Slide 1

Controllo normale 1.Durante il reaching con il braccio sinistro si attiva LeftTrap 2.During il reaching con il braccio destro si attiva il RightTrap Left movement Right movement - - - - - - - Resting... M U S C L E S A C T I V I T Y V Slide 2 NonAHP 1.Durante il reaching sn si attiva il LeftTrap 2.Durante il reaching ds si attiva il RightTrap Left movement Right movement - - - - - - - Resting... M U S C L E S A C T I V I T Y V Slide 3 Left movement Right movement - - - - - - - Resting... M U S C L E S A C T I V I T Y V Slide 4 Left movement Right movement - - - - - - - Resting... Paziente AHP. 1.Durante il reaching sn si attiva il LeftTrap 2.Durante il reaching ds si attiva il RightTrap is activated 3. Durante il reaching sn il RightTrap pi attivo del sn. Per la parte destra sempre pi attiva della sinistra (anche nella condizione di risposo; probabilmente an active process induced by disinhibition, in order to establish new compensatory pathways see Ghika et al., 1995; Cao et al., 1998) Slide 5 Slide 6 CONCLUSION From the activity registered in the proximal muscles of the affected side we can infer that AHP patient had, similarly to normal subjects, the intention to move Next question would be: is this intentional response related to the operation of neural mechanisms that govern normal motor behaviour so to influence the motor performance of the intact hand when the patients try to execute bimanual movements? Slide 7 We decided to use a paradigm proposed by Kelso and coworkers in which the subjects had to reach for easy target (near and large) and difficult target (far and small). They found that the Movement Time was much shorter for easy target than for difficult target in unimanual performance. However, when the two conditions were combined they did not find that the limb producing a short movement to an easy target arrived earlier than the limb producing the difficult movement. there was a strong tendency for both movements to be initiated and terminated synchronously. In particular, the hand moving to the easy target slowed down when moving with the hand going to the difficult target. Slide 8 The question is: what happens when an hemiplegic patient with anosognosia, who cannot move the contralesional hand, but is convinced of being able to move it, is asked to perform unimanual and bimanual asymmetric movements? Slide 9 We slightly modified this paradigm to adapt it to right brain-damaged patients. In the Kelso et al. experiments targets were positioned to the right and left of the starting positions. In our paradigm the targets were positioned on the radial plane to minimise the interaction with visual neglect. easy difficult Hand (Left or Right) Space (Near or Far) Action (Unimanual, Ba, Bs) -normal subjects -patient with AHP Slide 10 RESULTS IN NORMAL SUBJECTS 1.LH and RH had similar MT in unimanual condition Movement Time is much shorter for easy target than for difficult target in unimanual conditions. 1.In bimanual condition the hands reaching is simultaneous. 2.In Ba conditions the hand that reaches for near targets slowed down. Conclusion: the hands were influenced by the simultaneous acting of the other hand in asymmetrical conditions. Slide 11 Predictions When patients with AHP are asked to perform bilateral reaching movements They should not attempt bilateral hands movements No difference in the MT of the R hand in the different conditions of the experiment No intention Intention Intention They should attempt bilateral movements MT of the R hand in the Unilateral and Bilateral conditions should differ Slide 12 Case report: Patient LM 41-year-old right-handed man damage in the right hemisphere caused left hemiplegia, left hemianaesthesia and severe personal and extrapersonal left-sided neglect. We tested him 71 days after the stroke Well oriented in time and space had no global reasoning or language problems. He could readily understand and follow test instructions and was very cooperative. Slide 13 At the time of testing he still showed left hemiplegia and left anaesthesia, whereas personal and extrapersonal neglect were improved He also showed a severe ansognosia for hes hemiplegia Like CR he believed that he was able to use his left arm and hand and to walk and carry out without any problem several daily activities Slide 14 Slide 15 Patient and controls right hand - Also in patient LM the action of the right hand in near space is influenced by the simultaneous perceived action of the contralesional plegic hand Slide 16 Slide 17 The intention was not an abstract will related to the previous knowledge of being able to move, but was actually implemented in the muscles fibers activated by the spared cortical circuits for motor programming and movement execution goes so far as to influence the motor parameter of the right hand when the patients has the false belief of simultaneously moving the left hand. These experiments strongly suggest that AHP patients do have the intention to move the plegic limb Slide 18 Next steps studiare aspetti bimanuali puramente motori studiare coinvolgimento distale attraverso lo studio cinematico del grasping Slide 19 1. aspetti bimanuali puramente motori Slide 20 Slide 21 Planner (movement selection ) LimbWorld Sensory Information/actual state Goals/ Prior intention Efference copy Forward model (Movement predictor/predicted state) B Sense of agency A Comparator Urge to move/intention C x x Desired state Motor awareness compa rator affordances In A, the comparator; in B, the predictor; in C, the locus of emergence of intention to move. According to our hypothesis: 1.a damage to the comparator that has to match the prediction with the actual state of the system prevents the detection of the difference between the movement/no movement conditions. 2.A part of the motor system functions normally. Patients have intentions and make predicitons. This leads to the construction of a non-veridical motor awareness that may represent the bases of the firm belief of being still able to move. The discrepancy is not detected Anosognosia comp arator Berti and Pia, 2007 Slide 22 Gabriella Bottini Department of Pyshcology, University of Pavia Eraldo Paulesu Department of Pyshcology, University of Milano Bicocca Martina Gandola Department of Pyshcology, University of Pavia Nicola Smania Rehabilitation Unit, Verona Hospital Andrea Stracciari Neurology Unit, SantOrsola Hospital, Bologna Lorenzo Pia Lucia Spinazzola Department of Pyshcology, Turin University Grazie a voi e a: Slide 23 Goals/ Prior intention Sense of agency Urge to move/intention Motor awareness affordances