A typical visual scene will contain many different objects, few of which will be relevant to the task at hand. Thus, attentional mechanisms are needed to find relevant objects and suppress distracters. An understanding of these attentional mechanisms will ultimately help in developing a visual prosthesis for people with severe visual impairments, and will also help in developing treatments for people with brain disorders affecting attention, including ADHD. The long term goal of this proposal is to not only uncover attentional influences on visual processing in the brain, but also to understand the neuronal mechanisms by which these effects occur. It is particularly important to understand how the attentional mechanism operates under naturalistic conditions, such as when we freely move our gaze to find objects based on their features (e.g. visual search, or finding a """"""""face in a crowd""""""""). Our focus is on visual area V4, which is an intermediate processing stage in the cortical pathway important for object recognition. New results suggest that the attentional bias in favor of behaviorally relevant stimuli may involve not only changes in the average firing rate of V4 neurons, but also the synchronous timing of V4 activity. The first specific aim is to test hypotheses about the different functional contributions of the upper and lower layers in area V4 to feature-based attention in visual search. The next aim is to establish the specific contributions of firing rates and neural synchrony to the behavioral performance of animals engaged in visual search.
The third aim i s to determine the contribution of prefrontal cortex to the attentional effects on V4 neuronal responses and synchrony during visual search.
These aims will give us a better understanding of the functional anatomy of attention in the visual cortex, the contributions of specific biological mechanisms of attention to behavior, and the nature of top-down feedback to the visual cortex. The central hypothesis of the research program is that neurons in prefrontal cortex induce changes in both firing rates and neural synchrony in ventral stream visual areas such as area V4, and that these changes mediate the selection of relevant objects under naturalistic conditions of visual search. These hypotheses test novel ideas, but they are well supported by preliminary data, and we are well-positioned to test them since we have had many years of experience with the techniques.
| Bichot, Narcisse P; Heard, Matthew T; DeGennaro, Ellen M et al. (2015) A Source for Feature-Based Attention in the Prefrontal Cortex. Neuron 88:832-44 |
| 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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