Specific Cues Can Improve Procedural Learning and Retention in Developmental Coordination Disorder and/or Developmental Dyslexia.

The present study investigates procedural learning of motor sequences in children with developmental coordination disorder (DCD) and/or developmental dyslexia (DD), typically-developing children (TD) and healthy adults with a special emphasis on (1) the role of the nature of stimuli and (2) the neuropsychological functions associated to final performance of the sequence. Seventy children and ten adults participated in this study and were separated in five experimental groups: TD, DCD, DD, and DCD + DD children and adults. Procedural learning was assessed with a serial reaction time task (SRTT) that required to tap on a specific key as accurately and quickly as possible when stimuli appeared on the screen. Three types of stimuli were proposed as cues: the classical version of the SRTT with 4 squares aligned horizontally on the screen, giving visuospatial cues (VS cues), and two modified versions, with 4 letters aligned horizontally on the screen (VS + L cues) and letters at the center of the screen (L cues). Reaction times (RT) during the repeated and random blocks allowed assessing three phases of learning: global learning, specific learning and retention of the sequence. Learning was considered as completed when RT evolved significantly in the three phases. Neuropsychological assessment involved, among other functions, memory and attentional functions. Our main result was that learning and retention were not influenced by the available cues in adults whereas learning improved with specific cues in children with or without neurodevelopmental disorders. More precisely, learning was not completed with L cues in children with neurodevelopmental disorders. For children with DD, learning was completed with the VS and VS + L cues whereas for children with DCD (with or without DD), learning was completed with combined VS + L cues. Comorbidity between DD and DCD had no more impact on procedural learning than DCD alone. These results suggest that learning depends on the nature of cues available during practice and that cues allowing learning and retention depend on the type of disorder. Moreover, selective attention was correlated with RT during retention, suggesting that this neuropsychological function is important for procedural learning whatever the available cues.

What happens when nothing happens? An investigation of pauses as a compensatory mechanism in early Alzheimer's disease.

Lexical-semantic impairment is one of the earliest symptoms of Alzheimer's disease (AD) and is usually examined by single word processing tasks. During speech production, pauses are often investigated as a hallmark of a patient's lexical-semantic decline. In the current study, we put forward the hypothesis that pauses reflect different processes according to the type of discourse. We believe that lexical and semantic impairment would predict a patient's pause frequency in a picture-based narrative (PBN) while anterograde memory would predict a patient's pause frequency in a memory-based narrative (MBN). To demonstrate this, we recruited 17 early AD patients and 17 matched controls. They underwent a full neuropsychological and language assessment and two narrative production assessments. We compared pause duration and frequency in the AD participants' and healthy controls' PBN and MBN. A multiple regression model was used in each narrative and in each group individually to assess the relationship between cognitive processes and pause frequency. Our results show that participants with AD produced more pauses in the PBN only. The frequency was predicted by semantic fluency performance with which it was positively correlated, contrary to what was expected. In the MBN, pause frequency in the AD participants was positively correlated with and predicted by their memory performance. We then examined the neuroanatomical correlates of pause frequency in the AD participants. Considering the PBN, pause frequency was also positively correlated with the grey matter density of the anterior temporal lobe. These findings suggest that patients use pauses as compensatory mechanisms in the earliest stages of AD. Pauses therefore may reflect the time required for the compensation and the realisation of a weak process depending on the narrative task and should be considered as a positive sign.

Discourse macrolinguistic impairment as a marker of linguistic and extralinguistic functions decline in early Alzheimer's disease.

BACKGROUND: Alzheimer's disease is characterized by macrolinguistic changes. This decline is often analyzed with quantitative scales. AIMS: To analyze discourse production in early Alzheimer's disease (AD) and to identify qualitative markers of macrolinguistic decline. METHODS & PROCEDURES: We analyzed macrolinguistic features of a clinical narrative task along with patients' cognitive changes. To do so, 17 early AD participants and 17 healthy controls were recruited and given a full neuropsychological and language assessment. Narrative discourses produced during the language assessment were transcribed and macrolinguistic features were qualitatively analyzed (i.e., local and global coherence marks and discourse informativeness). Inter-group comparison was complemented by intra-group correlation. As some inter-group comparisons revealed the existence of subgroups of patients, permutation tests were used to investigate how these subgroups differed vis-à-vis cognitive measures. OUTCOMES & RESULTS: Overall, the results indicate that AD participants presented declines in informativeness and global coherence, correlated with declines in memory and executive functions. Permutation tests showed that participants with AD producing referential errors or misinterpretations had a deeper lexical-executive decline and a lower Mini-Mental State Evaluation (MMSE). CONCLUSIONS & IMPLICATIONS: This study shows that two clinically relevant, qualitative signs differ in discourse production between typical ageing and early AD, namely information units and modalizing discourse. It also shows that macrolinguistic assessment is a useful tool for revealing impaired communication and cognition in early AD. Although lexical processing decline probably contributes to patients' macrolinguistic impairment, implications of extralinguistic functioning should be further investigated.

Temporal analysis of regional anaesthesia-induced sensorimotor dysfunction: a model for understanding phantom limb.

BACKGROUND: The peripheral deafferentation induced by regional anaesthesia (RA) results in misperception of size-shape (S) and posture (P) of the anesthetized limb. During RA, most patients seem to describe motionless 'phantom limbs' fixed in stereotyped illusory positions, suggesting that RA could unmask stable postural patterns. The question of whether movement illusions exist or not after anaesthesia needs a prospective study. This study aimed to describe the phenomenology of RA-induced kinesthetic illusions (K illusions). METHODS: We examined prospectively the body image alteration during infraclavicular blocks in 20 patients. Multimodal sensory testing (pinprick, heat-cold, pallesthesia, and arthrokinesia) and assessment of motor function were performed every 5 min for 60 min after administration of the local anaesthetics. Meanwhile, patients described phantom limb sensations (S, P, and K illusions). RESULTS: We individualized the occurrence of K illusions [44 (8) min] with respect to S illusions [7 (3) min; P<0.005] and P illusions [22 (4) min; P<0.001]. A close relationship between the onset of K illusions and proprioceptive impairment (arthrokinesia: r=0.92, P<0.001; pallesthesia: r=0.89, P<0001) and abolishment of motor activity (r=0.83, P<0.001) was identified. Finally, a principal component analysis showed that S and P illusions were essentially related to the proprioceptive impairment. CONCLUSIONS: This study analyses for the first time the temporal evolution of sensorimotor dysfunction and the onset of K illusions during RA. Our results suggest the involvement of an alteration of proprioception and motor functions in the origin of this phenomenon. These data agree with the motor awareness theory.