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THE BRAIN, SPEECH AND LANGUAGE: CONTROL CIRCUITS Pedro Amarante Andrade, PhD LCSC06 BIOSCIENCES FOR SPEECH AND LANGUAGE THERAPY LCSC06 | Biosciences for SLT CONTROL CIRCUITS Integrate and control the activities of the structures and pathways involved in motor performance Key point: Neither the basal ganglia not the cerebellum project directly onto lower motor neurons. LCSC06 | Biosciences for SLT CONTROL CIRCUITS CEREBELLUM AND BASAL GANGLIA • The cerebellum: coordinates motor and sensory information – Gets info from the cortex about what muscles SHOULD be doing, and compares this with what is ACTUALLY happening • The basal ganglia: involved in control of background movement, and initiation of movement patterns LCSC06 | Biosciences for SLT THE CEREBELLUM ‘little brain’ in Latin LCSC06 | Biosciences for SLT FUNCTIONS OF THE CEREBELLUM • Stores learned sequences of movements • Participates in fine tuning and co-ordination of movements produced elsewhere in the brain • Integrates all of these things to produce fluid and harmonious movements. So prime task is to ensure smooth coordination of muscles LCSC06 | Biosciences for SLT CEREBELLUM • Highly folded surface • Accounts for about a tenth of the brain mass yet contains half of its total amount of neurons LCSC06 | Biosciences for SLT CEREBELLUM Tortora and Derrickson 2012. Principles of anatomy and physiology. Pp 509 LCSC06 | Biosciences for SLT CEREBELLUM Tortora and Derrickson 2012. Principles of anatomy and physiology. Pp 509 LCSC06 | Biosciences for SLT ANTERIOR CEREBELLUM Spinocerebellum • projection area for the spinocerebellar proprioceptive information • Receives input from muscle and joint receptors (Golgi tendon organs & muscle spindles) via spinocerebellar tracts • Regulates posture, gait and truncal tone.; • It is connected to the spinal cord and controls postural muscle activity by influencing muscle tone. LCSC06 | Biosciences for SLT POSTERIOR CEREBELLUM Cerebrocerebellum • Connected to the contralateral cortex and thalamus • Lateral portions of the cerebellar hemispheres have a role in coordinating skilled, sequential voluntary muscle activity • Ensures that when one set of muscles initiates a movement, the opposing set acts as a brake, so that the body part in question arrives at its target precisely. LCSC06 | Biosciences for SLT FLOCCULONODULAR LOBE Vestibulocerebellum • The oldest part phylogenetically so aka the archicerebellum; • Connects with the vestibule of the inner ear and is involved in balance. • Contains the fastigial nucleus which connects with the 4 vestibular nuclei in the vestibular nuclei brainstem • Modulates equilibrium (balance) and orientation of head and eyes LCSC06 | Biosciences for SLT FLOCCULONODULAR LOBE Vestibulocerebellum LCSC06 | Biosciences for SLT PROJECTION TO THE CORTEX Cortex sends information to cerebellum via pontine nuclei cerebellum send information back to the cortex via the thalamus Cerebellum also receives sensory information from the brainstem and spinal cord (e.g. proprioceptive stimuli via spinocerebellar tracts) The basal ganglia form a complex collection of nuclei also involved in a loop from cortex to basal ganglia to thalamus and back to the cortex http://www.sofiatopia.org/equiaeon/ibrain12.jpg LCSC06 | Biosciences for SLT CEREBELLAR PEDUNCLES Superior Middle Inferior Fibre tracts enter/leave through the inferior, middle and superior cerebellar peduncles LCSC06 | Biosciences for SLT CEREBELLUM • Superior cerebellar peduncles: red nuclei (midbrain) • Middle cerebellar peduncles: pontine nuclei into cerebellum (largest) • Inferior cerebellar peduncles: a) Form spinocerebellar tract (sensory) b) From vestibular apparatus (inner ear) and vestibular nuclei of the medulla and pons c) From Inferior olivary nucleus d) To vestibular nuclei of the medulla and pons e) To reticular formation Tortora and Derrickson 2012. Principles of anatomy and physiology. Pp 508 LCSC06 | Biosciences for SLT CEREBELLAR ANATOMY http://humanphysiology.academy/Neu rosciences%202015/Chapter%205/A.5 p%20Cerebellar%20Pathways.html LCSC06 | Biosciences for SLT CEREBELLAR CONTROL CIRCUITS 1 loop important in planning and programming learned movements Primary motor & premotor regions Ventral thalamus Deep cerebellar nuclei Pontine nuclei Lateral cerebellar hemispheres LCSC06 | Biosciences for SLT CEREBELLAR CONTROL CIRCUITS 2 Primary motor cortex Ventral thalamic nuclei Deep cerebellar nuclei Corticospinal/ Corticobulbar fibres Intermediate cerebellar hemispheres LCSC06 | Biosciences for SLT CEREBELLAR CONTROL CIRCUITS Primary motor cortex Corticospinal/ Corticobulbar fibres Ventral thalamus Deep Intermediate cerebellar hemispheres & premotor regions cerebellar nuclei Pontine nuclei Lateral cerebellar hemispheres LCSC06 | Biosciences for SLT FUNCTIONS OF CEREBELLAR CONTROL CIRCUITS • Coordinate the timing between the single components of a movement • Scale the size of muscular actions • Coordinate the sequence of agonists and antagonist LCSC06 | Biosciences for SLT CEREBELLAR SPEECH MOTOR CONTROL SUMMARY: 1. Cortex sends preliminary advance information referring intended speech goals to cerebellum 2. These preliminary speech commands are provisional, imprecise and in excess of those needed to accomplish speech goal 3. Cerebellum is thus ‘primed’ to check the adequacy of the outcome, based on sensory information coming in from the periphery (i.e. muscle spindles, joint and tendon sensors) 4. Cerebellum updates the motor output from the cortex to help smooth the actions of agonist/antagonist muscle contractions LCSC06 | Biosciences for SLT BASAL GANGLIA CIRCUITS LCSC06 | Biosciences for SLT ANATOMY OF THE BASAL GANGLIA http://antranik.org/cerebral-white-matter-and-gray-matter-andbasal-ganglia/ https://kin450neurophysiology.wikispaces.com/Basal+Ganglia+II LCSC06 | Biosciences for SLT ANATOMY OF THE BASAL GANGLIA LCSC06 | Biosciences for SLT BASAL GANGLIA CIRCUITS • Important in generating components of motor programmes for speech • Cortex initiates impulses in excess of requirements to produce the motor act • Basal ganglia is modulate through inhibition these impulses • Important in regulating muscle tone, goal directed activities, automatic activities LCSC06 | Biosciences for SLT BASAL GANGLIA http://7e.biopsychology.com/vs11.html LCSC06 | Biosciences for SLT BASAL GANGLIA CONTROL CIRCUITS Selectively activates and inhibits movements. Provides internal cues for planning and refining slow continuous movement LCSC06 | Biosciences for SLT BASAL GANGLIA CONTROL CIRCUITS Caudate nucleus and putamen (the striatum): act together as a functional unit INPUT Globus pallidus interna and substantia nigra pars reticulata - main OUTPUT Globus pallidus externa, Sub thalamic nucleus, and substantia nigra pars compacta - intermediate LCSC06 | Biosciences for SLT BASAL GANGLIA CONTROL CIRCUITS Two Loops Direct = responsible for activating movement overall excitatory Indirect = stopping unwanted movement overall inhibitory The two pathways operate together to provide balanced control of descending pathways. NB Do not confuse these loops with the direct/indirect activation pathway LCSC06 | Biosciences for SLT TWO LOOPS LCSC06 | Biosciences for SLT NEUROTRANSMITTERS • GABA (gamma aminobutyric acid) = inhibitory • Glutamate = excitatory + • Ach (acetylcholine) synapse in the striatum – excitatory + • Dopamine (substantia nigra) neuromodulatory The balance of these is crucial to normal functioning of the loops and therefore motor output LCSC06 | Biosciences for SLT DIRECT/INDIRECT PATHWAY OF BASAL GANGLIA Direct = Making movement (excitatory) Indirect = not moving (inhibitory) http://neurolove.tumblr.com/post/2745681497/lets-breakdown-thebasal-ganglia-pathways-there LCSC06 | Biosciences for SLT DIRECT/INDIRECT PATHWAY OF BASAL GANGLIA CORTEX Direct = Promoting movement (excitatory) Striatum Thalamus Globus Pallidus Subthalamus Substantia nigra Glutamate (+) GABA (-) Dopamina Aim = Reduce the natural inhibited state of the Thalamus :o( LCSC06 | Biosciences for SLT DIRECT/INDIRECT PATHWAY OF BASAL GANGLIA CORTEX Indirect = not moving (inhibitory) Striatum Thalamus Globus Pallidus Subthalamus Substantia nigra Glutamate (+) GABA (-) Dopamina Aim = Avoid unwanted movement (Thalamus and Subthalamus) :O( LCSC06 | Biosciences for SLT DIRECT/INDIRECT LOOPS OF BASAL GANGLIA Premotor/motor cortex Striatum External globus pallidus Subthalamic nucleus Indirect loop Substantia nigra Internal globus pallidus Direct loop Thalamus PATHWAYS GREEN = EXCITATORY RED = INHIBITORY LCSC06 | Biosciences for SLT NEUROMODULATORY EFFECT OF DOPAMINE •Direct Pathway: Stimulates •Indirect Pathway: Inhibits •Overall Excitatory LCSC06 | Biosciences for SLT OTHER FUNCTIONS/LOOPS OF THE BASAL GANGLIA An executive loop may regulate the initiation and termination of cognitive processes such as planning, working memory, and attention. The limbic loop may regulate emotional behaviour. The deterioration of cognitive and emotional function in both Huntington's disease and Parkinson's disease could be the result of disruption of these non-motor loops. LCSC06 | Biosciences for SLT SAME TYPICAL EXAMS QUESTIONS 1. Which of the two following components of the basal ganglia form a functional unit? I. putamen and globus pallidus II. Substantia nigra and putamen III. Putamen and caudate nucleus 2. Complete the following: the lentiform nucleus is composed of………………………………………………. LCSC06 | Biosciences for SLT 3. Which of the following statements is NOT true of the functions of the cerebellum? I.Stores learned sequences of movements II.Ensures smooth coordination of muscles III.Regulates postural adjustments during skilled movements LCSC06 | Biosciences for SLT 4. In addition to its role in movement control, list 2 other posited functions of the basal ganglia LCSC06 | Biosciences for SLT WHAT TO DO NOW • Read the scanned chapter by Ellison (2012), chapter 6, Moving On. This should consolidate your understanding of movement, and the complex pathways involved. • Chapter 10 in Atkinson and McHanwell provides a more comprehensive summary. • Chapter 2 in Duffy (2007), a text you will use next year also has a good summary LCSC06 | Biosciences for SLT THE CEREBELLUM ‘little brain’ in Latin Vestibulocerebellum = flocculonodular lobe LCSC06 | Biosciences for SLT CEREBELLAR CONTROL CIRCUITS 2 Primary motor cortex Ventral thalamic nuclei Deep cerebellar nuclei Corticospinal/ Corticobulbar fibres Intermediate cerebellar hemispheres LCSC06 | Biosciences for SLT DIRECT/INDIRECT PATHWAY OF BASAL GANGLIA Direct = Making movement (excitatory) Indirect = not moving (inhibitory) http://neurolove.tumblr.com/post/2745681497/lets-breakdown-thebasal-ganglia-pathways-there LCSC06 | Biosciences for SLT ANATOMY OF THE BASAL GANGLIA https://kin450neurophysiology.wikispaces.com/Basal+Ganglia+II LCSC06 | Biosciences for SLT