Presenter :Dr. Prashant MishraModerator : Dr. V Sharbandh Raj

OUTLINE: FRONTAL LOBE

1. Evolution2. Anatomy and connections3. Physiology4. Circuits and Neurotransmitters5. Dysfunction

Frontal lobe Syndromes Frontotemporal Lobe Dementia Frontal Lobe Epilepsy Expressive aphasia Schizophrenia Depression

6. Frontal lobeTesting

MAMMALS FRONTAL LOBE EVOLUTION

33% of Brain area Most recently evolved

Well developed only in primates

Human species is due to frontal lobe

Last to develop in ontogeny from age 1-> 6years

Gives our capacity to feel empathy, sympathy, understand humor and when others are being ironic, sarcastic or even deceptive.

FRONTAL LOBE

A. Lateral surface1. Posterior - Central

sulcus2. Inferio-Posterior –

sylvian fissure.

B. Medial surfaceC. Orbital surface

FUNCTIONAL FRONTAL LOBE ANATOMY

Lateral sulcus/Sylvian fissure

Central sulcus

Motor speech area of Broca

Frontal eye field

B 44, 45

B 9, 10, 11, 12

B 8

Primary motor areaPremotor area

Prefrontal area

B6 B4

Supplementarymotor area(medially)

Motor cortex1. Primary 2. Premotor3. Supplementary 4. Frontal eye

field5. Broca’s area

Prefrontal cortex1. Dorsolateral 2. Medial 3. Orbitofrontal

Sub cortical structures

1

2

a

b

cd

MOTOR CORTEX

PRIMARY MOTOR CORTEX

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 contra

lateral side

Motor fibres cross in medulla to opp. side

PRE MOTOR CORTEX Input:

thalamus, BG, sensory cortex

Output: primary motor cortex

Function: stores motor programs; controls coarse postural

movements

Lesions: moderate weakness in proximal muscles on contralateral side

SUPPLEMENTARY MOTOR CORTEX Input:

cingulate gyrus, thalamus, sensory cortex prefrontal cortex

Output: Premotor cortex, primary motor cortex

Function: intentional preparation for movement; procedural memory

Lesions: mutism, akinesis

FRONTAL EYE FIELDS

Input: Parietal cortex Temporal cortex

Output: Caudate nucleus Superior colliculus Paramedian pontine reticular Formation (PPRF)

Function: executive: selects target and commands movement (saccades)

Lesion: eyes deviate ipsilaterally with destructive lesion eyes deviate contralaterally with irritating lesions

BROCA’S SPEECH AREA (AREA 44,45) Input: Wernicke’s area

Output: primary motor cortex

Function: speech production (dominant

hemisphere); emotional, melodic component of

speech (non-dominant)

Lesions: motor aphasia; monotone speech

PRE FRONTAL CORTEX

LATERAL SURFACE FRONTAL LOBE

SULCI Vertical

Central sulcus Precentral sulcus

Horizontal Super frontal

sulcus Inf frontal sulci

• GYRI• Precentral gyrus• Superior frontal gyrus• Middle frontal gyrus• Inf erior frontal gyrus

MEDIAL SURFACE FRONTAL LOBE

Between cingulate sulcus and superior medial margin of hemisphere

Posterior part vertical sulcus

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 medial orbital gyrus presents a well-marked antero-posterior sulcus, the olfactory sulcus, for the olfactory tract; the portion medial to

this is named the gyrus rectus

M L

FUNCTIONAL ANATOMY OF PRE FRONTAL CORTEX

DORSOLATERAL PREFRONTAL CORTEX

Connections: motor / sensory convergence areas, thalamus, globus pallidus, caudate nucleus, substrantia nigra

Functions: motor planning, organization, and regulation monitors and adjusts behavior using ‘working

memory’

Lesions: executive function deficit; disinterest attention to relevant stimuli

Subcortical structures

DLPFC

DORSOMEDIAL PREFRONTAL CORTEX Connections:

temporal cortex parietal cortex thalamus, caudate, GP, substantia

nigra, cingulate cortex

Functions: motivation, initiation of activity

Lesions: Paucity of spontaneous movement and

gesture, Sparse verbal output (repetition may

be preserved), Lower extremity weakness and loss of

sensation, Incontinence

ORBITAL PREFRONTAL CORTEX Connections:

temporal cortex parietal cortex thalamus, globus pallidus, caudate, insula, amygdala

Part of limbic system

Function: emotional input, arousal, suppression of distracting signals Decision making

Lesions: Disinhibited, impulsive behaviour Inappropriate jocular affect, euphoria ,emotional lability, Poor judgment and insight, Distractibility

• The limbic system  • Hippocampus• Amygdalae•  anterior thalamic nuclei• Septum• limbic cortex• Fornix,

• functions including• Emotionbehavior, • motivation, • long-term memory,• olfaction

FIVE ‘FRONTAL SUBCORTICAL CIRCUITS’

1. Motor2. Oculomotor

3. Dorsolateral prefrontal Lateral4. Lateral orbitofrontal Inferior5. Anterior cingulate Medial

Prefrontal cortex

Motor cortex

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

Putamen

Globus Pallidus Thalamus

Hypo-thalamus

2.FRONTAL OCULOMOTOR CIRCUIT

Voluntary scanning eye movement Independent of visual stimuli

Frontal Eye field

Central Caudate

Globus Pallidus &

Substantia Nigra

Thalamus

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

Caudate

Globus Pallidus &Substantia Nigra

Thalamus

4. LATERAL ORBITOFRONTAL CIRCUIT

Emotional life and personality structure Arousal, motivation, affect

Infero-Lateral Pre-Frontal

Caudate

Globus Pallidus &Substantia Nigra

Thalamus

Orbito-Frontal

5. ANTERIOR CINGULATE CIRCUIT

Abulia –lack of initiative Akinetic mutism - neither move nor speak

MDThalamus

Ant. Cingulate

Striatum

Globus Pallidus &Substantia Nigra

Thalamus

NEUROTRANSMITTERS: DOPAMINERGIC TRACTS Origin: ventral tegmental

area in midbrain

Projections: prefrontal cortex

(mesocortical tract limbic system

(mesolimbic tract)

Function: reward; motivation; spontaneity; arousal

Mesocortical tract

2

3

4 1

NEUROTRANSMITTERS: NOREPINEPHRINE TRACTS Origin:

locus ceruleus in brainstem

lateral brainstem tegmentum

Projections: anterior cortex

Functions: alertness, arousal, cognitive processing of

somatosensory information

NEUROTRANSMITTERS: SEROTONIN TRACTS

Origin: raphe nuclei in brainstem

Projections: number of forebrain structures

Function: minor role in

prefrontal cortex; sleep, mood, anxiety, feeding

FRONTAL LOBE FUNCTION

Motor Cognitive Behavior ArousalVoluntary movements

Memory Personality Attention

Planning, Initiation

Problem solving

Social and sexual

Spontaneity Judgment Impulse control

Language Expression

Abstract thinking

Mood and affect

Eye movements

FRONTAL LOBE SYNDROMES

PHINEASE GAGE (1848)On 13th Sept 1848 a

railroad worker, hard working, diligent, reliable, responsible, intelligent, good humored, polite god fearing, family oriented foreman

Following an explosion iron bar drove into frontal lobe

1. He becomes unreliable and fails to come to work and when present he is "lazy."

2. He has no interest in going to church, constantly drinks alcohol, gambles, and "whores about."

3. He is accused of sexually molesting young children.

4. He ignores his wife and children and fails to meet his financial and family obligations.

5. He has lost his sense of humour. 6. He curses constantly and does so

in inappropriate circumstances. 7. Died of status epilepticus in 1861

• executive function deficit;

• disinterest / emotional reactivity;

• attention to relevant stimuli

• emotional lability, • disinhibition, • distractibility,• ‘hyperkinesis’

• apathy;• decreased

drive/awareness/spontaneous movements;

• akinetic-abulic& mutism

Medial

Lateral

Orbital

FROTNAL LOBE SYNDROMES

FRONTAL LOBE SYNDROMES The DLPFC is concerned with planning, strategy formation, and executive function. Abnorm in DLPFC

apathy, personality changes, abulia, and lack of ability to plan or to sequence. patients have poor working memory

The frontal operculum = expression of language. left frontal operculum lesion = Broca aphasia and defective verb

retrieval, right opercular lesions = expressive aprosodia.

Aprosodia is a neurological condition characterized by the inability of a person to properly convey or interpret emotional prosody.

Patients with orbitofrontal lesions shows disinhibition, emotional lability, and memory disorders.

Personality changes from orbital damage include impulsiveness, a jocular attitude, sexual disinhibition, and complete lack of concern for others.

Patients with superior mesial lesions typically develop akinetic mutism.

Patients with inferior mesial (basal forebrain) lesions tend to manifest anterograde and retrograde amnesia and confabulation. 

FRONTAL LOBE SYNDROME -CAUSES Mental retardation Traumatic brain injury

Brain tumors Degenerative dementias including 

Alzheimer disease,  Dementia with lewy bodies,  Parkinsonian dementias, Frontotemporal dementias

Cerebrovascular disease Multiple sclerosis

Schizophrenia Major depression Acute alcohol intoxication and drug abuse

CLINICAL PICTURE Profound change in personality. Lack of initiation and spontanity. Response are sluggish. Occasionally patient are hyperactive and

restless. Mood is often euphoric and out of keeping

with patients situation. Irritability and outbursts are common. Loss of finer senses. Judgements are impaired. Fail to plan and carry through ideas.

FRONTOTEMPORAL LOBE DEMENTIA FTLD is a neurodegenerative disease : frontal and temporal

lobe

Typical age of onset is between 50 and 60 yrs.

In contrast to Alzhiemer Disease, in which memory loss is usually the first symptom, the initial symptoms of FTLD often involve changes in personality, behavior, affective symptoms, and language function.

The core features of FTLD as defined by the Neary criteria (Neary et al., 1998) are early decline in social and personal conduct emotional blunting loss of insight.

FRONTAL LOBE EPILEPSY Frontal lobe epilepsy is characterized by recurrent seizures

arising from the frontal lobes.

In most centers frontal lobe epilepsy accounts for 20-30% of operative procedures involving intractable epilepsy.

Patients with frontal lobe seizures may present with a clear epileptic syndrome or with unusual behavioral or motor manifestations that are not immediately recognizable as seizures - may be associated with facial grimacing, vocalization, or speech arrest.

Seizures often bizarre and may be diagnosed incorrectly as psychogenic

EXPRESSIVE APHASIA Expressive aphasia, known as Broca's

aphasia caused by damage or developmental issues in (area 44,45).

For them, speech is difficult to initiate, non-fluent, labored, and halting.

Similarly, writing is difficult as well. Intonation and stress patterns are deficient. Language is reduced to disjointed words and sentence construction is poor.

Comprehension is generally preserved, meaning interpretation dependent on syntax and phrase structure is substantially impaired.  

Patients who recover go on to say that they knew what they wanted to say but could not express themselves.

SCHIZOPHRENIA & FRONTAL LOBE some schizophrenic symptoms are found in

frontal lobe disorder, in particular that involving dorsolateral prefrontal cortex.

Symptoms included are those of the affective changes, impaired motivation, poor insight.

Evidence EEG studies, in CT scan, with MRI, cerebral blood flow studies. Hypofrontality in PET.

DEPRESSION & FRONTAL LOBE  Right frontal lobe demonstrated increased

activity in response to negative moods whereas left frontal activity decreases.

Not only reductions in left frontal activity, but injuries to the left frontal lobe have been consistently associated with depression, "psycho-motor" retardation, apathy, irritability, and blunted mental functioning. 

In severely depressed patients demonstrate insufficient activation and a significant lower integrated amplitude of the eeg evoked response over the left vs right frontal lobe.

FRONTAL LOBE HISTORY TAKING Personality changes (over familiar, tactless

and sexual indiscretions) Hyperorality Distractibility Poor motivation Inability to adapt to new situations Poor problem solving skills

FRONTAL LOBE TESTS1. Attention2. Memory3. Abstraction4. Judgment5. Planning6. Language7. Motor sequencing

Tests of attention and memoryo Alternative sequence (e.g. copying

MNMN)o Luria’s ‘fist-edge-palm’ test (show 3X)oGo/no-go:

o”tap once if I tap twice, don’t tap if I tap once”

o“tap for A” oread 60 letters at 1/sec; N: < 2

errors

Tests of attention and memory cont’

oDigit spanorepeat 3-52; 3-52-8; 3-52-8-67..” N: >5oRecency test

o“recall sequence of stimuli / events”o Imitation (of examiner) / utilization (of

objects presented)

Tests of abstraction and judgment

o Interpret proverbs (e.g.“the golden hammer opens iron doors”)

o Explain why conceptually linked words are the same (e.g. coat & skirt)

o Plan & structure a sequential set of activities (“how would you bake a cake?”)

o Insight / reaction to own illness

Language testso Thurstone / word fluency test (“recite as

many words beginning with ‘F’ in 1 min as you can, then with ‘A’, ‘S’”); N: >15

oRepetition (Broca’s vs transcortical)o “Ball”o “Methodist”

MOTOR SEQUENCING: KINETIC MELODY1. Hand position test (three-step hand

sequence)2. Rhythm tapping tasks3. Go no go test4. Copying tasks

FRONTAL RELEASE SIGN – PRIMITIVE REFLEXES

Grasp reflex Forceful grapping of object

on touching palm or sole

Sucking reflex By touching the lips

Groping reflex Involuntary following with

hand/eye of moving object

Snout reflex

Palmomental

Glabellar tap

Formal Tests• Abstract thinking and set shifting

• Wisconsin Card Sorting Test• Visuo-motor track, conceptualization, set shift

• Trail Making• Attention, shift sets

• Stroop Color & Word Test• Planning

• Tower of London Test• Block design • Maze lest

Wisconsin Card Sorting Test

• Used to assess the following "frontal" lobe functions: • strategic planning, • organized searching, • utilizing environmental feedback to shift cognitive sets, • directing behavior toward achieving a goal• modulating impulsive responding.

perseverence

Trail Making Test

A

C12

73 D

5 B4

6

It provides information about • visual search speed• scanning, • speed of processing, • mental flexibility, and executive functioning.

Stroop Color and Word Tests

RED BLUE ORANGE YELLOW GREEN RED PURPLE REDGREEN YELLOW BLUE REDYELLOW ORANGE RED GREEN BLUE GREEN PURPLE RED

“Please read this as fast as you can”

Lesion : anterior cingulate cortex and dorsolateral prefrontal cortex

attention, shifting

Tower of London Tests

Use:for the assessment of executive functioning specifically to detect deficits in planning

Reference:

1. CTP 2. OTP3. Snells neuroanatomy4. Internet

Thank You