Introduction to Neuroanatomy Regional Anatomy Why Neuroanatomy - PDF document

Introduction to Neuroanatomy Regional Anatomy Why Neuroanatomy • Structure-function relationships – Localization of function in the CNS • Non-invasive brain imaging – CAT: structure, low resolution – MRI: structure, high resolution – PET: function, low resolution – f MRI: function, high resolution 1

Dual approach to learning neuroanatomy: • Functional anatomy – Neural structures that serve particular functions; e.g., pain path from skin to cortex for perception • Regional anatomy – Localization of structures in particular brain regions Dual approach to learning neuroanatomy: • Functional anatomy – Neural structures that serve particular functions; e.g., pain path from skin to cortex for perception • Regional anatomy – Localization of structures in particular brain regions • Localization of function Lecture objectives: • Overview of brain structures to “demystify” anatomical content in Neural Science lectures • Survey brain structure-function relations to provide background for first labs First half of lecture: • Quick review of basic CNS organization • Use development to understand principles of structural organization of CNS Second half: Functional localization 2

CNS Organizational Principles • 1) Tubular organization of central nervous system • 2) Columnar/longitudinal organization of spinal and cranial nerve nuclei • 3) Complex C-shaped organization of cerebral cortex and deep structures Brief Overview of Mature CNS Neuroanatomy • Tubular organization of central nervous system QuickTime™ and a Video decompressor are needed to see this picture. 3

Brief Overview of Mature CNS Neuroanatomy • Tubular organization of central nervous system • Columnar/longitudinal organization of spinal and cranial nerve nuclei Nuclei : locations of Ganglia : locations of neuron cell bodies w/in neuron cell bodies in the central nervous the periphery system Tracts : locations of Nerves : locations of axons w/in the central axons in the periphery nervous system Dorsal surface Dorsal root Ventral Gray matter root White matter Spinal nerve Ventral surface Brief Overview of Mature CNS Neuroanatomy • 1) Tubular organization of central nervous system • 2) Columnar/longitudinal organization of spinal and cranial nerve nuclei • 3) Complex C-shaped organization of cerebral cortex and nuclei and structures located beneath cortex – Lateral ventricle – Basal ganglia – Hippocampal formation & Fornix 4

QuickTime™ and a Video decompressor are needed to see this picture. Development, as a guide to understanding regional anatomy of the CNS 5

Neural Induction •Portion of the dorsal ectoderm becomes committed to become the nervous system : Neural plate Ectoderm Neural plate Neural groove Neural tube wall: neurons & glia of CNS Neural Neural tube cavity: tube ventricular system Neural crest: PNS White matter neurons, etc Gray matter Neural Tube Closure Defects • Spina bifida: caudal neural tube • Anencephaly: rostral neural tube 6

Brain vesicles: Rostral Forebrain Midbrain Neural Tube Development Hindbrain Rostral neural tube forms the brain Spinal cord Caudal neural tube forms the spinal cord Caudal Cephalic flexure 3-vesicle stage Forebrain Midbrain Hindbrain Spinal cord Cervical flexure Cephalic flexure 3-vesicle stage 5-vesicle stage Cerebral Lateral Forebrain hemisphere ventricle Midbrain Diencephalon Midbrain 3rd Hindbrain Pons & ventricle Cerebellum Cerebral aqueduct Medulla 4th ventricle Spinal cord Central canal Cephalic flexure …by the 5 vesicle stage, all 7 major brain divisions are present 7

7 major brain divisions 7 CNS divisions on MRI: Midbrain Cerebral hemispheres Cerebellum Pons Diencephalon Medulla •Cerebral hemispheres •Diencephalon •Midbrain Spinal cord •Cerebellum •Pons •Medulla •Spinal cord Ventricles Lateral 3rd ventricle ventricle Lateral Quadra- 3rd ventricle ventricle geminal 4th ventricle 4th ventricle Cisterna Cisterns Interpeduncular magna Quadra- geminal Cisterna magna Lumbar Lumbar Interpeduncular 8

The cephalic flexure persists into maturity Cephalic flexure Spinal cord & brain stem have a similar developmental plan • Segmentation • Nuclear organization: columnar 9

Dorsal horn Alar plate Sulcus limitans Central canal Basal plate Ventral horn Dorsal horn Central canal Ventral horn Dorsal horn Dorsal root Ventral root Ventral horn Similarities between SC and brain stem development •Sulcus limitans separates sensory and motor nuclei •Nuclei have columnar shape Key differences • 1) central canal enlargement � motor medial and sensory lateral • 2) migration away from ventricle • 3) >> sensory and motor 10

Alar plate and migrating neuroblasts Basal plate Medulla development Striated/branchio. 4th Vent Striated/somite Alar plate Autonomic. Vestibular/auditory. Somatic sensory. Taste/viscerosensory Sulcus limitans Basal plate Inferior olivary nucleus Alar plate Basal plate Pons development 4th Vent Striated/branchio. Alar plate Striated/somite Vestibular/auditory. Somatic sensory. Taste/viscerosensory Autonomic. Basal plate Pontine nuclei Sulcus limitans Alar plate Basal plate 11

Midbrain development Cerebral aq. Alar plate Somatic sensory. Autonomic. Striated/somite Red Basal plate Sub. nigra Sulcus limitans nucleus More like spinal Cord b/c fewer nuclear classes and cerebral aqueduct Basal plate Similarities between forebrain and hindbrain/spinal development •Tubular Key differences • 1) CH more complex than BS/SC • 2) Cortical gyri more complex anatomy than nuclei • 3) Subcortical nuclei are C-shaped – Confusing: structure in two places on image Diencephalon • Thalamus – Gateway to cortex • Hypothalamus – Control of endocrine and bodily functions – Circadian rhythms – Etc. 12

QuickTime™ and a Video decompressor are needed to see this picture. Cerebral Cortex Development Parietal Frontal Occipital Temporal 13

Cingulate gyrus Parahippocampal gyrus 14

Forebrain Development & C-shaped Structures • Cerebral cortex • Lateral ventricles • Striatum • Hippocampal formation and fornix Lateral ventricle Striatum Putamen Caudate nucleus Lateral ventricle Nucleus accumbens QuickTime™ and a Video decompressor are needed to see this picture. 15

LV and CP Putamen Caudate nucleus Lateral ventricle Nucleus accumbens QuickTime™ and a Video decompressor are needed to see this picture. QuickTime™ and a Video decompressor are needed to see this picture. 16

Fornix Mammillary body Amygdala Hippocampal formation QuickTime™ and a Video decompressor are needed to see this picture. QuickTime™ and a Video decompressor are needed to see this picture. 17

QuickTime™ and a Video decompressor are needed to see this picture. Summary • 7 Major components of the central nervous system & Ventricles • All present from ~ 1st prenatal month • Longitudinal organization of SC and BS nuclei – Columns – Anatomical and functional divisions • C-shape organization of cerebral hemisphere structures and diencephalic – Cerebral cortex – Lateral ventricle – Striatum – Hippocampal formation and fornix Functional Anatomy 18

• Regional neuroanatomy : spatial relations between brain structures within a portion of the nervous system • Functional neuroanatomy : those parts of the nervous system that work together to accomplish a particular task, for example, visual perception Functional Localization How does structure relate to function? • Heart structure predicts pumping function • Muscle structure--with particular bone attachments--predicts function • Brain?? Superior parietal lobule-attention Brain functions: Inferior frontal Determined more by how lobule-speech information is routed to a particular brain region than the intrinsic characteristic features of the region. 19

Overall Aims of Lecture • Functional localization of neural systems • Functional organization of the thalamo- cortical systems • Cortical circuitry Topics cut across all lectures •add to preparation for lab •basis for better understanding of lectures on neural systems Specifics… • Functional localization of touch pathway in brain stem – To understand hierarchical organization of a neural system – To begin to become familiar with internal brain structure • Organization of visual pathway – Segue into… • Functional organization of the thalamo-cortical systems • Cortical circuitry 20

Dorsal column-medial lemniscal system for touch • Sensory receptor neurons • Dorsal column of spinal cord • Medial lemniscus in brain stem • Thalamus • Cortex QuickTime™ and a Video decompressor are needed to see this picture. Myelin-stained section MRI 21

Tract Nuclueus Myelin-stained section MRI QuickTime™ and a Video decompressor are needed to see this picture. QuickTime™ and a Video decompressor are needed to see this picture. 22