Plasticity of visual evoked potentials in patients with neurofibromatosis type 1.

OBJECTIVE

The inability to properly process visual information has been frequently associated with neurofibromatosis type 1 (NF1). Based on animal studies, the cause of cognitive disabilities in NF1 is hypothesized to arise from decreased synaptic plasticity. Visual cortical plasticity in humans can be investigated by studying visual evoked potentials (VEPs) in response to visual stimulation.

METHODS

VEP plasticity was assessed by measuring the increase of the peak amplitudes C1, P1, and N1 induced by 10-min modulation of checkerboard reversals in 22 adult NF1 patients and 30 controls. VEP signals were recorded pre-modulation, during modulation, and at 2, 7, 12, 17, 22, 27 min post-modulation.

RESULTS

The P1 amplitude increased significantly comparing post-modulation to pre-modulation in the control group. This potentiation was not observed in the NF1 group.

CONCLUSIONS

Visual cortical plasticity could be measured using VEPs in response to visual stimulation in the control group. Individuals with NF1 may have reduced visual cortical plasticity, as indicated by their non-potentiated response to VEP induction. These findings should be interpreted with caution due to high inter-subject variability.

SIGNIFICANCE

The present study contributes to an improved assessment of the feasibility for using neurophysiological outcome measures in intervention studies of cognitive deficits among patients with NF1.