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Anil Bollimunta, Richard Krauzlis; Neuronal correlates of change detection in Superior Colliculus during covert spatial attention. Journal of Vision 2014;14(10):515. doi: 10.1167/14.10.515.
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© ARVO (1962-2015); The Authors (2016-present)
Inactivation of the intermediate layers of the Superior Colliculus (SC) causes deficits in covert spatial attention (Lovejoy & Krauzlis, 2010). However, these deficits are not accompanied by corresponding changes in attentional modulation in the cortex (Zenon & Krauzlis, 2012). To clarify the neuronal mechanisms through which SC controls covert attention (Krauzlis et. al., 2013), here we tested how the activity of SC neurons is modulated during an attention task requiring the detection of a change in the direction of a motion stimulus. Rhesus macaques were trained to report a change in the direction of motion at a cued location, while ignoring changes at a foil location, by releasing a lever during maintained fixation. The stimuli were random dot motion patches and the change in direction was set to be near threshold. Receptive fields (RF) of SC neurons were mapped using a delayed visually guided saccade task, and one of the two motion patches was placed within the RF during the motion direction change detection task. SC neurons showed transient increases (decreases) in firing rate when the change happened inside (outside) the RF. (1) This transient signal appeared as early as ~120 ms after change onset. (2) The firing rate, after change onset, was higher for correct responses than for misses when the change happened within the RF. (3) The firing rate increased earlier for shorter reaction times (RTs) than for longer RTs. These results show that, in addition to the sustained changes in activity found with spatial cues, SC neurons also exhibit transient changes related to detection of behaviorally relevant events. Inactivation of SC could disrupt this 'change-detection activity' causing behavioral deficits during covert attention tasks that have been previously reported (Zenon & Krauzlis, 2012).
Meeting abstract presented at VSS 2014
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