CNS Control of Movement

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CNS Control of Movement Cognitive Neuroscience, Fall, 2011

Dept of Clinical Neuroscience Karolinska Institute joel.

se Charles Sherrington (1857-1952) Basic Concepts

Planning Execution Feedback Useful both as operational

and as a conceptual principal for thinking about the

1 CNS Control of Movement Cognitive Neuroscience, Fall, 2011 Joel Kaplan, Ph.D. Dept of Clinical Neuroscience Karolinska Institute Charles Sherrington ( ) Basic Concepts Localization Hierachy in Voluntary Movement Control Planning Execution Feedback Useful both as operational description of phases of voluntary control of movement, and as a conceptual principal for thinking about the location and function of the underlying neural circuits. Sensory-motor integration within and between levels is critical Voluntary - Involuntary distinction Motor Cortex Areas 1

Penfield s brain stimulation studies showed that activation of small bits of

The studies demonstrate Somatotopic Organization.

(Pyramidal tract) The Monosynaptic Stretch Reflex (AKA Myotatic Reflex )

Is from the perspective of Spinal Reflexes (see BFTTB site : Beginner

2 Penfield s brain stimulation studies showed that activation of small bits of primary motor cortex caused movements of specific muscles. The studies demonstrate Somatotopic Organization. Pyramidal Tract Into the Spinal Cord Pathway to SC from Primary Motor Cortex (Pyramidal tract) The Monosynaptic Stretch Reflex (AKA Myotatic Reflex ) Neurologic test for the status of stretch reflex: Knee jerk response to percussion of the patellar tendon. But this doesn t work independently of a lot of processing going on in the spinal cord. We must consider SC circuitry; The best way to study SC circuitry and function Is from the perspective of Spinal Reflexes (see BFTTB site : Beginner neurological) Question? If the stretch reflex is as powerful as Kaplan says, then how does excitatory input from the cortex (or from anywhere else, for that matter) cause any movement at all?? Gamma loop function The Gamma Loop: ( gain setting ) The players in the gamma loop 2

Supplementary info on gamma system anatomy and physiology ( supplementary = FYI, optional) Gamma loop

same muscle, then why does the knee jerk reflex Work? There s another problem for the motor system.

system. But also pre-set is the length of the knee s flexor muscles (hamstrings).

Shouldn t a contraction the hamstring muscle always fight the ability of quadriceps contraction to extend

Illustrate using the elbow joint which is flexed by the biceps and extended by the triceps.

(painful) stimulation of the bottom of one foot.

limb position) and in muscle (reporting muscle length or tension).

3 Supplementary info on gamma system anatomy and physiology ( supplementary = FYI, optional) Gamma loop circuit Study question: If the sensory nerve ends up stimulating both alpha and gamma motor neurons to the same muscle, then why does the knee jerk reflex Work? There s another problem for the motor system. The length of a muscle, in this case the extensor muscles for the knee (quadriceps), is pre-set by the gamma system. But also pre-set is the length of the knee s flexor muscles (hamstrings). So how does the knee ever extend? Shouldn t a contraction the hamstring muscle always fight the ability of quadriceps contraction to extend the knee? Reciprocal inhibition of flexors and extensors that act on the same joint. Illustrate using the elbow joint which is flexed by the biceps and extended by the triceps. Coordinated movement of both legs, explored through study of the leg withdrawal reflex response to noxious (painful) stimulation of the bottom of one foot. Review, time permitting Also contributing to locomotory control are proprioceptors: in joints (reporting limb position) and in muscle (reporting muscle length or tension). Here is a reflex involving a Muscle tension receptor (the golgi tendon organ ) - In series with muscle fiber Clasp-knife reflex Extreme case, protects muscle from overload. Normal: slow muscle contraction as contraction force increases. Thought to be important for fine motor acts, such as manipulation of fragile objects, which require steady but not too powerful grip. 3

4 Locomotion in Decerebrate Cat Decerebrate Rat Preparation 4

Explore ingestive and taste responses in

Driven Oral Motor Responses (From Video:

5 Explore ingestive and taste responses in the Chronically Maintained Decerebrate THE GAPE RESPONSE Neurology of of Taste-Driven Oral Motor Response Normal Anencephalic Steiner, 1973 Anterior Anterior digastric digastric Taste Driven Oral Motor Responses (From Video: Charlie Rose III ~27:00) FEEDBACK Voluntary movement without Spinal sensory function: Subject brings cup to mouth; Tries to walk Inferior Inferior pharyngeal pharyngeal constrictor constrictor 2 sec sec // division 5

(from Gazzaniga tex: Left: following instructions to Trace shapes, even in patient w/ Sensory neuropathy.

, wrist/toe) Mirror Neurons/ Merging of Action/Perception (Basketball example in video) Observers with skill

25 See description In Gazzaniga Goal Directed Behavior: Requiring Brain Cortex: Premotor Cortex; (movement planning)

6 (from Gazzaniga tex: Left: following instructions to Trace shapes, even in patient w/ Sensory neuropathy. PREDICTION Waiter-Book example in video Script w/ pen mounted in Different places (e.g., wrist/toe) Mirror Neurons/ Merging of Action/Perception (Basketball example in video) Observers with skill observing skilled performance Fig See accompanying text in Gazzaniga Fig 7.25 See description In Gazzaniga Goal Directed Behavior: Requiring Brain Cortex: Premotor Cortex; (movement planning) Primary Motor Cortex Basal Gangla Loop -- Cortex BG Thalamus Cortex Cerebellum Loop -- Powerful reciprocal connections with Motor Cortex -- Integrates sensory information (vestibular, proprioceptive, ++) 6

7 Cortical Regions Involved in Movement Planning and Execution Motor Cortex generally Refers to Areas 4 and 6 Primary Motor Cortex (Area 4) often abbreviated M1 Pyramidal Tract Fig 7.15 in Gazzaniga Electrophysiological Experiments 7

Primary Motor Cortex (M1) Electrophysiology: Movement Direction

very specific movement of individual muscles.

Current view: Movement direction in M1 is encoded by population coding

Cerebellum Loops Population vectors for those 2 cells, for right or left

8 Primary Motor Cortex (M1) Electrophysiology: Movement Direction Representation Cell s Movement Tuning Curve This is a very broad tuning curve, as is typical across M1 neurons. This came as a bit of a surprise given the earlier view that M1 contained a fine-grained movement map. Remember that that electrical stimulation of specific M1 sites yielded very specific movement of individual muscles. Yet movements are so accurate. Current view: Movement direction in M1 is encoded by population coding Tuning curves for 2 cells in primary motor ctx Basal Ganglia and Cerebellum Loops Population vectors for those 2 cells, for right or left movements Population vectors for many cells during accurate movement each of 8 directions. The Thalamus is a critical relay in both the Basal Ganglia and Cerebellar loops Thalamus Overview Ventral Anterior Dorsolateral Basal Ganglia output to ventral lateral, ventral anterior and centromedian Cerebellum (via its deep nuclei) projection to cortex via ventral lateral division 8

9 Basal Ganglia In Coronal and Horizontal Slices Basal Ganglia (basic loop) Cerebellum Critical for proper execution of planned, voluntary, multi-joint movements. Instructs primary motor cortex about movement direction, timing and force. (For quick movements, instructions are based on prediction; too fast for feedback to be of use. Movement timing. Learning Cerebellar Syndrome Voluntary Movement Overview Ataxic Gait Video, if time 9

10 Fig in Gazzaniga 10

Chapter 13. The Nature of Muscle Spindles, Somatic Reflexes, and Posture

Chapter 13. The Nature of Muscle Spindles, Somatic Reflexes, and Posture Chapter 13 The Nature of Muscle Spindles, Somatic Reflexes, and Posture Nature of Reflexes A reflex is an involuntary responses initiated by a sensory input resulting in a change in the effecter tissue