Acquired cerebellar lesions in adults and children can lead to the development of a complex behavioural pattern termed ‘Cerebellar Cognitive Affective Syndrome’ (Schmahmann and Sherman, Brain, 1998; 121: 561–79), which is characterized by reduced cognitive efficiency associated with specific neuropsychological deficits (executive and visuospatial disorders), expressive language disorders (mild agrammatism and anomia) and affective disorders with blunting of affect. It is not known whether a symptomatological picture such as this can also be found in congenital cerebellar malformations. We studied the behavioural developmental profile of 27 patients including children and adults with congenital malformations confined to the cerebellum, the largest studied sample to date. Extensive clinical and neuropsychological investigations highlight the presence of a wide range of disorders supporting the important role played by the cerebellum in the acquisition of higher-order cognitive and affective skills. The type and extent of cerebral reorganization processes in the presence of malformative lesions are difficult to predict and may possibly account for the variability of clinical phenotypes. It is, therefore, more difficult to identify a syndromic picture defined as exactly as is the case with acquired lesions. However, the pattern of deficits that we document is in remarkable agreement with the general profile of the Cerebellar Cognitive Affective Syndrome. Malformations affecting the cerebellar vermis induce affective and social disorders and evolve towards more unfavourable pictures often associated with an autistic symptomatology. Malformations of cerebellar hemispheres are more frequently associated with selective neuropsychological deficits involving mainly executive functions and visuospatial and linguistic abilities. Motor deficits are generally less severe, and tend to improve slowly and progressively, in some cases reaching almost complete functionality. Finally, the overall favourable evolution with an onset of skills in advanced age in a consistent subset of subjects suggests that individual follow-ups should be performed in order to monitor the quality and stability of impairments and acquired abilities over time.

Perception of the final position of a moving object or creature is distorted forward along its actual or implied motion path, thus enabling anticipation of its forthcoming position. In a previous research, we demonstrated that viewing static snapshots that imply body actions activates the human motor system. What remains unknown, however, is whether extrapolation of dynamic information and motor activation are higher for upcoming than past action phases. By using single-pulse transcranial magnetic stimulation, we found that observation of start and middle phases of grasp and flick actions engendered a significantly higher motor facilitation than observing their final postures. Differential motor facilitation during start and end postures was independent of finger configuration at the different hand apertures. Subjective ratings showed that modulation of motor facilitation was not due to the amount of implied motion per se but to the forward direction of the motion path toward upcoming phases. Thus, motor facilitation proved maximal for the snapshots evoking ongoing but incomplete actions. The results provide compelling evidence that the frontal component of the observation–execution matching system is preferentially activated by the anticipatory simulation of future action phases and thus plays an important role in the predictive coding of others’ motor behaviors.

Cerebral lesions may alter the capability of bilingual subjects to separate their languages and use each language in appropriate contexts. Patients who show pathological mixing intermingle different languages within a single utterance. By contrast, patients affected by pathological switching alternate their languages across different utterances (a self contained segment of speech that stands on its own and conveys its own independent meaning). Cases of pathological mixing have been reported after lesions to the left temporoparietal lobe. By contrast, information on the neural loci involved in pathological switching is scarce. In this paper a description is given for the first time of a patient with a lesion to the left anterior cingulate and to the frontal lobe—also marginally involving the right anterior cingulate area—who presented with pathological switching between languages in the absence of any other linguistic impairment. Thus, unlike pathological mixing that typically occurs in bilingual aphasia, pathological switching may be independent of language mechanisms.