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- Björkman, Anders, et al.
(författare)
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Loss of inhibition in ipsilateral somatosensory areas following altered afferent nerve signaling from the hand
- 2018
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Ingår i: Neuroscience Research. - : Elsevier BV. - 0168-0102. ; 135, s. 32-36
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Tidskriftsartikel (refereegranskat)abstract
- Cutaneous stimulation of the hand results in increased neural activity in the contralateral primary somatosensory cortex (S1) in humans, whereas an inhibition of neurons is seen in the ipsilateral S1.The aim of this study was to assess changes in neural activity in the S1 bilaterally, with a focus on the ipsilateral hemisphere, following altered afferent nerve signaling from the hand. Three cohorts, all with altered afferent nerve signaling from the hand, participated in the study. There were: 18 patients with traumatic median nerve injury, 10 patients with vibration induced neuropathy and 11 healthy subjects who had their dominant hand and wrist immobilized for 72 h. In addition, 36 healthy subjects were included as controls. Each subject was examined using functional magnetic resonance imaging at 3 T. All three study cohorts showed enlarged activation in the contralateral S1 during tactile stimulation compared to healthy controls. Moreover, inhibition of the ipsilateral S1 was significantly decreased or completely lost. Thus, somatosensory areas of both hemispheres respond to changed afferent nerve signaling from the hand. The loss of inhibition of neurons in the ipsilateral S1 suggests an important role of the ipsilateral hemisphere in the cerebral adaptation following a change in afferent nerve signaling.
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| 2. |
- Eliasson, Moa, et al.
(författare)
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Spider monkeys (Ateles geoffroyi) are less sensitive to the odor of aliphatic ketones than to the odor of other classes of aliphatic compounds.
- 2015
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Ingår i: Neuroscience research. - : Elsevier. - 0168-0102 .- 1872-8111. ; 99, s. 46-54
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Tidskriftsartikel (refereegranskat)abstract
- Aliphatic ketones are widely present in body-borne and food odors of primates. Therefore, we used an operant conditioning paradigm and determined olfactory detection thresholds in four spider monkeys for a homologous series of aliphatic 2-ketones (2-butanone to 2-nonanone) and two of their isomers (3- and 4-heptanone). We found that, with the exception of the two shortest-chained ketones, all animals detected concentrations <1ppm (parts per million), and with five odorants individual animals even reached threshold values <0.1ppm. Further, we found a significant correlation between olfactory sensitivity of the spider monkeys and carbon chain length of the 2-ketones which can best be described as a U-shaped function. In contrast, no significant correlation was found between olfactory sensitivity and position of the functional carbonyl group. Across-odorant and across-species comparisons revealed the following: spider monkeys are significantly less sensitive to the odors of aliphatic ketones than to the odor of other classes of aliphatic compounds (1-alcohols, n-aldehydes, n-acetic esters, and n-carboxylic acids) sharing the same carbon length. Spider monkeys do not differ significantly in their olfactory sensitivity for aliphatic ketones from squirrel monkeys and pigtail macaques, but are significantly less sensitive to these odorants compared to human subjects and mice. These findings support the notion that neuroanatomical and genetic properties do not allow for reliable predictions with regard to a species' olfactory sensitivity. Further, we conclude that the frequency of occurrence of a class of odorants in a species' chemical environment does not allow for reliable predictions of the species' olfactory sensitivity.
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