Medicine Marrow Pg No 557-566 (Neurology)
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Questions and Answers

What is the primary function of the dorsolateral prefrontal cortex?

  • Executive function (correct)
  • Behavioral response
  • Theory of mind
  • Emotion & motivation

    • The orbital prefrontal cortex is involved in regulating emotions.

    False

    Name one condition resulting from severe prefrontal cortex dysfunction.

    Akinetic mutism

    The prefrontal cortex plays a role in ___________, including understanding oneself.

    <p>metacognition</p> Signup and view all the answers

    Match the following symptoms with their associated condition:

    <p>Akinetic mutism = Worst form of apathy Gait apraxia = Normal Pressure Hydrocephalus Urinary incontinence = Bilateral lesions of paracentral lobule Primitive reflexes = Pre motor cortex involvement</p> Signup and view all the answers

    What is the primary function of the Superior Parietal Lobule?

    <p>Generating praxicons</p> Signup and view all the answers

    Ideational apraxia involves the presence of an idea but poor execution of actions.

    <p>False</p> Signup and view all the answers

    What is visual agnosia?

    <p>Inability to identify objects by vision.</p> Signup and view all the answers

    The inability to dress oneself is known as ______.

    <p>dressing apraxia</p> Signup and view all the answers

    Match the types of apraxia with their definitions:

    <p>Ideational apraxia = Inability to execute actions due to absent ideas Ideomotor apraxia = Inability to execute actions with present ideas Constructional apraxia = Inability to perceive and imagine geometric relationships Dressing apraxia = Inability to dress oneself</p> Signup and view all the answers

    What percentage of motor fibers originate from the Premotor Area (PMA) and Supplementary Motor Area (SMA)?

    <p>30%</p> Signup and view all the answers

    Betz cells have the highest threshold to initiate motor activity.

    <p>False</p> Signup and view all the answers

    Which brain structure is responsible for the finesse of fine skilled voluntary movements?

    <p>Cerebellum</p> Signup and view all the answers

    The __________ supplies blood to the medial surface of the motor homunculus, responsible for the lower limb.

    <p>anterior cerebral artery (ACA)</p> Signup and view all the answers

    Match the following components of motor function with their respective roles:

    <p>PMA/SMA = Prepare for movement Primary motor cortex = Initiate movement Cerebellum = Finesse in movement Basal ganglia = Planning and coordination</p> Signup and view all the answers

    What condition is associated with a impairment in language comprehension due to temporal lobe lesions?

    <p>Wernicke's aphasia</p> Signup and view all the answers

    Visual agnosia is the inability to identify objects by vision.

    <p>True</p> Signup and view all the answers

    What part of the temporal lobe is primarily involved in processing auditory information?

    <p>Auditory Cortex</p> Signup and view all the answers

    The medial temporal lobe is known for being the most __________ foci in the body.

    <p>epileptogenic</p> Signup and view all the answers

    Match the following auditory-related conditions with their descriptions:

    <p>Deafness = Inability to hear sounds Pure word deafness = Inability to recognize spoken words Auditory agnosia = Difficulty in identifying or understanding sounds Wernicke's aphasia = Impaired language comprehension</p> Signup and view all the answers

    What is primarily impaired in the parietal lobe regarding sensory functions?

    <p>Tactile localization</p> Signup and view all the answers

    The tone is significantly affected by a lesion in the parietal lobe.

    <p>False</p> Signup and view all the answers

    What artery supplies blood to the primary sensory cortex and primary motor cortex?

    <p>Middle Cerebral Artery</p> Signup and view all the answers

    The parietal lobe is located posterior to the __________ sulcus.

    <p>central</p> Signup and view all the answers

    Match the following functions with their corresponding sensory abilities affected by a lesion in the parietal lobe:

    <p>Tactile localization = Impaired Two-point discrimination = Impaired Stereognosis = Impaired Graphesthesia = Impaired</p> Signup and view all the answers

    What is the primary function associated with the angular gyrus?

    <p>Reading</p> Signup and view all the answers

    Hemispatial neglect is characterized by neglecting activities related to the right hemisphere only.

    <p>False</p> Signup and view all the answers

    What syndrome is characterized by a lesion in the dominant angular gyrus and includes symptoms like alexia and agraphia?

    <p>Gerstman syndrome</p> Signup and view all the answers

    A lesion in the ___ hemisphere can result in left hemispatial neglect.

    <p>right</p> Signup and view all the answers

    Match the following types of visual field defects with their corresponding lobes:

    <p>Frontal lobe = C/L hemianopia Parietal lobe = Inferior homonymous quadrantanopia (Pie in floor) Temporal lobe = U/L superior homonymous quadrantanopia (Pie in sky) Occipital lobe = C/L (Right) homonymous hemianopia</p> Signup and view all the answers

    Which of the following is a feature of Kluver-Bucy syndrome?

    <p>Hypersexuality</p> Signup and view all the answers

    The uncus is a structure that affects memory within the limbic system.

    <p>True</p> Signup and view all the answers

    What type of visual perception difficulty is characterized by needing to touch objects to recognize them?

    <p>Hypermetamorphosis</p> Signup and view all the answers

    Components of the diencephalon involved in Kluver-Bucy syndrome include the anterior group of thalamic nuclei, the hypothalamus, and the __________.

    <p>mamillary body</p> Signup and view all the answers

    Match the brain structures with their functions or characteristics in Kluver-Bucy syndrome:

    <p>Amygdala = Involved in memory and emotion Hippocampus = Critical for forming new memories Hypothalamus = Regulates feeding and satiety Cingulate gyrus = Involved in emotional processing</p> Signup and view all the answers

    What type of weakness is associated with an MCA lesion?

    <p>Face and upper limb weakness</p> Signup and view all the answers

    An ACA lesion primarily causes weakness in the upper limb.

    <p>False</p> Signup and view all the answers

    What is characterized by spasticity and hypertonia?

    <p>Upper motor neuron lesion</p> Signup and view all the answers

    A lesion in the left frontal eye field will cause a patient to look towards the ______.

    <p>left</p> Signup and view all the answers

    Match the following areas with their effects on language:

    <p>Broca's area = Non-fluent aphasia Lesions anterior to central sulcus = Fluency affected Lesions posterior to central sulcus = Comprehension affected Wernicke's area = Fluent aphasia</p> Signup and view all the answers

    What happens with a brain stem lesion (PPRF)?

    <p>Look away from the lesion side</p> Signup and view all the answers

    Lesions posterior to the central sulcus affect fluency.

    <p>False</p> Signup and view all the answers

    What motor response is characterized by a Jacksonian march?

    <p>Contralateral motor simple partial seizure</p> Signup and view all the answers

    What visual condition is characterized by cortical blindness with patients being unaware of their blindness?

    <p>Anton's syndrome</p> Signup and view all the answers

    Color agnosia and cerebral achromatopsia can both result from bilateral lesions in the occipital lobe.

    <p>True</p> Signup and view all the answers

    What is the visual memory function primarily associated with?

    <p>Visual association area (18,19)</p> Signup and view all the answers

    A lesion in the primary visual area (17) would result in __________ with macular sparing.

    <p>C/L congruent homonymous hemianopia</p> Signup and view all the answers

    Match the visual conditions with their descriptions:

    <p>Optic ataxia = Overshoot on finger-nose test Oculomotor apraxia = Difficulty in visually guided movements Cerebral achromatopsia = Inability to perceive color Color agnosia = Inability to name colors despite normal vision</p> Signup and view all the answers

    Which area of the brain is primarily responsible for grammar and syntax in language output?

    <p>Broca's area</p> Signup and view all the answers

    Dysarthria is an abnormality related to language comprehension.

    <p>False</p> Signup and view all the answers

    What is the function of the arcuate fasciculus in the brain?

    <p>Connects Broca's area and Wernicke's area.</p> Signup and view all the answers

    The initial step of the auditory process is the __________.

    <p>tone of sound</p> Signup and view all the answers

    Match the following speech-related abnormalities with their definitions:

    <p>Aphasia = Inability to comprehend or produce language Dysarthria = Motor speech disorder affecting articulation Pure word deafness = Inability to understand spoken words Apraxia of speech = Impairment in the ability to plan speech movements</p> Signup and view all the answers

    Which component is responsible for the physical production of speech sounds?

    <p>Larynx</p> Signup and view all the answers

    The superior temporal gyrus is associated with Broca's area.

    <p>False</p> Signup and view all the answers

    Which brain area is responsible for processing auditory information?

    <p>Primary auditory area</p> Signup and view all the answers

    Study Notes

    Prefrontal Cortex (PFC) / Area 9, 10, 11, 12

    • Dorsolateral PFC is responsible for executive function, which involves cognitive inhibition, response inhibition, and set shifting.
    • Medial PFC, including the cingulate gyrus, plays a role in emotion and motivation.
    • Orbital PFC is responsible for behavioral responses based on reward and punishment.
    • Frontal pole is crucial for theory of mind, including empathy and metacognition.
    • Executive function is time-frame dependent, goal-directed activity with potential consequences in the form of apathy, abulia, and akinetic mutism.
    • Behavioral response is based on reward/punishment and includes judgement, insight, problem solving, personality, fluency, and abstract thinking.
    • Theory of mind refers to understanding oneself and others' perspectives.
    • Bilateral frontal lobe pathology can lead to prefrontal personality changes, urinary incontinence due to lesions of the paracentral lobule, primitive reflexes due to premotor cortex involvement, and akinetic mutism, the most severe form of apathy.

    Superior Parietal Lobule

    • The superior parietal lobule generates praxicons, which are movement formulas and sensory guidance for movement.
    • Apraxia is the inability to execute learned voluntary skilled actions despite normal cerebellum, motor and sensory function, and comprehension.
    • Lesions in the superior parietal lobule lead to an inability to generate praxicons.
    • Ideational apraxia occurs when the idea for the action is absent, while ideomotor apraxia occurs when the idea is present, but the execution is poor.

    Inferior Parietal Lobule (IPL)

    • The supramarginal gyrus is involved in gnosis, which is the ability to recognize objects by touch, vision, or sound.
    • Visual agnosia is the inability to identify objects by vision and affects the supramarginal gyrus and parieto-occipital association area, responsible for visuospatial orientation.

    Dominant Parietal Lobe

    • The dominant parietal lobe, usually left-sided, is responsible for language function.
    • 90-95% of left-handed individuals and 50-60% of right-handed individuals have their dominant parietal lobe on the left side.

    Non-dominant Parietal Lobe

    • The non-dominant parietal lobe, typically on the right side, is responsible for visuospatial functions.
    • Pseudoapraxia, which includes constructional apraxia, dressing apraxia, and visuospatial disorientation, can occur due to lesions in this area.
    • Constructional apraxia is the difficulty in perceiving and imagining geometric relationships, affecting tasks like drawing.
    • Dressing apraxia makes it difficult to dress oneself, as the individual may struggle with the spatial understanding needed for proper clothing placement.
    • Visuospatial disorientation refers to difficulty differentiating places and understanding spatial relationships in their environment.

    Functions of the Frontal Lobe

    • Area 4, also known as the primary motor cortex or precentral gyrus, originates only 30% of motor fibers.
    • Betz cells, specialized cells with the lowest threshold to initiate motor activity, are present in area 4 and initiate fine skilled voluntary movement.

    Premotor Area (PMA) & Supplementary Motor Area (SMA)

    • The Premotor Area and Supplementary Motor Area originate 30% of motor fibers.
    • They prepare for fine skilled voluntary movements, regulating factors like postural tone, proximal muscle alignment, and antagonist muscle inhibition.
    • Lesions in the Premotor area can lead to spasticity due to tone issues and the presence of primitive reflexes.
    • The process of fine skilled voluntary movement involves preparation by PMA/SMA, initiation by the primary motor area, finesse by the cerebellum, and planning and coordination by the basal ganglia.

    Motor Homunculus

    • The motor homunculus represents the body's representation in the motor cortex.
    • The lower limb is controlled by the medial surface of the motor cortex supplied by the anterior cerebral artery (ACA).
    • The face and upper limb are controlled by the superolateral surface of the motor cortex supplied by the middle cerebral artery (MCA).

    Neurology

    • Lesions in the middle cerebral artery can cause weakness in the face and upper limb as well as urinary incontinence due to involvement of the paracentral lobule on the medial surface.
    • Lesions in the anterior cerebral artery can lead to lower limb weakness.
    • Lesions of the motor cortex can result in contralateral weakness, specifically affecting fine skilled voluntary movements, and an upper motor neuron lesion characterized by spasticity (hypertonia).
    • A lesion in the motor cortex can initiate contralateral motor simple partial seizures known as Jacksonian marches.
    • Upper motor neurons extend from the cortex to the anterior horn cell in the grey matter.

    Frontal Eye Field (FEF)

    • The frontal eye field controls voluntary eye movements.
    • Activation of the left FEF stimulates the right lateral rectus (LR) and left medial rectus (MR) muscles, resulting in looking to the right.
    • A lesion in the left FEF prevents the patient from looking to the right, causing them to involuntarily look to the left.
    • Lesions in the frontal lobe cause the patient to look towards the side of the lesion.
    • Lesions in the brainstem, specifically the pontine paramedian reticular formation (PPRF), cause the patient to look away from the side of the lesion.

    Broca's Area/Area 44, 45

    • Broca's area is involved in the fluency of speech and is responsible for grammatical structure and rhythm.
    • Lesions anterior to the central sulcus affect fluency, while lesions posterior to the central sulcus affect comprehension.
    • Damage to Broca's area leads to non-fluent aphasia, affecting speech production but not comprehension.

    Hemispatial Neglect

    • Hemispatial neglect, also known as anosognosia or asomatognosia, is a neurological condition where individuals fail to attend to stimuli on one side of their body.
    • This neglect is often associated with lesions in the right parietal lobe, specifically affecting the extrapersonal space (space outside the body).
    • Lesions in the left parietal lobe do not typically lead to hemispatial neglect.
    • Individuals with hemispatial neglect often exhibit deficits in visual scanning and body schema, leading to neglect of activities related to the neglected side.

    Gerstmann Syndrome

    • Gerstmann syndrome is a neurological condition characterized by four specific impairments:
      • Alexia (impaired reading)
      • Agraphia (impaired writing)
      • Anomia (impaired naming)
      • Finger anomia (difficulty naming or identifying the fingers) or Acalculia (difficulty with arithmetic)
      • Right-left disorientation
    • It is caused by a lesion in the dominant angular gyrus.

    Occipital Lobe

    • The occipital lobe is responsible for vision.

    Unilateral Occipital Lobe Lesions

    • A lesion in the primary visual area (17) results in contralateral congruent homonymous hemianopia with macular sparing, meaning the patient cannot see the opposite visual field except for the central part of their vision.
    • Lesions in the visual association areas (18, 19), also known as the parastriate and perstriate cortex, are responsible for various visual functions like ocular fixation, size/shape/color perception, and visual memory.
    • Damage to these areas can lead to color agnosia, the inability to recognize colors.

    Bilateral Occipital Lobe Lesions

    • Bilateral lesions of the occipital lobe can lead to Anton's Syndrome, a condition where the patient experiences cortical blindness but is unaware of their blindness.
    • They may confabulate visual descriptions, attribute their inability to see to other factors like dim lighting, or claim they have not worn their glasses.
    • Despite the blindness, light reflexes remain intact.
    • Other visual deficits include color agnosia and cerebral achromatopsia, the inability to perceive colors.

    Balint's Syndrome

    • Balint's syndrome results from bilateral lesions in the occipital lobes and is characterized by three core symptoms:
      • Optic ataxia, difficulty coordinating visual information with movement, resulting in overshooting on finger-nose tests.
      • Oculomotor apraxia, difficulty making voluntary eye movements towards a specific target.
      • Simultagnosia, the inability to perceive multiple objects simultaneously, leading to difficulty in understanding the overall scene.

    Language vs. Speech

    • Language refers to the basic concept of communication and is processed primarily in the dominant hemisphere. Damage to the language areas results in aphasia.
    • Speech refers to the motor output of language. Damage to the speech areas results in dysarthria.

    Areas and Physiology of Speech

    • Primary motor cortex: Connected to muscles responsible for speech production.
    • Broca's area (44, 45): Responsible for grammar, syntax, rhythm, and fluency of language output.
    • Primary auditory area: Processes auditory information.
    • Wernicke's area (22): Involved in language comprehension.
    • Inferior temporal gyrus: Broca's speech area is located within this gyrus.
    • Superior temporal gyrus: Wernicke's area is located here.
    • Premotor area: Part of the brain related to planning movements related to speech output.
    • Sylvian fissure: Boundary between different motor and sensory areas in the brain.
    • Internal Capsule: A neural pathway in the brain.
    • Arcuate fasciculus: A bundle of nerve fibers connecting Broca's area and Wernicke's area, vital for fluent speech output and comprehension.
    • Connecting fibers: Essential for communication between brain areas; damage can cause pure word deafness, the inability to understand words even with intact hearing.
    • Tone of sound: Initial step in the auditory process.
    • Brainstem nuclei: Control and coordinate speech movements.
    • Peripheral muscles: Larynx (vocal cords), Pharynx (palate), Oesophagus; these structures are crucial for physically producing speech sounds.

    Apathy

    • Apathy is characterized by a lack of motivation and interest in activities.
    • It can occur due to lesions in the medial prefrontal cortex, especially the areas involved in emotion regulation, or damage to thalamic connections, which play a role in relaying information related to motivation and reward.
    • Apathy can range in severity from mild (apathy) to moderate (abulia) and can be severe enough to be disabling (akinetic mutism).

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    Explore the various functions of the prefrontal cortex, including executive function, emotion, motivation, and theory of mind. This quiz delves into the roles of different areas within the PFC, their impact on behavior, and potential pathologies associated with frontal lobe dysfunction. Test your understanding of complex cognitive processes and their implications for personality and insight.

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