Chapter 21 - Resting Brain, Attention, and Consciousness

Attention

The ability to focus on one aspect of sensory input

Consciousness

Awareness of something

Brain becomes more active in ___ processing ongoing perceptual or motor signals

Cortical Areas

Resting State Activity using roughly __

20% of body’s oxygen and glucose

Resting State Activity

Engaging in task at same time task-relevant brain areas increase activity → decreases activity of some areas. Doesn’t mean the brain ignores sensory input though

Parts of the brain active in resting state may become consistently ___ when other sensory-motor areas associated with task performance become more active

Less Active

Default Mode Network Consists of:

Medial prefrontal cortext, posterior cingulate cortex, posterior parietal cortex, hippocampus, lateral temporal

Default Mode Network

Mental time travel: Tasks requiring a person to remember the past or imagine the future

Social Cognition: Thoughts, beliefs, and desires of another person inferred from their actions

Functions of Default Mode Network

Daydreaming, emotional state, language, and assessment of traits. Active depending on the task.

Hypothesis:

• Engaged in mental tasks when focused inward

• Resources shift to other brain networks on tasks involving sensory and motor output

Selective Attention

Directed toward select objects; filters out input

Exogenous Attention (Bottom-Up Attention)

Attention given to a salient sensory input; evade predators (Stimulus-Driven)

Endogenous Attention (Top-Down Attention)

Deliberately directed by and prioritized by the brain (Goal-Directed)

Selection History

Attention give due to prior experience

Attention Priority Map

• Stimulus Salience

• Behavioral Goal

• Selection History

Attention & Visual Sensistivity

Attention enhances visual sensitivity

Attention & Neural Responses

Attention enhances neural responses

Attention & Receptive Fields

Attention alters receptive fields

Bottom-Up Salience Map

Shows locations of conspicuous features

Top-Down Priority Map

Shows locations where attention should be directed

Lateral Intraparietal Cortex (Area LIP)

Priority map based on bottom-up and top-down inputs.

• Guides eye movements and attention

• Lesions in parietal cortex associated with neglect syndrome

Hemispatial Neglect Syndrome

Person ignores objects, people, and own body to one side of the center of the gaze. Associated with right-side lesions in posterior parietal cortex. Might be a disruption of ability to shift attention

Hypothesis: Left hemisphere attends to right hemifield, whereas right hemisphere attends to both right and left hemifields

Dorsal Attention Network

Directs attention to features and location of stimuli

• Posterior parietal cortex

• Frontal Cortex

• (Superior Parietal Lobule), (Intraparietal Sulcus), (Frontal Eye Fields)

Ventral Attention Network

Activates with detection of unexpected stimuli/

• Cortex at intersection of temporal and parietal lobes. Ventral portions of frontal cortex.

• (Temporoparietal Junction, Ventral Frontal Cortex)

Bottom-up Attention vs Top-down

• Bottom: signals reaching visual cortex from eyes feed into areas controlling - allocation of attention and parietal lobes (FEF, LIP)

• Top: Higher cortical areas project to and modulate the activity in the early sensory cortex

Materialism (Physicalism)

Consciousness arises from physical processes in the brain. Based on structure and function of nervous system.

Dualism

Mind and body are different things. One cannot be fully explained by the other

Consciousness

Nature of human consciousness is problematic; Defining it is controversial. Significance of degree of consciousness

Consciousness Categorization

Can be categorized based on its level of wakefulness and awareness of self or environment. Ranging from coma to generalized seizure to vegetative state, a person appears increasingly more awake, but all three states lack evidence for awareness

Binocular Rivalry

Different images seen by the two eyes. Perceptual awareness alternates

Theories of Consciousness

• Recurrent Processing Theory

• Global Workspace Theory

• Higher Order Theory

• Integrated Information Theory