Many Brain Regions Are Involved in Processes of Attention Several cortical regions are associated with the source or control of attention. The lateral intraparietal area—or LIP—is involved in the top-down control of attention in monkeys. The human homolog to this region is the intraparietal sulcus (IPS). Both encode a salience map (or priority map) controlling the voluntary shifts of attention. The frontal eye field (FEF) establishes gaze in accordance with cognitive goals (top-down processes) rather than with characteristics of stimuli. The temporoparietal junction (TPJ) helps shift attention to a new location after target onset.
Transcript
Many Brain Regions Are Involved in Processes of Attention
Several cortical regions are associated with the source or control of attention.
The lateral intraparietal area—or LIP—is involved in the top-down control of attention in monkeys.
The human homolog to this region is the intraparietal sulcus (IPS).
Both encode a salience map (or priority map) controlling the voluntary shifts of attention.
The frontal eye field (FEF) establishes gaze in accordance with cognitive goals (top-down processes) rather than with characteristics of stimuli.
The temporoparietal junction (TPJ) helps shift attention to a new location after target onset.
Cortical Regions Implicated in the Top-Level Control of Attention
A Frontoparietal Attentional Control Network
The Cortical Attentional Control Network
Diagnostic Test for Hemispatial Neglect
Brain Damage in Hemispatial Neglect
Three Views of the Human Brain
Frontal Lobe• 1/3 of all cerebral cortex
• Primary motor --- Area 4
• Premotor --- Area 6
• Supplementary motor --- Medial parts of Areas 6, 8
• Frontal eye field --- Inferior part of Area 8
• Broca’s area --- Areas 44, 45
• Prefrontal --- Areas 9, 10, 11, 12, 32 46, 47
The Prefrontal Cortex
Orbitofrontal Prefrontal CortexAlso named Ventral Prefrontal Cortex (VPFC)
Dorsolateral Prefrontal Cortex (DLPFC)
Box 18.2 Phineas Gage
The Prefrontal Areas Govern Our Most Complex Behavior
• The prefrontal cortex is the most anterior region of the frontal lobe. • Subdivided into
• Dorsolateral
• Dorsomedial
• Ventrolateral (orbitofrontal)
• Ventromedial (orbitofrontal)
• The textbook simplifies these subdivisions with just dorsolateral and orbitofrontal regions.
• Although note that Table 18.2 uses the term Mediofrontal which is the medial part of both dorsal and ventral subdivisions
• Prefrontal cortex is more prominent in humans and apes than other mammals.
Table 18.2 Core Characteristics of the Regional Prefrontal Syndromes
Major Functional subdivisions of the human frontal lobes
Functions of the Prefrontal Cortex• Dorsolateral area functions in intellectual activities such as
planning, judgement, problem solving and conceptualizing– Executive Functions
• Goal Selection• The development of an action plan.• Sequencing• Initiation.• Monitoring Outcome.• The inhibition of distracting or completion of a complex task.
• Orbitofrontal area functions in visceral and emotional activities– Behavioral self-regulation– Evaluating hedonic information– Error correction in conjunction with Anterior Cingulate Cortex
• Frontal Poles Autonoetic Awareness– Self knowledge– Binding together the awareness of oneself as continuous through time
The PreFrontal Lobes Govern Our Most Complex Behavior
• Neuroeconomics studies brain mechanisms active during economic decision making.
• Two main underlying systems:• A valuation system to rank choices on worth and reward
• A choice system to consider alternatives and make the decision
• Neuroeconomics research confirms that prefrontal cortex inhibits impulsive decisions, enforcing loss aversion.
• The prefrontal cortex is also activated when faced with more uncertainty or, with the amygdala, when feeling regret for a costly decision.
• Consciousness Is the Most Mysterious Property of the Nervous System
• Awareness of external events– Circuits for perceptual awareness across all sensory modalities
– Integration across modalities and mental representation in working memory
• The default mode network (daydreaming mode)– Circuits that are active when the brain is awake and at rest, and attention is not
being directed to external events.
– Parts of Temporal, Parietal and Frontal lobes
– fMRI maps suggest reliance on the frontoparietal network, as well as medial frontal cortex and cingulate.
• Subjective Sense of Self– The Frontal Poles (particularly on the right):
– Autonoetic consciousness and self awareness
– Humor and theory of mind.
The PreFrontal Lobes Govern Our Most Complex Behavior
Bi-directional connections with almost all parts of the brain so prefrontal cortex can coordinate processing across wide regions of the CNS
The human orbitofrontal cortex: linking reward to hedonic experienceMorten L. Kringelbach, Nature Reviews Neuroscience 6, 691-702 (September 2005)
Table 18.1 Regional Prefrontal Syndromes
• caused by head trauma, tumours, degenerative diseases, neurosurgery and cerebrovascular disease
• a set of behaviors commonly encountered in neuropsychiatric patients• disinhibition,• stimulus-bound behavior,• Disorganization• social inappropriateness• overactivity,• apathy,• Perseveration
• no longer useful because it implies damage to a specific region of the brain. The clinical presentations involved reflect dysfunction in several parts of the brain, some of which are in the frontal lobes and some of which are not.
Frontal Lobe Disorder “Syndrome”
• Common post-TBI psychiatric comorbidities include affective, cognitive, and behavioral disorders
• personality changes commonly seen after TBI : disinhibition, impulsivity, and inadequate self-monitoring of interpersonal behavior.
• Personality changes associated with TBI can be difficult to differentiate from mania or hypomania
Traumatic Brain Injury “TBI”
Dysfunctions of Medial and LateralOrbitofrontal Cortex in Psychopathy
• Psychopathy: a developmental disorder with two main components:– 1. emotional dysfunction
• reduced guilt
• reduced empathy
• reduced attachment to significant
– 2. predisposition to antisocial behavior from an early age
– Psychopathy also has increased risk for both instrumental and reactive aggression
• instrumental aggression is purposeful and goal directed
• reactive aggression is triggered by a frustrating or threatening events
– strongly heritable component (67% heritability)
– Communication between amygdala and medial Orbital Frontal Cortex • reduced amygdala responding to emotional words
• reduced amygdala responses to emotional expressions
• reduced autonomic responses to the distress cues of other individuals
– expressions of fear and sadness serve as social reinforcers
• Role of the Amygdala– Make emotional judgments based on facial stimuli
– Makes it possible to judge complex social emotions
• Role of the medial OFC– goal-directed instrumental action selection
• learning of stimulus–outcome associations
• learning of response–outcome associations
– representation of reinforcement information
– increased activity to personal as opposed to impersonal moral choices
• Role of the dorsal anterior cingulate cortex– monitoring and resolution of response conflict
• Psychopathy response pattern– reduced amygdala responses to the emotional words
