* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Basal nuclei
Nervous system network models wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Proprioception wikipedia , lookup
Time perception wikipedia , lookup
Haemodynamic response wikipedia , lookup
Environmental enrichment wikipedia , lookup
Synaptogenesis wikipedia , lookup
Biochemistry of Alzheimer's disease wikipedia , lookup
Human brain wikipedia , lookup
Neuroeconomics wikipedia , lookup
Metastability in the brain wikipedia , lookup
Optogenetics wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Eyeblink conditioning wikipedia , lookup
Central pattern generator wikipedia , lookup
Neuroanatomy wikipedia , lookup
Cognitive neuroscience of music wikipedia , lookup
Embodied language processing wikipedia , lookup
Hypothalamus wikipedia , lookup
Development of the nervous system wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Aging brain wikipedia , lookup
Neuroplasticity wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Synaptic gating wikipedia , lookup
Neuroanatomy of memory wikipedia , lookup
Neural correlates of consciousness wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Some Terminologies White matter : myelinated fibre tracts Gray matter : areas of neuronal cell bodies Tracts : collections of axons subserving similar function or location in CNS Nerves : peripheral axons Nucleus : collection of neurons subserving similar function in CNS – e.g., red nuclei Ganglion : collection of neurons in CNS or PNS – e.g., basal ganglia Brain components Cerebral cortex Cerebral cortex Basal nuclei (lateral to thalamus) Basal nuclei Thalamus (medial) Thalamus Diencephalon Hypothalamus Hypothalamus Cerebellum Cerebellum Midbrain (Mesencephalon) Brain stem Brain stem (midbrain, pons, and medulla) Pons Medulla oblongata Spinal cord Brain Stem – ventral and lateral view Midbrain, Pons, Medulla – dorsal view Brain Stem Similar to spinal cord but contains embedded nuclei Controls automatic behaviors necessary for survival e.g., Cardiovascular, respiratory, and digestive control centers Associated with 10 of the 12 pairs of cranial nerves (olfactory and optics) Does the same basic sensory and motor functions for the head that the spinal cord does for the rest of the body Reception and integration of all synaptic input from spinal cord Relaying sensory information to cerebellum, thalamus, and to different portions of the brainstem & arousal and activation of cerebral cortex Regulation of muscle reflexes involved with equilibrium and posture Role in sleep-wake cycle (maintenance of consciousness) Plays a role in modulating the sense of pain Reticular formation Core of the brainstem Receives and integrates the information carried by most of the sensory, motor and visceral pathways that pass through the brainstem Red nucleus – largest nucleus of the reticular formation; red nuclei are relay nuclei for rubro-spinal tract Information is used in various reflexes - circulatory and respiratory reflexes, coughing, swallowing Plays a role in modulating sensitivity of spinal reflexes and regulating transmission of sensory information (esp. pain) into ascending pathways Ascending fibres carry signals to arouse and activate the cerebral cortex Reticular Activation System (RAS) - controls the overall degree of cortical alertness Reticular formation Reticular Activation System (RAS): • Controls the overall degree of cortical alertness => ability to direct attention • Helps the cerebellum to regulate muscle tones & generate smooth movements Three broad columns extending through the core of the brain stem Has axon connections with hypothalamus, thalamus, cerebellum, and spinal cord Basal Ganglia Masses of gray matter found deep within the cortical white matter Composed of three parts Caudate nucleus The putamen and the globus pallidus (The lentiform nuclei) Fibers of internal capsule running between and through caudate and lentiform nuclei Basal Ganglia Putamen Globus Pallidus The basal nucleii (ganglia) have an inhibitory role in motor control Functions of Basal Ganglia Act by modifying ongoing activity in motor pathways Inhibit muscle tone (proper tone – balance the excitatory and inhibitory inputs to motor neurons that innervate skeletal muscle) Select and maintain purposeful motor activity while suppressing unwanted patterns of movement Monitor and coordinate slow and sustained contractions, especially those related to posture and support Regulate attention and cognition Control timing and switching Motor planning and learning Connectivity between different sections of the basal ganglia Two pathways DIRECT 1. Direct: ♦ Inhibition of internal GP so no longer keeps thalamus from exciting cortex ♦ Facilitate the ongoing action Two pathways 2. Indirect: ♦ Causes subthalamus to activate internal GP, suppressing thalamic activation ♦ Suppressing unwanted movements INDIRECT Damage to Basal Ganglia Huntington’s disease - degeneration of the caudate nucleus Chorea - rapid, uncontrolled jerky movements Parkinson’s disease - damage to basal ganglia neurons and a deficiency in dopamine Increased muscle tone or rigidity Resting tremors Slowness in initiating and carrying out motor behaviours Parkinson’s Disease: A Motor Disorder Degeneration of DA neurons within the substantia nigra (SN) which project to the striatum. Under normal circumstances these terminals convert tyrosine to L-dopa which is synthesized to DA. Loss of the pre-synaptic neurons results in DA release Possible to lose ~80% of DAergic cells in the SN without manifesting symptoms Examination of a PD brain reveals loss of SN cells and the presence of Lewy bodies in large numbers. Parkinson’s Disease • Loss of excitation from substantia nigra to caudate & putamen • Results in increased activity in indirect pathway • Causes overactivity in the internal GP • Inhibits the thalamus resulting in decreased cortical motor activity INDIRECT Parkinsons’ Disease: symptoms 1. Akinesia/Bradykinesia: poverty or slowness of automatic and voluntary movements, incl. speech 2. Rigidity: abnormal muscle tone consisting of stiffness (poor range or motion), cogwheeling, spontaneous facial movement 3. Resting tremor: (4-7/sec freq.), referred to as “pill rolling”; may lessen with intentional movement 4. Postural instability: patients often unsteady, may carry centre of gravity out front (falls); difficulty righting 5. Gait disturbance: fixed, stooped posture and shuffling gait 6. Non-motor features may also occur Disruption in writing as a result of Parkinson's disease Not only speed, but size of movement decreases over time micrographia Parkinson’s Disease: Cognition Symptoms Bradyphrenia: slowing of thought processes Memory, specifically retrieving info in nonstructured situations/spatial working memory Emotional functioning: depression is common Decrease in executive functioning