Motor control Neurophysiology page 1 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Contents Is nervous system (NS) necessary for behaviour? Neurophysiology Motor control page 2 Contents Is nervous system (NS) necessary for behaviour? What was first? Sensory neurone or motor neurone? NS phylogenesis with regard to motor control Basic units that control movement in mammals Logic of motor control. Fusimotor system. Direct control by motor cortex Basal ganglia = plans of actions Cerebellum – a mystery? Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Is nervous system necessary for behaviour? Neurophysiology Motor control page 3 Is nervous system necessary for behaviour? Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Behaviour was first, neurones were second Neurophysiology Motor control page 4 Behaviour was first, neurones were second Protists have no neurones, yet they display: Active predation Phototaxis Gravitaxis Chemotaxis Mechanoresponsiveness Single-cell organisms perform both sensory and motor function Cilia-driven locomotion Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

What was first? Sensory neurones or motor neurones? Neurophysiology Motor control page 5 What was first? Sensory neurones or motor neurones? (Sensory receptor)-like neurones controlling non-neural motility of primitive ciliated organisms => Sensory neurones were first Sensory-motor unit Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor neurones have evolved along with muscle cells. Neurophysiology Motor control page 6 Motor neurones have evolved along with muscle cells. Muscle cells are controlled by motor neurones Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Cnidaria Neurophysiology page 7 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Molluscs – ganglia Pedal ganglia Neurophysiology page 8 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

F M H Output Motor control Vertebrate brain Neurophysiology page 9 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Vertebrate brain Brain of the tiger salamander Neurophysiology Motor control page 10 Vertebrate brain Brain of the tiger salamander C. J. Herrick (1868-1960) Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Vertebrate brain Brain of the tiger salamander Neurophysiology Motor control page 11 Vertebrate brain Brain of the tiger salamander Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Levels of mammalian motor control Motor cortex Neurophysiology Motor control page 12 Levels of mammalian motor control Motor cortex Basal ganglia Brain stem Cerebellum Spinal cord Motor unit Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Spinal cord Sensory & motor nerves Neurophysiology Motor control page 13 Spinal cord Sensory & motor nerves 31 pairs of spinal nerves Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Spinal cord α motor neurone γ motor neurone Neurophysiology Motor control page 14 Spinal cord α motor neurone γ motor neurone Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Muscle fibre Muscle Muscle fasciculus Muscle fibre Neurophysiology Motor control page 15 Muscle fibre Muscle Muscle fasciculus Muscle fibre Myofibril α motor neurone Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Motor unit = α motor neurone + extrafusal muscle fibres Neurophysiology Motor control page 16 Motor unit = α motor neurone + extrafusal muscle fibres Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Muscle structure Extrafusal fibres Intrafusal fibres Neurophysiology Motor control page 17 Muscle structure Extrafusal fibres Intrafusal fibres Muscle spindle Alfa motoneurone Gamma motoneurone Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Proprioception Muscle spindle Sensory ending Neurophysiology Motor control page 18 Proprioception Muscle spindle Sensory ending Motor ending (γ) Golgi tendon organ Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Golgi tendon organ Neurophysiology page 19 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Muscle spindle Neurophysiology page 20 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Neurophysiology Motor control page 21 Muscle spindle - Stretch reflex vs. Voluntary contraction Spindle lengthened α and γ co-activation Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Spinal reflexes Afferent inhibition Stretch reflex Neurophysiology Motor control page 22 Spinal reflexes Afferent inhibition Stretch reflex Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Spinal reflexes Recurrent inhibition Tendon reflex Neurophysiology Motor control page 23 Spinal reflexes Recurrent inhibition Tendon reflex Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Spinal reflexes Flexor withdrawal reflex Neurophysiology page 24 Spinal reflexes Flexor withdrawal reflex Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Levels of mammalian motor control Motor cortex Neurophysiology Motor control page 25 Levels of mammalian motor control Motor cortex Basal ganglia Brain stem Cerebellum Spinal cord Motor unit Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Motor cortex Motor homunclus Neurophysiology page 26 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Motor cortex Primary - agranular Premotor - dysgranular Neurophysiology Motor control page 27 Motor cortex Primary - agranular Premotor - dysgranular Supplementary - dysgranular Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Motor cortex connections; Tracts MII PM MI SI av talamus Neurophysiology Motor control page 28 Motor cortex connections; Tracts MII PM MI SI av talamus vl talamus pallidum n. ruber cerebellum pont. rf medul. rf spinal cord Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Pyramidal tract Neurophysiology page 29 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Red nucleus – a relict Corticorubral tract Neurophysiology Motor control page 30 Red nucleus – a relict Corticorubral tract Nucleus ruber is under the control of the cerebellum Rubrospinal tract Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Brain stem control of posture Pontine reticular nuclei Neurophysiology Motor control page 31 Brain stem control of posture Pontine reticular nuclei Stimulates antigravity muscles. Afferent connections: All vestibular nuclei Cerebellum Vestibular nuclei Relaxes antigravity muscles. Afferent collaterals from: - Pyramidal tract - Rubrospinal tract - Other motor pathways Medullary reticular nuclei Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control How to explain voluntary movements? Neurophysiology page 32 How to explain voluntary movements? Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Motor cortex Organisation of CNS Neurophysiology Motor control page 33 Motor cortex Organisation of CNS Cerebral cortex = neural substrate for mnemonic representation of the external and inner world Sensory signals lose meaning unless they can control behaviour Each structure has an output Motor as well as sensory cortical areas represent (code, remember) real ‘objects’. Similar to primary sensory cortices that code sensory primitives, primary motor cortex codes motor ‘primitives’ – muscles. The premotor and suplementary motor cortices code for more abstract motor ‘objects’, e.g. movements. Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Motor cortex Organisation of CNS Neurophysiology Motor control page 34 Motor cortex Organisation of CNS Cerebral cortex = neural substrate for mnemonic representation of the external and inner world Sensory signals lose meaning unless they can control behaviour Each structure has an output Sensory cortical areas send their output to the associative areas which represent reality in a complex and abstract way. As the overall goal is to control behaviour, these cortices send their output to areas that store plans of actions, patterns of behaviour. Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Motor cortex Organisation of CNS Neurophysiology Motor control page 35 Motor cortex Organisation of CNS Cerebral cortex = neural substrate for mnemonic representation of the external and inner world Sensory signals lose meaning unless they can control behaviour Each structure has an output Primary sensory cortical areas are a representational substrate located closer to the input side of information flow. Motor cortex is a representational substrate closer to the output side, i.e., closer to structures that control behaviour. Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Motor cortex Organisation of CNS Neurophysiology Motor control page 36 Motor cortex Organisation of CNS Cerebral cortex = neural substrate for mnemonic representation of the external and inner world Sensory signals lose meaning unless they can control behaviour Each structure has an output The CNS structures, activated in this order: Sensory neurone, Thalamus, Primary sensory cortex, Higher-order sensory cortices, Associative cortical areas, Prefrontal cortex, Striatum, Pallidum, Thalamus, Motor cortex, and Motor neurone, can be considered an improved reflex arc. .....(conditioned) Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Phylogenetic principle of inteligence Neurophysiology Motor control page 37 Phylogenetic principle of inteligence Thalamo-cortico-striatal system Mesencephalon Medulla Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control From stimulus to voluntary action Neurophysiology Motor control page 38 From stimulus to voluntary action Sensory organ – stimulus detection, registration of reality Thalamus - ? Primary sensory cortex – sensory primitives Higher-order sensory cortices – abstract representations Associative cortical areas – abstract non-sensory representations Prefrontal cortex – interpreter of information Striatum – database of efferent programs (action templates) Pallidum – ‘point of no return’, release vs. termination of action Thalamus - ? Motor cortex – representation of motor units Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Basal ganglia Striatum = caudate nucl. + putamen Neurophysiology Motor control page 39 Basal ganglia Striatum = caudate nucl. + putamen Globus pallidus Nucleus accumbens Nucleus subthalamicus Substantia nigra Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Basal ganglia Neurophysiology page 40 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Basal ganglia Neurophysiology page 41 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Motor cortex connections; Tracts MII PM MI SI av talamus Neurophysiology Motor control page 42 Motor cortex connections; Tracts MII PM MI SI av talamus vl talamus pallidum n. ruber cerebellum pont. rf medul. rf spinal cord Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Cerebellum Neurophysiology Motor control page 43 Cerebellum Motor control (both voluntary and automatic) can proceed without the cerebellum. Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Cerebellum Neurophysiology page 44 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Neurophysiology page 45 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Neurophysiology page 46 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Neurophysiology page 47 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Neurophysiology page 48 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Neurophysiology Motor control page 49 The cerebellum has probably evolved as a means of maintaining our body in optimal orientation relative to gravity under all circumstances through motor control. In support of this hypothesis is the fact that the oldest part of the cerebellum is the flocculus which responds to vestibular signals by maintaining body balance and corresponding eye movements. Mozek vyda pokyn. Ale potrebuje zpetnou vazbu. Cestou ze skolky kup chleba. Co vidis? U Kalicha. Zaboc doleva! Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Cerebellum Anatomical division Anterior lobe Neurophysiology Motor control page 50 Cerebellum Anatomical division Anterior lobe Posterior lobe Flocculonodular lobe ‘Functional’ division Vestibulocerebellum (flocculonodular l.) Spinocerebellum (medial part) Cerebrocerebellum (lateral part) Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Cerebellum – fine neural structure Purkynje cell Neurophysiology Motor control page 51 Cerebellum – fine neural structure Purkynje cell Granule cell (3/4 of all) Parallel fibre Climbing fibre Mossy fibre Deep cerebellar nucleus Inferior olive (in the medulla) Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Cerebellum – afferent connections Neurophysiology Motor control page 52 Cerebellum – afferent connections Cortico-ponto-cerebellar pathway Olivocerebellar tract (climbing fibres from the inferior olive) Spinocerebellar pathway Vestibulocerebellar pathway Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Cerebellum – efferent connections Thalamus Basal ganglia Neurophysiology Motor control page 53 Cerebellum – efferent connections Thalamus Basal ganglia Nucleus ruber Nucleus reticularis pontis Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Cerebellar lesion Cerebellar activation during speaking Neurophysiology Motor control page 54 Cerebellar lesion Cerebellar activation during speaking Play from web Play from web Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Cerebellum Neurophysiology Motor control page 55 Cerebellum The cerebellum is probably one of two elementary feedback mechanisms of the motor system that adjust movements. The first is the fusimotor system (gamma motoneurone) which functions on the basis of spinal feedback. The second is the cerebellum that works like software. It adjusts signals – that are sent to muscles by the motor cortex – in a way that the result exactly corresponds to the wanted movement. Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Play from web Neurophysiology page 56 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control The end Neurophysiology page 57 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Neurophysiology page 2 Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control coactivation of the alpha and gamma motor neurons Neurophysiology Motor control page 2 coactivation of the alpha and gamma motor neurons coactivation keeps the muscle spindle reflex from opposing the muscle contraction Activation of muscle spindles on opposite sides of a joint elicits reflexes on both sides and fixates it. The purpose of patelar reflex test is to determine how much background excitation, or “tone,” the brain is sending to the spinal cord Golgi tendon organ: reflex provides a negative feedback mechanism that prevents the development of too much tension on the muscle Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Ovládání svalu – fusimotorický systém Neurophysiology page 2 Ovládání svalu – fusimotorický systém Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Ovládání svalu – fusimotorický systém Svalové vřeténko Neurophysiology Motor control page 2 Ovládání svalu – fusimotorický systém Svalové vřeténko signalizuje natažení (délku) intrafusálního vlákna. Golgiho šlachové tělísko signalizuje napětí svalu. Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad

Motor control Ovládání svalu – fusimotorický systém Alfa motoneuron Neurophysiology Motor control page 2 Ovládání svalu – fusimotorický systém Alfa motoneuron aktivuje kontrakci svalu (extrafusálních vláken) Gamma motoneuron aktivuje kontrakci intrafusálních vláken Department of Physiology, 2nd Faculty of Medicine, Charles University Copyright © 2011 Luděk Nerad