Furthermore, apnoea-related reductions in airflow lead to hypoxia and hypercapnia. A range of neurocognitive Epigenetics Compound Library chemical structure impairments have been associated with OSA, including

decreases in memory, attention and executive function (Campana et al., 2010). These symptoms negatively impact the daily life of patients, with reports of difficulty accomplishing routine work tasks (Ulfberg et al., 1996), and increased risk of motor vehicle (Tregear et al., 2009) and occupational (Ulfberg et al., 2000) accidents. Although the pathophysiology of these cognitive deficits remains largely unknown, several studies have shown alterations in brain structure and function in patients with OSA. For example, patients with OSA show decreased grey matter in various brain regions (Joo et al., 2010b; Morrell et al., 2010; Torelli

et al., 2011), and differences in neural activation of sensorimotor and autonomic brain regions during respiratory challenges (Zimmerman & Aloia, 2006). Furthermore, studies using transcranial magnetic stimulation (TMS) have shown increased motor thresholds (Joo et al., 2010a) and prolonged cortical silent periods (CSPs) in patients with OSA (Civardi et al., 2004; Grippo et al., 2005), reflecting cortical hypoexcitability (see Civardi et al., 2009). These changes may result from diminished corticospinal fibre integrity in patients (Macey et al., 2008), and are presumed to be a consequence of chronic intermittent hypoxaemia and sleep fragmentation (Morrell et al., 2003; Ohga et al., 2003). Plasticity of cortical circuits is an important component of the Alectinib cost brain’s ability to adapt, learn and recover from injury. It is also known to be a fundamental process in memory function, which has been shown to be defective in OSA (Jackson et al., 2011). The application of repetitive trains of TMS (rTMS) is commonly used to non-invasively induce plasticity of neural circuits within the

human motor cortex. A recently developed protocol known as continuous theta burst stimulation Loperamide (cTBS) uses a specific pattern of rTMS that can suppress motor-evoked potentials (MEPs) for up to 1 h (Huang et al., 2005), and is thought to induce long-term depression (LTD)-like synaptic changes (Cardenas-Morales et al., 2010) within cortical circuits (Di Lazzaro et al., 2005). The primary aim of this study was to examine motor cortex plasticity in patients with moderate-to-severe OSA using cTBS. As mouse models of OSA have shown impaired hippocampal plasticity (Xie et al., 2010) and sleep fragmentation could affect processes that promote plasticity (Diekelmann & Born, 2010), we hypothesised that cortical plasticity would be reduced in patients with OSA. Furthermore, as increased intracortical inhibition (ICI) can reduce neuroplastic capacity of cortical circuits (Ziemann et al., 2001), a secondary aim of this study was to quantify baseline ICI in patients with OSA compared with controls. Based on previous observations of increased CSP in OSA (Civardi et al.