Frontal Cortex

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.

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

6. Divisions of the Frontal Cortex

7. Primary Motor Cortex

8. Prefrontal Cortex

9. 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.

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

12. Impaired Response Inhibition • Stroop

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15. Perseveration • Carrie’s timing task with frontals

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

17. Wisconsin Card Sort Task (WCST) Test Cards

19. Wisconsin Card Sorting Task (WCST)

20. Alternating & Sequencing Deficits

21. ***VIDEO: Pick’s Disease

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

23. Frontal Eye Fields

24. Exploratory Eye Movement Deficits

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

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

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

28. Orbitofrontal & Ventromedial Prefrontal Cortex

29. Phineas Gage

32. 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

33. 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.

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

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

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

37. 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

38. Anterior Cingulate

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

40. ***Striatum Pict – Sagittal?

41. 5 Frontal-Subcortical Circuits • Motor • Oculomotor • Dorsolateral prefrontal • Lateral orbitofrontal • Anterior cingulate

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

43. 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)

44. 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

45. 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