Motor equivalence and sensorimotor transformations

Transcript

1 Motor equivalence and sensorimotor transformations A Right hand B Right hand (wrist fixed) C Left hand D Teeth E Foot A Locate hand and cup (egocentric coordinates) B Plan hand movement (endpoint trajectory) C Determine intrinsic plan (joint trajectory) D Execute movement (joint torques) Movement planning Inverse kinematics Inverse dynamics Cup Elbow angle trajectory Elbow torque Shoulder angle trajectory Shoulder torque

2 Motor Control processes

3 Internal models for motor control Desired behavior Inverse model Motor command Forward model Predicted behavior Efference copy Actual behavior

4 Overall organization of neural structures that control movement

5 The corticospinal and corticobulbar tracts

6 Descending projections from the brainstem to the spinal cord

7 Spatial distribution of lower motor neurons in the ventral horn of the spinal cord

8 Location of local circuit neurons that supply the medial region of the ventral horn

9 Overview of descending motor control

10 Stretch reflex circuitry

11 Stretch reflex circuitry

12 Stretch reflex gain

13 Negative feedback regulation of muscle tension by Golgi tendon organs

14 Spinal cord circuitry responsible for the flexion-crossed extension reflex

15 Kinematics of walking a Periodo di appoggio Periodo di oscillazione b

16 Kinematics of walking Tronco A I Coscia 60 Coscia Gamba A I A I Gamba Piede Piede c Gamba Coscia Piede a b Periodo di appoggio Periodo di oscillazione

17 Muscle activity during walking 1 M. ileopsoas M. sartorio M. bicipite femorale 4 M. semitendinoso 5 5 M. tibiale anteriore 6 M. grande gluteo 7 M. retto femorale 6 8 M. vasto laterale M. gastrocnemio 10 M. soleo 9 10 Periodo di appoggio Periodo di oscillazione

18 Central pattern generator Zona intermedia E Mn Muscolo quadricipite F Mn Muscolo semitendinoso 1s

19 Reflex pathways contributing to locomotion Fibre Ia + + Ia GTO Fibre Ib + + GTO Ib + + a b c d Recettori cutanei Recettori cutanei

20 Mesencephalic locomotor region RLM Mesencefalo/ Ponte LC Nuclei del rafe Ponte FR Bulbo NA Glu 5-HT FR Midollo lombare

21 Control scheme for locomotion Aree corticali motorie Controllo visuomotorio Aree corticali visive Nuclei della base Regione locomotoria mesencefalica Attivazione/ frequenza del passo Facilitazione della fase flessoria Tronco dell encefalo Coordinazione intersegmentaria/ regolazione on line e anticipatoria Cervelletto Midollo spinale Schema del passo Segnali afferenti Apparato muscoloscheletrico

22 Center of pressure Force of gravity Center of mass Ground reaction force Center of pressure Center of mass projected onto base of support Base of support 4 cm Trajectory over time Center of pressure Center of mass 1 cm

23 Descending systems for postural control

24 Feedforward and feedback mechanisms of postural control

25 Maintaining the center of mass over the support base A Bringing center of mass back over base of support 1 Surface moves backward 2 Body sways forward 3 Recovery B Extending base of support to capture center of mass 1 Disturbance 2 Responses Sway Stepping Using arm for support

26 Hip and Ankle strategies A Stance determines postural response B Platform width affects postural response C Adaptation of postural response ABD QUAD Hip strategy QUAD HAM Hip strategy (on beam) Narrow beam PSP HAM GAS Time (ms) Move to wide platform Adaptation over successive trials on wide platform Ankle strategy Trial 1 ABD 3 QUAD PSP 5 Wide platform HAM GAS Ankle strategy (on platform) Time (ms)

27 Anticipatory maintenance of body posture Unsupported stance BIC HAM GAS BIC HAM GAS Supported stance BIC Rigid support BIC HAM GAS HAM GAS Time (s)

28 Anticipatory maintenance of body posture Center of mass position is controlled during walking by foot placement Limb support 4 Foot placement during stepping Double CoM at time of: Right heel down (step 4) Single 3 Double Right toe off (step 2) Left heel down (step 3) Single 2 Direction of progression (increasing time) 1 Left toe off (step 1) Path of the CoM

29 Adaptation of postural responses

30 Basal Ganglia are critical for adaptating postural responses to initial conditions A Control Upright Seated PSP ABD HAM QUAD GAS TIB Time (ms) Time (ms) B Parkinson disease Upright Seated PSP ABD PSP HAM GAS TIB ABD QUAD HAM QUAD GAS TIB Time (ms) Time (ms)

31 Contribution by tactile inputs