The Resting Brain, Attention, & Consciousness Chapter 21 PDF

The Resting Brain, Attention, & Consciousness Chapter 21   Understand the resting state of the brain Learning  Learn about areas of the brain involved in attention processing objectives  Discuss the theories of consciousness and its neural correl...

The Resting Brain, Attention, & Consciousness Chapter 21   Understand the resting state of the brain Learning  Learn about areas of the brain involved in attention processing objectives  Discuss the theories of consciousness and its neural correlates   Attention: ability to focus on one aspect of sensory input  Preferentially process some information and ignore the rest  Attention has significant effects on Introduction perception.  Corresponding changes in sensitivity of neurons at many brain locations  Consciousness: awareness of something  Neural basis of the conscious brain?   What’s going on when you’re awake but kind of… zoned out? Just chilling?  Generally, neurons become more active in cortical areas processing ongoing perceptual or motor information.  Resting state activity  Some regions are fairly quiet.  Others surprisingly active Resting state  Revealed by PET and fMRI imaging of whole brain brain activity   Engaging in task  decreases in activity of some brain areas, whereas task-relevant areas become more active.  Resting brain activity: fundamental and significant Default mode network   Patterns in brain activity changes consistent across human subjects  Brain areas active in resting state  Medial prefrontal cortex, posterior cingulate cortex, posterior parietal cortex, hippocampus, lateral temporal  Together, the default mode network Default mode network   Two hypotheses  The sentinel hypothesis  Broadly monitoring the environment  Rare disorder: simultagnosia  The internal mentation hypothesis  Supports thinking and remembering, like daydreaming  Imaging: state like remembering Functions of default mode network   Selective attention—directed, filers out input  Limited capacity of attention  Attention-deficit hyperactivity disorder Attention  Exogenous attention—bottom–up attention  Like animal detecting predator  Endogenous attention—top–down attention  Deliberately directed by the brain   Attention enhances visual sensitivity and reduces detection / reaction times Behavioral consequences of attention Attention selectivity   What happens to neural activity?  What brain areas are involved?  Effects of attention observed in high-level cognitive and numerous sensory areas  Consequences of allocating attention revealed  Imaging studies in humans Shifting  Individual neuron changes in animal studies attention fMRI imaging  Subjects view stimulus of attention to  Location of cued sector changes  Brain activity shifts location retinotopically.   Same–different discrimination task: color, PET imaging shape, speed of attention to  (A) Selective attention experiment visual  (B) Divided attention experiment features  Subtract B from A shows brain activity associated with attention to one feature. PET imaging  V4, IT, and other visual areas in temporal lobe of attention to color and shape visual  Area MT speed of motion features   Attention: experimental versus normal conditions  What happens to attention under normal conditions?  Assumption: Attention changes location prior to eye movement.  Experiments of Wurtz, Goldberg, and Robinson Enhanced  Recorded neural activity from several brain regions neuronal  Response enhancement in posterior parietal cortex  May speed visual processing and reaction times responses in parietal cortex Enhanced  Effect of attention on the neuronal response of a neuron in posterior parietal responses in cortex parietal cortex   V4 neuronal response is greater when attention is directed to “effective” stimuli even if stimuli are visually the same Effect of attention in visual cortical area V4   Cortical, subcortical areas  Guide attention Brain circuits  Saccadic eye movements for control of  The pulvinar nucleus  Projects to many areas of attention cortex  Regulates visual information flow   Frontal eye fields (FEF)  Cortical area in frontal lobe Attention &  FEF neurons— motor fields eye  Experiment of Moore and colleagues  Train monkeys to look at display of small light movements spots  Place electrode in FEF and determine motor field of neurons at its tip  Small electrical stimulation  enhancement?   Results Attention &  FEF is involved in directing attention, enhances visual performance. eye  FEF lowers stimulus detection threshold when distractions are around movements  FEF stimulation mimics physiological and behavioral effects of attention.   Results Attention &  FEF is involved in directing attention, enhances visual performance. eye  FEF lowers stimulus detection threshold when distractions are around movements  FEF stimulation mimics physiological and behavioral effects of attention.   Hypothesis of how certain visual features grab attention  Bottom–up attention  Salience map shows locations of conspicuous features.  Top–down attentional modulation from cognitive input Direction  Priority map shows locations where attention should be directed.  Based on stimulus salience and cognitive input attention with salience & priority maps   Lateral intraparietal cortex (area LIP) A priority map —priority map based on bottom–up and top–down inputs in the parietal  Guides eye movements and attention lobe  Lesions in parietal cortex associated with neglect syndrome   Attentional disorder where person ignores objects, people, and their own body to one side of the center of the gaze. Hemispatial  Associated with right-sided lesions in posterior parietal cortex neglect  Neglect syndrome might be a syndrome disruption of ability to shift attention.  Hypothesis: Left hemisphere attends to right hemifield, whereas right hemisphere attends to both right and left hemifields.   Bottom–up attention  Input from visual areas in the occipital lobe reaches area LIP.  Construction of salience map Frontoparietal  Visual processing is enhanced; eyes may move. attention  Top–down attention network  Attention effects occur first in frontal and parietal areas.  Priority map in LIP and FEF  Visual processing is enhanced; eyes may move.   Materialist perspective  Consciousness arises from physical processes  Based on structure and function of nervous system Conscious-  Alternative: dualism ness  Mind and body are different things.  One cannot be fully explained by the other.   Nature of human consciousness problematic  Even defining consciousness is controversial. What is  The easy problems of consciousness conscious-  Phenomena answerable by scientific methodology ness?  Example: sleep–awake difference  The hard problem of consciousness  The experience itself  Why the experience is the way it is   Whare are the minimal neuronal events sufficient for a specific conscious percept? Neural correlates of conscious- ness Neural correlates of  Experimental approach with bistable visual conscious- images—changes in neural activity? ness   Different images seen by the two eyes.  Perceptual awareness alternates  Experimentally demonstrated Neuronal  Neural recordings in monkey area IT show changes correlates of correlated with perceptions.  Neural activity in IT may be neural correlate of this awareness. alternating perception in binocular rivalry   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 Visual awareness & human brain activity   Imagining imagery activates same visual processes  Similar results with neuronal probe recording in human subject Visual awareness & human brain activity   Small steps succeeding in studying neural correlates of consciousness (NCC) Challenges in  Challenges of interpreting NCC study data the study of  What is “minimal” brain activity sufficient for conscious experience? conscious-  Is the neural activity a prerequisite for conscious experience or consequence of the experience but not NCC? ness  Can attention be confounded with awareness?  The “hard problem” of consciousness remains.   Resting state activities likely include monitoring environment and daydreaming.  Attention confers behavioral flexibility.  We use attention to focus mental resources. Summary  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. Quiz hint!  Brain regions involved in attention & consequences if they get lesioned Questions?