• INCLUSION CRITERIA:

ALL SUBJECTS -

All subjects will be volunteers and be 18 years of age or older.

PATIENTS -

Subjects with unilateral or bilateral lesions of prefrontal or parietal cortex will be selected for participation in the behavioral and brain-imaging studies described within this protocol.

Control subjects with unilateral or bilateral lesions of temporal cortex will also be studied.

Finally, patients with amygdala lesions will also be studied to test the specific hypothesis outlined in Experiment 4.

In order to obtain a sufficient number of focal lesion patients representative of different brain regions, patients with different etiologies will be studied, provided the damage is circumscribed.

The main etiologies that we will consider are stroke, lobectomy, and tumor.

We will restrict groups to include patients with the same etiology, lesion location, and lesion volume. Lesion location will consider the two hemispheres separately.

Patients who also have non-amygdala subcortical lesions will be grouped separately from patients with cortical-only lesions.

Our goal is to not group patients with more focal brain lesions compromising a single region (e.g., middle frontal gyrus) with patients with more massive damage (e.g., large extents of superior, middle, and inferior frontal gyrus).

Focal lesion patients will not be excluded on the basis of medication.

NORMAL VOLUNTEERS -

Neurologically normal, age-matched volunteers will be recruited from the local community through normal Clinical Center channels.

EXCLUSION CRITERIA:

The following criteria will be used to exclude patients or healthy volunteers from participation in this study:

• Patients with language impairments that prevent them from understanding our tasks or follow instructions will be excluded.
• Patients with a WAIS-R Full-Scale IQ of less than 75 will be excluded.
• Patients with severe cognitive dysfunction as assessed by the neuropsychological tests.
• Subjects with moderate or severe depression as assessed by the Beck Depression Inventory (scores greater than 18).
• Patients who cannot perform control tasks to the same level of performance as the control subjects will be excluded.
• Subjects with contraindication to MRI scanning will be excluded from any testing which involves the use of MRI. These contraindications include subjects with the following devices or conditions: a) central nervous system aneurysm clips; b) implanted neural stimulator; c) implanted cardiac pacemaker or defibrillator; d) cochlear implant; e) ocular foreign body (e.g., metal shavings); f) insulin pump; g) metal shrapnel or bullet; h) any implanted device that is incompatible with MRI.
• Subjects with a history of any neurological or psychiatric disorder not related to the focal lesion (e.g., epilepsy, schizophrenia, etc.)
• Subjects with any previous head injuries not related to the focal lesion.
• Subjects with a history of drug or alcohol abuse or addiction (determined by a qualified neurologist/psychiatrist).
• Subjects with conditions that preclude entry into the scanner (e.g., morbid obesity, claustrophobia, etc.) will not be included in brain imaging studies.
• Female subjects of child-bearing age will be excluded from brain imaging studies if they are pregnant or refuse to undergo a urine pregnancy test.
• Subjects with visual, auditory, motor, or language problems that would prohibit them from being able to properly perform the visual attention tasks, to understand instructions, indicate their responses, or to communicate with the experimenter via an intercom system.
• Subjects who have undergone radiation treatment or chemotherapy during a one-year period prior to the experiment.