2024-25 Functional organisation of the nervous system v5.pdf

5 minute: Introduction Functional organisation of the nervous system Richard Wingate Learning objectives Students will understand: the general functional organisation of the CNS axis; autonomic system spinal cord hindbrain (medulla and pons), cerebellum m...

5 minute: Introduction Functional organisation of the nervous system Richard Wingate Learning objectives Students will understand: the general functional organisation of the CNS axis; autonomic system spinal cord hindbrain (medulla and pons), cerebellum midbrain forebrain (cortex, basal ganglia and thalamus) the significance of regions and maps in the cortex https://www.youtube.com/watch?v=vk7ZFzrN6mc prosopagnosia damage to the cortex “agnosia” deficits in knowing about… Chuck Close 1940-2021 The lecture is in 3 parts Part 1. The cerebral cortex Part 2. Other brain regions and the spinal cord Part 3. Functional integration Part 1 The Cerebral Cortex i. regional specialisation ii. distributed networks iii. asymmetry iv. maps Features of cortical organisation i. regional specialisation ii. distributed networks iii. asymmetry frontal parietal iv. maps prefrontal occipital temporal Features of cortical organisation i. regional specialisation FUNCTION ii. distributed networks iii. asymmetry motor sensory iv. maps cognition vision hearing Features of cortical organisation i. regional specialisation ii. distributed networks iii. asymmetry iv. maps cognition vision Decision making Executive function & cognition cognition Phineas Gage (1823-1860) “…he changed overnight, from a responsible, sociable, capable man into an impatient, impulsive, unreliable one who had difficulty making decisions” Eduardo Leite's skull after it was pierced by an iron bar Photograph: Ricardo Moraes/Reuters “Brazilian construction worker has a lucky escape” guardian.co.uk, Friday 17 August 2012 20.52 BST A builder is recovering after an operation to remove a 1.8m-long iron bar from his head. The bar fell from the fifth floor of a building under construction, went through Eduardo Leite's hard hat, pierced the back of his skull and exited between his eyes. Prefrontal leucotomy First performed by Egas Moniz in 1936 Nobel Prize in 1949 "these patients are not only no longer distressed by their mental conflicts but also seem to have little capacity for any emotional experiences - pleasurable or otherwise. They are described by the nurses and the doctors, over and over, as dull, apathetic, listless, without drive or initiative, flat, lethargic, placid and unconcerned, childlike, docile, needing pushing, passive, lacking in spontaneity, without aim or purpose, preoccupied and dependent." Hoffman, 1949 (N. Engl. J. Med. 241:233-236). 10,365 leucotomy operations in England and Wales, 1942 - 1954 Vision Primary visual cortex V3a,b V4 vision Vision Dorsal & Ventral Integrating vision with Primary visual cortex specific actions (what and where) V3a,b Recognition of specific object (including faces) V4 there is no convergence onto a single consciousness “area” Features of cortical organisation i. regional specialization ii. distributed networks iii. asymmetry motor sensory iv. maps cognition vision hearing  resting state network activity (MRI) low frequency correlations Default Mode Network language dorsal attention somatosensory executive motor and control of sensory attention ventral attention recognition of vision visual salient features frontoparietal decision making Resting State (RS) fMRI – reviewed in Lee et al 2013 AJNR Am J Neuroradiol 34:1866 –  vision Default Mode Network language dorsal attention somatosensory executive motor and control of sensory attention ventral attention recognition of vision visual salient features frontoparietal decision making  attention Default Mode Network language dorsal attention somatosensory executive motor and control of sensory attention ventral attention recognition of vision visual salient features frontoparietal decision making  cognition Default Mode Network language dorsal attention somatosensory executive motor and control of sensory attention ventral attention recognition of vision visual salient features frontoparietal decision making Language i. regional specialization ii. distributed networks iii. asymmetry iv. maps corpus callosum connects the hemispheres What if the connection is cut? “Patient AC” corpus callosum severed cannot read words seen in the left visual field “pure alexia”  Word form area control “AC” horizontal view AC cannot read words seen in the left visual field sagittal right occipital left cortex visual N. Molko et al., J Cogn Neurosci 14, 629 (May 15, 2002). field Features of cortical organisation i. regional specialisation ii. distributed networks iii. asymmetry frontal parietal iv. maps prefrontal occipital temporal cortical maps in “primary” areas motor sensory knee motor hand head sensory Summary of Part 1 Cerebral cortex characterised by regional specialisation distributed networks asymmetry maps Part 2: Other brain regions and the spinal cord Diencephalon Midbrain Cerebellum Hindbrain (pons and medulla) Spinal cord Autonomic nervous sytem How does cortex integrate with the rest of the nervous system? Diencephalon Thalamus Relay of sensory information to the cortex Integrating basal ganglia and cerebellar output Hypothalamus Physiological homeostasis (blood pressure, heartrate etc) Midbrain cranial nerves III, IV motor control of eye movement driven by both visual and auditory cues (superior and inferior colliculi) Dopamine (substantia nigra) cerebellum and hindbrain Cerebellum Widespread effects on all brain areas – timing and errors Pons – relaying information to the cerebellum, Medulla – relays, cranial nerves, swallowing, breathing, life support  spinal cord cervical C1-C8 enlargement at limb levels thoracic T1-T12 lumbar L1-L5 sacral S1-S5 coccygeal  spinal cord pressure, touch, pain, stretch central pattern generator (cpg) gives coordinated integrated flex & movement extend  cervical connections to and from C1-C8 brainstem and spinal cord thoracic T1-T12 lumbar L1-L5 sacral S1-S5 coccygeal autonomic nervous sytem parasympathetic hindbrain & sacral T1-T6 spinal cord chest, head, neck sympathetic thoracic spinal cord Part 2: Functional integration metabolic regulation autonomic nervous system/hypothalamus learning and prediction thalamus, cerebellum and basal ganglia overview evaluate and evaluate and update update METABOLISM & PHYSIOLOGY BEHAVIOUR autonomic nervous system and hormones circadian rhythms energy metabolism reproductive behaviour body temperature METABOLISM & hypothalamus PHYSIOLOGY defensive behaviour blood pressure/electrolytes local sub-cortical circuits can act autonomously evaluate and update Spinal cord reflexes Central pattern BEHAVIOUR generators Senses and feedback sensory input interactions with the world SENSES AND BEHAVIOUR thalamus and sensation somatosensation, proprioception, nociception, interoception, SIGNALS FROM THE vision, hearing BODY Learning and prediction evaluate and interactions update with the world are evaluated SENSES AND BEHAVIOUR Learning and prediction basal ganglia cerebellum (reward and salience) (error calculation and motor learning) Learning and prediction basal ganglia cerebellum (reward and salience) (error calculation and motor learning) Cortex excites thalamus Reciprocal connections = a conversation Basal ganglia and cerebellum modulate cortical activity: faciliate/disfacilitate reciprocal connections cortical interactions are allocated to different cortical layers cortical output exclusive ouput to all sub-cortical regions Layer V output bypasses thalamus bypasses basal ganglia behaviour Summary of Part 3 central nervous system balances local neural control networks metabolism brain monitors, evaluates and predicts generates behaviour