Attention is a critical factor in sensory and cognitive performance. Problems in controlling and directing attention can lead to serious deficits in performance and behavior. More complete information about the neural mechanisms underlying attention will be important for understanding how it facilitates perception and guides behaviors. The proposed experiments will extend our understanding of the neuronal basis of attention by testing the hypothesis that attentional modulation depends on the same neuronal circuits that mediate sensory response normalization. Response normalization is a well-established mechanism that adjusts sensory signals based on the overall activity in a large group of neurons with similar response properties. We propose that attentional modulations in visual cerebral cortex act through this normalization mechanism, such that attentional modulation cannot occur in conditions when normalization is weak or eliminated. We will test this hypothesis by using extracellular recordings to measure directly both attentional modulation and response normalization in the activity of individual neurons in cerebral cortex.
One specific aim i s to extend preliminary observations on the relationship between spatial attention and response normalization in two ways. First, although preliminary results have shown a correlation between attention and normalization across neurons in the middle temporal visual area (MT), we will examine that relationship within neurons by varying the spatial separation between pairs of stimuli in a way that will modulate normalization. Second, we will examine the relationship between spatial attention and response normalization in area V4, to see whether they are correlated in a visual area with markedly different properties. The second specific aim is to examine whether feature-based attention, like spatial attention, is also correlated with normalization. In one set of experiments, we will examine direction-based attention in MT, because direction-based attention is known to be robust in MT. In other experiments we will examine speed- based attention MT, which will provide a valuable comparison because speed is represented in a different functional architecture than direction in MT. Collectively these experiments will provide a critical test of the hypothesis that attention depends on normalization mechanisms. In doing so they have the potential of greatly extending our understanding of the neural mechanisms that underlie attention.

Public Health Relevance

Attention is critical to perceptual and cognitive performance, and attention deficits are the most commonly diagnosed behavioral disorder of childhood, with attention deficit hyperactivity disorder (ADHD) affecting as many as 5% of children in the United States [35]. Better understanding of basic neuronal mechanisms related to attention and their interaction with sensory signals is needed for guiding assessment, diagnosis and treatment of deficits of attention. The proposed research will investigate how attention affects visual signals in cerebral cortex, and in particular how it interacts with sensory mechanisms involved in the integration of multiple visual stimuli.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY005911-27
Application #
8247086
Study Section
Cognitive Neuroscience Study Section (COG)
Program Officer
Steinmetz, Michael A
Project Start
1986-09-01
Project End
2014-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
27
Fiscal Year
2012
Total Cost
$197,925
Indirect Cost
$79,925
Name
Harvard University
Department
Biology
Type
Schools of Medicine
DUNS #
047006379
City
Boston
State
MA
Country
United States
Zip Code
02115
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Ray, Supratim; Ni, Amy M; Maunsell, John H R (2013) Strength of gamma rhythm depends on normalization. PLoS Biol 11:e1001477
Ni, Amy M; Ray, Supratim; Maunsell, John H R (2012) Tuned normalization explains the size of attention modulations. Neuron 73:803-13
Ray, Supratim; Maunsell, John H R (2011) Different origins of gamma rhythm and high-gamma activity in macaque visual cortex. PLoS Biol 9:e1000610
Ray, Supratim; Maunsell, John H R (2011) Network rhythms influence the relationship between spike-triggered local field potential and functional connectivity. J Neurosci 31:12674-82
Cohen, Marlene R; Maunsell, John H R (2011) Using neuronal populations to study the mechanisms underlying spatial and feature attention. Neuron 70:1192-204
Bosking, William H; Maunsell, John H R (2011) Effects of stimulus direction on the correlation between behavior and single units in area MT during a motion detection task. J Neurosci 31:8230-8
Cohen, Marlene R; Maunsell, John H R (2011) When attention wanders: how uncontrolled fluctuations in attention affect performance. J Neurosci 31:15802-6
Ni, Amy M; Maunsell, John H R (2010) Microstimulation reveals limits in detecting different signals from a local cortical region. Curr Biol 20:824-8
Cohen, Marlene R; Maunsell, John H R (2010) A neuronal population measure of attention predicts behavioral performance on individual trials. J Neurosci 30:15241-53

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