Electronic Thesis and Dissertation Repository


Master of Science




Martinez T.J.

2nd Supervisor

Diedrichsen J.



Attention allows us to focus on only important sensory stimuli in a world full of distractors. However, the ability to allocate attention to important targets becomes more difficult when the distractors are located within the same as compared to when they are in the opposite visual hemifield. The neural mechanisms underlying this effect remains unclear. We recorded neuronal responses in lateral prefrontal cortex (LPFC), an area involved in the generation of signals related to attention, of two macaque monkeys while they performed a covert spatial attention task in two different conditions. Two stimuli were either separate in the left and right visual hemifield or both within the same visual hemifield. Consistent with previous studies, behavioral performance was lower in the within than in the across condition. Moreover, the proportion of single neurons in the LPFC showing selectivity for the attended location was significantly reduced in the within relative to the across condition. Additionally, we demonstrate that the activity of single neurons and simultaneous neuronal ensembles in the primate LPFC, can accurately decode attentional signals in across condition rather than within condition. Ensemble decoding accuracy was sensitive to the noise correlation structure and dynamics of the neural ensembles. Our findings provide a neurophysiological correlate of the behavioral anisotropy observed during tasks that required attending to targets and distracter in different vs same hemifields. They further suggest that anisotropies in the representation of space by individual neurons and neuronal ensembles in the LPFC determine the efficiency of attentional filtering performance in primates.

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