Neuroimaging Techniques and Brain Anatomy

Lecture 011425

• Course Description: Includes lectures, objectives, exams, grading, and the Moodle website.
• Divisions and Orientation: Discusses the CNS and PNS, along with planes of section.
• Imaging: Covers anatomical views (MRI, CT) and functional views (PET, fMRI).
• Cells of the Nervous System: Details neurons and glial cells.
• Case Study: Features multiple sclerosis.

Course Information

• Moodle: Information about the META COURSE for all course listings (lectures and labs). Specific course details (BIOL 4460/5560 01/PT 5502, ОТ 5502 01 02, BIOL 4415L/5515L). Spring 2025.
• Syllabus: Includes course description and links to recorded lectures ("General").
• News Forum: Announcements about posts and events.
• Weekly Posts: PowerPoint presentations (PDF) distributed before classes.
• Objectives: Goals for each module, interactive study guides (best!), vocabulary terms, and relevant concepts for each goal.
• Laboratories: Objectives and Atlas images for dissections in the second module (supplemental lecture material - Neuroanatomy).
• Reading Quizzes: Ten quizzes, 50 points each, open-book, due during class time, posted in the syllabus. Missed quizzes can be submitted as student-generated quizzes (50% credit during the module).
• Examinations: One exam per module, no cumulative final. Remediation opportunity for Exam ONE only up to 75%.

Course Description (additional)

• Modules: One exam per module; Covers Neurobiology (neurophysiology and development); Neuroanatomy (regional neuroanatomy and pathways); Systems Neuroscience I (sensory neurobiology and pathways); and Systems Neuroscience II (motor and integrative neurobiology and pathways).
• Emphases: Mechanisms, Pathways, Pathology, and Case Studies.

Basic Divisions of Nervous System

• Central Nervous System (CNS): Includes cerebrum, thalamus, midbrain, pons, cerebellum, medulla, and spinal cord.
• Brainstem: Composed of the midbrain, pons, and medulla.
• Peripheral Nervous System (PNS): Comprises spinal nerves and autonomic nerves.

Planes of Section

• Sagittal: Midline, longitudinal axis.
• Axial: Horizontal, separates top from bottom.
• Coronal: Perpendicular to the long axis.

Neural Imaging

• Computerized Tomography (CT) Scans: X-ray beams rotated around patient, multiple views ("slices") reveal differing densities (air, blood, bone, brain).
• MRI (Magnetic Resonance Imaging): Two types of relaxation measures (T1 and T2) to provide higher resolution and contrast for tissue identification.

Typical CT scan

• air: -800 (black)
• water: 0
• brain matter: 35
• bone: 1200 (white)
• fat: -80
• CSF: 10
• blood 75.

Magnetic Resonance Imaging (MRI) Scan

• Two coils, change proton spin, measure relaxation time (T2, T1).
• T2 = horizontal spin relaxation
• T1 = vertical spin relaxation.

Functional MRI (fMRI)

• BOLD (Blood Oxygen Level Dependent): Measures changes in blood flow to parts of the brain during activity. Detect changes in blood flow by change in image intensity.

Positron Emission Tomography (PET)

• Introduce radioactively tagged substances into brain.
• Detect gamma rays emitted at 180º, measure changes in neuronal activity.
• Label ligands for studying receptors.

Single Photon Emission Computed Tomography (SPECT)

• Uses a wider variety of isotopes for studying specific events.
• Less spatial resolution, more diversity of isotopes.

Neurons - Functional Morphology

• Input Zone: Includes apical (distant) and basal (proximal) dendrites, and soma (cell body).
• Trigger Zone: Axon hillock and initial segment (spike initiation zone).
• Propagation Zone: Axon, myelin sheath, Nodes of Ranvier, and collateral branches.
• Output Zone: Axon terminal and synaptic boutons (synaptic vesicles contain neurotransmitters).

Types of Neurons - Morphology

• Unipolar (pseudo-unipolar)
• Bipolar
• Multipolar (pyramidal, Purkinje, stellate, granule).

Neuronal Organelles

• Plasma membrane: Electrical signaling of neurites.
• Cytoskeletal elements: Transport, architecture, and signaling.
• Nucleus: Genetic control center.
• Rough ER/Ribosomes: Protein synthesis.
• Smooth ER/Golgi: Protein modifications and packaging.
• Golgi apparatus: Vesicle modifications.
• Mitochondria: Metabolism.

Neurophysiology

• Plasma membrane: Electrical signaling of neurites.
• Dendritic arbor and spines: Input zone.
• Axon hillock (Myelinated): Signal integration and conduction.
• Axonal terminal and synaptic boutons: Output zone.
• Protein pumps: Sodium-potassium pump, calcium pumps.
• Ion channels: Non-gated and gated by stimuli.
• Synaptic proteins: NT release and uptake.
• Receptor proteins: Ionotropic, metabotropic, and signal transduction.

Neuronal Transport

• Nucleus: Codes for messenger RNA.
• Rough ER: Ribosomal synthesis of proteins.
• Smooth ER/Golgi: Protein modification and packaging.
• Microtubules/Neurofilaments: Transports in the cell body and neurites.
• Transport of organelles, Vesicles, Neurotransmitters, and Enzymes: Movement of these elements within the neuron.
• Transmitters synthesized in Soma (peptides) or at terminal (e.g., Ach).

Neurofilaments, Microfilaments, and Microtubules

• Neurofilaments: Intermediate filaments (10 nm) for structural support.
• Microfilaments: Small filaments (3-5 nm) involved in cell-cell signaling.
• Microtubules: Scaffold filaments (axonal transport, cell division), comprised of a/β tubulin polymers, and dependent on GTP. MAPs (microtubule associated proteins) regulate polymerization (e.g., MAP2, tau).

Axonal Trafficking

• Microtubule-based motors: Anterograde (kinesin) and retrograde (dynein) transport along microtubules.

Glial Cells

• Microglia: Resident macrophages, phagocyte for responses to injury/infection, and scavenging debris.
• Macroglia (CNS): Oligodendrocytes, astrocytes; (PNS): Schwann cells.
• Astrocytes: Most numerous glial cells, uptake extracellular potassium and released neurotransmitters, contribute to the blood-brain barrier, and modulate neuronal activity.
• Oligodendrocytes/Schwann cells: Produce myelin, enabling saltatory conduction, structural support for CNS parenchyma and neuronal migration during development.
• Gliosis: Reactive proliferation of glial cells.

Glial Cell Tumors

• astrocytoma
• glioblastoma multiforme
• oligodendrocytoma
• ependymoma
• schwannoma

Case Study: Multiple Sclerosis

• 28-year-old woman showed weakness, numbness, and sensory issues in left leg.
• MRI scans showed abnormal signals in the peri-ventricular white matter and spinal cord, suggestive of demyelination.
• Initial recovery, later vision loss in right eye treated with corticosteroids.
• Developed tremor and dysarthria, transient episodes of double vision.
• Various stages and symptoms illustrated different progression patterns.