Experimental Cortical Plasticity

Experimental Cortical Plasticity

For many years the department of neurophysiology is working on sensory processing in the mammalian brain and its plasticity in the course of learning and recovery from lesions. The current experimental studies of my group (Experimental Cortical Plasticity) are concerned with the cellular mechanisms of the modulatory action of transcranial magnetic stimulation (TMS). TMS allows non-invasively the activation of superficially located cortical areas. In terms of a “virtual lesion”, single pulses transiently disturb cortical activity, enabling functional studies. Repetitive stimulation (rTMS) on the other hand has a sustained modulatory action on cortical excitability, offering a potential therapeutic use. Using a combination of immunohistochemical, molecularbiological, electrophysiological and behavioural methods, we try to unravel the cellular mechanisms behind the effects of rTMS. On one hand, we study the effects of rTMS on sensory processing itself and the relationship to changes in cortical protein expression, on the other hand, we further test how rTMS can modulate plasticity of the sensory system. Modulation of synaptic plasticity in terms of homeostatic metaplasticity is currently the favoured hypothesis of rTMS action. These projects are currently supported by the Deutsche Forschungsgemeinschaft (FU 256/3-1, 3-2, neuronal mechanism of rTMS; SFB 874, TP A4, integration of sensory stimuli within the rat barrel cortex and its modulation artificial stimulation, as with rTMS).

Current Projects

Topic: Cellular Mechanisms of Transcranial Magnetic Stimulation (TMS)

  • Time course of changes in cortical protein expression following theta-burst stimulation via TMS
  • Age-dependence of TMS effects on parvalbumin expression in fast-spiking interneurons
  • Changes in the electrical properties of fast-spiking interneurons following TMS-induced reduction in parvalbumin expression
  • Effects of theta-burst TMS on inhibitory sensory interactions in rat barrel cortex
  • Dose-dependence of theta-burst TMS (number of stimulation blocks) on changes in cortical protein expression
  • Dependence of theta-burst TMS effects on NMDA receptor activation
  • Effect of theta-burst TMS on critical period of rat visual cortex

Topic: Sensory integration and plasticity of rat barrel cortex

  • Mechanisms of sensory adaptation and detection of change in rat barrel cortex
  • Dependence of barrel cortex map plasticity on natural and artificial modulation of cortical excitability
  • Spatiotemporal integration of multi-whisker stimulation in rat barrel cortex

Methods and techniques

  • single-/multi-unit recordings in vivo
  • local field potential and EEG recording/analysis
  • repetitive transcranial magnetic stimulation (rTMS)
  • intracortical microstimulation (ICMS)
  • microiontophoresis
  • piezoelectric whisker stimulation
  • visual stimulation
  • intrinsic optical imaging
  • patch clamp recording (in vitro)
  • immunohistochemistry with multi-fluorescent labelling
  • 3D neuronal imaging with ApoTome and Neurolucida / Autoneuron
  • Western Blot
  • Microdialysis & HPLC
  • Behavioural testing (water maze, radial maze, visual acuity test, operant chamber)