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frontal lobe ppt svs medical college
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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