title: Re-wiring the brain: increased functional connectivity within primary somatosensory cortex following synchronous co-activation.
abstract: The primary somatosensory cortex shows precise topographical organisation, but can be quickly modified by alterations to sensory inputs. Temporally correlated sensory inputs to the digits can result in the merging of digit representations on the cortical surface. Underlying mechanisms driving these changes are unclear but the strengthening of intra-cortical synaptic connections via Hebbian mechanisms has been suggested. We use fMRI measures of temporal coherence to infer alterations in the relative strength of neuronal connections between digit regions 2 and 4 following 3 hours of synchronous and asynchronous co-activation. Following synchronous co-activation we find a 20% increase in temporal coherence of the fMRI signal (p=0.0004). No significant change is seen following asynchronous co-activation suggesting that temporal coincidence between the two digit inputs during co-activation is driving this coherence change. In line with previous work we also find a trend towards reduced separation of the digit representations following synchronous co-activation and significantly increased separation for the asynchronous case. Increased coherence is significantly correlated with reduced digit separation for the synchronous case. This study shows that passive synchronous stimulation to the digits strengthens the underlying cortical connections between the digit regions in only a few hours, and that this mechanism may be related to topographical re-organisation.
authors: Centre for Imaging Sciences, Institute of Population Health, University of Manchester, M13 9PT, UK; Magnetic Resonance Imaging and Analysis Research Centre (MARIARC), University of Liverpool, L69 3GE, UK. Electronic address: rishma.vidyasagar@manchester.ac.uk.
authors: Rishma
authors: R
authors: Vidyasagar
authors: Department of Physical Therapy Education, Elon University, Campus Box 2085, Elon, NC 27244-2085, USA.
authors: Stephen E
authors: SE
authors: Folger
authors: Centre for Imaging Sciences, Institute of Population Health, University of Manchester, M13 9PT, UK.
authors: Laura M
authors: LM
authors: Parkes
mesh_terms: D000328:Adult; D063132:Connectome / Q000379:methods*; D003344:Cortical Synchronization / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D005385:Fingers / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D010812:Physical Stimulation / Q000379:methods*; D013003:Somatosensory Cortex / Q000502:physiology*; D014110:Touch / Q000502:physiology*
keywords: BOLD; Coherence; Cortical reorganisation; Plasticity; Somatotopy; fMRI