerebellar involvement inhe modulation of cognitive functions. However, it still remainso be clarified how the cerebellum interacts with brain regionsub-serving different cognitive domains. In this study we usedagnetic resonance imaging (MRI) and voxel based morphom-

try (VBM) to investigate changes of cerebral gray matter (GM)ensity in 15 patients with a focal cerebellar damage (CD) com-ared to 15 healthy controls. T2-weighted scans and T1-eighted volumes were collected from each subject. With thexception of the cerebellar lesion, none of the patients showedny additional brain MRI abnormality. T1-volumes were ana-

yzed by voxel-based morphometry. Consistent with their neu-opsychological abnormalities, patients with right-CD com-ared to controls showed a reduction of GM density mainly

nvolving the left frontal, parietal and temporal lobes. Con-ersely, patients with left-CD did not show any significant neu-opsychological or cerebral GM abnormality. The present studyndicates that specific GM changes may be detected in patientsith isolated CD and cognitive dysfunction. We discuss thendings in terms of cerebellar influence on the neuronal net-orks involved in higher level functions of the associationortex. © 2009 IBRO. Published by Elsevier Ltd. All rightseserved.

ey words: cerebellum, cognition, lesion, MRI, VBM.

ver the last few decades, an increasing body of evidenceas been produced indicating that the cerebellum is notnly involved in motor control but also in the modulation ofognitive and affective functions (Schmahmann and Pan-

Corresponding author. Tel: �39-06-5150-1547; fax: �39-06-5150-1213.-mail address: m.bozzali@hsantalucia.it (M. Bozzali).bbreviations: CD, cerebellar damage; GM, gray matter; IQ, intellectualuotient; LCD, left cerebellar damage; MNI, Montreal Neurologic Institute;PRAGE, magnetization-prepared rapid-acquisition gradient echo; MRI,agnetic resonance imaging; RCD, right cerebellar damage; VBM, voxel-

aased morphometry; WAIS-R, Wechsler Adult Intelligence Scale Re-ised.

306-4522/09 $ - see front matter © 2009 IBRO. Published by Elsevier Ltd. All rightoi:10.1016/j.neuroscience.2009.02.001

827

ya, 1997; Riva and Giorgi, 2000; Molinari et al., 2002; Ito,006; Ramnani, 2006). A strong support for this viewomes from functional magnetic resonance imaging (fMRI)tudies on healthy subjects, which have demonstrated withigh anatomical resolution a direct involvement of the cer-bellum in several cognitive functions (Grodd et al., 2005).onsistently, a number of studies investigating patientsith focal cerebellar lesions have shown behavioral defi-its in several cognitive domains (Molinari et al., 1997,004; Schmahmann and Sherman, 1998; Leggio et al.,000, 2008; Gottwald et al., 2004; Hokkanen et al., 2006).rom an anatomical point of view, the cerebellum containsore than half of all the neurons in the brain, and exhibits

trong interconnections with the contralateral cerebralemisphere either in feed-forward and feedback directionsRamnani et al., 2006). Higher order cerebral regions, suchs the dorsolateral prefrontal cortex, the parietal and theuperior temporal lobes project to the cerebellum throughhe pontine nuclei. Conversely, the cerebellar nucleiroject to the contralateral cerebral cortex through thehalamus. It is known that there is a higher rate of cerebellarfferents compared to efferents (Carpenter, 1991). This an-tomical observation may suggest that the cerebellum inter-

aces with the cerebral cortex with a prominent role of func-ional integration (Gottwald et al., 2004). Within such a com-lex network, supratentorial lesions are known to result in aontralateral cerebellar metabolic dysfunction (reduced bloodow) that has been defined as crossed cerebellar diaschisisTien and Ashdown, 1992; Yamauchi et al., 1999; Chakra-arty, 2003). The opposite effect, due to focal cerebellar

esion, has also been described to result in a functional im-airment of the contralateral cerebral cortex (crossed cer-bello-cerebral diaschisis) (Boni et al., 1992; Sonmezoglu etl., 1993; Gomez Beldarrain et al., 1997; Komaba et al.,000). In this case, the motor and cognitive deficits that maye observed are strictly consequent with a functional releasef cerebellar modulation on the contralateral cerebral cortex.atients with isolated focal lesions of the cerebellum repre-ent therefore an interesting model to investigate the physi-logical role of the cerebellum in vivo in both motor andigher level cerebral functions. Although the exact mecha-ism of interaction between the cerebellum and the cerebralortex still remains largely obscure, it is reasonable to as-ume that these functional connections are based on specificnatomical substrates and that dysfunction may result intructural modifications. A recent MRI volumetric study hashown a direct association between cerebellar tissue dam-ge and development of the contralateral cerebral volumes

nd vice versa, in pre-term infants (Limperopoulos et al.,

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S. Clausi et al. / Neuroscience 162 (2009) 827–835828

005). This study demonstrates that the development of theerebral hemispheres and of the cerebellum is strictly inter-ependent and associated with reciprocal structural modifi-ations. Moreover, a recent report suggests that vermian androntal lobes volumes are interrelated with respect to cogni-ive decline in elderly people (Paul et al., 2009).

In order to better understand the specific role of theerebellum in the different cerebral functions it would berucial to investigate the structural cerebral changes occur-ing in adults with a focal cerebellar lesion and no previousistory of any neurological impairment. In these cases, theutative structural changes are expected to be subtle, toppear in a chronic phase of the clinical course, and to beistributed in the cerebral hemisphere contralateral to theerebellar damage (CD). Structural changes with these char-cteristics are likely to be below the intrinsic spatial resolutionf conventional MRI, and to be detectable by quantitative MRIechniques. Voxel-based morphometry (VBM) is a spatially-pecific and unbiased method of analysis of MR imageseflecting the regional gray matter (GM) density at a voxelcale (Ashburner and Friston, 2000). This technique haslready been successfully used to investigate structuralhanges in neurological and psychiatric disorders (Bozzali etl., 2006; Di Paola et al., 2007; Spencer et al., 2007; Yamadat al., 2007). In the current study, we employed VBM tossess the presence and the extension of GM cerebral ab-ormalities in patients with an isolated cerebellar lesion in ahronic clinical stage. The aim was therefore to identify spe-ific patterns of cerebral GM abnormalities that might accountor the neuropsychological characteristics of the studied pa-ients, thus potentially highlighting the mechanisms of theerebellar interface with the cerebral hemispheres and itsodulation of cerebral functioning.

EXPERIMENTAL PROCEDURES

ubjects

ifteen consecutive patients (12 men, 3 women) with a focal

able 1. Main demographic and clinical characteristics of the studied

ase Age (years) Gender Vascular factors Me

1 66 M AH Nif2 48 F — Le3 42 M — —4 61 M AH —5 60 M — —6 71 M IHD —7 59 M — —8 48 F — —9 55 M AH; IHD Ac0 63 F AH Ac1 61 M — —2 45 M — —3 33 M — —4 59 M AH Nim5 34 M — Ac

R, right; L, left; M, male; F, female; AH, arterial hypertension; IHD, isc

erebellar lesion attending a specialist neuro-rehabilitation clinic t

ere recruited for the present study. The mean (SD) age of theatients was 53.7 (11.4) years, ranging from 33 to 71 years. Allatients suffered from an isolated event (ischemic, hemorrhagic orurgical), which selectively involved their cerebellar parenchyma.s some of the recruited patients were affected by cerebrovascu-

ar factors (see Table 1), the absence of any additional brainbnormality was carefully investigated by inspection of T2-eighted MRI scans, which were previously collected from eachatient for clinical purposes. When enrolled in the study, all pa-ients had reached a stable, even though partial recovery from thelinical event. The median time between the acute event andecruitment was 21 months. Fifteen sex- and age-matched healthyolunteers [12 men, 3 women; mean (SD) age�53.5 (12.3) years]ere also studied and served as control group. Major systemic,sychiatric and neurological illnesses (with the exception of CD inatients) were carefully investigated and excluded in all the stud-

ed subjects. History of alcohol abuse was also excluded in eachubject. The main demographic and clinical characteristics (in-luding vascular risk factors and related medications) of the stud-ed patients are summarized in Table 1. Eight patients (53%) had

unilateral ischemic lesion, and four (27%) a unilateral hemor-hagic lesion. The remaining three patients (20%) underwent aurgical intervention to remove an extra-axial tumor (meningioma)hat resulted in a macroscopic CD. Each patient underwent aomprehensive neurological examination, and was scored using aodified version of the cerebellar motor deficit scale proposed byppollonio et al. (1993), whose global score ranges from 0 (ab-ence of any motor deficit) to 42 (presence of motor deficits at theighest degree) (Table 2). A t-test for impaired samples was usedo assess that there was no significant difference in motor impair-ent between patients with right-CD (n�8) and left-CD (n�7)

P-values ranging from 0.3 and 0.7).Local ethical committee approval and written informed con-

ent were obtained from each subject before study initiation.

europsychological assessment and statisticalnalysis

o obtain a comprehensive assessment of the cognitive functions,n extensive neuropsychological battery was administered toach patient by two trained neuropsychologists. The intellectual

evel was assessed using the Wechsler Adult Intelligence Scaleevised (WAIS-R) (Wechsler, 1997; Orsini and Laicardi, 2001),hich provides global measures of verbal (verbal intellectual quo-

Cerebellar lesion

Type Volume (ml) Side

Hemorrhagic 0.7 Rne sodium Surgical 17.6 R

Ischemic 16.7 RIschemic 18.5 RHemorrhagic 0.6 RHemorrhagic 16.6 RIschemic 17.1 RSurgical 13.5 R

lic acid; atenolol Ischemic 0.3 Llic acid; felodipine Ischemic 11.3 L

Ischemic 68.8 LHemorrhagic 16.7 LSurgical 3.4 LIschemic 17.5 L

lic acid; nimodipine Ischemic 5.0 L

rt disease; —, absence of vascular risk factors and medication.

patients

dication

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etylsalicyetylsalicy

odipineetylsalicy

ient, IQ) and non-verbal (performance IQ) intelligence. Visuo-

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S. Clausi et al. / Neuroscience 162 (2009) 827–835 829

patial abilities were assessed using the Raven’s progressiveatrices (Raven, 1947; Carlesimo et al., 1996), WAIS-R Blockesign and Object Assembly subtests, the freehand copying ofrawings and the copying drawings with landmarks (Gainotti et al.,977; Carlesimo et al., 1996). Executive functions were evaluatedsing a phonemic fluency task (Borkowsky et al., 1967; Carlesimot al., 1996), a temporal rules induction test (Villa et al., 1990) andAIS-R Similarities. Verbal memory was investigated using for-ard and reverse digit spans based on the WAIS-R subtest “Digitpan,” free serial immediate and delayed recall of Rey’s 15 Wordsest (Rey, 1958; Carlesimo et al., 1996). Visual and spatial short

erm memory was assessed by immediate visual recognition testCarlesimo et al., 1996) and forward and backward Corsi’s Block-apping Test (Corsi, 1972).

The scores obtained from each administered test were cor-ected for age and level of education with exception of the

AIS-R, for which scores and subscores were corrected for agenly (Orsini and Laicardi, 2001). All of the tests were administered

n their Italian versions. Statistical comparisons among patients,rouped according to side of the CD, and controls were assessedsing one-way ANOVA. Group differences were then analyzed bypplying a post hoc analysis using Bonferroni correction for mul-iple comparisons.

R imaging and MRI data analysis

D-T1-weighted magnetization-prepared rapid-acquisition gradi-nt echo (MPRAGE) (TR�11.0 ms; Te�4.4 ms, TI�300 ms; flipngle�15°; voxel size�1 mm3) was obtained from each subjectsing a system operated at 1.5 T (Siemens, Magnetom Vision,rlangen, Germany).

The 3D T1-MPRAGEs were processed for VBM analysissing SPM2 (Wellcome Department Cogn. Neurol, London; http://ww.fil.ion.ucl.ac.uk/spm). For each subject, images were firstanually reoriented according to the default template in SPM2.erebellar lesions were drawn on every patient’s 3D MPRAGE inative space using MRIcro (http://www.sph.sc.edu/comd/rorden/ricro.html), thus creating a region of interest for each individual

esion and a corresponding lesion mask, smoothed to 8 mmWHM, and a 0.001% threshold. Then VBM pre-processing waserformed according with the Brett and colleagues (2001) protocolo obtain segmented GM images into the standard proportionaltereotaxic space [Montreal Neurological Institute (MNI)]. Lesionask was used to exclude the area of the lesion from the com-utation of the cost function, in order to preserve transformationsrom potential biases. Statistical analysis of the regional GM den-ity was performed after smoothing the segmented images with a

able 2. Clinical assessment of motor disability

RCD patients

Mean value

lobal score 8.67otor function sub-scoresDysarthria 0.44Eyes movements 1.61Muscular tone 0.58Postural tremor 0.89Upper limbs ataxia 1.42Lower limbs ataxia 0.78Upright stance 1.39Gait ataxia 1.44

Mean (SD) motor scores obtained by patients with RCD and LCD att al., 1993). See text for further details.

2 mm3 FWHM gaussian kernel. e

VBM statistical analysis was performed using an ANOVAodel to compare the GM maps across three groups: patientsith right cerebellar damage (RCD), patients with left cerebellaramage (LCD), and healthy controls. Categorical comparisonsere performed between each group of patients and controls.egional differences were considered statistically significant atluster level after correction for multiple comparisons (P�0.05).n additional ANOVA model including the same conditions waserformed to investigate possible correlations between the re-ional GM density for each of the three considered groups and theerebellar lesion volumes. Finally, patients’ GM density was ex-racted at the individual level from those cerebral clusters showingignificant changes in the group comparison with healthy controls.hen, we tested for possible correlations between individual val-es of regional GM density and the correspondent clinical (scoresbtained at the modified version of the cerebellar motor scaleroposed by Appollonio et al., 1993) and neuropsychologicalcores.

Stereotaxic coordinates are reported in MNI space (Cocoscot al., 1997).

esion characterization

or each patient, a detailed assessment of the macroscopic CD,ncluding lesion volume and localization was performed. Lesionxtension was assessed on the 3D-T1-MPRAGEs after spatialormalization to the stereotaxic space. Lesion volume was calcu-

ated by using MRIcro and expressed in ml. The involvement ofpecific cerebellar structures (lobules, vermis, nuclei) was evalu-ted with the reference of the Schmahmann 3D MRI atlas of theuman cerebellum (Schmahmann et al., 2000) and the 3D MRItlas of the human cerebellar nuclei (Dimitrova et al., 2002).

RESULTS

europsychological data

he results of neuropsychological testing obtained fromatients and controls are shown in Table 3. None of theealthy controls had any complaint of cognitive problemsr any evidence of cognitive deficits on neuropsychologicalesting. Statistical analysis among the three studied groupspatients with RCD, patients with LCD and controls) did nothow any significant difference in total, verbal and perfor-ance IQ. Conversely, significant differences were found

or the following cognitive assessments: phonemic flu-

LCD patients

Mean value SD Range

5.25 6.69 0–42

0.33 0.82 0–41.17 1.47 0–40.25 0.22 0–20.54 0.60 0–80.88 1.17 0–80.50 1.00 0–80.92 1.28 0–40.67 1.21 0–4

ed version of the Appollonio cerebellar motor deficit scale (Appollonio

SD

6.29

0.460.990.710.781.101.281.431.33

a modifi

ncy task (one-way ANOVA: F2,29�5.7; P�0.01), tem-

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S. Clausi et al. / Neuroscience 162 (2009) 827–835830

oral rules induction test (F2,29�5.6; P�0.01), digit spanorward (F2,29�4.1; P�0.05), delayed recall of Rey’s 15

ords Test (F2,29�3.3; P�0.05), and forward Corsipan (F2,29�4.4; P�0.05). A post hoc analysis using Bon-erroni’s correction indicated that such differences wereotally explained by significantly lower scores in RCD pa-ients than in controls. In contrast, patients with LCD com-ared to controls did not show any significant difference. Inummary, only patients with RCD showed subtle abnor-alities in tests exploring executive functions, short and

ong-term verbal memory, and short-term spatial memory.

able 3. Neuropsychological assessment

LCD patien

ntellectual levelWAIS-R total IQ 101.2 (8.4)WAIS-R verbal IQ 103.2 (9.9)WAIS-R performance IQ 98.2 (8.8)

isuo-spatial abilitiesRaven progressive matrices 30.0 (3.7)WAIS-R Block design 10 (2.2)WAIS-R Object Assembly 8.6 (2.1)Copying drawings 10.2 (0.9)Copying drawings with landmarks 66.3 (3.2)

xecutive functionsPhonemic fluency task 39.8 (7.2)Temporal rules induction test 8.9 (3.9)WAIS-R similarities 10.6 (0.9)

erbal memoryDigit span-forward 6.1 (0.7)Digit span-backward 4.3 (1.2)Rey’s 15 words: short-term 48 (6.1)Rey’s 15 words: long-term 10.2 (1.7)

isuo-spatial memoryImmediate visual memory 20.3 (1.1)Spatial span forward 5.6 (0.5)Spatial span backward 5.1 (0.7)

There are here reported mean (SD) scores from patients (grouped inas performed using the one-way ANOVA and post hoc Bonferroni’ignificantly different between patients and controls ( * ). See text forIQ, intelligence quotient.

able 4. Regional distribution of reduced GM density in the cerebral

rain region Side BA

up temporal gyrus L 38nf frontal gyrus R 45, 47id frontal gyrus R 10id frontal gyrus L 46, 9

nf frontal gyrus L 45, 46, 10ngular gyrus L 39upramarginal gyrus L 40arahippocampal gyrus L 36usiform gyrus L 20, 37

There are here reported the regions of significantly decreased greyach region is expressed in number of voxels. Only regions that suonsidered. Stereotaxic coordinates are reported in MNI space. See t

sup, superior; inf, inferior; mid, middle; R, right; L, left; BA, Brodmann area.

BM

one of the considered 3D-MPRAGE scans were affectedy macroscopic artefacts, as assessed by visual examina-ion. Patients with LCD, compared to controls, did not showny significant change in GM density. In contrast, patientsith RCD, compared to controls, showed widespread re-ions of reduced GM density that survived after correctionor multiple comparisons (Pcorrected�0.05) (Table 4). Theattern of abnormalities included inferior frontal and middlerontal gyri bilaterally, superior temporal, parahippocam-

RCD patients Healthy controls

102.9 (17.4) 110.3 (14.5)100.1 (17.7) 108.8 (13.5)105.9 (15.7) 111.8 (14.8)

27.8 (3.5) 30.4 (3.5)12.4 (3.3) 12.3 (3.5)10.3 (3.5) 10.6 (2.7)9.7 (1.7) 9.8 (0.7)

68.5 (1.7) 66.4 (3.5)

24.4 (13.5)* 35.4 (7.3)14.3 (5.1)* 9.7 (2.1)11.1 (3.2) 11.9 (3.3)

5 (1.2)* 5.9 (0.7)4 (1.5) 4.4 (0.7)

40.1 (7.8) 44.0 (6.5)8 (3.3)* 10.6 (2.0)

19.3 (2.2) 19.8 (1.1)4.7 (0.9)* 5.6 (0.6)4.5 (1.6) 5.6 (1.1)

ith RCD and those with LCD) and healthy controls. Statistical analysisent. The table highlights those mean values that have been foundtails.

RCD patients

Coordinates (mm) Peak Z-score

x y z

�42 2 �15 4.5345 44 �10 4.3929 56 7 4.19

�44 36 32 4.13�52 21 15 4.07�51 �62 37 4.24�54 �42 42 3.89�24 �8 �29 4.02�29 �32 �22 3.67

nsity in patients with RCD compared to healthy controls. The size offter correction for multiple comparisons (Pcorrected�0.05) have beenrther details.

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S. Clausi et al. / Neuroscience 162 (2009) 827–835 831

al, supramarginal, angular, and fusiform gyri in the leftemisphere (Fig. 1).

No significant correlation was found between lesionolumes and regional GM density in the patient groups.onversely, a significant correlation was found betweenM density in the left superior temporal gyrus (peak coor-inates: x��42, y�2; z��15) and scores obtained byatients with RCD at the phonological fluency test (r�0.8;�0.001).

esion characterization

or each studied patient lesion type, volume and side areummarized in Table 1. The anatomical distribution ofissue damage in terms of cerebellar structures involved byach lesion is reported in Table 5. A visual representationf each lesion is also presented overlaid on the T1-eighted template in stereotaxic space (Fig. 2). Lesionolumes between patients with RCD and LCD (meanSD]�12.7 [7.5] and 9.5 [23.5] ml, respectively) were not

(A)

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Left view

Top view

L R

ig. 1. Distribution of regions of reduced GM density in the cerebral coolor in red on the MNI template of SPM2 in left lateral (A), right lateras lower (P�0.001Uncorrected) than in Table 5.

ignificantly different (P-value�0.29). However, the vol- c

me and location of left cerebellar lesions showed a moreeterogeneous distribution (Fig. 2, Table 5).

DISCUSSION

his study was focused on investigating the pattern ofrain abnormalities occurring in patients with an isolatederebellar lesion. The macroscopic CD was carefully as-essed in each patient (Table 5), and VBM was employedo identify and quantify the presence of regional changes inerebral GM density. All patients were first clinically as-essed, and an extensive neuropsychological battery wasdministered to each of them to obtain a full definition ofheir cognitive profile. As expected, all the patients showednly minimal signs of motor impairment on neurologicalxamination, as demonstrated by low scores reported athe ataxia scales (Table 2). At the time of enrollment, all ofhem were in a chronic phase of the clinical evolution,hich is in most cases characterized by an excellent re-

Right view

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atients with RCD compared to healthy controls. Regions are rendered(C), and bottom view (D). For the purpose of illustration the threshold

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rtex of pl (B), top

overy from motor deficits (Kelly et al., 2001). At neuro-

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S. Clausi et al. / Neuroscience 162 (2009) 827–835832

sychological testing, patients with RCD showed signifi-antly lower scores than controls at tests for executiveunctions, short- and long-term verbal memory, and short-erm spatial memory (Table 3). It is unlikely that theseeuropsychological results were affected by motor deficitsuring test performance. As mentioned above, all the re-ruited patients (with no significant difference betweenhose with RCD and those with LCD) showed only minimaligns of residual motor disability in any explored function,ncluding dysarthria (Table 3). From a radiological point ofiew, T2-weighted scans were carefully inspected in eachatient to exclude any macroscopic abnormality in regionsifferent from the cerebellum. Altogether these clinical andadiological data suggest that the neuropsychological ab-ormalities observed in patients with RCD were exclu-ively due to an isolated involvement of the cerebellum.his interpretation is also consistent with previous func-

ional neuroimaging studies that demonstrated in healthyubjects a participation of the cerebellum in several cog-itive functions including attention (Allen et al., 1997), ver-al memory (Grasby et al., 1993; Andreasen et al., 1995),nd visuo-spatial abilities (Parsons and Fox, 1997). Theypothesis is that the cerebellum plays a relevant role inodulating the activity of the cerebral cortex when en-aged in cognitive as well as in motor functions. An acuteelease of such a functional effect has been demonstratedn patients with unilateral cerebellar lesion, whose singlehoton emission computerized tomography (SPECT) in-estigation showed a hypo-activation of the contralateralerebral hemisphere (crossed cerebellocerebral diaschi-is) (Rousseaux and Steinling, 1992; Hausen et al., 1997;agiuchi et al., 2001). It remains however to be clarified

he neurobiological mechanism that underlies the interac-ion between the cerebellum and the cerebral cortex. At aacroscopic level, a recent study has demonstrated that in

able 5. Anatomical distribution of the CD

Case Hemispheric lobules

I–II III IV V VI Crus I

atients with RCD 1 — — — — — —2 — — x x x x3 — — x x x x4 — — — x x x5 — — — — — —6 — — — x x x7 — — — — x x8 — — — — x x

atients with LCD 9 — — — — — —10 — — — — — —11 — — — x x x12 — — — x x x13 — — — — — —14 — x x x x x15 — — x x x —

The extension of CD is here summarized for each studied patient. Iteference of the Schmahmann 3D MRI atlas of the human cerebellum (Dimitrova et al., 2002). See text for further details.

F, fastigial; I, interpositum; D, dentate; x, anatomical structure invol

reterm-infants with brain damage there is a direct corre- c

ation between cerebral and cerebellar volumes duringevelopment (Limperopoulos et al., 2005). This indicateshat the cerebellum and cerebral cortex interact duringevelopment not only at a functional level but also inetermining their structural profile. It is moreover in agree-ent with the theory of evolutionary development of the

erebellar hemisphere associated with the expansion ofhe cerebral association cortex (Leiner et al., 1989). In theurrent study we investigated adults who had normal brainevelopment and were completely healthy before sufferingrom an isolated cerebellar lesion. In a chronic stage ofheir condition, patients with RCD compared to normalontrols presented with a specific pattern of reduced cere-ral GM density (Fig. 1, Table 4). As expected on the basisf anatomical knowledge, the pattern of reduced cerebralM density was mainly contralateral to the cerebellar le-

ion and mostly localized in the prefrontal, parietal andemporal cortex. GM abnormalities in the prefrontal cortext well with the subtle neuropsychological deficit of execu-ive functions that were observed in RCD patients (Table 3).

oreover, an interesting correlation was found betweenM density in the left superior temporal gyrus of patientsith RCD and the scores they obtained at the phonologicaluency task. On the other hand, GM changes in the leftngular and supramarginal gyrus, and in the left parahip-ocampus may account for the visuo-spatial and verbalemory dysfunctions (Table 3). Although the cortical GMbnormalities were mainly contralateral to the CD, someegions of reduced GM density were also found in the rightrefrontal cortex of patients with RCD. A large body ofunctional imaging data has been published so far, whichndicates a bilateral rather than an unilateral involvement ofhe cerebral cortex in many cognitive functions (Andreasent al., 1995; Vohn et al., 2007; Carbon et al., 2008), includ-

ng those traditionally believed to be linked to a specific

Vermis Deep nuclei

VII B VIII A VIII B IX X F I D

— — — — — — — — xx x — — — — — — —x x x — — x — — xx x x x x x — — x— — — x — — — — xx x — — — x x x xx x x x — x — — xx x x — — — — — —— x — — — — — — —x x x x — x — — —x x x x x x x x xx x x x — x — x —x x x x — x — — —— — — — — x — x x— — — — — — — — —

ated on individual T1-weighted volumes in stereotaxic space with theann et al., 2000) and the 3D MRI atlas of the human cerebellar nuclei

sue damage; —, anatomical structure spared by tissue damage.

Crus II

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was evaluSchmahm

erebral hemisphere (i.e. language function). Prefrontal

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S. Clausi et al. / Neuroscience 162 (2009) 827–835 833

ortices show large anatomical connections between eachther through the genu of the corpus callosum, and haveeen shown to co-activate in a number of cognitive para-igms (Chen and Desmond, 2005; Halari et al., 2006;hibuya-Tayoshi et al., 2007). Conversely, the anatomicalonnections between the cerebellum and the cerebral cor-ex are known to be strictly contralateral (Schmahmannnd Pandya, 1997; Ramnani, 2006). We hypothesize thatunilateral CD might affect not only those cortical regions

contralateral) which have direct anatomical cerebello-ce-ebral connections. Rather, other cerebral regions (i.e.psilateral to the CD) might be included in a broader neu-

(A) RCD group

(B) LCD group

Case 1 Case 2

Case 5

Case 9 Case 10

Case 14Case 13

Case 6

-59

-56

-57

-61

-61 -61

-61-64

ig. 2. The localization of the cerebellar lesion in each studied patieneft (B) CD. Subjects are listed in the same order as used in Table 4.

onal network that also suffers from the functional release i

f the cerebellum. In support of this view, there is evidencerom lesional studies in rodents, showing that an acuteerebellar lesion induces abnormal activity also in the ip-ilateral sensorimotor cortex (Oulad Ben Taib and Manto,008). This reinforces the hypothesis of an impaired con-ectivity (via corpus callosum) between the brain regionontralateral to the CD, and its homologous region located

n the other cerebral hemisphere.We can only speculate about the pathophysiological

rocesses underlying the GM changes observed in theerebral cortex. A reduction of GM density might reflecteuronal loss as well as synaptic disruption and remodel-

Case 8

Case 11 Case 12

Case 15

Case 3 Case 4

Case 7

-580

-56

48 -55

-61

ted here. Subjects are grouped in those with right (A) and those withfor further details.

-6

-67

-

t is repor

ng. There is emerging acceptance that neuronal plasticity

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AM

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A

A

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B

B

B

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C

C

C

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S. Clausi et al. / Neuroscience 162 (2009) 827–835834

s directly affected by the levels and signaling properties ofeurotrophic factors (Pang et al., 2004). As a consequencef CD, the neurons of the contralateral cerebral cortex willndergo a reduction of the synaptic inputs that they nor-ally receive from the cerebellum. This may eventually

nduce a structural reorganization of these cortical neu-ons. Similar structural changes are also likely to affectther cortical regions which are anatomically and function-lly connected with the former regions.

A part of the recruited patients were affected by cerebro-ascular risk-factors (Table 1). One might argue that theseactors could be, at least partially, responsible for the GMensity reductions that we observed. Although we cannotxclude such a possibility, it seems unlikely. Indeed, silent

acunar lesions are typically detectable, using T2-weightedRI scans, in patients with chronic cerebrovascular disease

Shintani et al., 1998). According to exclusion criteria, none ofur patients had any abnormality in the cerebral white matter,

hus suggesting the CD as the unique cause of neurologicalmpairment. Moreover, MR abnormalities suggestive ofhronic cerebrovascular sufferance do not usually presentith a preferential regional distribution, such as that we found

n our cohort of patients using VBM. Finally, the reduction oferebral GM density found in RCD patients was extremelyocalized, and well fitting with the location of the CD.

In this study we did not find either cognitive abnormal-ties or cerebral GM changes in patients with LCD com-ared to controls. Interestingly, neuropsychological andeuroimaging results were again consistent to each other,hus reinforcing the findings obtained in patients with RCD.here are several reasons that might explain such a dis-repancy of results between the two groups of patients.atients with LCD presented with a more heterogeneous

esion distribution and extension than patients with RCDTables 1 and 5, and Fig. 2). This might reduce the sensi-ivity of the voxel-based approach, which is only able toetect abnormalities common to the whole group. Addition-lly, the two groups of patients showed a different exten-ion of damage in the cerebellar nuclei. Cerebellar nucleiere involved in six of eight patients from the RCD group

75%) and in two of seven patients (28%) from the LCDroup (Table 4). Especially the damage of the dentateucleus, which was preponderant in RCD patients, mighte relevant in determining cognitive deficits (Kim et al.,994) and, according to our results, the correspondent GMhanges of the cerebral cortex. Indeed, connections be-ween the ventrolateral portion of the dentate and theerebral association cortex are believed to participate theost in cognitive processes (Middleton and Strick, 2001).

The main limitation of this study is the small number ofubjects who have been recruited; therefore, these prelim-nary results need to be replicated in further studies involv-ng larger populations. Indeed, we cannot exclude theossible high influence of few individuals on our groupesults. Nevertheless, the consistence between VBM find-ngs and neuropsychological data provides significant sup-

ort to our interpretation.

CONCLUSION

n conclusion, the current study indicates that isolated CDay induce cerebral GM changes consistent with the neu-

opsychological deficits observed. This convergence is rel-vant for the understanding of cerebro-cerebellar interac-ion in cognition.

cknowledgments—The present work was in part supported byURST and Italian Ministry of Health grants to M.M. and C.C.

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(Accepted 2 February 2009)(Available online 7 February 2009)