Frontal Cortex

1
Frontal Cortex
2
Frontal Lobes

• Traditionally considered to be the seat of
  intelligence.
• This is probably because
• The frontal cortex is the most recent to evolve.
• Humans have particularly large frontal lobes
  compared to other animals.
• The frontal cortex is the brain lobe least
  amenable to quantitative testing.

3
(No Transcript)
4
(No Transcript)
5
Divisions of the Frontal Cortex

1. Motor cortex
2. Premotor cortex
3. Prefrontal cortex
4. Orbitofrontal Ventromedial prefrontal cortex
5. Anterior cingulate gyrus
6. Brocas area

6
Divisions of the Frontal Cortex
7
Primary Motor Cortex
8
Prefrontal Cortex
9
Working memory

• Refers to the capacity to keep track of and
  update information at the moment
• E.g., 7 - 2
•  Patricia Goldman-Rakic
•  ODR paradigm (oculomotor delayed-response)
•  Electrodes record activity from monkey neurons
  during the task.
•  Different neurons respond to different task
  characteristics.

10

• Regional Specialization
• Superior prefrontal convexity (dorsal) spatial
  location
• Inferior prefrontal convexity (ventral)objects,
  faces

11
(No Transcript)
12
Impaired Response Inhibition

• Stroop

13
Purple Red Green Black Blue Yellow Green Red Purpl
e Blue
Blue Brown Blue Red Green Green Yellow Red Yellow
Orange

• Green
• Yellow
• Red
• Purple
• Blue
• Red
• Black
• Yellow
• Orange
• Blue

14
Purple Red Green Black Blue Yellow Green Red Purpl
e Blue
Green Yellow Red Yellow Orange Blue Brown Blue Red
Green

• Blue
• Red
• Green
• Yellow
• Black
• Yellow
• Orange
• Red
• Purple
• Blue

15
Perseveration

• Carries timing task with frontals

16
Shifting Difficulty

• Reduced fluency
• Generate animals beginning with C
• Difficulty generating hypotheses and flexibly
  shifting to new task demands

17
Wisconsin Card Sort Task (WCST)
Test Cards
18
(No Transcript)
19
Wisconsin Card Sorting Task (WCST)
20
Alternating Sequencing Deficits
21
VIDEO Picks Disease
22
Alternating Sequencing Deficits

1. Motor
2. Planning organizing tasks
3. Developing strategies for learning new tasks

23
Frontal Eye Fields
24
Exploratory Eye Movement Deficits
25
Other Dorsolateral Deficits

1. Pseudo-depression
2. Perceptual deficits
3. Corollary discharge

26
Mirror Neurons Characteristic Firing
Properties of Inferior DLPFC

• Motor
• Visual
• Somatosensory
• Body-part centered

(Fadiga et al., 2000)
27
Mirror Propertyof Human DLPFC
(Iacoboni et al., 1999)
28
Orbitofrontal Ventromedial Prefrontal Cortex
29
Phineas Gage
30
(No Transcript)
31
(No Transcript)
32
The Case of Phineas Gage
An explosion projected a tamping rod through his
left cheek. Miraculously, he recovered and had
normal intellegence.
Months later, however, Gage began to have
startling changes in personality and in mood.
He became extravagant and anti-social, a
fullmouth and a liar with bad manners, and could
no longer hold a job or plan his future.   He
was quick to anger and often got into fights.
"The equilibrium between his intellectual
faculties and animal propensities seems to have
been destroyed. - Harlow
33

• This is hypothesized to occur as a result of
  impoverished social learning as a result of
  failure to make appropriate mappings between
  events and their outcomes.

34
Personality Changes

• Lack of concern for the future
• Consistently poor decision-making 
• Impulsiveness
• Failure to obey rules
• Lack of social graces
• Disposed to imitation

35
Personality Changes II

• Mild euphoria
• Silliness facetiousness
• Pseudo-depression
• Irritability

36
Orbitofrontal Cortex
Decision-Making
Reinforcement Value of Sensory Stimuli
Empathy
37
Orbitofrontal Cortex

• Secondary odor taste cortices
• Deficits in perceiving auditory or visual
  emotional cues
• Can be Modality Specific
• Cells respond to the rewarding or aversive nature
  of stimuli
• Primary reinforcers
• Learned (secondary) Reinforcers

• Cells respond better to real than to 2-D faces
• Cells respond preferentially to specific faces
• Cells change their response to objects when
  reward associations change

38
Anterior Cingulate
39
Anterior Cingulate

• Bilateral lesions produce
• Akinetic mutisminability to initiate speech
•  Minimal movement
•  Incontinence
•  No emotional display to pain
•  Profound apathy
•  Indifference

40

• Striatum Pict Sagittal?

41
5 Frontal-Subcortical Circuits

1. Motor
2. Oculomotor
3. Dorsolateral prefrontal
4. Lateral orbitofrontal
5. Anterior cingulate

42
Frontal-Subcortical Circuits II

• Frontal lobe ?
• Striatum (caudate, putamen, ventral striatum) ?
• Globus pallidus Substantia nigra ?
• Specific thalamic nuclei ?
• Frontal lobe

43
Summary I

• Motor cortex
• Loss of voluntary control over a specific body
  area
• Deficits of fine motor control
• Reduction of strength speed
• Premotor cortex
• Impairs the integration of sequences into fluid
  actions
• Reflex changes (i.e., grasp reflex)

44
Summary II

• Prefrontal cortex
• Working memory problems
• (superiorwhere inferiorwhat)
• Difficulty generating new items or hypotheses
• Lack of inhibition
• Perseveration
• Difficulty planning sequences or organizing
  strategies
• Eye movement deficits

45
Summary III

• Orbitofrontal
• Ventromedial prefrontal cortex
• Personality emotional changes
• Disregard for rules
• Imitation
• No IQ or dorsolateral problems
• Anterior cingulate
• Problems with initiating movements
• Apathy
• No emotional response to pain