Transcript Chapter 21: Attention

Bear: Neuroscience: Exploring the
Brain 3e
Chapter 21: Attention
Slide 1
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Introduction
Attention: State of selectively processing
simultaneous sources of information
Benefits: Performance of behavioral tasks
Brain Imaging – changes in cortical activity
Behavioral manifestations
Visual attention
Slide 2
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Introduction
Functions of attention
Concentrate on one object in visual field
Selectively attend to information (while ignoring
other information)
Preferential processing of sensory information
Attention-deficit hyperactivity disorder
Demonstrates critical nature of intact attentional
mechanisms
Brain imaging studies
Show that cortical activity is altered by attention
Slide 3
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Behavioral Consequences of Attention
Visual attention
Move eyes until object imaged on fovea
Shifting attention
Enhanced visual processing
(1) Enhanced detection
(2) Faster reaction times
Slide 4
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Behavioral Consequences Of Attention
Enhanced Detection
Slide 5
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Behavioral Consequences Of Attention
Faster Reaction Times
Attention: Increases reaction speed
Slide 6
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Behavioral Consequences Of Attention
Neglect Syndrome as an Attentional Disorder
Person ignores objects, people, and their
own body to one side of the center of the
gaze
Slide 7
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Physiological Effects of Attention
Shifting attention
What happens to neural activity?
What brain areas are involved?
Observed in high-level cognitive and
numerous sensory areas
e.g., Area V1 to visual cortical areas
in the parietal and temporal lobes
Slide 8
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Physiological Effects of Attention
Slide 9
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Physiological Effects Of Attention
Functional MRI
Imaging of Attention
to Location
Subjects view
stimulus
Change location
of attended
sector
Brain activity
shifts
retinotopically
Slide 10
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Physiological Effects of Attention
PET Imaging of Attention to Features
Same-different discrimination task
Features: Color, shape, speed
(A) Selective attention: one feature
(B) Divided attention: all features
Subtract B from A shows brain activity
associated with attention to one feature
Slide 11
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Physiological Effects of Attention
PET Imaging of Attention to Features (Cont’d)
V4, IT and other visual areas in temporal
lobe Color & shape
Area MT Speed of motion
Slide 12
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Physiological Effects Of Attention
PET Imaging of Attention to Features (Cont’d)
Slide 13
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Physiological Effects Of Attention
Enhanced Neuronal Responses in Parietal
Cortex
Attention: Experimental vs. Normal
conditions
What happens to attention under normal
conditions?
Assumption: Attention changes location
prior to eye movement
Wurtz, Goldberg, and Robinson
Record neural activity from several brain
regions
Slide 14
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Physiological Effects Of Attention
Enhanced Neuronal Responses in Parietal
Cortex (Cont’d)
Posterior parietal cortex neurons
Directing eye movements
Response significantly enhanced neuronal
response when eyes went to target
Spatially selective effect – not a general
increase in excitablility
Slide 15
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Physiological Effects Of Attention
Receptive Field Changes in Area V4
Slide 16
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
How is Attention Directed?
Cortical, subcortical areas
Modulate the activity of neurons in sensory
cortex areas
The Pulvinar Nucleus
Guiding attention
Muscimol
GABA agonist
Neuron activity
suppressed
Slide 17
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
How is Attention Directed?
Attention and Eye Movements
Eye moves to attended object
Eye movements & attention closely related
Recent experiments
Brain circuitry: Directing eyes to objects
of interest
Frontal Eye Fields (FEF)
Cortical area
FEF neurons
Slide 18
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
How is Attention Directed?
Attention and Eye Movements (Cont’d)
Experiment
Train monkeys to look at display of small light
spots
Place electrode in FEF and determine motor
field of neurons at the tip
Small electrical stimulation enhancement?
Results
FEF involved in directing attention; Enhancing
visual performance
V4 activity increased
Slide 19
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
How is Attention Directed?
Attention and Eye Movements
Results (Cont’d)
FEF stimulation mimics physiological and
behavioral effects of attention
Electrical stimulation of superior
colliculus
Conclusion
Guidance of attention
Integrated with system to move eyes
Slide 20
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
Concluding Remarks
Studies of attention
Point to flexibility of the human brain
More mental energy to one location
Enhanced sensitivity & reaction time
Ignoring competing stimuli
Need for attention
e.g.,- Cannot process information in area
V1
Selects what information should access the
limited processing resources
Slide 21
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins
End of Presentation
Slide 22
Neuroscience: Exploring the Brain, 3rd Ed, Bear, Connors, and Paradiso Copyright © 2007 Lippincott Williams & Wilkins