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Frontal Cortex

Frontal Cortex. Frontal Lobes. Traditionally considered to be the seat of intelligence. This is probably because: The frontal cortex is the most recent to evolve. Humans have particularly large frontal lobes compared to other animals.

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Frontal Cortex

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  1. Frontal Cortex

  2. Frontal Lobes • Traditionally considered to be the seat of intelligence. • This is probably because: • The frontal cortex is the most recent to evolve. • Humans have particularly large frontal lobes compared to other animals. • The frontal cortex is the brain lobe least amenable to quantitative testing.

  3. Divisions of the Frontal Cortex • Motor cortex • Premotor cortex • Prefrontal cortex • Orbitofrontal & Ventromedial prefrontal cortex • Anterior cingulate gyrus • Broca’s area

  4. Divisions of the Frontal Cortex

  5. Primary Motor Cortex

  6. Prefrontal Cortex

  7. Working memory • Refers to the capacity to keep track of and update information at the moment • E.g., 7 + - 2 •  Patricia Goldman-Rakic •  ODR paradigm (oculomotor delayed-response) •  Electrodes record activity from monkey neurons during the task. •  Different neurons respond to different task characteristics.

  8. Regional Specialization: • Superior prefrontal convexity (dorsal)— spatial location • Inferior prefrontal convexity (ventral)—objects, faces

  9. Impaired Response Inhibition • Stroop

  10. Purple Red Green Black Blue Yellow Green Red Purple Blue Blue Brown Blue Red Green Green Yellow Red Yellow Orange Green Yellow Red Purple Blue Red Black Yellow Orange Blue

  11. Purple Red Green Black Blue Yellow Green Red Purple Blue Green Yellow Red Yellow Orange Blue Brown Blue Red Green Blue Red Green Yellow Black Yellow Orange Red Purple Blue

  12. Perseveration • Carrie’s timing task with frontals

  13. Shifting Difficulty • Reduced fluency • Generate animals beginning with “C” • Difficulty generating hypotheses and flexibly shifting to new task demands

  14. Wisconsin Card Sort Task (WCST) Test Cards

  15. Wisconsin Card Sorting Task (WCST)

  16. Alternating & Sequencing Deficits

  17. ***VIDEO: Pick’s Disease

  18. Alternating & Sequencing Deficits • Motor • Planning & organizing tasks • Developing strategies for learning new tasks

  19. Frontal Eye Fields

  20. Exploratory Eye Movement Deficits

  21. Other Dorsolateral Deficits • Pseudo-depression • Perceptual deficits • Corollary discharge

  22. Mirror Neurons: Characteristic Firing Properties of Inferior DLPFC • Motor • Visual • Somatosensory • Body-part centered (Fadiga et al., 2000)

  23. “Mirror” Propertyof Human DLPFC (Iacoboni et al., 1999)

  24. Orbitofrontal & Ventromedial Prefrontal Cortex

  25. Phineas Gage

  26. The Case of Phineas Gage An explosion projected a tamping rod through his left cheek. Miraculously, he recovered and had “normal intellegence”. Months later, however, Gage began to have startling changes in personality and in mood. He became extravagant and anti-social, a fullmouth and a liar with bad manners, and could no longer hold a job or plan his future.   He was quick to anger and often got into fights. "The equilibrium between his intellectual faculties and animal propensities seems to have been destroyed.” - Harlow

  27. This is hypothesized to occur as a result of impoverished social learning as a result of failure to make appropriate mappings between events and their outcomes.

  28. Personality Changes • Lack of concern for the future • Consistently poor decision-making  • Impulsiveness • Failure to obey rules • Lack of social graces • Disposed to imitation

  29. Personality Changes II • Mild euphoria • Silliness & facetiousness • Pseudo-depression • Irritability

  30. Orbitofrontal Cortex Decision-Making Reinforcement Value of Sensory Stimuli Empathy

  31. Orbitofrontal Cortex • Secondary odor & taste cortices • Deficits in perceiving auditory or visual emotional cues • Can be Modality Specific • Cells respond to the rewarding or aversive nature of stimuli • Primary reinforcers • Learned (secondary) Reinforcers • Cells respond better to real than to 2-D faces • Cells respond preferentially to specific faces • Cells change their response to objects when reward associations change

  32. Anterior Cingulate

  33. Anterior Cingulate Bilateral lesions produce: • Akinetic mutism—inability to initiate speech •  Minimal movement •  Incontinence •  No emotional display to pain •  Profound apathy •  Indifference

  34. ***Striatum Pict – Sagittal?

  35. 5 Frontal-Subcortical Circuits • Motor • Oculomotor • Dorsolateral prefrontal • Lateral orbitofrontal • Anterior cingulate

  36. Frontal-Subcortical Circuits II Frontal lobe  Striatum (caudate, putamen, ventral striatum) Globus pallidus & Substantia nigra  Specific thalamic nuclei  Frontal lobe

  37. Summary I Motor cortex • Loss of voluntary control over a specific body area • Deficits of fine motor control • Reduction of strength & speed Premotor cortex • Impairs the integration of sequences into fluid actions • Reflex changes (i.e., grasp reflex)

  38. Summary II Prefrontal cortex • Working memory problems (superior—where; inferior—what) • Difficulty generating new items or hypotheses • Lack of inhibition • Perseveration • Difficulty planning sequences or organizing strategies • Eye movement deficits

  39. Summary III Orbitofrontal& Ventromedial prefrontal cortex • Personality & emotional changes • Disregard for rules • Imitation • No IQ or dorsolateral problems Anterior cingulate • Problems with initiating movements • Apathy • No emotional response to pain

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