P 131. Repetitive TMS over the left posterior parietal cortex affects the regulation of body sway

Society Proceedings / Clinical Neurophysiology 124 (2013) e39–e187

Conclusion: Overall cerebellar tDCS changes tests of cognitive and affective functions, possibly through cerebellum-cerebral pathways. Although whether changes induced by cerebellar tDCS in cognition, emotional recognition and learning observed in our experiments can be behaviorally relevant remains to be clarified, cerebellar DC stimulation might be a “window” for modulating complex mental process. References Ferrucci R, Marceglia S, Vergari M, et al. Cerebellar transcranial direct current stimulation impairs the practice-dependent proficiency increase in working memory. J Cogn Neurosci 2008;20:1687–97. Ferrucci R, Giannicola G, Rosa M, et al. Cerebellum and processing of negative facial emotions: cerebellar transcranial DC stimulation specifically enhances the emotional recognition of facial anger and sadness. Cogn Emot 2012;26:786–99. doi:10.1016/j.clinph.2013.04.207

Poster Session II Cognitive Neuroscience II P 130. The impact of dorsolateral prefrontal cortex in the control of heart rate variability investigated by repetitive transcranial magnetic stimulation—K. Sakreida a,b, S. Gauggel a (a University Hospital of RWTH Aachen, Institute of Medical Psychology and Medical Sociology, Aachen, Germany, b University Hospital of RWTH Aachen, Division of Clinical and Cognitive Neurosciences, Department of Neurology, Aachen, Germany) The central autonomic network appears to support goal-directed behavior and adaptability since it serves as an integrated component of an internal regulation system through which the brain controls visceromotor, neuroendocrine, pain, and behavioral responses essential for survival. It includes predominantly a multiplicity of subcortical brain structures, but also medial prefrontal and insular cortex. There is also evidence on the impact of the dorsolateral prefrontal cortex (DLPFC) in central autonomic functions as it integrates sensorimotor input information and anticipations, and thus, regulates behavioural outcome. Moreover, behavioural inhibition is suggested to be a core function of DLPFC with emphasis on the right hemisphere. The aim of this study is to provide evidence on effects in heart rate variability by manipulating the cortical excitability of the DLPFC. For that reason neuro-navigated repetitive low frequency transcranial magnetic stimulation is applied over right and left DLPFC as well as right and left dorsolateral premotor cortex as control target sites. Electrocardiogram is recorded before, during, and after stimulation. Preliminary data point to a pronounced right-lateralized effect in cardiac autonomic balance during as compared to post rTMS application. Certainly, this study will contribute to a better understanding of autonomic functions and the relationship to the frontal cortex. doi:10.1016/j.clinph.2013.04.208

P 131. Repetitive TMS over the left posterior parietal cortex affects the regulation of body sway—F. Hirschauer, W. Stadler, A. Geipel, J. Hermsdörfer, L. Johannsen (Technische Universität München, Munich, Germany) Introduction: During upright stance, skin contact with an earthfixed referent provides tactile feedback about own body sway relative to the contact location. In this situation body sway variability is reduced compared to standing without contact. Recent studies on the time course of sway before, during and after periods of intermittent touch contact indicated that the stabilisation of sway is a

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time-consuming integrative process. In addition, it has been suggested that dorsolateral prefrontal cortex is involved in the processing of tactile feedback for the control of body sway. Objectives: Using repetitive TMS, we aimed to investigate the influence of activity inhibition within the left posterior parietal cortex (PPC) as well as the left lateral prefrontal cortex (PFC) on the time course of sway stabilisation after the onset of finger tip contact as well as sway destabilisation after contact removal. We expected that PPC inhibition would disrupt the processing of tactile feedback for sway control indicated by more delayed and less strong sway reduction compared to PFC inhibition. Materials and methods: In two sessions, separated by a week, 5 adult participants received 20 min of 1 Hz repetitive TMS stimulation at 110% passive motor threshold over the left PPC (CP3) and lateral PFC (F3) respectively. Before and after each stimulation interval, blind-folded and ear-plugged participants stood quietly on a force plate with their right forearm as well as fingers of the right hand reaching forward. In this posture, the fingers were held at hip level slightly above a contact plate of which its vertical position was controlled by a linear motor. Body sway was assessed in terms of Centre-of-Pressure (CoP) motion and trunk kinematics in the anteroposterior direction. Within each of six trials of 120 s duration, five pairs of touch onset and removal were timed at random intervals by driving the contact plate upwards until contact was established, respectively downwards until contact was safely removed. The minimum time period between subsequent onsets and removals was 7 s. Time course of sway was evaluated across 3 s before and after each contact event. Results: As expected, sway reduction was attenuated as well as rate of sway stabilisation and destabilisation were lower after PPC inhibition. In addition, body sway was generally increased. In contrast, sway control with or without tactile feedback remained unaffected compared to both pre-stimulation baselines after lateral PFC stimulation. Conclusion: 1 Hz repetitive TMS over the left PPC disrupts the sensorimotor control of body balance as well as the sensory reorganization following onset and removal of tactile body sway-related feedback from the finger tips of the right hand. doi:10.1016/j.clinph.2013.04.209

P 132. Modulation of encoding-related networks by intermittent TBS stimulation in healthy aging—D. Vidal-Pineiro a, J.P. MartinTrias a, I. Mena-Sanchez a, E.M. Arenaza-Urquijo a, R. Sala-Llonch a, N. Bargalló b, D. Bartrés-Faz a,c (a Universitat de Barcelona, Dept. Psiquiatria i Psicobiologia Clinica, Barcelona, Spain, b Hospital Clˇ´nic de Barcelona, Radiology Service, Barcelona, Spain, c Institut d’Investigacions Biomèdiques Agust Pi i Sunyer IDIBAPS, Barcelona, Spain) Question: Memory dysfunction is one of the main cognitive hallmarks of aging. Repetitive Transcranial Magnetic Stimulation induces brain plasticity changes that may underlie its capacity to modulate associative memory in elders (Solé-Padullés et al., 2006). Memory recall also depends on the manner in which stimuli are encoded (Innocenti et al., 2010) (i.e. the depth or shallowness of the processing) according to level of processing (LOP) theory (Craik and Lockhart, 1972). Our aim was to investigate the impact of a single session of excitatory intermittent theta burst stimulation (iTBS) on behavioral outcomes and the expression of brain networks in healthy elders, related to an episodic memory task with two types of processing. Materials and methods: After an initial MRI scanner and neuropsychological testing 21 healthy elder subjects (71.6yo.) were randomly assigned to Real (n = 11) or Sham iTBS group. Subjects underwent a baseline functional MRI session (Siemens 3T) followed by Real or