Occipital GABA levels in older adults and their relationship to visual perceptual suppression
Kabilan Pitchaimuthu,Qi-Zhu Wu,Olivia Carter,Bao N Nguyen,Sinyeob Ahn,Gary F. Egan,Allison M McKendrick +6 more
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TLDR
The results show increased visual cortical GABA levels, and reduced Glx levels, in older adults, and challenge current assumptions regarding neurobiological changes that occur within the aging human visual cortex and their association with certain age-related changes in visual perception.Abstract:
Several studies have attributed certain visual perceptual alterations in older adults to a likely decrease in GABA (Gamma Aminobutyric Acid) concentration in visual cortex, an assumption based on findings in aged non-human primates. However, to our knowledge, there is no direct evidence for an age-related decrease in GABA concentration in human visual cortex. Here, we estimated visual cortical GABA levels and Glx (combined estimate of glutamate and glutamine) levels using magnetic resonance spectroscopy. We also measured performance for two visual tasks that are hypothesised to be mediated, at least in part, by GABAergic inhibition: spatial suppression of motion and binocular rivalry. Our results show increased visual cortical GABA levels, and reduced Glx levels, in older adults. Perceptual performance differed between younger and older groups for both tasks. When subjects of all ages were combined, visual cortical GABA levels but not Glx levels correlated with perceptual performance. No relationship was found between perception and GABA levels in dorsolateral prefrontal cortex. Perceptual measures and GABA were not correlated when either age group was considered separately. Our results challenge current assumptions regarding neurobiological changes that occur within the aging human visual cortex and their association with certain age-related changes in visual perception.read more
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GABAergic Inhibition Gates Perceptual Awareness During Binocular Rivalry
TL;DR: It is found that drugs that modulate the two dominant GABA receptor types in the brain, GABAA (clobazam) and GABAB (arbaclofen), increase perceptual suppression during rivalry relative to a placebo, the first causal link between GABAergic inhibition and binocular rivalry in humans.
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Role of gamma-amino-butyric acid in the dorsal anterior cingulate in age-associated changes in cognition.
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Older Adults Exhibit Greater Visual Cortex Inhibition and Reduced Visual Cortex Plasticity Compared to Younger Adults.
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GABA levels in ventral visual cortex decline with age and are associated with neural distinctiveness.
Jordan D. Chamberlain,Holly C. Gagnon,Poortata Lalwani,Kaitlin Cassady,Molly Simmonite,Rachael D. Seidler,Stephan F. Taylor,Daniel H. Weissman,Denise C. Park,Thad A. Polk +9 more
TL;DR: For instance, this article found that older adults exhibited lower GABA levels and less distinct activation patterns for faces and houses in the ventral visual cortex relative to younger adults, and individual differences within older adults positively predicted individual differences in neural distinctiveness.
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Total GABA level in human auditory cortex is associated with speech-in-noise understanding in older age
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TL;DR: The hypothesis that inhibitory mechanisms in the auditory system are reduced in aging is supported, and this reduction relates to functional impairments.
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