title: Effects of stimulus salience on touchscreen serial reversal learning in a mouse model of fragile X syndrome.
abstract: Fragile X syndrome (FXS) is the most common inherited form of intellectual disability in males and the most common genetic cause of autism. Although executive dysfunction is consistently found in humans with FXS, evidence of executive dysfunction in Fmr1 KO mice, a mouse model of FXS, has been inconsistent. One possible explanation for this is that executive dysfunction in Fmr1 KO mice, similar to humans with FXS, is only evident when cognitive demands are high. Using touchscreen operant conditioning chambers, male Fmr1 KO mice and their male wildtype littermates were tested on the acquisition of a pairwise visual discrimination followed by four serial reversals of the response rule. We assessed reversal learning performance under two different conditions. In the first, the correct stimulus was salient and the incorrect stimulus was non-salient. In the second and more challenging condition, the incorrect stimulus was salient and the correct stimulus was non-salient; this increased cognitive load by introducing conflict between sensory-driven (i.e., bottom-up) and task-dependent (i.e., top-down) signals. Fmr1 KOs displayed two distinct impairments relative to wildtype littermates. First, Fmr1 KOs committed significantly more learning-type errors during the second reversal stage, but only under high cognitive load. Second, during the first reversal stage, Fmr1 KOs committed significantly more attempts to collect a reward during the timeout following an incorrect response. These findings indicate that Fmr1 KO mice display executive dysfunction that, in some cases, is only evident under high cognitive load.
authors.affiliation: The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA.
authors.forename: Price E
authors.initials: PE
authors.lastname: Dickson
authors.forename: Beau
authors.initials: B
authors.lastname: Corkill
authors.forename: Eric
authors.initials: E
authors.lastname: McKimm
authors.forename: Mellessa M
authors.initials: MM
authors.lastname: Miller
authors.forename: Michele A
authors.initials: MA
authors.lastname: Calton
authors.forename: Daniel
authors.initials: D
authors.lastname: Goldowitz
authors.forename: Charles D
authors.initials: CD
authors.lastname: Blaha
authors.forename: Guy
authors.initials: G
authors.lastname: Mittleman
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001289:Attention Deficit Disorder with Hyperactivity / Q000209:etiology; D003072:Cognition Disorders / Q000209:etiology; D004192:Discrimination, Psychological / Q000502:physiology; D004195:Disease Models, Animal; D056344:Executive Function / Q000502:physiology; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics; D005600:Fragile X Syndrome / Q000150:complications* / Q000235:genetics; D007859:Learning Disabilities / Q000209:etiology* / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010775:Photic Stimulation; D012193:Reversal Learning / Q000502:physiology*; D012691:Serial Learning / Q000502:physiology*
chemical_list: D051860:Fragile X Messenger Ribonucleoprotein 1; C497684:Fmr1 protein, mouse
keywords: Behavioral flexibility; Executive function; Fmr1; Fragile X syndrome