TY - JOUR
T1 - Orientation discrimination performance is predicted by GABA concentration and gamma oscillation frequency in human primary visual cortex
AU - Edden, Richard A.E.
AU - Muthukumaraswamy, Suresh D.
AU - Freeman, Tom C.A.
AU - Singh, Krish D.
PY - 2009/12/16
Y1 - 2009/12/16
N2 - Neuronal orientation selectivity has been shown in animal models to require corticocortical network cooperation and to be dependent on the presence of GABAergic inhibition. However, it is not known whether variability in these fundamental neurophysiological parameters leads to variability in behavioral performance. Here, using a combination of magnetic resonance spectroscopy, magnetoencephalography, and visual psychophysics, we show that individual performance on a visual orientation discrimination task is correlated with both the resting concentration of GABA and the frequency of stimulus-induced gamma oscillations in human visual cortex. Behaviorally, a strong oblique effect was found, with the mean angular threshold for oblique discrimination being five times higher than that for vertically oriented stimuli. Similarly, we found an oblique effect for the dependency of performance on neurophysiological parameters. Orientation detection thresholds were significantly negatively correlated with visual cortex GABA concentration for obliquely oriented patterns (r = -0.65, p<0.015) but did not reach significance for vertically oriented stimuli (r = -0.39, p = 0.2). Similarly, thresholds for obliquely oriented stimuli were negatively correlated with gamma oscillation frequency (r = -0.65, p<0.017), but thresholds for vertical orientations were not (r = -0.02, p = 0.9). Gamma oscillation frequency was positively correlated with GABA concentration in primary visual cortex (r = 0.67, p<0.013). These results confirm the importance of GABAergic inhibition in orientation selectivity and demonstrate, for the first time, that interindividual performance on a simple visual task is linked to neurotransmitter concentration. The results also suggest a key role for GABAergic gamma oscillations in visual discrimination tasks.
AB - Neuronal orientation selectivity has been shown in animal models to require corticocortical network cooperation and to be dependent on the presence of GABAergic inhibition. However, it is not known whether variability in these fundamental neurophysiological parameters leads to variability in behavioral performance. Here, using a combination of magnetic resonance spectroscopy, magnetoencephalography, and visual psychophysics, we show that individual performance on a visual orientation discrimination task is correlated with both the resting concentration of GABA and the frequency of stimulus-induced gamma oscillations in human visual cortex. Behaviorally, a strong oblique effect was found, with the mean angular threshold for oblique discrimination being five times higher than that for vertically oriented stimuli. Similarly, we found an oblique effect for the dependency of performance on neurophysiological parameters. Orientation detection thresholds were significantly negatively correlated with visual cortex GABA concentration for obliquely oriented patterns (r = -0.65, p<0.015) but did not reach significance for vertically oriented stimuli (r = -0.39, p = 0.2). Similarly, thresholds for obliquely oriented stimuli were negatively correlated with gamma oscillation frequency (r = -0.65, p<0.017), but thresholds for vertical orientations were not (r = -0.02, p = 0.9). Gamma oscillation frequency was positively correlated with GABA concentration in primary visual cortex (r = 0.67, p<0.013). These results confirm the importance of GABAergic inhibition in orientation selectivity and demonstrate, for the first time, that interindividual performance on a simple visual task is linked to neurotransmitter concentration. The results also suggest a key role for GABAergic gamma oscillations in visual discrimination tasks.
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U2 - 10.1523/JNEUROSCI.4426-09.2009
DO - 10.1523/JNEUROSCI.4426-09.2009
M3 - Article
C2 - 20016087
AN - SCOPUS:72449167471
SN - 0270-6474
VL - 29
SP - 15721
EP - 15726
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 50
ER -