Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Neuroscience: Exploring the Brain, 3e i/MIB/

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Introduction Attention: State of selectively processing simultaneous sources of information Benefits performance of behavioral tasks Importance emphasized by attention-deficit hyperactivity disorder Brain Imaging – changes in cortical activity Study attention by examining behavioral manifestations, e.g., visual attention

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Behavioral Consequences of Attention Attention enhances visual detection

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Behavioral Consequences of Attention Attention Decreases Reaction Times i/MIB/

Copyright © 2007 Wolters Kluwer Health | 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

Copyright © 2007 Wolters Kluwer Health | 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

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Physiological Effects of Attention PET Imaging Attention to Features –Same-different discrimination task: 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 V4, IT and other visual areas in temporal lobe  Color & shape –Area MT  Speed of motion

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Physiological Effects of Attention PET Imaging of Attention to Features (Cont’d) Color Shape Motion

Copyright © 2007 Wolters Kluwer Health | 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

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Physiological Effects of Attention Enhanced Neuronal Responses in Parietal Cortex –Wurtz, Goldberg, and Robinson Implications of Superior Colliculus work for explaining these findings

Copyright © 2007 Wolters Kluwer Health | 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 excitability

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Physiological Effects of Attention Receptive Field Changes in Area V4 (Response to effective stim. But attention directed at location of ineffective stim.)

Copyright © 2007 Wolters Kluwer Health | 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

Copyright © 2007 Wolters Kluwer Health | 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

Copyright © 2007 Wolters Kluwer Health | 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

Copyright © 2007 Wolters Kluwer Health | 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

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Physiological Effects of Attention

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Physiological Effects of Attention: LIP Neurons Respond best if Star is flashed on

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Physiological Effects of Attention: LIP Neurons: Is Increased activity For ‘cued’ star Attention related?

Copyright © 2016 Wolters Kluwer All Rights Reserved Consciousness Materialist perspective –Consciousness arises from physical processes –Based on structure and function of nervous system Alternative: dualism –Mind and body are different things. –One cannot be fully explained by the other.

Copyright © 2016 Wolters Kluwer All Rights Reserved What Is Consciousness? Nature of human consciousness problematic –Even defining consciousness is controversial. The easy problems of consciousness –Phenomena answerable by scientific methodology –Example: sleep–awake difference The hard problem of consciousness –The experience itself –Why the experience is the way it is

Copyright © 2016 Wolters Kluwer All Rights Reserved Neural Correlates of Consciousness The minimal neuronal events sufficient for a specific conscious percept Experimental approach with bistable visual images—changes in neural activity?

Copyright © 2016 Wolters Kluwer All Rights Reserved Neuronal Correlates of Alternating Perception in Binocular Rivalry Different images seen by the two eyes. –Perceptual awareness alternates Experimentally demonstrated –Neural recordings in monkey area IT show changes correlated with perceptions. –Neural activity in IT may be neural correlate of this awareness.

Copyright © 2016 Wolters Kluwer All Rights Reserved Visual Awareness and Human Brain Activity Rivalry experiments in humans using fMRI to record brain activity –Using rival images of a face and a house –Recording in FFA (faces) and PPA (places) –Produced alternating patterns of brain activity in FFA and PPA Imagining imagery activates same visual processes –Similar results with neuronal probe recording in human subject

Copyright © 2016 Wolters Kluwer All Rights Reserved Visual Awareness and Human Brain Activity Entorhinal cortex neuron in human: Selective response to seen or imagined dolphins.

Copyright © 2016 Wolters Kluwer All Rights Reserved Challenges in the Study of Consciousness Small steps succeeding in studying neural correlates of consciousness (NCC) Challenges of interpreting NCC study data –What is “minimal” brain activity sufficient for conscious experience? –Is the neural activity a prerequisite for conscious experience or consequence of the experience but not NCC? –Can attention be confounded with awareness? The “hard problem” of consciousness remains.

Copyright © 2016 Wolters Kluwer All Rights Reserved Concluding Remarks Resting state activities likely include monitoring environment and daydreaming. Attention confers behavioral flexibility. –We use attention to focus mental resources. –Network of brain areas, priority maps –Allocation of attention followed by selective enhanced processing in sensory cortex Many mysteries remain about consciousness of information we attend to.

Copyright © 2007 Wolters Kluwer Health | 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 –Ignore competing stimuli –Can be seen in brain imaging studies –Effects receptive field properties Why do we need attention? –Cannot process all information simultaneously –Selects what information should access the limited processing resources

Copyright © 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins

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Copyright © 2007 Wolters Kluwer Health | 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 –Associated with right-sided lesions –Hypothesis: Left hemisphere attends to right hemifield whereas right hemisphere attends to both right and left hemifields