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The Frontal Lobes

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Became disorganized, showed little emotion, and began to miss ... Agrammatism. Damage to the supplementary motor cortex. Mute. Symptoms of Frontal Lobe Lesions ... – PowerPoint PPT presentation

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Title: The Frontal Lobes


1
Bryan Kolb Ian Q. Whishaws
Fundamentals of Human Neuropsychology, Sixth
Edition Chapter 15 Lecture PPT
Prepared by Gina Mollet, Adams State College
2
The Frontal Lobes
3
Portrait 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

4
Anatomy 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

5
Anatomy 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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Connections 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

9
Connections 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

10
Connections 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

11
Connections 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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A 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

15
Functions 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

16
Functions 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

17
Functions of the Prefrontal Cortex
  • Context Cues
  • Orbital Frontal - Social Interactions
  • Autonoetic Awareness
  • Self knowledge
  • Binding together the awareness of oneself as
    continuous through time

18
Asymmetry of the Frontal Lobes
  • Left
  • Language
  • Encoding memories
  • Right
  • Nonverbal movements, facial expression
  • Retrieving memories

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Heterogeneity 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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Snapshot 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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Symptoms 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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Symptoms 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

27
Symptoms 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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Symptoms 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

31
The Wisconsin Card Sorting Test
32
The Stroop Test
33
Symptoms 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

34
Testing Associative Learning
35
Symptoms 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

36
Experiments Showing Deficits of Temporal Memory
37
Symptoms 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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Symptoms of Frontal Lobe Lesions
  • Impaired social and sexual behavior
  • Example Phineas Gage

40
Symptoms 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

41
Symptoms 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

42
Symptoms 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

43
Clinical Neuropsychological Assessment of Frontal
Lobe Damage
44
Imaging Frontal Lobe Function
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Diseases 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
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