Somatosensory map expansion and altered processing of tactile inputs in a mouse model of fragile X syndrome.
Fragile X syndrome (FXS) is a common inherited form of intellectual disability caused by the absence or reduction of the fragile X mental retardation protein (FMRP) encoded by the FMR1 gene. In humans, one symptom of FXS is hypersensitivity to sensory stimuli, including touch. We used a mouse model of FXS (Fmr1 KO) to study sensory processing of tactile information conveyed via the whisker system. In vivo electrophysiological recordings in somatosensory barrel cortex showed layer-specific broadening of the receptive fields at the level of layer 2/3 but not layer 4, in response to whisker stimulation. Furthermore, the encoding of tactile stimuli at different frequencies was severely affected in layer 2/3. The behavioral effect of this broadening of the receptive fields was tested in the gap-crossing task, a whisker-dependent behavioral paradigm. In this task the Fmr1 KO mice showed differences in the number of whisker contacts with platforms, decrease in the whisker sampling duration and reduction in the whisker touch-time while performing the task. We propose that the increased excitability in the somatosensory barrel cortex upon whisker stimulation may contribute to changes in the whisking strategy as well as to other observed behavioral phenotypes related to tactile processing in Fmr1 KO mice.
Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden. Electronic address: konrad.juczewski@nih.gov.
Konrad
K
Juczewski
Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Helen
H
von Richthofen
VIB Center for the Biology of Disease, KU Leuven, Leuven, Belgium; Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy; Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland.
Claudia
C
Bagni
Department of Neurophysiology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands.
Tansu
T
Celikel
Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
Gilberto
G
Fisone
Department of Systems Neuroscience, Medical Faculty, Ruhr University Bochum, Bochum, Germany. Electronic address: patrik.krieger@rub.de.
Patrik
P
Krieger
D000344:Afferent Pathways / Q000473:pathology*; D000818:Animals; D004195:Disease Models, Animal; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics / Q000378:metabolism*; D005600:Fragile X Syndrome / Q000150:complications / Q000235:genetics / Q000473:pathology*; D006801:Humans; D008124:Locomotion / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011930:Reaction Time / Q000235:genetics; D013003:Somatosensory Cortex / Q000473:pathology*; D014110:Touch / Q000502:physiology*; D014738:Vibrissae / Q000294:innervation*
D051860:Fragile X Messenger Ribonucleoprotein 1; C497684:Fmr1 protein, mouse
Barrel cortex; Behavior; FMRP; Fmr1 KO; Fragile X syndrome; Gap-crossing task; Hyperexcitation; In vivo electrophysiology; Sensory processing; Whisker system