Title: The Frontal Lobes
1Bryan Kolb Ian Q. Whishaws
Fundamentals of Human Neuropsychology, Sixth
Edition Chapter 15 Lecture PPT
Prepared by Gina Mollet, Adams State College
2The Frontal Lobes
3Portrait Losing Frontal-Lobe Functions
- E.L.
- Highly organized college professor
- Became disorganized, showed little emotion, and
began to miss deadlines - Scores on intelligence and memory tests were
superior - Showed impairment on frontal lobe tests
4Anatomy of the Frontal Lobes
- Constitute 20 of the neocortex
- Subdivisions
- Motor Area 4
- Premotor Areas 6 and 8
- Can be divided into
- Lateral area 6 Premotor cortex
- Medial area 6 Supplementary motor cortex
- Area 8 Frontal eye field
- Area 8A Supplementary eye field
5Anatomy of the Frontal Lobes
- Prefrontal Cortex
- Area of the frontal lobe that receives input from
the dorsomedial nucleus of the thalamus - Divisions
- Dorsolateral Prefrontal Cortex
- Inferior Frontal Cortex
- Also called Orbitofrontal cortex
- Medial Frontal Cortex
- Sometimes considered part of the cingulate
- Many areas of the frontal lobe are multimodal
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8Connections of the Motor and Premotor Areas
- Motor Cortex
- Projects to spinal motor neurons, cranial nerves
that control the face - Projects to the basal ganglia and the red nucleus
- Premotor
- Projections to the spinal cord
- Projections to the motor cortex
9Connections of the Motor and Premotor Areas
- Premotor
- Receives projections from parietal areas PE and
PF - Receives projections from dorsolateral prefrontal
area - Eye fields
- Receive from PG and the superior colliculus
10Connections of the Prefrontal Areas
- End of dorsal and ventral streams of visual input
- Dorsolateral Prefrontal Area
- Reciprocal connections with the posterior
parietal and STS - Extensive connections with the cingulate cortex,
basal ganglia, and superior colliculus - Receives input from dopaminergic cells in
tegmentum
11Connections of the Prefrontal Areas
- Orbital Frontal Cortex
- Receives from the temporal lobe, amygdala,
gustatory cortex, somatosensory cortex, olfactory
cortex, dopaminergic cells in tegmentum - Projects to hypothalamus and amygdala
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14A Theory of Frontal-Lobe Function
- Planning and selection
- Persistence and ignoring distracting stimuli
- Memory for what you have already done
- Executive Functions
- Responds to both internal, external, and context
cues
15Functions of the Premotor Cortex
- Selects movements to be executed
- Functions to choose behavior in response to
external cues - An increase in activity in the premotor cortex is
seen when cues become associated with movement
16Functions of the Prefrontal Cortex
- Controls cognitive processes so that appropriate
movements are selected at the correct time - Internal Cues
- Temporal memory Memory for what has just
happened - External Cues
- Feedback about rewarding properties of stimuli
- Orbital Frontal Cortex - Learning by association
17Functions of the Prefrontal Cortex
- Context Cues
- Orbital Frontal - Social Interactions
- Autonoetic Awareness
- Self knowledge
- Binding together the awareness of oneself as
continuous through time
18Asymmetry of the Frontal Lobes
- Left
- Language
- Encoding memories
- Right
- Nonverbal movements, facial expression
- Retrieving memories
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20Heterogeneity of Frontal-Lobe Function
- Frontal lobes perform a variety of functions
- Frontal damage is unlikely to produce impairment
to all functions
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22Snapshot Heterogeneity of Function in the
Orbitofrontal Cortex
- Stephen Frey and Michael Petrides
- Examined functions of the orbital region using
PET - Increased activity in area 13 to unpleasant
auditory stimuli - Increased activity in area 11 when learning new
visual information - Functional dissociation between the two areas
- Area 13 Responds to affective qualities
- Area 11 Processes new visual information
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24Symptoms of Frontal Lobe Lesions
- Disturbances of Motor Function
- Loss of fine movements, speed, and strength
- Typically appears after damage to the primary
motor cortex - Loss of movement programming
- Damage to the premotor or dorsolateral cortex
- Changes in voluntary gaze
- Damage to the frontal eye fields
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26Symptoms of Frontal Lobe Lesions
- Disturbances of Motor Function
- Corollary discharge or reafference
- Internal neural signal that movement will occur
- Frontal lobe damage disrupts corollary discharge
- Speech Problems
- Damage to Brocas area
- Agrammatism
- Damage to the supplementary motor cortex
- Mute
27Symptoms of Frontal Lobe Lesions
- Convergent vs. Divergent Thinking
- Convergent thinking Only one answer to the
question - Divergent thinking Questions that ask for a
variety of responses - Frontal lobe patients are impaired on divergent
thinking - Loss of behavioral spontaneity
- Decreased verbal fluency
- Decreased design fluency
- Reduction in general behaviors
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30Symptoms of Frontal Lobe Lesions
- Increased perseveration
- Inability to form a strategy
- Larger deficit when completing novel tasks
- Loss of response inhibition
- The Wisconsin Card Sorting Task
- The Stroop Test
31The Wisconsin Card Sorting Test
32The Stroop Test
33Symptoms of Frontal Lobe Lesions
- Take more risks
- Iowa Gambling Task
- Appears after damage to
- the orbitofrontal cortex
- Deficits in self-regulation
- Loss of associative learning
- Inability to select from
- competing responses
34Testing Associative Learning
35Symptoms of Frontal Lobe Lesions
- Poor Temporal Memory
- Five animal experiments indicate a role for the
frontal lobe in temporal memory - Area 46
- Role in providing an internal representation of
spatial information - Active during delayed response test
- Medial regions
- Role in object recognition
36Experiments Showing Deficits of Temporal Memory
37Symptoms of Frontal Lobe Lesions
- Poor Temporal Memory
- Studying Temporal Memory in Humans
- Recency memory
- Tests memory for the order in which things have
occurred - Frontal lobe patients show impairment on this
task - Recent Findings on Temporal Memory
- Critical role for the prefrontal cortex
- Fuster and colleagues
- Single cell recording of sensory associations
across time
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39Symptoms of Frontal Lobe Lesions
- Impaired social and sexual behavior
- Example Phineas Gage
40Symptoms of Frontal Lobe Lesions
- Impaired social and sexual behavior
- Changes in personality
- Pseudodepression
- Appears after lesions of the left frontal lobe
- Outward apathy, indifference, loss of initiative
- Reduced sexual interest, Little or no verbal
output - Pseudopsychopathy
- Appears after lesions of the right frontal lobe
- Immature behavior, lack of tact and restraint
- Promiscuous sexual behavior
- Coarse language, lack of social graces, increased
motor activity
41Symptoms of Frontal Lobe Lesions
- Impaired social and sexual behavior
- Deficits in Social and sexual behavior
- Orbitofrontal lesions
- Reduce inhibitions and may introduce abnormal
sexual behavior - Leads to deficits in identifying facial
expressions - Dorsolateral lesions
- Reduce interest in sexual behavior
42Symptoms of Frontal Lobe Lesions
- Spatial Deficits?
- May be a role for the frontal lobe in selecting
visual locations - Symptoms Associated with Damage to the Frontal
Facial Area - Sensory and motor functions of the face are
preserved after damage - Left Loss of verbal fluency
- Right Loss of design fluency
43Clinical Neuropsychological Assessment of Frontal
Lobe Damage
44Imaging Frontal Lobe Function
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46Diseases Affecting the Frontal Lobe
- Schizophrenia
- Abnormality in the mesocortical dopaminergic
projection - Decrease in blood flow to the frontal lobes, and
frontal lobe atrophy - Parkinsons Disease
- Loss of dopamine cells in the substantia nigra
that project to the prefrontal cortex - Korsakoffs
- Alcohol-induced damage to the dorsomedial
thalamus and a deficiency in frontal lobe
catecholamines