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The Frontal Lobe
- 1. THE CASE OF PHINEAS GAGE 1848
- 2. FRONTAL LOBE Dr. Pavithra Arunachaleeswaran JR & PG, Department of Psychiatry, SSIMS & RC.
- 3. LARGEST OF ALL THE LOBES 33% of brain area Well developed in PRIMATES FRONTAL LOBE IS WHAT MAKES A HUMAN, HUMAN Gives us the capacity to feel, empathize sympathize, understand, humor, sarcasm, deception
- 4. LIES ANTERIOR TO THE CENTRAL SULCUS LIES ABOVE THE POSTERIOR RAMUS OF LATERAL SULCUS/ SYLVIAN FISSURE
- 5. PRECENTRAL SULCUS PRECENTRAL GYRUS SUPERIOR & INFERIOR FRONTAL SULCUS SUPERIOR, MIDDLE AND INFERIOR FRONTAL GYRUS SYLVIAN FISSURE – ANTERIOR LIMB ASCENDING LIMB PARS ORBITALIS PARS TRIANGULARIS PARS OPERCULARIS CENTAL SULCUS
- 7. OLFACTORY SULCUS GYRUS RECTUS ORBITAL SULCUS ANTERIOR POSTERIOR MEDIAL LATERAL ORBITAL GYRUS
- 8. FUNCTIONAL ANATOMY OF FRONTAL LOBE
- 9. PRIMARY MOTOR AREA • PRECENTRAL GYRUS – superolateral surface • PARACENTRAL LOBULE – medial surface • BETZ CELLS • PROJECTION FIBLES – corticospinal tract corticonuclear tract • HOMUNCULUS – representation of the body parts in the motor cortex • INVERTED HOMUNCULUS • NOT PROPERTIONAL to the SIZE of the body part • PROPORTIONAL to the INTRICACY of movement needed.
- 10. PREMOTOR AREA • Anterior to motor area • Posterior parts of SUPERIOR, MIDDLE, INFERIOR Frontal Gyri PROGRAMMING & PLANNING INTENDED MOVEMENTS & CONTROL OF MOVEMENTS IN PROGRESS SUPPLEMENTARY MOTOR AREA • Area 4, 6, 8 – medial surface • Movements of contralateral limbs. – when stronger stimulus + • COORDINATED MOVEMENTS between hands ALIEN HAND SYNDROME • PLANNING MOTOR MOVEMENTS • TEMPORAL ORGANIZATION OF MULTIPLE MOVEMENTS • (-) Impair memory based sequencing of movements
- 11. FRONTAL EYE FIELD MOTOR SPEECH AREA • AREA 8 • In the MIDDLE FRONTAL GYRUS • CONJUGATE EYE MOVEMENTS – movement of eyes in opposite direction • GAZE DEVIATION - IPSILATERALLY • AREA 44, 45 • In the INFERIOR FRONTAL GYRUS of DOMINANT HEMISPHERE • INJURY - APHASIA
- 12. PREFRONTAL AREA • Area Anterior to frontal motor areas • AREAS – 9 – 12, 32, 45, 47 DIVISIONS: • DORSOLATERAL PREFRONTAL CORTEX • MEDIAL PREFRONTAL CORTEX • ORBITOFRONTALL CORTEX CELLULAR STRUCTURE: Thin & granular reduced size and number of pyramidal cells in LAYER 5.
- 13. DLPFC: • ORGANIZATION OF SELF ORDERED TASKS • NEURAL NETWORK OF WORKING MEMORY • EXECUTIVE FUNCTIONS: • PLANNING & ORGANISATIONAL SKILLS • ABSTRACTION • MOTIVATION • ATTENTION • COGNITIVE FLEXIBILITY Predict consequences of actions Emotional affect • PROBLEM SOLVING Decision making Calculating thinking • OCCULOMOTOR CONTROL • Decision regarding voluntary eye movements & inhibiting reflex saccades
- 14. OFC CONNECTIONS: thalamic nuclei superior temporal cortex DLPFC & OFC within frontal cortex AUDITORY & VISUAL ASSOCIATION PROCESSING OF OBJECTS MPC CONNECTIONS: Limbic system amygdala OFC dysfunction: DISINHIBITION SYNDROME mild inappropriate social behavior full blown mania emotional lability poor insight & judgement distractibility
- 15. VASCULAR SUPPLY
- 16. FRONTAL CIRCUIT SYSTEM • FRONTAL – SUBCORTICAL CIRCUITS – organizational network of the brain BRAIN BEHAVIOUR RELATIONSHIP • 5 CIRCUITS – named according to their function / cortical site of origin • MOTOR FUNCTIONS: • MOTOR CIRCUIT – supplementary motor area • OCCULOMOTOR CIRCUIT – frontal eye fields • EXECUTIVE, COGNITIVE, MOTIVATION & PERSONALITY: • DORSOLATERAL PREFRONTAL • LATERAL ORBITO FRONTAL • ANTERIOR CINGULATE
- 17. STRUCTURES: • FRONTAL LOBE • STRIATUM • GLOBUS PALLIDUS • SUBSTANTIA NIGRA • THALAMUS CLOSED LOOP OPEN LOOP Circuits integrate information with anatomically discrete but functionally related brain regions Dedicated neurons that remain anatomically segregated from parallel chains of neurons for other circuits Circuit projects to areas outside the loop. Open afferent and efferent components are regions that share function with the specific circuit
- 18. FRONTAL LOBE STRIATUM GLOBUS PALLIDUS INTERNA SUBSTANTIA NIGRA GLOBUS PALLIDUS EXTERNA SUBTHALAMIC NUCLEI THALAMUS GABA GLUTAMINERGIC DIRECT INDIRECT CLOSED LOOP Numerous structures, NT, receptors are involved in this circuit Lesions in different brain regions may have similar behavioral effects& variety of pharmacologic interventions may have similar effects on behavioral disturbances
- 19. DORSOLATERAL PREFRONTAL CIRCUIT FRONTAL LOBE STRIATUM GLOBUS PALLIDUS INTERNA SUBSTANTIA NIGRA GLOBUS PALLIDUS EXTERNA SUBTHALAMIC NUCLEI THALAMUS 9 &10 Dorsolateral head of caudate Mediodorsal globus plallidus interna Rostrolateral SN Dorsal globus pallidus externa Lateral subthalamic Ventral anterior & mediodorsal
- 20. EXECUTIVE FUNCTION: • Organise behavioral response • Solve complex problems • Activation of remote memories • Self direction • Independence from environmental contigencies, • shifting & maintaining behavioral sets • Generating motor programs
- 21. LATERAL ORBITOFRONTAL CIRCUIT FRONTAL LOBE STRIATUM GLOBUS PALLIDUS INTERNA SUBSTANTIA NIGRA GLOBUS PALLIDUS EXTERNA SUBTHALAMIC NUCLEI THALAMUS 10 & 11 Ventromedial caudate Mediodorsal globus plallidus interna Rostromedial SN Dorsal globus pallidus externa Lateral subthalamic Ventral anterior & mediodorsal
- 22. SOCIAL FUNCTIONING: • Empathic, civil & socially appropriate behavior • Personality • Response to social cues • ROLE IN • OCD – increased activity in OFC & increased caudate metabolism • MANIA
- 23. ANTERIOR CINGULATE CIRCUIT FRONTAL LOBE STRIATUM GLOBUS PALLIDUS INTERNA SUBSTANTIA NIGRA GLOBUS PALLIDUS EXTERNA SUBTHALAMIC NUCLEI THALAMUS 24 Ventral striatum – ventomedial caudate, ventral putamen, NA, olfactory tubercle Rostromedial globus plallidus interna Rostrodorsal SN Rostal pole globus pallidus externa Medial subthalamic Mediodorsal thalamus
- 25. OPEN CIRCUIT: Unify diverse brain regions into functional system relevant to specific behavior Relate functions have similar phylogenetic origins
- 26. FRONTAL LOBE SYNDROME: • No focal neurologic deficits • Frontal lobe personality • Apathy • Euphoria • Short lived irritability • Social inappropriateness • Higher order cognitive problems • EXECUTIVE FUNCTION • ATTENTION MEMORY • ABSTRACTION • Behavioral symptoms vary from patient – patient depending on the site of lesion
- 27. BROCA’S APHASIA • Nonfluent, dysarthric, dysprosodic, effortful speech • Telegraphic speech • Agrammatic • Repetition & reading aloud – impaired • Auditory & reading comprehension intact • Naming may show paraphrasic responses
- 28. ASSESSMENTS OF FRONTAL LOBE FUNCTION • HISTORY (PMP, change in personality) & MSE • ATTENTION • DIGIT SPAN • SUSTAINED ATTENTION - indicate A’s as I read out by taping on desk (omission error, commission error, perseveration error), - serial subtraction 100 – 7. • ABSTRACTION • PROVERBS • SIMILARITIES • DISSIMILARITIES • MEMORY • IMMEDIATE, RECENT, REMOTE • JUDGEMENT • SOCIAL JUDGEMENT • LANGUAGE
- 29. Language • Handedness – for dominant hemisphere • Spontaneous speech • Verbal fluency • COWA – controlled oral word fluency test - As many words as possible starting with F, A, S in 1 minute - Categorical verbal fluency Observe: perseveration ( within – task perseveration – same word, between-task perseveration – previous letter) intrusion errors(disinhibited association – not starting from any of the letter) Disinhibitory deficits – socially inappropriate / vulgar words • Comprehension • Pointing commands • questions that can be answered with yes/ no • Motor commands • Repetition • Naming & word finding • Reading - reading aloud, reading comprehension • Writing
- 31. WISCONSIN CARD SORTING TEST • SET SHIFTING based on feedback • Assess mental flexibility & goal directed behavior • Patient needs to discover by trial & error, the expected sorting of cards by COLOUR, SHAPE / NUMBER Developed by GRANT & BERG
- 32. STROOP TEST ASSESS : Ability to resolve response conflict & response inhibition
- 33. TRAIL MAKING Connect numbers Connect numbers & alphabets in series ASSESS : Visuo – motor tracking, conceptualization, set shifting
- 34. TOWER OF LONDON TEST RULES: • Build pyramid according to a specified arrangement • Fewest moves • Only one hand • Only 1 block at a time • Larger piece NEVER on top of smaller piece
- 35. GRAPHICAL SEQUENCE TESTS ALTERNATING SEQUESNCE - VISUAL PATTERN COMPLETION TEST Assess loss of sequence / perseveration in reproduction of sequence.
- 36. FAB • Devised by Dubois B in 2000. • Bed side assessment of frontal lobe functions • SUBTESTS: • CONCEPTUALIZATION • MENTAL FLEXIBILITY • MOTOR PROGRAMMING • SENSITIVITY TO INTERFERANCE • INHIBITORY CONTROL • ENVIRONMENTAL AUTONOMY • TOTAL SCORE = sum of all the scores • DURATION – 10 mins
- 44. CONCLUSION: • Frontal lobe is what makes us what we are as a person • Lesion of the frontal lobe changes our personality as a whole. • Executive function & personality is not a unitary construct and it is impossible to device a single test to measure it • The FAB is the most common battery of tests for bedside assessment of frontal lobe function
- 45. THANK YOU
- 46. REFERENCES: • DeJong’s Neurologic Examination • Inderbir Singh’s Text book of Human Neuroanatomy • Mental Status Examination in Neurology – Strub & Black • Goldberg E, Bougakov D. Neuropsychologic assessment of Frontal Lobe Dysfunction. Psychiatr Clin N Am. 2005;28(3): 567-80. • Dubois B, Slachevsky A, Litvan I, Pillon B. The FAB: a frontal assessment batter at bedside • Cummings JL, Mega MS. Frontal – subcortical circuits & Neuropsychiatric disorders. J Neuropsychiatry Clin Neurosci. 1994;6(4):358-70. • Malloy PF, Richardson ED. Assessment of frontal lobe Function. J Neuropsychiatry Clin Neurosci.1994;6(4):399-410.