12 Motor system II Motor system II2 Introduction Motor system II3 http://www.frontiersin.org/files/Articles/42416/fnhum-07-00085-HTML/image_m/fnhum-07-00085-g001.jpg http://www.slideshare.net/drpsdeb/presentations Subcortical (stem) pathways controlling lower motoneurons Motor system II4 Medial system • Axial muscle control • Tr. Vestibulospinalis – Reflex control of balance and postural control • Tr. Reticulospinalis – Muscle tone regulation (postural control) • Tr. Tectospinalis – Coordination of head and eyes movements Lateral system • Distal muscle control • „Reflex“ control of the limbs • Replaced by tr. corticospinalis • Tr. Rubrospinalis • Tr. Rubrobulbaris Fixed action pattern and rhythmic movement Motor system II5 • Fixed action pattern (e.g. Swallowing) – Neuronal networks for complex motor activity • Central pattern generator (e.g. Walking, breathing) – Neuronal networks generating rhythmic activity – „Spontaneously repeated fixed action patterns“ – No need of feedback • Localization – Walking – brain stem, lower thoracic and upper lumbar spinal cord – Breathing – brain stem – Swallowing - medulla oblongata/brain stem • Variously expressed voluntary control – Walking (full control) – Breathing (partial control) – Swallowing (limited control) http://www.slideshare.net/drpsdeb/presentations Fixed action pattern and rhythmic movement Motor system II6 • Fixed action pattern (e.g. Swallowing) – Neuronal networks for complex motor activity • Central pattern generator (e.g. Walking, breathing) – Neuronal networks generating rhythmic activity – „Spontaneously repeated fixed action patterns“ – No need of feedback • Localization – Walking – brain stem, lower thoracic and upper lumbar spinal cord – Breathing – brain stem – Swallowing - medulla oblongata/brain stem • Variously expressed voluntary control – Walking (full control) – Breathing (partial control) – Swallowing (limited control) http://www.slideshare.net/drpsdeb/presentations Fixed action pattern and rhythmic movement Motor system II7 Fig. 1. Neural control of locomotion. A) Increments in the intensity of stimulation of the MLR in the high decerebrate cat increased the cadence (step cycles/sec) of locomotion. Adapted from Shik et al. 1966.[22] B) Schematic of the velocity command hypothesis: a command signal specifying increasing body velocity descends from deep brain nuclei via the MLR to the spinal cord and drives the timing element of the spinal locomotor CPG to generate cycles of increasing cadence. Extensor phase durations change more than flexor phase durations. The command signal also drives the pattern formation layer to generate cyclical activation of flexor and extensor motoneurons. Loading of the activated muscles (e.g. supporting the moving body mass) is resisted by the muscles' intrinsic spring-like properties. This is equivalent to displacement feedback. Force and displacement sensed bymuscle spindle and Golgi tendon organ afferents reflexly activate motoneurons. A key role of these afferents is to adjust the timing of phase transitions, presumably by influencing or overriding the CPG timer. Adapted from Prochazka & Ellaway 2012.[23] https://en.wikipedia.org/wiki/Central_pattern_generator Fixed action pattern and rhythmic movement Motor system II8 Whelan PJ. Shining light into the black box of spinal locomotor networks. Philosophical Transactions of the Royal Society of London B: Biological Sciences. 2010;365:2383–2395. Cortical control of lower motor neuron Motor system II9 Tractus corticospinalis Tractus corticobulbaris Voluntary motor activity Voluntary motor activity Motor system II10 Idea Association cortex Premotor + Motor cortex Basal Ganglia Lateral cerebellum Movement Intermediate Cerebellum ExecutionPlanning http://www.slideshare.net/drpsdeb/presentations Voluntary motor activity Motor system II11 • Result of cooperation of upper and lower motor neuron • Basal ganglia – Motor gating – initiation of wanted and inhibition of unwanted movements • Cerebellum – Movement coordination http://www.slideshare.net/drpsdeb/presentations Pyramidal tract Motor system II12 • Upper motor neuron – Primary motor cortex • Lower motor neuron – Anterior horn of spinal cord • Tractus corticospinalis lateralis – 90% of fibers • Tractus corticospinalis anterior – 10% of fibers – Cervical and upper thoracic segments • Tractus corticobulbaris http://images.slideplayer.com/14/4330915/slides/slide_34.jpg Primary motor cortex Motor system II13 http://www.emunix.emich.edu Motor cortex Motor system II14 • Primary motor cortex (area 4) – Somatotopic organization – Control of lower motor neuron • Premotor cortex (area 6 laterally) – Preparation of strategy of movement • Sensor motor transformation • Movement patterns selection • Supplementary motor cortex (area 6 medially) – Involved in planning of complex movements • Movement of both limbs • Complex motion sequences – Activated also by complex movement rehearsal http://www.slideshare.net/CsillaEgri/presentations Basal ganglia Motor system II15 • Corpus striatum – Nucleus caudatus – Putamen • Globus pallidus (Pallidum) – Externum – Internum • Nucleus subthalamicus • Substantia nigra – Pars compacta – Pars reticulata • Thalamic motor nuclei http://www.slideshare.net/CsillaEgri/presentations Basal ganglia Motor system II16 • Corpus striatum – Nucleus caudatus – Putamen • Globus pallidus (Pallidum) – Externum – Internum • Nucleus subthalamicus • Substantia nigra – Pars compacta – Pars reticulata • Thalamic motor nuclei http://www.slideshare.net/CsillaEgri/presentations Basal ganglia - inputs Motor system II17 Corpus striatum • Connections from all cortical areas with two exceptions – primary visual and primary auditory cortex • The most of connections from – Frontal and parietal association areas – Motor areas http://www.slideshare.net/CsillaEgri/presentations Basal ganglia Motor system II18 Motor control realized by two circuits ✓Direct pathway Motor cortex activation ✓Indirect pathway Motor cortex inhibition Direct pathway Motor system II19 Cortex Corpus striatum Globus pallidus internus (Gpi) Thalamus Cortex http://www.slideshare.net/drpsdeb/presentations Direct pathway Motor system II20 http://www.slideshare.net/drpsdeb/presentations • Thalamic motor nuclei activate motor cortex • Tonic inhibitions of thalamic motor nuclei by GPi • Activated corpus striatum transiently inhibits Gpi, resulting in transient disinhibition of thalamic motor nuclei Direct pathway Motor system II21 http://www.slideshare.net/drpsdeb/presentations • Thalamic motor nuclei activate motor cortex • Tonic inhibitions of thalamic motor nuclei by GPi • Activated corpus striatum transiently inhibits Gpi, resulting in transient disinhibition of thalamic motor nuclei Direct pathway Motor system II22 http://www.slideshare.net/drpsdeb/presentations • Thalamic motor nuclei activate motor cortex • Tonic inhibitions of thalamic motor nuclei by GPi • Activated corpus striatum transiently inhibits Gpi, resulting in transient disinhibition of thalamic motor nuclei Indirect pathway Motor system II23 http://www.slideshare.net/drpsdeb/presentations Kortex Corpus striatum Globus pallidus externus (GPe) GPiNucleus subthalamicus (NS) Indirect pathway Motor system II24 http://www.slideshare.net/drpsdeb/presentations • NS activates GPi • GPe tonically inhibits NS • Corpus striatum transiently inhibits GPe NS disinhibition Gpi activation Indirect pathway Motor system II25 http://www.slideshare.net/drpsdeb/presentations • NS activates GPi • GPe tonically inhibits NS • Corpus striatum transiently inhibits GPe NS disinhibition Gpi activation Indirect pathway Motor system II26 http://www.slideshare.net/drpsdeb/presentations • NS activates GPi • GPe tonically inhibits NS • Corpus striatum transiently inhibits GPe NS disinhibition Gpi activation Indirect pathway Motor system II27 http://www.slideshare.net/drpsdeb/presentations • NS activates GPi • GPe tonically inhibits NS • Corpus striatum transiently inhibits GPe NS disinhibition Gpi activation Indirect pathway Motor system II28 http://www.slideshare.net/drpsdeb/presentations • NS activates GPi • GPe tonically inhibits NS • Corpus striatum transiently inhibits GPe NS disinhibition Gpi activation Indirect pathway Motor system II29 http://www.slideshare.net/drpsdeb/presentations • NS activates GPi • GPe tonically inhibits NS • Corpus striatum transiently inhibits GPe NS disinhibition Gpi activation • Less important is a direct inhibition of Gpi by GPe Direct and indirect pathway differences Motor system II30 http://www.slideshare.net/drpsdeb/presentations • Direct pathway ➢ Motor cortex activation • Indirect pathway ➢ Motor cortex inhibition Direct and indirect pathway differences Motor system II31 http://www.slideshare.net/drpsdeb/presentations • Direct pathway ➢ Motor cortex activation • Indirect pathway ➢ Motor cortex inhibition Dopaminergic projections Motor system II32 http://www.slideshare.net/drpsdeb/presentations • Dopaminergic projections are crucial for the function of corpus striatum • S. nigra pars compacta • Direct pathway activation ➢ D1 receptors • Indirect pathway inhibition ➢ D2 receptors Dopaminergic projections Motor system II33 http://www.slideshare.net/drpsdeb/presentations • Dopaminergic projections are crucial for the function of corpus striatum • S. nigra pars compacta • Direct pathway activation ➢ D1 receptors • Indirect pathway inhibition ➢ D2 receptors Basal ganglia Motor system II34 • Beside motor loop there are other loops associated with other thalamic nuclei • „Gating“ of the other sort of information • Association loop • Limbic loop • Basal ganglia play an important role in information processing in general and this is crucial for thinking process • Connections of corpus striatum are plastic what allows learning and this was very important during evolution http://www.slideshare.net/CsillaEgri/presentations Cerebellum Motor system II35 • Coordination • Cerebellum plays an important role not only in the coordination of movement, but also in the "coordination" of thoughts http://www.slideshare.net/HarshshaH103/cerebellum-its-function-and-releveance-in-psychiatry 80. Hierarchic organization of motor system – reflex vs. voluntary motor activity Motor system II36 • Hierarchy of movement • Reflex – economical, uniform, protective, fast • Rhytmic – economical solution for complex uniform actions (breathing, walking…) • Voluntary – non-economical, unique, relatively slow • Classification and description of reflexes • Fixed action pattern and rhythmic movement (definition and examples) • Voluntary motor control • Overview of structures involved in planning and execution of voluntary motor activity • Motor cortex organization (primary, premotor and supplementray motro cortex…) • Brief description of pyramidal tract 81. The basic functions of basal ganglia Motor system II37 • Brief description of basal ganglia function (loops, motor, non-motor) • Overview of basal ganglia nuclei and the conncetions • Description of direct and indirect pathway