olfactory bulb

Examples of olfactory bulb in the following topics:

• Olfactory (I) Nerve

  • The olfactory nerve, or cranial nerve I, is the first of the 12 cranial nerves.
  • The specialized olfactory receptor neurons of the olfactory nerve are located in the olfactory mucosa of the upper parts of the nasal cavity.
  • The olfactory nerves consist of a collection of many sensory nerve fibers that extend from the olfactory epithelium to the olfactory bulb, passing through the many openings of the cribriform plate of the ethmoid bone.
  • Olfactory receptor neurons continue to emerge throughout life and extend new axons to the olfactory bulb.
  • These interactions are transduced into electrical activity in the olfactory bulb, which then transmits the electrical activity to other parts of the olfactory system and the rest of the central nervous system via the olfactory tract.

• Overview of the Cerebrum

  • The cerebrum contains the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb.
  • The frontal lobe is located at the front of the brain, over the eyes, and contains the  olfactory bulb.
  • The olfactory sensory system is unique in that neurons in the olfactory bulb send their axons directly to the olfactory cortex, rather than to the thalamus first.
  • Damage to the olfactory bulb results in a loss of the sense of smell.
  • The olfactory bulb also receives "top-down" information from such brain areas as the amygdala, neocortex, hippocampus, locus coeruleus, and substantia nigra.

• Taste and Smell at Birth and in Old Age

  • Intrauterine olfactory learning is demonstrated by behavioral evidence that newborns respond positively to the smell of their own amniotic fluid.
  • The unique scent of the mother (to the infant) is referred to as her olfactory signature.
  • Studies demonstrate that the changes to the olfactory bulb and main olfactory system following birth are extremely important and influential for maternal behavior.
  • Pregnancy and childbirth result in a high state of plasticity of the olfactory system that may facilitate olfactory learning within the mother.
  • Human olfactory system. 1: Olfactory bulb 2: Mitral cells 3: Bone 4: Nasal epithelium 5: Glomerulus (olfaction) 6: Olfactory receptor cells

• Sensory Areas

  • Olfactory information, however, passes through the olfactory bulb to the olfactory cortex, bypassing the thalamus.
  • The olfactory cortex is located in the uncus, found along the ventral surface of the temporal lobe.

• Limbic System

  • The septal nuclei receive reciprocal connections from the olfactory bulb, hippocampus, amygdala, hypothalamus, midbrain, habenula, cingulate gyrus, and thalamus.

• Overview of Sensation

  • The olfactory system is the sensory system used for the sense of smell (olfaction).
  • In humans, olfaction occurs when odorant molecules bind to specific sites on the olfactory receptors in the nasal cavity.
  • They come together at a structure (the glomerulus) that transmits signals to the olfactory bulb in the brain.

• Tissues and Aging

  • The sense of smell begins to degenerate with the loss of olfactory sensory neurons and loss of cells from the olfactory bulb.

• Hypothalamus

  • The hypothalamus is thus richly connected with many parts of the central nervous system, including the brainstem, reticular formation and autonomic zones, and the limbic forebrain (particularly the amygdala, septum, diagonal band of Broca, olfactory bulbs, and cerebral cortex).
  • In all four groups, common odors were processed similarly involving only the olfactory brain.

• Sensory Modalities

  • These receptor neurons then synapse at the olfactory cranial nerve, which sends the information to the olfactory bulbs in the brain for initial processing.

• Thalamus

  • Together, the two halves of the thalamus are a prominent bulb-shaped mass, about 5.7 cm in length, located obliquely (about 30°) and symmetrically on each side of the third ventricle.
  • In particular, every sensory system (with the exception of the olfactory system) has a thalamic nucleus that receives sensory signals and sends them to the associated primary cortical area.