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Studies of olfactory system neural plasticity: the contribution of the unilateral naris occlusion technique.

Coppola DM - Neural Plast. (2012)

Bottom Line: Early experiments emphasized naris occlusion's deleterious and age-critical effects.More recent studies have focused on life-long vulnerability, particularly on neurogenesis, and compensatory responses to deprivation.This paper focuses on recent data, new theories, and underappreciated caveats related to the use of this technique in studies of olfactory plasticity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Randolph Macon College, Ashland, VA 23005, USA. dcoppola@rmc.edu

ABSTRACT
Unilateral naris occlusion has long been the method of choice for effecting stimulus deprivation in studies of olfactory plasticity. A significant body of literature speaks to the myriad consequences of this manipulation on the ipsilateral olfactory pathway. Early experiments emphasized naris occlusion's deleterious and age-critical effects. More recent studies have focused on life-long vulnerability, particularly on neurogenesis, and compensatory responses to deprivation. Despite the abundance of empirical data, a theoretical framework in which to understand the many sequelae of naris occlusion on olfaction has been elusive. This paper focuses on recent data, new theories, and underappreciated caveats related to the use of this technique in studies of olfactory plasticity.

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Related in: MedlinePlus

Anatomical and histological effects of UNO. (a) Adult mouse that underwent left UNO as a neonate. Note the normal right naris and apparently unaffected morphology around the location of the occluded naris. (b) Bernhard von Gudden's drawing of the brain from a young adult rabbit that had undergone UNO as a neonate ([4]; dorsal view reflected right/left to match other panels; occl: occluded). (c) Horizontal section through the olfactory bulbs of a young-adult mouse that had UNO as a neonate. Note all layers of the occluded bulb (left) are thinner than open-side bulb on the right (ONL: olfactory nerve layer; GL: glomerular layer; EPL: external plexiform layer; MCL: mitral cell layer; IPL: internal plexiform layer; GCL: granule cell layer; AOB: accessory olfactory bulb). (d) Histological sections through olfactory mucosa of young-adult mouse that had UNO as a neonate. Right column: open-side; left column: occluded side; top row: H&E stain; bottom row: OMP immunolabeling (arrows: mature OSN cell bodies) (layers: 1: sustentacular layer; 2: olfactory receptor cells; 3: basal cell layer; 4: lamina propria).
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fig1: Anatomical and histological effects of UNO. (a) Adult mouse that underwent left UNO as a neonate. Note the normal right naris and apparently unaffected morphology around the location of the occluded naris. (b) Bernhard von Gudden's drawing of the brain from a young adult rabbit that had undergone UNO as a neonate ([4]; dorsal view reflected right/left to match other panels; occl: occluded). (c) Horizontal section through the olfactory bulbs of a young-adult mouse that had UNO as a neonate. Note all layers of the occluded bulb (left) are thinner than open-side bulb on the right (ONL: olfactory nerve layer; GL: glomerular layer; EPL: external plexiform layer; MCL: mitral cell layer; IPL: internal plexiform layer; GCL: granule cell layer; AOB: accessory olfactory bulb). (d) Histological sections through olfactory mucosa of young-adult mouse that had UNO as a neonate. Right column: open-side; left column: occluded side; top row: H&E stain; bottom row: OMP immunolabeling (arrows: mature OSN cell bodies) (layers: 1: sustentacular layer; 2: olfactory receptor cells; 3: basal cell layer; 4: lamina propria).

Mentions: Ideas concerning the influence of deprivation and enrichment on the quality of human relationships can be summed up in the following aphorisms: concerning deprivation it is said that “absence makes the heart grow fonder,” a sentiment that has been expressed at least since Roman times; concerning abundance, Chaucer tells us that “familiarity breeds contempt,” a perhaps cynical but resonant view of human nature. Enlightenment thinkers, too, were keenly interested in the effects of deprivation and enrichment—not on the heart—but on the organ of thought. In 1688 the Irish politician and scientist William Molyneux posed a question, in a letter to John Locke, later known as “Molyneux's Problem,” concerning the role of experience in visual perception that was to occupy philosophers and scientists for the ensuing three centuries [1]. Later, Charles Darwin considered the heritable effects of deprivation and enrichment on the nervous system. He concluded in his 1868 opus entitled The Variation of Animals and Plants Under Domestication, after observing smaller crania in domesticated rabbits compared to their wild counterparts, “We thus see that the most important and complicated organ in the whole organization is subject to the law of decrease in size from disuse [2].” But it is the neuroanatomist and psychiatrist, Bernhard von Gudden, working at the same time as Darwin, who should be credited with pioneering the neurobiological study of sensory manipulation on brain development [3]. Among his other innovations, Gudden developed the unilateral deprivation model. Brilliant in its simplicity, this paradigm affords a within-subject comparison of different amounts of sensory stimulation on brain development. A century before Hubel and Wiesel won their 1981 Nobel Prize, in part, for their studies of the effects of unilateral deprivation by lid suture on visual cortex, Gudden had already invented the method and described its effects on the visual system in his monograph of 1870 [4, 5]. In this same series of studies he also described, for the first time, the effects of unilateral nostril occlusion (UNO) on the olfactory system, the topic of this paper. Gudden established that occluding one nostril of newborn rabbits caused a pronounced reduction in the size of the olfactory bulb on the same side after six weeks (Figure 1). While the history of UNO studies is neither as bulging nor ballyhooed as that of unilateral eyelid suture, the technique has, nevertheless, formed the mainstay of olfactory neuroplasticity studies and remains in active use more than four generations after its invention. In 1994 Brunjes provided an excellent review of the literature, up to that time, on the effects of UNO on the olfactory system [6]. Thus, after a brief discussion of olfaction and UNO phenomenology, the current paper will focus on more recent findings, new interpretations of the older literature, and remaining questions.


Studies of olfactory system neural plasticity: the contribution of the unilateral naris occlusion technique.

Coppola DM - Neural Plast. (2012)

Anatomical and histological effects of UNO. (a) Adult mouse that underwent left UNO as a neonate. Note the normal right naris and apparently unaffected morphology around the location of the occluded naris. (b) Bernhard von Gudden's drawing of the brain from a young adult rabbit that had undergone UNO as a neonate ([4]; dorsal view reflected right/left to match other panels; occl: occluded). (c) Horizontal section through the olfactory bulbs of a young-adult mouse that had UNO as a neonate. Note all layers of the occluded bulb (left) are thinner than open-side bulb on the right (ONL: olfactory nerve layer; GL: glomerular layer; EPL: external plexiform layer; MCL: mitral cell layer; IPL: internal plexiform layer; GCL: granule cell layer; AOB: accessory olfactory bulb). (d) Histological sections through olfactory mucosa of young-adult mouse that had UNO as a neonate. Right column: open-side; left column: occluded side; top row: H&E stain; bottom row: OMP immunolabeling (arrows: mature OSN cell bodies) (layers: 1: sustentacular layer; 2: olfactory receptor cells; 3: basal cell layer; 4: lamina propria).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368527&req=5

fig1: Anatomical and histological effects of UNO. (a) Adult mouse that underwent left UNO as a neonate. Note the normal right naris and apparently unaffected morphology around the location of the occluded naris. (b) Bernhard von Gudden's drawing of the brain from a young adult rabbit that had undergone UNO as a neonate ([4]; dorsal view reflected right/left to match other panels; occl: occluded). (c) Horizontal section through the olfactory bulbs of a young-adult mouse that had UNO as a neonate. Note all layers of the occluded bulb (left) are thinner than open-side bulb on the right (ONL: olfactory nerve layer; GL: glomerular layer; EPL: external plexiform layer; MCL: mitral cell layer; IPL: internal plexiform layer; GCL: granule cell layer; AOB: accessory olfactory bulb). (d) Histological sections through olfactory mucosa of young-adult mouse that had UNO as a neonate. Right column: open-side; left column: occluded side; top row: H&E stain; bottom row: OMP immunolabeling (arrows: mature OSN cell bodies) (layers: 1: sustentacular layer; 2: olfactory receptor cells; 3: basal cell layer; 4: lamina propria).
Mentions: Ideas concerning the influence of deprivation and enrichment on the quality of human relationships can be summed up in the following aphorisms: concerning deprivation it is said that “absence makes the heart grow fonder,” a sentiment that has been expressed at least since Roman times; concerning abundance, Chaucer tells us that “familiarity breeds contempt,” a perhaps cynical but resonant view of human nature. Enlightenment thinkers, too, were keenly interested in the effects of deprivation and enrichment—not on the heart—but on the organ of thought. In 1688 the Irish politician and scientist William Molyneux posed a question, in a letter to John Locke, later known as “Molyneux's Problem,” concerning the role of experience in visual perception that was to occupy philosophers and scientists for the ensuing three centuries [1]. Later, Charles Darwin considered the heritable effects of deprivation and enrichment on the nervous system. He concluded in his 1868 opus entitled The Variation of Animals and Plants Under Domestication, after observing smaller crania in domesticated rabbits compared to their wild counterparts, “We thus see that the most important and complicated organ in the whole organization is subject to the law of decrease in size from disuse [2].” But it is the neuroanatomist and psychiatrist, Bernhard von Gudden, working at the same time as Darwin, who should be credited with pioneering the neurobiological study of sensory manipulation on brain development [3]. Among his other innovations, Gudden developed the unilateral deprivation model. Brilliant in its simplicity, this paradigm affords a within-subject comparison of different amounts of sensory stimulation on brain development. A century before Hubel and Wiesel won their 1981 Nobel Prize, in part, for their studies of the effects of unilateral deprivation by lid suture on visual cortex, Gudden had already invented the method and described its effects on the visual system in his monograph of 1870 [4, 5]. In this same series of studies he also described, for the first time, the effects of unilateral nostril occlusion (UNO) on the olfactory system, the topic of this paper. Gudden established that occluding one nostril of newborn rabbits caused a pronounced reduction in the size of the olfactory bulb on the same side after six weeks (Figure 1). While the history of UNO studies is neither as bulging nor ballyhooed as that of unilateral eyelid suture, the technique has, nevertheless, formed the mainstay of olfactory neuroplasticity studies and remains in active use more than four generations after its invention. In 1994 Brunjes provided an excellent review of the literature, up to that time, on the effects of UNO on the olfactory system [6]. Thus, after a brief discussion of olfaction and UNO phenomenology, the current paper will focus on more recent findings, new interpretations of the older literature, and remaining questions.

Bottom Line: Early experiments emphasized naris occlusion's deleterious and age-critical effects.More recent studies have focused on life-long vulnerability, particularly on neurogenesis, and compensatory responses to deprivation.This paper focuses on recent data, new theories, and underappreciated caveats related to the use of this technique in studies of olfactory plasticity.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Randolph Macon College, Ashland, VA 23005, USA. dcoppola@rmc.edu

ABSTRACT
Unilateral naris occlusion has long been the method of choice for effecting stimulus deprivation in studies of olfactory plasticity. A significant body of literature speaks to the myriad consequences of this manipulation on the ipsilateral olfactory pathway. Early experiments emphasized naris occlusion's deleterious and age-critical effects. More recent studies have focused on life-long vulnerability, particularly on neurogenesis, and compensatory responses to deprivation. Despite the abundance of empirical data, a theoretical framework in which to understand the many sequelae of naris occlusion on olfaction has been elusive. This paper focuses on recent data, new theories, and underappreciated caveats related to the use of this technique in studies of olfactory plasticity.

Show MeSH
Related in: MedlinePlus