We must often search cluttered scenes for items of immediate behavioral relevance - e.g. our food, our car keys, our child, and so on. In each case, we use our memory of the object's features to effectively guide our search, so that we are not forced to inspect every object in a crowded scene individually. Efficient visual search is critical for efficient visually guided behavior. Although much is known about the biological mechanisms that underlie the ability to attend to locations, very little is known about the mechanisms underlying visual search guided by object features. We do not yet understand where the information about the relevant object features is stored in the nervous system, how that information is used to guide eye movements to inspect object that are good candidates for the searched-for item, or how the feature information modulates the information processed in our visual cortex. To design an effective neural prosthesis or to treat people with attentional disorders, we need a better understanding of feature attention in visual search at the systems level. A better understanding of feature attention will likely also give us insight into the mechanisms underlying visual working memory and visual imagery, as these related functions seem to involve at least partially overlapping neural circuits. Two key structures that may play a role in the guidance of feature attention during visual search are the prefrontal cortex and the pulvinar nucleus of the thalamus. In fact, the pulvinar may serve to relay critical feature information from prefrontal cortex to visual cortex.
Our Aims are focused on these two structures, and we are guided by our preliminary data regarding their functions.
In Aim 1, we will simultaneously record from neurons in Area 45 of the prefrontal cortex, the frontal eye fields (FEF) and area V4 of visual cortex during performance of a visual search task. These recordings will test hypotheses about how prefrontal cells influence the subsequent processing of object feature information in FEF and area V4.
In Aim 2, we will use newly developed optogenetic techniques during performance of the same tests of feature attention used in Aim 1, to test causal hypotheses about how the prefrontal cortex influences both behavior during search and the responses of FEF and V4 neurons. The optogenetic techniques we have successfully implemented with our collaborators will allow us to suppress neural circuits at precise locations and for precise periods of time.
In Aim 3, we will record simultaneously from the pulvinar, area V4, and the inferior temporal cortex during the same tests of feature attention. We will test hypotheses about how the pulvinar regulates cortical processing during feature attention, including its role in synchronizing and de-synchronizing activity in cortical population. We will then test our conclusions using the same optogenetic techniques used in Aim 2, to suppress pulvinar activity at critical times during the performance of the tasks. In total, we expect these studies to give us the best account so far of how the interactions among multiple brain structures leads to effective visual processing during attention to object features.
The aims of the project are to give us mechanistic, biological insights into how attention to object features regulates the processing of incoming visual information. These new insights will aid in the development of a neuro-prothesis for blindness and will also help us develop new treatments for people suffering attentional disorders.
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| Mulliken, Grant H; Bichot, Narcisse P; Ghadooshahy, Azriel et al. (2015) Custom-fit radiolucent cranial implants for neurophysiological recording and stimulation. J Neurosci Methods 241:146-54 |
| Ungerleider, Leslie G; Galkin, Thelma W; Desimone, Robert et al. (2014) Subcortical projections of area V2 in the macaque. J Cogn Neurosci 26:1220-33 |
| Gattass, Ricardo; Galkin, Thelma W; Desimone, Robert et al. (2014) Subcortical connections of area V4 in the macaque. J Comp Neurol 522:1941-65 |
| Lepage, Kyle Q; Gregoriou, Georgia G; Kramer, Mark A et al. (2013) A procedure for testing across-condition rhythmic spike-field association change. J Neurosci Methods 213:43-62 |
| Gregoriou, Georgia G; Gotts, Stephen J; Desimone, Robert (2012) Cell-type-specific synchronization of neural activity in FEF with V4 during attention. Neuron 73:581-94 |
| Zhou, Huihui; Desimone, Robert (2011) Feature-based attention in the frontal eye field and area V4 during visual search. Neuron 70:1205-17 |
| Bichot, Narcisse P; Heard, Matthew T; Desimone, Robert (2011) Stimulation of the nucleus accumbens as behavioral reward in awake behaving monkeys. J Neurosci Methods 199:265-72 |
| Buffalo, Elizabeth A; Fries, Pascal; Landman, Rogier et al. (2011) Laminar differences in gamma and alpha coherence in the ventral stream. Proc Natl Acad Sci U S A 108:11262-7 |
| Buffalo, Elizabeth A; Fries, Pascal; Landman, Rogier et al. (2010) A backward progression of attentional effects in the ventral stream. Proc Natl Acad Sci U S A 107:361-5 |
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