Neuroanatomy and Functioning of Motor Cortex, Cerebellum, and Basal Ganglia, Slides of Brain and Cognitive Science

Download Neuroanatomy and Functioning of Motor Cortex, Cerebellum, and Basal Ganglia and more Slides Brain and Cognitive Science in PDF only on Docsity! Motor Cortex, Cerebellum and Basal Ganglia Docsity.com ‘Macacue monkey Humen Suppemertay Primary Primary Primexy somatic motor '¢a mgr taex Supplomentay MOLE Cotex sensory cortex Corpus Comal moter ate calosum sus bums Posterar cartes petit Prenoror cater Somatotopic organization of motor cortex Monkey and human LH S ae et Medal Later Docsity.com The motor cortex receives inputs from the cerebellum via the thalamus. VLo and VLc = oral (rostral) and caudal portions of the ventrolateral nucleus; VPLo = oral portion of the ventral posterolateral nucleus; X = nucleus X. Docsity.com The functional organization of the primary motor cortex of a rat changes after transection of the facial nerve. Organization of primary motor cortex is plastic Docsity.com As a movement becomes more practiced, it is represented more extensively in primary motor cortex Any evidence for comparable plasticity in visual cortex? Experienced-based plasticity, not just after damage Docsity.com <a _f® Figure 1| Behavioural paredige. a, Embesliod control stup. Each monkey had its anms restrained {inserted up to the elbow in horizontal tubes, shown at bottom of image). and a prosthetic arm positianed next to its shoulder, ‘Spiking activity was processed (boxes at top right) and used to control the (hroc-dimnenssonal arm volocty ane the gripper aperture velocity im meal time. Pood targets were presented [top left) at arbitrary positions. e 1b, Timeline of trial persads during the aantinucus sclffocding task, Each ‘trial started with presentation of a food piece, and a successful trial ended with (he monkey unloading (UL) the food from the gripper inte ts mouth (see Methods). Owing to the continuous nature of the task, there were no dear bouncdarics between the task periods, Docsity.com 1. Record from cells in motor cortex while monkey controls robot arm with a joystick 2. Find the preferred direction for each cell in the regions that’s active. 3. Find the “population vector” = vector sum of preferred directions. 4. Send this signal to the arm. 5. Add in a correction while the monkey is learning. 6. Gradually reduce the correction. Docsity.com Neurons in the Primary Motor Cortex Are Activated Directly by Peripheral Stimulation Under Particular Conditions The simplest behaviors controlled by the primary motor cortex are those elicited directly by sensory stimuli. Motor cortical neurons receive strong sensory inputs from the limb whose muscles they control. When a standing human subject pulls on a handle, the sudden postural perturbation elicits a rapid counter-response in the stretched muscle at a latency shorter than a simple reaction time but longer than for a spinal reflex. However, this counter-response happens only when the person is told to resist. Such rapid motor adjustments are mediated mainly by relatively simple transcortical pathways through which somatosensory inputs reach the primary motor cortex directly via projections from the thalamus or primary sensory cortex. This transcortical pathway provides a degree of flexibility to rapid responses that is unavailable in spinal reflexes. These long-loop or transcortical responses are selectively increased in several movement disorders, such as Parkinson disease and myoclonus, while spinal reflexes remain normal. Docsity.com Pre-motor cortex Docsity.com Cell activity in the motor cortex depends on whether a sequence of movements is guided by visual cues or by prior training. Monkeys were required to press three buttons either in a sequence presented by lighting three panels in turn or in a sequence they had learned previously. After being instructed to perform the observed sequence or the trained sequence, there was a delay before the animal was given a signal to initiate the movement. Raster plots represent cell discharge before and during movement on 16 trials, and the histogram shows the summed activity over all trials. The cell in the primary cortex fired in both conditions. The cell in the lateral premotor area fired only when the visually cued sequence was used, whereas the cell in the supplementary motor area fired only when the trained sequence was used. Docsity.com A set-related neuron in the dorsal premotor area becomes active while the monkey prepares to make a movement to the left Docsity.com Mirror Cells lateral ventral premotor area An individual cell in the ventral premotor area is active whether the monkey performs a task or observes someone else perform the task. The fact that the same cell is active during action or observation suggests that it is involved in the abstract representation of the motor task. Docsity.com Activity in Supplementary Motor Area during mental rehearsal of a complex sequence of finger movements: PET imaging Docsity.com The Cerebellum Dorsal view mid-saggital view Ventral view Cortex, white matter, deep nuclei Output is from deep nuclei via peduncles Docsity.com ¥ cell ‘i Precerebellar nucleus cell (spinocerebellar pathways, brainstem reticular nuclei, pontine nuclei, etc.) Granule Inferior olivary nucleus cell Deep cerebellar neurons: Purkinje cell Descending motor systems Inhibitory cortical side loop Main excitatory loop Docsity.com  Stellate cell layer Granular layer White matter Glomerulus Granule cell dendrite Docsity.com VIVVVYVEREN Docsity.com Activity in dentate nucleus significantly greater when subject is mentally active during movement. A f MRI image (color) overlaid on an anatomical image (gray) shows activation of the dentate nucleus during two pairs of tests. Passive sandpaper experience Judge degree of roughness lift and drop a series of objects identify the felt object Docsity.com Time Horizontal displacement (em) Cc Horizontal displacement (cm) Left Right Left Right -50 0 50 ——t—_—— lh Before a" Prisms After Throw direction Gaze direction Docsity.com