Brain Development Overview

Brain Development

• Basal Telencephalon develops into the basal ganglia: striatum and amygdala
• Dorsal Telencephalon develops into the neocortex
• Diencephalon develops into the thalamus and hypothalamus
• Midbrain includes structures like the substantia nigra, VTA, auditory and visual tecta (colliculi)
• Ventricles and the cerebral aqueduct are important structures within the brain.
• Neurogenesis occurs in the cortex, initially with symmetric cell division for progenitor cell expansion (radial glia), then asymmetric division to generate post-mitotic cells that migrate and differentiate
• Cortical Development happens in an inside-out pattern
• Final stages of brain development include: differentiation, axon guidance, synaptogenesis, target-dependent cell death, synaptic pruning
• Four Lobes: frontal, parietal, temporal, and occipital lobes
• Frontal Lobe contains areas like the prefrontal cortex, motor cortex, and sensorimotor cortex

Brain Structures and Function

• Thalamus and Hypothalamus are key structures in the forebrain
• Midbrain and Hindbrain are important for motor control and other functions
• Meninges, BBB, CSF, ventricles work together to protect and nourish the brain
• CSF flows in a specific direction

Imaging Techniques

• MRI is a structural/static imaging technique that provides information about the general brain structure.
• DTI is a structural/static technique that focuses on white matter.
• PET is a functional technique that uses 2-DG to measure metabolic function, which is directly related to electrical activity.
• fMRI is a functional technique that measures changes in blood flow, also related to electrical activity. It can be used to study differences between patient groups.

Chemical Senses

• Taste (Gustation):
  • Five tastant categories: sweet, sour, salty, bitter, umami
  • Tongue, palate, and nasal cavity all contribute to taste perception
  • Taste buds contain taste receptor cells
  • Taste receptor cells are not neurons, but contain microvilli which receive tastant stimuli.
  • Taste transduction involves local depolarizing potentials, transmitter release, and stimulation of gustatory afferents.
  • Serotonin is released for salty and sour, while ATP is released for sweet, bitter, and umami.
  • Salty and sour taste receptor cells are depolarized by amiloride-sensitive Na+ channels and H+ channels, respectively.
  • Sweet, bitter, and umami work via GPCRs, PLC, IP3, Ca2+ release, and Ca2+-activated Na+ channels.
  • Bitter receptors are the most diverse, while sweet and umami receptors are more specific.
  • Central taste pathway involves cranial nerves VII, IX, and X, the NST, thalamus, and gustatory cortex.
  • Taste receptor cells have a 2-week turnover rate.
• Olfaction:
  • Olfactory epithelium in the roof of the nasal cavity
  • Olfactory receptor cells (OSNs) are true neurons, their axons form the primary sensory afferents (cranial nerve I)
  • Olfactory bulb receives input from OSNs.
  • Vomeronasal organ is mainly found in animals.
  • Supporting cells create mucus.
  • Basal cells are the progenitors of OSNs.
  • Odorant transduction: odor receptors are GPCRs on cilia.
  • Golf activates adenylyl cyclase to produce cAMP which opens cAMP-gated Na+ and Ca2+ channels and Cl- channels
  • Olfactory receptor cells have a 4-8 week turnover rate.