title: Cerebral blood flow changes in limbic regions induced by unsolvable anagram tasks.
abstract: OBJECTIVE
  The study addressed the question of whether unsolvable as opposed to solvable cognitive problems activate discrete neuronal systems in the human brain.
  
  
  METHODS
  Twelve healthy humans tried to solve unsolvable anagrams. Solvable anagrams and a resting baseline after each anagram task served as control conditions in a within-subject design. Activation was measured with the equilibrium infusion method by using 15O-labeled water and positron emission tomography, with absolute quantitation of anatomically defined regional cerebral blood flow (CBF).
  
  
  RESULTS
  Compared to rest, both anagram tasks increased activity in frontal and temporal regions. The soluble task condition increased hippocampal activation and decreased mammillary bodies activity, while unsolvable anagrams were associated with increased CBF to the mamillary bodies and amygdala and decreased hippocampal activity.
  
  
  CONCLUSIONS
  A limbic network integrating negative emotion and cognition seems reflected in reciprocal diencephalic and limbic activation with solvable and unsolvable anagrams. Since unsolvable anagrams have been used to induce learned helplessness in humans, this finding may provide an initial step toward clarifying its neural substrate.
authors.affiliation: Department of Psychiatry, School of Medicine, University of Pennsylvania, Philadelphia, USA.
authors.forename: F
authors.initials: F
authors.lastname: Schneider
authors.forename: R E
authors.initials: RE
authors.lastname: Gur
authors.forename: A
authors.initials: A
authors.lastname: Alavi
authors.forename: M E
authors.initials: ME
authors.lastname: Seligman
authors.forename: L H
authors.initials: LH
authors.lastname: Mozley
authors.forename: R J
authors.initials: RJ
authors.lastname: Smith
authors.forename: P D
authors.initials: PD
authors.lastname: Mozley
authors.forename: R C
authors.initials: RC
authors.lastname: Gur
mesh_terms: D000328:Adult; D000679:Amygdala / Q000098:blood supply / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000098:blood supply / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006380:Helplessness, Learned; D006801:Humans; D008032:Limbic System / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008326:Mammillary Bodies / Q000098:blood supply / Q000502:physiology; D008959:Models, Neurological; D010104:Oxygen Radioisotopes; D011340:Problem Solving / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000098:blood supply / Q000502:physiology; D014055:Tomography, Emission-Computed; D014867:Water
chemical_list: D010104:Oxygen Radioisotopes; D014867:Water