PSYC301 Lecture 03 - Neuroanatomy II PDF

PSYC301: Neuroanatomy II (the brain) Jay Hosking, PhD 1  Overview A. Nervous system layout B. Terminology and directions C. Spinal cord D. Major divisions of the brain E. The telencephalon: cortex and deeper...

PSYC301: Neuroanatomy II (the brain) Jay Hosking, PhD 1  Overview A. Nervous system layout B. Terminology and directions C. Spinal cord D. Major divisions of the brain E. The telencephalon: cortex and deeper structures F. Blood flow, skull, meninges, CSF 2  Learning objectives 1. Know the major divisions of the nervous system. What symptoms would you expect with damage at each particular division? 2. Know all the neuroanatomical directional terms and apply them when talking about brain structures. 3. Draw and label a cross section of the spinal cord. 4. List the descending sections of the spinal cord in order. Where would damage cause a greater loss of function, and why? 5. List and discuss the divisions of the human brain, both in 3 divisions and in 5 divisions. 6. Know brain structures within each of the myelencephalon, metencephalon, mesencephalon, diencephalon, and telencephalon. Coarsely, describe what damage to these areas might produce in terms of dysfunction. 7. Describe the location and function of the corpus callosum. 8. Know the major fissures. 9. Know the major components of the limbic system and basal ganglia. 10. Know the lobes of the cerebral cortex. 11. Know the anatomical features that protect the brain. 3 12. (Optional:) Read the remainder of the Pinel & Barnes chapter 3.  The nervous system (Well, the vertebrate nervous system) Central Peripheral (CNS) (PNS) 4 Layout  The nervous system (Well, the vertebrate nervous system) Central Peripheral (CNS) (PNS) Brain Spinal cord 5 Layout  The nervous system (Well, the vertebrate nervous system) Central Peripheral (CNS) (PNS) Somatic Autonomic Brain Spinal cord (SNS) (ANS) 6 Layout  The nervous system (Well, the vertebrate nervous system) Central Peripheral (CNS) (PNS) Somatic Autonomic Brain Spinal cord (SNS) (ANS) Afferent Efferent (sensory) (motor) SNS: external environment, (mostly) conscious 7 Layout  The nervous system (Well, the vertebrate nervous system) Central Peripheral (CNS) (PNS) Somatic Autonomic Brain Spinal cord (SNS) (ANS) Afferent Efferent Afferent Efferent (sensory) (motor) ANS: internal environment, (mostly) non-conscious 8 Layout  The nervous system (Well, the vertebrate nervous system) Central Peripheral (CNS) (PNS) Somatic Autonomic Brain Spinal cord (SNS) (ANS) Afferent Efferent Afferent Efferent Sympathetic NS Parasympathetic NS 9 Layout  ANS efferents Sympathetic: mobilize energy Parasympathetic: conserve energy Not always mutually exclusive / in opposition to one another 10 Layout  Clusters and bundles Cell clusters: Nucleus/nuclei (CNS) vs. ganglion/ganglia (PNS) (except when the old anatomists screw it up) Bundle of axons: Tract (CNS) vs. nerve (PNS) vs. fibres (all) 11 Terminology  Anatomical dimensions dorsal Ant. Post. Ant. Post. The neuraxis Note that we bipedal species Critical for ventral have a weird neuraxis describing brain regions! 12 Terminology  Anatomical dimensions Sections/cuts 13 Terminology  Spinal cord Intermittent projections from spinal cord – why? Narrows/tapers when from cervical to coccygeal – why? Ends in cauda equina Grey/white matter divisions (Grey is inner “H”) Ventral Dorsal/ventral organization Spinal cord damage: loss of function related to segment of damage! 14 Spinal cord  Major divisions of the brain (3) Midbrain Hindbrain Appear early in development Termed the forebrain, midbrain, and hindbrain Forebrain 15 18-21-day-old Divisions  Major divisions of the brain (3) We have disproportionately large forebrains as compared to, say, fish 16 Divisions  Major divisions of the brain (5) Arguably more useful than three-division map 17 Divisions  Our roadmap A structural MRI What kind of section? 18 Divisions  Myelencephalon (aka the medulla) Or medulla oblongata (go wild) Lots of tracts Involuntary control of life-sustaining functions Doctors reluctant to perform surgery here Insults here are often fatal 19 Divisions  The reticular formation aka The reticular activating system ~100 nuclei Runs from myelencephalon to mesencephalon Critical for arousal, wakefulness, attention, sleep Damage to this region causes major disruptions to life, and/or can be fatal 20 Divisions  Metencephalon Again, lots of tracts Comprised of multiple regions 21 Divisions  Metencephalon Also houses reticular formation 22 Divisions  Metencephalon The pons: large white-matter bulge, continuing from spinal cord/medulla Damage to this region? 23 Divisions  Metencephalon The cerebellum: 10% of brain volume, >50% of neurons Critical for motor coordination, more Damage to this region? 24 Divisions  Mesencephalon aka The midbrain Comprised of a roof (tectum) and a floor (tegmentum) 25 Divisions  Mesencephalon Tectum: Comprised of two pairs of bumps (colliculi) aka The Boston Pizza Part of Your Brain Superior colliculi: vision with respect to eye movement Inferior colliculi: audition with respect to head/body orientation Outside of conscious access Damage to these regions? (e.g. Parinaud’s syndrome) 26 Divisions  Mesencephalon Tegmentum: Contains top of reticular formation More fibres Periacqueductal grey Dopamine-producing regions Substantia nigra Ventral tegmental area (VTA) Red nucleus Pattern of function for these? Damage to these? 27 Divisions  Diencephalon Comprised of two structures: The thalamus and hypothalamus 28 Divisions  Diencephalon Thalamus: Many nuclei: inputs from sensory systems, cerebellum, basal ganglia Often called a “relay centre” for sensory information True, but: receives almost as much from cortex as it sends to cortex And so many other inputs Corticothalamic loops? Damage to this region? 29 Divisions  Diencephalon Hypothalamus: Many nuclei Key intersection with endocrine system via the pituitary gland Diverse functions: sex, aggression, feeding, sleep, wake, more Damage to this region? 30 Divisions  Telencephalon The largest division of the human brain Not just the cortex, but also the underlying structures Damage here is wide-ranging in its symptoms, and is much of what we’ll be discussing in this course 31 Divisions  Telencephalon The cerebral cortex: aka The cortex, neocortex The largest and most prominent feature of the human brain 32 Telencephalon  Telencephalon The cerebral cortex: aka The cortex, neocortex The largest and most prominent feature of the human brain The cortex is highly convoluted — why? cf. The lissencephalic (smooth) cortices of other mammals, birds, etc. 33 Telencephalon  Convolutions Gyrus/gyri and sulcus/sulci Sulci sometimes called fissures Not functionally meaningful, per se But damage may show up in one and not other (?!?) 34 Telencephalon  Hemispheres The cerebrum is divided into two hemispheres Separating the hemispheres: The longitudinal fissure 35 Telencephalon  Connecting the hemispheres Left and right hemispheres are only connected by a few tracts (commissures) Largest: the corpus callosum 36 Telencephalon  Disconnecting the hemispheres i.e. Split-brain patients Callosotomy, a rare treatment for epilepsy A person with two minds? Learning point: contralateral organization Learning point: left hemisphere dominance for language Object presented to left vs. right hemisphere? https://www.youtube.com/watch?v=ZMLzP1VCANo 37 Telencephalon  More fissures, and lobes Four lobes of the brain — where do they get their names? Central fissure separates frontal and parietal lobes Lateral fissure separates temporal lobe from frontal/parietal Deep in the lateral fissure: the insula 38 Telencephalon  The limbic “system”: not a system The Papez “Circuit”, aka the Limbic “System” à Amygdala, HTh, mammillary body, hippocampus, fornix, cingulate cortex, septum, olfactory bulb Again, symptoms from damage can vary from region to region (we’ll come back to these) 39 Telencephalon  Basal ganglia Includes striatum (caudate + putamen) and globus pallidus, sometimes others (e.g. subthalamic nucleus) Nucleus accumbens is a subregion of striatum/caudate, sometimes called ventral striatum Critical in movement, skills, habits, decision making Again, more on this later 40 Telencephalon  Anatomy of the cortical layers Different neurons at different layers Input layers, output layers Different parts of the cortex look different – why? 41 Telencephalon  Anatomy of the cortical layers These differences between parts of the cortex can be used to make maps e.g. Brodmann areas 42 Telencephalon  Do we only use 5%/10%/etc. of our brains? No. 43 Telencephalon e.g. A simple voluntary movement Prefrontal cortex Premotor areas Motor cortex Basal ganglia Pons Cerebellum So much more 44 Telencephalon Cerebral blood flow Limited supply No reserves No redundancy Implications for brain dysfunction? 45 Support  Cerebral blood flow Limited supply No redundancy No reserves Implications for brain dysfunction? 46 Support  The blood-brain barrier (BBB) on W po Tightly packed Protects brain Active transport for large molecules 47 Support  Skull and meninges Primarily protection for the brain 48 Support  Skull and meninges Primarily protection for the brain 49 Support  Cerebrospinal fluid (CSF) and ventricles Support, protection, nutrition 50 Support  Hydrocephalus Treated by a shunt 51 Support  Summary of brain structures It’s a lot, but you can do it! 52 Support