Session 16a - Frontal Lobes - Motor Function

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Information about Session 16a - Frontal Lobes - Motor Function
Education

Published on March 6, 2014

Author: FraserNelson

Source: slideshare.net

PSYC 3390 NEUROPSYCHOLOGY UNIT 16A - THE FRONTAL LOBES INSTRUCTOR: FRASER NELSON

ANATOMY OF THE FRONTAL LOBES • CONSTITUTE 20% OF THE NEOCORTEX • SUBDIVISIONS – MOTOR: AREA 4 – PREMOTOR: AREAS 6 AND 8 • CAN BE DIVIDED INTO: – LATERAL AREA 6: PREMOTOR CORTEX – MEDIAL AREA 6: SUPPLEMENTARY MOTOR CORTEX – AREA 8: FRONTAL EYE FIELD – AREA 8A: SUPPLEMENTARY EYE FIELD

ANATOMY OF THE FRONTAL LOBES • PREFRONTAL CORTEX – AREA OF THE FRONTAL LOBE THAT RECEIVES INPUT FROM THE DORSOMEDIAL NUCLEUS OF THE THALAMUS – DIVISIONS • DORSOLATERAL PREFRONTAL CORTEX • INFERIOR FRONTAL CORTEX – ALSO CALLED ORBITOFRONTAL CORTEX • MEDIAL FRONTAL CORTEX – ALSO CONSIDERED PART OF THE CINGULATE CORTEX • MANY AREAS OF THE FRONTAL LOBE ARE MULTIMODAL

•Image credit: http://en.wikipedia.org/wiki/Frontal_eye_fields CONNECTIONS OF THE MOTOR AND PREMOTOR AREAS • MOTOR CORTEX – PROJECTS TO SPINAL MOTOR NEURONS, CRANIAL NERVES THAT CONTROL THE FACE – PROJECTS TO THE BASAL GANGLIA AND THE RED NUCLEUS • PREMOTOR – PROJECTIONS TO • THE SPINAL CORD • THE MOTOR CORTEX – INDIRECT MOVEMENT PATHWAY

CONNECTIONS OF THE MOTOR AND PREMOTOR AREAS • PREMOTOR – RECEIVES PROJECTIONS FROM • PARIETAL AREAS PE AND PF • DORSOLATERAL PREFRONTAL AREA • FRONTAL EYE FIELDS (AREA 8 AND 8A) – RECEIVE FROM POSTERIOR PARIETAL LOBE AREA PG AND THE SUPERIOR COLLICULUS

CONNECTIONS OF THE PREFRONTAL AREAS • TERMINUS OF BOTH THE DORSAL AND VENTRAL STREAMS OF VISUAL INPUT • DORSOLATERAL PREFRONTAL AREA – RECIPROCAL CONNECTIONS WITH THE POSTERIOR PARIETAL AND STS – EXTENSIVE CONNECTIONS WITH • PREMOTOR, SUPPLEMENTARY MOTOR, AND PRIMARY MOTOR AREAS • THE CINGULATE CORTEX, BASAL GANGLIA, AND SUPERIOR COLLICULUS

CONNECTIONS OF THE PREFRONTAL AREAS • INTERIOR (ORBITAL) FRONTAL CORTEX – RECEIVES FROM THE TEMPORAL LOBE, AMYGDALA, GUSTATORY CORTEX, SOMATOSENSORY CORTEX, OLFACTORY CORTEX, DOPAMINERGIC CELLS IN TEGMENTUM – PROJECTS TO HYPOTHALAMUS AND AMYGDALA

A THEORY OF FRONTAL-LOBE FUNCTION • • • • • MOVEMENT PLANNING AND SELECTION PERSISTENCE AND IGNORING DISTRACTING STIMULI MEMORY EXECUTIVE FUNCTIONS RESPONDS TO BOTH INTERNAL, EXTERNAL, AND CONTEXT CUES

ROLE OF FRONTAL LOBE IN MOVEMENT

FUNCTIONS OF THE DORSOLATERAL PREFRONTAL CORTEX (DL-PFC) IN MOVEMENT • INVOLVED IN THE DECISION TO EXECUTE VOLUNTARY MOVEMENTS – EXTENSIVE CONNECTIONS WITH • SENSORY ASSOCIATION AREAS: POSTERIOR PARIETAL CORTEX • MOTOR AREAS: PREMOTOR, SUPPLEMENTARY MOTOR, AND PRIMARY MOTOR CORTEX • GOLDMAN-RAKIC, 1987 – ACTIVITY IN DL-PFC OBSERVED PRECEDING REACHING MOVEMENT IN MONKEY • SUGGESTING DL-PFC INVOLVED IN THE DECISION TO MAKE THE MOVEMENT • ROLANI & ZILLES, 1996 – ACTIVATION OBSERVED IN DL-PFC AND PREMOTOR AREA PRIOR TO MAKING MOVEMENTS IN RESPONSE TO AN EXTERNAL CUE – THESE ACTIVATION PATTERNS ALSO WERE OBSERVED IN RESPONSE TO IMAGINED MOVEMENTS • SUGGESTING THAT THESE AREAS ARE INVOLVED IN THE PLANNING, AS OPPOSED TO THE EXECUTION OF MOVEMENTS

FUNCTIONS OF THE PREMOTOR CORTEX • SELECTS MOVEMENTS TO BE EXECUTED • FUNCTIONS TO CHOOSE BEHAVIOR IN RESPONSE TO EXTERNAL CUES • ROLAND & COLLEAGUES – AN INCREASE IN ACTIVITY IN THE PREMOTOR CORTEX IS SEEN WHEN CUES ARE ASSOCIATED WITH EXTERNAL CUES OR MOVEMENTS

FUNCTIONS OF THE SUPPLEMENTARY MOTOR CORTEX • ROLAND & COLLEAGUES – SMA IS INVOLVED IN THE SELECTION AND DIRECTION OF MOTOR SEQUENCES • CEREBRAL BLOOD FLOW WAS INCREASED DURING A TASK INVOLVING A SEQUENCE OF 16 MOVEMENTS OF THE FINGERS AS OPPOSED TO REPETITIVE MOVEMENT OF ONE FINGER

Image credit: http://en.wikipedia.org/wiki/Frontal_eye_fields FUNCTIONS OF THE FRONTAL EYE FIELDS • INVOLVED IN THE ‘SELECTION’ OF EYEMOVEMENTS – EITHER IN RESPONSE TO ENVIRONMENTAL CUES OR INTERNAL EVENTS – PASSINGHAM • AREA 8 - STIMULUS-DIRECTED MOVEMENTS (ENVIRONMENTAL CUES) • AREA 8A - MOVEMENT IN RESPONSE TO INTERNAL CUES

FUNCTIONS OF THE PRIMARY MOTOR CORTEX • CONTROLS THE MOVEMENTS AND COORDINATION OF THE MUSCLES – CONTAINS SOMATOTOPIC MAP • HEAVILY INTERCONNECTED WITH – MOTOR ASSOCIATION AREAS (DL-PFC, PRE-MOTOR, AND SUPPLEMENTARY MOTOR AREAS) – SOMATOSENSORY CORTEX • STEREOGNOSIS - ABILITY TO IDENTIFY OBJECTS BY TOUCH • DAMAGE TO THE PRIMARY MOTOR CORTEX DOES NOT RESULT IN PARALYSIS – REDUCES SPEED, ACCURACY, AND FORCE OF MOVEMENT – ASTEROGNOSIS MAY ALSO BE PRESENT

SPINAL MOTOR PATHWAYS • 2 MAIN CORTICOSPINAL PATHWAYS TO INITIATE AND CONTROL MOVEMENT – LATERAL SYSTEM • 2 TRACTS – LATERAL CORTICOSPINAL TRACT » CONTROLS CONTRALATERAL MOVEMENT OF LIMBS AND EXTREMITIES – RUBROSPINAL TRACT » CONTROLLING MOVEMENTS OF THE LIMBS AND HANDS » RUBRO REFERS TO THE RED NUCLEUS IN THE ROSTRAL MIDBRAIN • ADDITIONAL INFORMATION  HTTP://THEBRAIN.MCGILL.CA/FLASH/A/A_06/A_06_CL/A_06_CL_MOU/A_06_CL_MOU.HTM L

SPINAL MOTOR PATHWAYS • VENTROMEDIAL SYSTEM – VESTIBULOSPINAL TRACT • MAINTAINING BALANCE – RETICULOSPINAL TRACT • MAINTAINING POSTURE – TECTOSPINAL TRACT • CONTROLLING HEAD AND EYE MOVEMENTS • ADDITIONAL INFORMATION  HTTP://THEBRAIN.MCGILL.CA/FLASH/A/A_06/A_06_CL/A_06_CL_M OU/A_06_CL_MOU.HTML –

SYMPTOMS OF FRONTAL LOBE LESIONS • DISTURBANCES OF MOTOR FUNCTION 1. 2. 3. LOSS OF FINE MOVEMENTS, SPEED, AND STRENGTH LOSS OF MOVEMENT PROGRAMMING CHANGES IN VOLUNTARY GAZE

DISTURBANCES OF MOTOR FUNCTION • LOSS OF FINE MOVEMENTS, SPEED, AND STRENGTH – ASSOCIATED WITH DAMAGE TO THE PRIMARY MOTOR CORTEX – DAMAGE TO THE PREFRONTAL CORTEX CAN ALSO LEAD TO WEAKNESS IN THE MUSCLES OF THE HAND

DISTURBANCES OF MOTOR FUNCTION • LOSS OF MOVEMENT PROGRAMMING – ASSOCIATED WITH DAMAGE TO THE PREMOTOR OR DORSOLATERAL CORTEX • LASHLEY – FRONTAL LOBES ARE INVOLVED IN THE CHAINING OF COMPLEX SEQUENCES OF MOVEMENTS • KOLB AND MILNER, 1981 – STUDY OF FRONTAL-LOBOTOMY PATIENTS FURTHER SUPPORTED THE ROLE OF FRONTAL LOBE IN MOVEMENT PLANNING

DISTURBANCES OF MOTOR FUNCTION • CHANGES IN VOLUNTARY GAZE – DAMAGE TO THE FRONTAL EYE FIELDS • HANS-LEUKAS TEUBAR (1964) – VISUAL MATCHING TASK – SUBJECTS WITH DAMAGE TO THEIR FRONTAL EYE FIELDS STRUGGLED TO FIND THE DUPLICATE ITEM AS A RESULT OF DECREASED CONTROL OF GAZE

DISTURBANCES OF MOTOR FUNCTION • SACCADIC EYE MOVEMENTS – ROLE OF SC VS. FEF • GUITTON (1982) – STUDIED THE ABILITY OF SUBJECTS WITH FRONTAL LOBE DAMAGE TO MAKE SACCADES IN REACTION TO THE PRESENTATION OF NOVEL STIMULI – RESULTS • LESION SUBJECTS WERE ABLE TO MAKE INVOLUNTARY SACCADES TOWARDS THE VISUAL FIELD WHERE THE STIMULI WAS PRESENTED BUT WERE UNABLE TO INHIBIT THE SACCADE WHEN INSTRUCTED • ELUCIDATES DISSOCIATION OF CONTROL OF SACCADE – SC INVOLVED IN INVOLUNTARY SACCADIC MOVEMENTS – FEF MORE INVOLVED IN CONTROL OF VOLUNTARY SACCADES

DISTURBANCES OF MOTOR FUNCTION • COROLLARY DISCHARGE – A MECHANISM FOR DISTINGUISHING SELF-GENERATED FROM EXTERNALLY-GENERATED SENSATION BASED ON THE PRESENCE OF A SIGNAL PRIOR TO THE ONSET OF THE SENSATION TO PREPARE THE BODY FOR IT • E.G. INTERNAL NEURAL SIGNAL THAT MOVEMENT WILL OCCUR – FRONTAL LOBE DAMAGE DISRUPTS COROLLARY DISCHARGE – BIZZI & SCHILLER (1971) • MULTIPLE TYPES OF CELLS WITHIN FEF FIRE IN RESPONSE TO DIFFERENT TYPES OF EYE-MOVEMENT • AS OPPOSED TO GENERATING THESE MOVEMENTS, THESE CELLS ONLY FIRE AS A CONSEQUENCE OF A MOVEMENT IN ACTION - THUS GIVING EXAMPLES OF COROLLARY DISCHARGE SIGNALS THAT HELP TO DIFFERENTIATE SELF-GENERATED FROM EXTERNAL MOVEMENT

DISTURBANCES OF MOTOR FUNCTION • SPEECH PROBLEMS – DAMAGE TO BROCA’S AREA • AGRAMMATISM – DAMAGE TO THE SUPPLEMENTARY MOTOR CORTEX • MUTE – DURATION OF IMPAIRMENT DEPENDS ON LATERALIZATION OF DAMAGE

CLINICAL NEUROPSYCHOLOGICAL ASSESSMENT OF FRONTAL LOBE DAMAGE

END OF LECTURE

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