2. Frontal Lobe
Largest of all lobes
Sagitally : ~ 1/3rd of the cerebral hemisphere
3 major areas in each lobe
Dorsolateral aspect
Medial aspect
Inferior orbital aspect
3. Lateral surface frontal lobe
Precentral sulcus – parallel to central sulcus, between them precentral gyrus
Sup and inf frontal sulci divide sup, middle and inf frontal gyri
4. Medial surface Frontal lobe
Between cingulate sulcus and superior medial margin of hemisphere
Posterior part vertical sulcus – paracentral lobule
5. Orbital surface Frontal lobe
Divided into four orbital gyri by
a well-marked H-shaped orbital
sulcus.
The medial, anterior, lateral,
and posterior orbital gyri.
the olfactory sulcus, for the
olfactory tract;
the portion medial to this is
named the straight gyrus, and
is continuous with the superior
frontal gyrus on the medial
surface.
6. Vascular supply
Medial parts of frontal lobe: Anterior cerebral
artery
Convexity : Superior (rolandic) division of MCA
Inferior surface: ACA and MCA
Underlying deep white matter: penetrating arteries
(lenticulostriate) from stem of MCA
7.
8. Primary Motor Cortex
Precentral gyrus; Brodmann’s Area 4
Input
thalamus, BG, sensory, premotor
Output
motor fibers to brainstem and spinal cord
Function
executes design into movement
Lesions
/ tone; power; fine motor function on contralateral
side
9. Bedside tests
1. Motor strength of hand grip.
The patient is asked to grip the examiners fingers.
Strength should be roughly equal, with greater strength on the
dominant side. It should be difficult for the examiner to free her/his
fingers.
2. Motor speed as in finger tapping;
but does not discriminate from the premotor cortex.
poor performances suggest
local lesions - vascular or neoplastic
generalized lesion - degenerative disease
10. Pre Motor Cortex
Sup. Frontal gyrus Lat. Surface; Brodmann Area 6,8
Input
thalamus, BG, sensory cortex
Output
primary motor cortex
Function
Planning complex movements; controls coarse postural
movements
Lesions
moderate weakness in proximal muscles on contralateral side
11. 1. Sensorimotor abilities
asking the patient touch each finger to the thumb in succession
as rapidly as possible. Watch for speed and dexterity.
2. Apraxia
to demonstrate the use of a shovel.
12. Supplementary Motor Cortex
Sup. Frontal gyrus Med. Surface; Brodmann’s area 6,8
Input
cingulate gyrus, thalamus, sensory & prefrontal cortex
Output
premotor, primary motor
Function
intentional preparation for movement; procedural memory
Lesions
mutism, akinesia
13. Frontal eye fields
Middle Frontal Gyrus; Broadman’s area 8
Input
parietal / temporal (ventral = what is target)
posterior parietal cortex (dorsal = where is target)
Output
caudate; superior colliculus; PPRF
Function
executive: selects target and commands movement (saccades)
Lesion
eyes deviate ipsilaterally with destructive lesion
contralaterally with irritating lesions
14. Voluntary eye movements are of two types.
Pursuit.
Saccades.
Bedside test:
1. Ask the patient to follow the movement of a finger from left
to right and up and down.
2. Ask the patient to look from left to right, up and down (with
no finger to follow).
Note inability to move or jerky movement.
15. Broca’s speech area
Inf. Frontal Gyrus (Pars Triangularis &Pars Opercularis)
Brodman’s area 44,45
Input
Wernicke’s
Output
primary motor cortex
Function
speech production (dominant hemisphere); emotional,
melodic component of speech (non-dominant)
Lesions
motor aphasia; monotonous speech
16. Asymmetry of the Frontal Lobes
Left
Language
Encoding memories
Right
Nonverbal movements, facial expression
Retrieving memories
17. Functional Frontal Lobe Anatomy
Five ‘frontal sub cortical circuits’
1. Motor
2. Oculomotor
3. Dorsolateral prefrontal
4. Lateral orbitofrontal
5. Anterior cingulate
18. 1. Frontal subcortical Motor Circuit
Supplementary Motor & Premotor :
planning, initiation & storage of motor programs; fine-tuning of movements
Motor :
final station for execution of the movement according to the design
SMA,
Premotor,
Motor
Caudate
Globus
Pallidus
Thalamus
VL,VA,CM
Hypo-
thalamus
19. 2.Frontal Oculomotor Circuit
Voluntary scanning eye movement
Independent of visual stimuli
Frontal
Eye field
Central
Caudate
DM Globus
Pallidus &
Substantia Nigra
Thalamus
VA, MD
20. 3.Dorsolateral Prefrontal Circuit
Executive functions:
motor planning, deciding which stimuli to attend to, shifting cognitive sets
Attention span and working memory
Lateral
Pre-Frontal
DL
Caudate
DM Globus
Pallidus &
Substantia
Nigra
Thalamus
VA, MD
21. 4. Lateral Orbitofrontal Circuit
Emotional life and personality structure
Infero-
Lateral
Pre-Frontal
VM
Caudate
DM Globus
Pallidus &
Substantia
Nigra
Thalamus
VA, MD
Orbito-
Frontal
23. 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
Changes in voluntary gaze
Damage to frontal eye field
Change in speech
Motor aphasia; dysprosody (monotonous speech)
Speech is sparse, slow, hesitant, disturbance of rhythm
and articulation, difficulty in word finding, wrong
words are chosen & often mispronounced,
perseveration, agrammatism
telegraphic language
24. Dorsolateral prefrontal lobe syndrome
Executive dysfunction.
Inability to organize & plan.
Inability to initiate, stop and modify behavior in
response to changing stimuli.
Impaired problem solving
Inability to inhibit responses
Perseveration & inability to shift thought process
Impaired fluency
Memory problems:
Defective working memory.
Defective retrieval.
Impaired attention.
Lack of initiative & spontaneity.
Impaired abstract thinking
Impaired problem solving, creativity
Impaired language & verbal fluency
25. Orbit frontal syndrome
Disinhibition and impulsivity of thought,
affection and action
Failure to appreciate consequences of one’s
action.
A flat affect, blunted emotional response.
Imitation and utilization behavior
Euphoria, hypomania, Grandiosity
26. Anterior cingulate syndrome
Akinetic mutism
Represents a wakeful state of profound apathy, with indifference to
pain, thirst & hunger and absence of motor & psychic initiative.
Manifested by lack of spontaneous movement, absent verbalization
and failure to respond to questions & commands
Abulia -- similar but less severe , lack of spontaneity, apathy, and
paucity of speech and movement
28. Bilateral Frontal lobe lesion
1. Apathy, Abulia, akinetic mutism,
2. Impulsiveness and irritability
3. Inability to sustain attention
4. gait disturbances
5. Sphincter disturbance
6. Active learning, problem solving, judgment:- impaired
7. Frontal release sign
a. Snout
b. Suck
c. Palmomental
d. Grasp
e. Brow tapping
29. Frontal Assessment Battery
1. Similarities (conceptualization)
2. Lexical fluency (mental flexibility)
3. Motor series “Luria” test (programming)
4. Conflicting instructions (sensitivity to interference)
5. Go–No Go (inhibitory control)
6. Prehension behavior (environmental autonomy)
Interpreting results
A cut off score of 12 out of 18 on the FAB has a sensitivity of 77% and
specificity of 87% in differentiating between frontal dysexecutive type
dementias and DAT
30. Similarities (conceptualization)
“In what way are they alike?” A banana and a orange
(In the event of total failure: “they are not alike” or partial failure “both
have a peel”, help the patient by saying “both a banana and an orange
are….”; but credit 0 for the item; do not help the patient for the two
following items)
A table and a chair
A tulip, a rose, and a daisy
Score: only category responses (fruits, furniture, flowers) are considered
correct.
Three correct: 3
Two correct: 2
One correct: 1
None correct: 0
31. Lexical fluency (mental flexibility)
Say as many words as you can beginning with the letter ‘S,’
any words except surnames or proper nouns.”
If the patient gives no response during the first 5 seconds, say:" for
instance, snake.” If the patient pauses 10 seconds, stimulate him by
saying: “any word beginning with the letter ‘S.’ The time allowed is 60
seconds.
Score (word repetitions or variations [shoe, shoemaker], surnames, or
proper nouns are not counted as correct responses)
More than nine words: 3
Six to nine words: 2
Three to five words: 1
Less than three words: 0
Controlled oral word association test (COWAT)
32. Motor series (programming)
“Look carefully at what I’m doing.”
The examiner performs alone three times with his left hand the series of
Luria “fist–edge–palm.” “Now, with your right hand do the same series,
first with me, then alone.” The examiner performs the series three times
with the patient, then says to him/her: “Now, do it on your own.”
Score
six correct consecutive series alone: 3
at least three correct consecutive series alone: 2
fails alone, but performs 3 correct consecutive series with examiner: 1
cannot perform 3 correct consecutive series even with the examiner: 0
33. Conflicting instructions (sensitivity to
interference)
“Tap twice when I tap once.”
To be sure that the patient has understood the instruction, a series of three trials is
run: 1-1-1.
“Tap once when I tap twice.”
To be sure that the patient has understood the instruction, a series of three trials is
run: 2-2-2.
The examiner performs the following series: 1-1-2-1-2-2-2-1-1-2.
Score
No error: 3
One or two errors: 2
More than two errors: 1
Patient taps like the examiner at least four consecutive times: 0
34. Go–No Go (inhibitory control)
“Tap once when I tap once.”
To be sure that the patient has understood the instruction, a
series of three trials is run: 1-1-1.
“Do not tap when I tap twice.”
To be sure that the patient has understood the instruction, a series of 3
trials is run: 2-2-2.
The examiner performs the
following series: 1-1-2-1-2-2-2-1-1-2.
Score
No error: 3
One or two errors: 2
More than two errors: 1
Patient taps like the examiner at least four consecutive times: 0
35. Prehension behavior (environmental
autonomy)
“Do not take my hands.”
The examiner is seated in front of the patient. Place the patient’s hands
palm up on his knees. Without saying anything or looking at the patient,
the examiner brings his hands close to the patient’s and touches the
palms of both the patient’s hands
If the patient takes the hands, the examiner will try again after asking
him/her: “Now, do not take my hands.”
Score
Patient does not take the examiner’s hands: 3
Patient hesitates and asks what he/she has to do: 2
Patient takes the hands without hesitation: 1
Patient takes the examiner’s hand even after he/she has been
told not to do so: 0
36. Post Graduates (in) Medicine Learning Some Concepts
P Prehension Orbitofrontal
G Go-No-Go “
M Motor series dorsolateral
L Lexical fluency “
S similarities “
C Conflicting insturctns “
37. History in frontal lobe pathology
Personality changes (over familiar, tactless and
sexual indiscretions)
Hyperorality
Distractibility
Poor motivation
Inability to adapt to new situations
Poor problem solving skills
38. Tests at bedside
Abstract thinking: Proverb interpretation
FAB
Cognitive estimates
“What is the height of an average woman”?
Primitive reflexes
Neurological test
Check for anosmia (olfactory nerve involvement)
Motor aphasia (Broca’s area involvement)
39. Formal Tests
• Wisconsin Card Sorting Test
• Trail Making
• Stroop Color & Word Test
• Tower of London Test
• Block design
• Maze lest
40. Wisconsin Card Sorting Test
“Please sort the 60 cards under
the 4 samples.
I won’t tell you the rule, but I will
announce every mistake.
The rule will change after 10
correct placements.”
Used to assess the following "frontal" lobe functions:
•strategic planning,
•organized searching,
•shift cognitive sets,
•directing behavior toward a goal
•modulating impulsive responding.
41. Trail Making Test
A
C1
2
7
3 D
5 B
4
6
Various levels of difficulty:
1. “Please connect the letters in alphabetical order as fast as you can.”
2. “Repeat, as in ‘1’ but alternate with numbers in increasing order”
•visual search
speed
•scanning,
•speed of
processing,
•mental
flexibility,
•executive
functioning.
42. Stroop Color and Word Tests
To test attention, cognitive inhibiton
Lesion : Left ventro-lateral aspect of frontal / orbito-frontal
RED BLUE ORANGE YELLOW
GREEN RED PURPLE RED
GREEN YELLOW BLUE RED
YELLOW ORANGE RED GREEN
BLUE GREEN PURPLE RED
“Please read this as fast as you can”
43. Tower of London Tests
Use:for the assessment of executive functioning
(specifically planning)
Various levels of difficulty:
e.g. “Please rearrange the balls on the pegs, so that each peg has
one ball only. Use as few movements as possible”
44. Frontal lobe epilepsy
Clinical Features
Frequent seizure with clustering
Brief stereotyped
Nocturnal
Sudden onset and cessation
No psychic aura or postictal confusion
Rapid evolution with awareness lost at onset
Prominent complex bilateral motor automatism involving lower limbs
Prominent ictal posturing and tonic spasm
Versive head and eye turning
Bizarre automatism
Frequent secondary generalization
Status epilepticus common
45. Frontal lobe epilepsy
EEG
May show no ictal or interictal abnormality
May show bilateral spike waves
May show focal changes often widespread
Imaging/ pathology
Hemartoma
Benign tumors
Gliomas
Angioma
Dysplasia
Post traumatic
Atrophy
Tuberculoma
Cysticercosis