This is a medical grade presentation on Neurology- Frontal lobe clinical anatomy, physiology, functions, diseases. Can be used as last minute revision and notes on frontal lobe with easy pointers to remember.

1. FRONTAL LOBE
Dr. Suranjana Basak
DrNB Senior Registrar, Dept. Of Neurology
Fortis Hospital, Mohali

3. ✤ Precentral gyrus (motor strip) lies just anterior to central sulcus
✤ On medial surface, frontal lobe extends to cingulate sulcus
✤ Paracentral lobule = extensions of pre central + post central gyri
onto the medial hemisphere above cingulate sulcus. Bladder control.
Anatomy
Medial Surface
Lateral Surface

4. Important Areas
✤ Supplementary motor & premotor regions
- area 6 anterior to pre central gyrus.
✤ Premotor area area - anterior to primary
motor cortex
✤ Frontal eye fields in middle frontal gyrus
✤ Inferior frontal gyrus :
i. Pars Orbitalis
ii. Pars Triangularis
iii. Pars Opercularis

5. Inferior surface
✤ Pars Opercularis and Triangularis (Dominant) -
Motor Speech Area/ Bro’s ( Areas 44,45)
✤ Inferior surface medial to inferior frontal gyrus =
Orbital Gyri
✤ Separated by olfactory sulcus from gyrus rectus
= most medial structure on orbital surface
✤ Olfactory bulbs and tracts overlie the olfactory
sulcus

6. Frontal Lobe Functional Anatomy
✤ Motor Cortex
i. Primary (BA 4)
ii. Premotor (BA 6 Lateral)
iii. Supplementary (BA 6 Medial)
iv. Frontal Eye Field (BA 8)
v. Broca’s Speech Area (BA 44,45)
✤ Prefrontal cortex
i. Dorsolateral prefrontal cortex
(DLPFC)
ii. Medial prefrontal cortex (MPC)
iii. Orbitofrontal cortex (OFC)

7. Blood Supply of Frontal Lobe
Blue- Anterior Cerebral Artery, Pink - Middle Cerebral Artery, Yellow - Posterior Cerebral Artery
Lateral Medial

8. Primary Motor Cortex M1/Area 4
✤ Location: Anterior wall of central sulcus &
adjacent portions of pre central gyrus
✤ Lowest threshold for stimulation to cause
muscle contraction of opposite side of body
✤ Cortex of M1 - Agranular, heterotypical. Most
characteristic feature - presence of giant
pyramidal neurone (Betz cells) in lamina V
✤ Localisation of function within the pre central
gyrus is depicted by motor homunculus
Area Gigantopyramidalis

9. Motor Homunculus
✤ Homunculus - distorted figure with size of an
anatomical part proportional to the amount of
cortex to which it is related.
✤ The phylogenetic acquisition of speech & complex
hand function has caused expansion of cortical
areas representing the tongue, mouth, lips, thumb
& fingers
✤ Neurons controlling the lower extremities and
perineal musculature are in the paracentral lobule,
which plays an important role in bowel and bladder

10. Functions of Primary Motor Cortex
✤ Conscious control of voluntary movement
✤ Encodes parameters defining individual movements or simple movement
sequences
✤ Encodes force, direction, extent and speed of the movement

11. Area 6
✤ Similar to Area 4 except for absence of giant bets cells. But much greater developed layer 3
✤ Regulation of autonomic and motor processes
✤ Stimulation of area 6 and area 8 cause deviation of head and eyes to opposite side and complex limb
movements
✤ Depression or inhibition of motor activity at lower levels of brain
✤ Central regulation of autonomic processes
✤ Vogt and Vogt (1935) observed that extirpation of the premotorcortex does not cause permanent paralysis, but
leads to disturbance of skilled movements & appearance of spasticity & rigidity of movements, grasping reflexes
and vasomotor disorders.
✤ Lesions of the more anterior and medial parts of the motor cortex cause less paralysis and more spasticity and
may allow the emergence of primitive reflexes, such as grasping and groping responses.

12. Pre Motor Cortex
✤ Location: Anterior to primary cortex between pre
central gyrus and posterior border of prefrontal
area (area 6)
✤ Planning & execution of movements (basis of
Luria’s hand sequence/fist-edge-palm test)
✤ Receives afferents from other areas of the cortex
incl. sensory cortex and projects to the motor
cortex and motor thalamus
✤ Some fibres descend and make up a part of
extrapyramidal system

13. Functions of Pre Motor Cortex
✤ Sensorimotor integration
✤ Lesions cause inability to make use of sensory feedback in the performance of
smooth movements
✤ Performs more complex, task related processing than primary motor cortex
✤ Controls learned, repetitive or patterned motor skills
✤ Lesion: Inability to make use of sensory feedback in performance of smooth
movements and apraxia

14. Supplementary Motor Area
✤ Areas of cortex lying on medial aspect of hemisphere
just anterior to primary motor cortex
✤ Planning motor movements such as a sequence of
actions provided from memory
✤ Crucial for temporal organization of multiple movements
✤ Lesions of SMA impair memory based sequencing of
movements
✤ Also coordinates movements between hands and lesions
in this area may cause Alien Hand syndrome

15. Syndrome of SMA
✤ Not well recognized and can easily be confused with corticospinal
weakness.
✤ Patients have reduced spontaneous movements and difficulty in performing
volitional motor acts to command in the contralateral limbs, although the
limbs function normally in automatic motor activities, for example, dressing
✤ Lesion: Mutism, contralateral motor neglect, impairment of bibrachial
coordination

16. Other Clinical Aspects
✤ Seizures may arise as simple partial or complex partial. Seizures arising from
motor cortex typically produce focal Jacksonian epilepsy of contralateral limbs
✤ Partial complex seizures arising from frontal lobe are bizarre and likely confused
with pseudoseizures
✤ M1 receives association fibres from premotor and supplementary motor areas
and insula
✤ These connections are involved in preparation and planning for voluntary
movements that are then executed by the primary motor cortex

18. Decoding a Motor Command
1. Reception and decoding of a motor command in Wernickes
area
2. Transmission through the arcuate fasciculus
3. To the left premotor area
4. To the left motor cortex
5. Transmission information across the corpus callosum
6. To the right premotor area
7. To the right motor cortex
Apraxic syndromes may occur with lesions along these pathways

19. Frontal Eye Field / Area 8
✤ Located anterior to the premotor cortex and superior to
Broca’s area in caudal part of middle frontal gyrus(BA-8)
✤ Centre for voluntary eye movements independent of visual
stimuli
✤ Participates in initiation of voluntary horizontal saccades
✤ The FEF controls horizontal conjugate saccades to the
opposite side
✤ Left FEF initiates a command to look right.
✤ Lesion: Eyes deviate ipsilaterally with destructive lesion &
contralaterally with irritating lesions

20. ✤ The saccadic pathway arises in the frontal lobe and descends to
the contralateral pons
✤ A left FEF-initiated command to look right is thus transmitted
down to the right PPRF, which simultaneously influences the right
sixth nerve to contract the lateral rectus and the left third nerve to
contract the yoked medial rectus—both contract, according to
Hering’s law, exactly the same amount

21. Broca’s Area/ Area 44
✤ Location: Inferior frontal gyrus.
✤ In the majority of individuals, this area lies on the left or
dominant hemisphere.
✤ Input: Wernicke’s area
✤ Output: primary motor cortex
✤ Function: speech production (dominant hemisphere);
emotional, melodic component of speech (non-dominant)
✤ Lesions: motor aphasia

22. Broca’s Aphasia
✤ Speech : Nonfluent, labored, interrupted by many word-finding pauses, and usually dysarthric.
✤ It is impoverished in function words but enriched in meaning-appropriate nouns.
✤ Speech is telegraphic but quite informative.
✤ Output may be reduced
✤ In addition, fluency, naming and repetition are impaired.
✤ Comprehension of spoken language is intact except for syntactically difficult sentences with a passive voice
structure or embedded clauses, indicating that Broca’s aphasia is not just an “expressive” or “motor” disorder
and that it also may involve a comprehension deficit in decoding syntax.
✤ The cause is most often infarction of Broca’s area (the inferior frontal convolution and surrounding anterior
perisylvian and insular cortex due to occlusion of the superior division of the MCA). Mass lesions, including
tumor, intracerebral hemorrhage, and abscess, also may be responsible.

23. Prefrontal Cortex
✤ Location: Anterior to area 6, area 8, and the
motor speech centers are areas referred to as the
prefrontal cortex. It includes areas 9 to 12, 32, 45,
47, and others.
✤ These areas are connected with the somesthetic,
visual, auditory, and other cortical areas by long
association bundles and with the thalamus and
the hypothalamus by projection fibers.
✤ It is the main projection site for the dorsomedial
nucleus of the thalamus.

24. Clinically PFC divided to:
✤ Dorsolateral Prefrontal Cortex (DLPFC)
✤ Medial Prefrontal Cortex (MPC)
✤ Orbitofrontal Cortex (OFC)

25. Dorsolateral Prefrontal Cortex (DLPFC)
✤ DLPFC is important in the organization of self-ordered tasks. It plays a critical role in the
neural network subserving working memory
✤ The responsibility for executive function largely resides with the DLPFC and its
connections.
✤ Plan, carry out, and monitor a series of actions intended to accomplish a goal. Planning
and organizational skills, the ability to benefit from experience, abstraction, motivation,
cognitive flexibility, and problem solving.
✤ Role as well in the ability to predict the consequences of actions, emotional expression
(affect), “go/no-go” decision making, personality, and the sense of time

26. ✤ The DLPFC is also important in oculomotor control, which is responsible for decision
making regarding voluntary eye movements and inhibiting unwanted reflex saccades.
✤ The dorsolateral prefrontal cortical area may be involved in mechanisms responsible
for inhibiting unwanted saccades. Antisaccades are voluntary saccades away from a
target
✤ Patients with frontal lobe disease, progressive supranuclear palsy, Parkinson’s
disease, Alzheimer’s disease, and schizophrenia, when asked to look away from a
visual stimulus, may be unable to inhibit a saccade toward the target (prosaccade) and
are therefore unable to make an antisaccade or make it only after a prosaccade.
Dorsolateral Prefrontal Cortex (DLPFC)

27. Medial Prefrontal Cortex (MPC)
✤ MPC has connections with the several thalamic nuclei, particularly the
dorsomedian, and with the superior temporal cortex. There are connections
with other portions of the frontal lobe, including the OFC, the DLPFC and the
medial motor areas. The MPC is important in auditory and visual associations.
✤ The ventrolateral prefrontal cortex is concerned with mnemonic processing of
objects.
✤ The anterior cingulate gyrus circuit is associated with motivation, will power,
initiation of activity

28. Orbitofrontal Cortex (OFC)
✤ OFC has important connections with the limbic system, including the amygdala.
✤ Emotional Behaviour
✤ Arousal
✤ Inhibition
✤ Suppression of distracting signals
✤ Patients with OFC dysfunction are also prone to display emotional lability, poor
judgment and insight, and distractibility.

29. Frontal Subcortical Circuits
✤ Five frontosubcortical circuits described by Goldman Rakic subserve cognition, behavior
and movement.
1. Motor
2. Oculomotor
3. Dorsolateral prefrontal
4. Lateral orbitofrontal
5. Anterior cingulate
Information originates from cerebral cortex -> travels to basal ganglia -> thalamus -> return to cortex

30. ✤ Supplementary Motor & Premotor: planning, initiation & storage of motor programs; fine-tuning of
movements
✤ Motor:final station for execution of the the movement according to the design
SMA,
Premotor,Mo
tor
Putamen VL Globus
Pallidus
VL, VA, CM
Thalamus
Motor Circuit

31. ✤ Independent of visual stimuli
✤ Voluntary scanning eye movement
Frontal Eye
Field Central
Caudate
DM Globus
Pallidus
Substantia
Nigra
VA, MD
Thalamus
Oculomotor Circuit

32. ✤ Executive functions: motor planning, deciding which stimuli to attend to, shifting cognitive sets
✤ Lesions will cause poor organizational strategies, poor memory search strategies, stimulus bound
behaviour, environmental dependency
Lateral
Prefrontal DL
Caudate
DM Globus
Pallidus
Substantia
Nigra
VA
Thalamus
DLPFC Circuit

33. ✤ Connects frontal monitoring functions to the limbic system.
✤ This circuit governs appropriate responses to social cues, empathy, social judgement, and interpersonal
sensitivity,
✤ Dysfunction of this circuit can lead to disinhibition, irritability, aggressive outburst and inappropriate social
response, OCS, emotional incontinence
VM
Caudate
DM Globus
Pallidus
Substantia
Nigra
MD
Thalamus
Orbito-frontal
Orbitofrontal Circuit

34. ✤ Anterior cingulate gyrus involved in motivated behaviour
✤ Lesions in this circuit result in apathy, abulia, impaired motivation, akinetic mutism, poverty of
speech, psychic emptiness, poor response inhibition
Anterior
Cingulate
Gyrus
Ventral
Striatum
RL Globus
Pallidus
Substantia
Nigra
MD
Thalamus
Anterior Cingulate Circuit

35. Executive function
✤ Defined as ‘complex set of cerebral process that operate in non-routine
situations and exert top- down volitional control over cognition and
behavior’.
✤ First order process – working memory, inhibition, monitoring and initiation
✤ Second order executive functions include: planning, organization, resisting
interference, set shifting, affect regulation, and context appropriate
behavior.

36. Working memory
✤ Working memory refers to the temporary maintenance of information that was just
experienced or just retrieved from long term memory.
✤ Rt prefrontal cortex is engaged in spatial working memory task and left is engaged
in verbal working memory task.
✤ Ventrolateral pre frontal cortex involved in the maintanace aspect of working
memory (holding information online)

37. Monitoring
✤ Dorsolateral prefrontal cortex monitor information held with in the working
memory.
✤ Anterior cingulate gyrus monitor one’s own performance. It plays an important role
in performance monitoring in relation to anticipated rewards, requiring both
continuous evaluation of current behaviour and future outcomes associated with
behaviour.

38. Initiation
✤ Medial frontal structures including supplementary motor area, presupplementary
motor area and anterior cingulate gyrus – play an important role in drive, motivation
and the initiation of behaviour.
✤ Medial frontal damage – impairments in initiation of speech and motor movements
✤ B/L damage of ant cingulate- Akinetic mutism

39. Second order executive functions
✤ Planning requires heavy working memory demands. Initial step-
generating and holding within the working memory one or more possible
future events.
✤ Organization – ordering or manipulation of objects, concepts, or responses,
such that the individual items are eventually arranged in a manner
conforms to higher order logic.
✤ Set shifting- ability to intentionally disengage from, current activity and
reengage in different way of thinking and activity.

41. ATTENTION
✤ DIGIT SPAN FORWARD
✤ repeat 3-5; 7-5-8; 3-9-4-8
✤ Tests attention , concentration , immediate memory
✤ Expected performance – 7+/- 2forward
✤ Another test of attention and concentration is a three-step task. For instance, tear a
piece of paper in half, then tear half of it in half, then tear one half in half again, so that
there are three different sizes. Give the patient an instruction such as, “Give the large
piece of paper to me, put the small piece on the bed, and keep the other piece.”

42. Working Memory
✤ BACKWARD DIGIT SPAN
✤ EP – 5+/-1
✤ Reverse digit span should not be more than 2 digits less than forward span.
✤ SERIAL 7s
✤ SPELL WORD BACKWARDS
✤ SAY MONTHS OF THE YEAR BACKWARDS ( Normal < 30 sec)

43. ABSTRACT THINKING (Ex)
✤ SIMILARITIES & DIFFERENCES
✤ FIND ANALOGIES
✤ INTERPRET PROVERBS
✤ Eg: “Don’t cry over splilt milk”
✤ A stich in time saves nine

44. JUDGEMENT
what she would do if she found a sealed, addressed, stamped letter on the
sidewalk, or if she smelled smoke in a crowded theater
Historical information from family members about the patient’s actual judgment
in reallife situations

45. FAB

46. Lexical Fluency

47. LURIA 3 STEP TEST (SET SHIFTING)

48. Fist Edge Palm Test
Gade

49. Conflicting Instructions (sensitivity to interference)
• Tap twice when I tap once.
• To ensure that the patient has understood the instruction, a series of 3
trials is run: 1-1-1.
• Tap once when I tap twice.
• To ensure that the patient has understood the instruction, a series of 3
trials is run: 2-2-2.
• The examiner then performs the following series: 1-1-2-1- 2-2-2-1-1-2.
• Score No errors: 3, 1 -2 errors: 2, > 2 errors: 1

50. Go – No Go (Response inhibition)
• “Tap once when I tap once.”
• “Do not tap when I tap twice.”
• Score No errors: 3, 1 -2 errors: 2, > 2 errors: 1
• Patient taps like the examiner at least four consecutive times: 0

51. Prehension Behaviour
• “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 own
hands close to the patient’s hands and touches the palms of both the patient’s
hands, to see if he will spontaneously take them.
• 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

52. Interpreting Results
• A cut off score of 12 on the FAB has a sensitivity of 77% and
specificity of 87% in differentiating between frontal dysexecutive type
dementias and AD.

54. 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.”

55. WCST
✤ After ten (or six) consecutive correct
sorts, the sorting principle is changed
✤ Responding in accordance to the previous
correct rule is considered a perseverative
error
✤ Provides a measure of the ability to identify
abstract categories and shift cognitive set

56. PERSEVERATION

58. STROOP TEST
✤ Part 1: read aloud color names printed in black ink
✤ Part 2: the patient has to name the color of dots
✤ Part 3: presented with color names printed in color ink. The color of the ink does
not correspond to the color name. Subject must name the color of the ink.
✤ ( response inhibition or ability to overcome cognitive interference )

59. PURPLE RED BLUE YELLOW GREEN BLACK
YELLOW BLACK GREEN PURPLE BLUE RED
_______________________________________________
XXXXX XXXXX XXXXX XXXXX XXXXX XXXXX
XXXXX XXXXX XXXXX XXXXX XXXXX XXXXX
_______________________________________________
RED BLACK GREEN BLUE PURPLE YELLOW
BLUE PURPLE RED BLACK YELLOW GREEN
_____________________________________________
One must resist automatic
tendency to read target word
(red) and instead engage in the
required behaviour of naming
the ink colour

60. FRONTAL RELEASE SIGNS
✤ The grasp reflex is obtained when the examiner's hand is gently inserted into the
palm of the patient's hand. The grasp reflex is fairly specific for a lesion of the
supplementary motor area on the medial surface of the contralateral frontal lobe
✤ The snout reflex is brought about by tapping the upper lip lightly. The contraction
of the muscles causes the mouth to resemble a snout
✤ The palmomental reflex occurs when a disagreeable stimulus is drawn from the
thenar eminence at the wrist up to the base of the thumb. There is ipsilateral
contraction of the orbicularis oris and mentalis muscles