Methylphenidate increases gamma-band oscillations power over parieto-occipital regions
Poster No:
2452
Submission Type:
Abstract Submission
Authors:
Valentina Mancini1, Caren Latreche2, Vincent Rochas2, Christoph Michel2, Peter Uhlhaas3, Stephan Eliez2
Institutions:
1Oxford University, Oxford, Oxfordshire, 2University of Geneva, Geneva, Switzerland, 3Charité, Berlin, Germany
First Author:
Co-Author(s):
Introduction:
Methylphenidate (MPH), a widely prescribed psychostimulant drug, is commonly employed in the treatment of attention deficit hyperactivity disorder (ADHD). Despite its extensive clinical use, the precise mechanisms through which MPH exerts its therapeutic effects on attention is yet to be fully understood. MPH primarily acts as a norepinephrine and dopamine reuptake inhibitor, increasing the availability of these neurotransmitters in the synaptic cleft. However, it is not entirely clear which neural circuits are preferentially modulated by MPH, and if there is a selective modulation of oscillatory activity. Gamma band oscillations (30-80 Hz) have been implicated in attention processes, especially within the visual system (1). During sustained attentional processes, there is an increase in the synchronization of neural activity in the gamma frequency range, which effectively and precisely establishes communication within and between brain areas (2). Despite the established link between gamma-band oscillations and attention, the impact of MPH on these oscillatory patterns has not yet been investigate so far. Investigating this aspect could provide valuable insights into the neural mechanisms underlying MPH's attention-enhancing effects.
Methods:
This study was conducted as part of a randomized trial administering MPH to youths with 22q11.2 deletion syndrome (3), a neurodevelopmental condition that confers high risk of developing multiple psychiatric conditions, including ADHD (4). Twenty-six deletion carriers (aged 8-24) completed the neuroimaging part of the study when they were on and off MPH. At each visit, we acquired high-density electroencephalography recordings with during two paradigms known to elicit a strong response in the gamma frequency range. We employed: a 40-Hz auditory steady state response (ASSR) task (5), and a visual inward moving grating task whereby participants are asked to report the change in speed of inward motion of the grating by button press (6). The outcomes of the visual grating task (performance and reaction times) were examined. Stimulus-elicited oscillatory responses were analyzed with time-frequency analysis using Morlet wavelets decomposition at sensor and source level, and intertrial phase coherence (ITC), as in previous studies (7, 8). In all the analyses, the effects of treatment were compared on/off medication in a within-subject design.
Results:
Deletion carriers on MPH had a better performance at the visual grating task (t = 3.1; p<0.01) and decreased reaction times (t= 2.3; p< 0.05) (figure 1). No differences in ASSR power or ITC were observed if deletion carriers were on or off MPH. Statistically significant differences were found at gamma-band frequencies over a cluster of parieto-occipital electrodes, with deletion carriers on MPH having higher gamma-band responses (60–70 Hz, 0.75–1.5 seconds, t =3.2, p< 0.01). At the source level, we found higher gamma-band responses at the level of the bilateral cuneus, precuneus, lingual gyrus and superior parietal cortex (figure 2).
Conclusions:
Our results indicate that MPH can successfully modulate attentional processes by increasing the number of correct responses to a visual attention task and decreasing the RT. Additionally, MPH can enhance gamma oscillations power during sustained attention in the visual grating task over regions involved in visual processing and attention. Conversely, in our data, MPH doesn't seem to influence the 40Hz-ASSR. A possible explanation is that the attentional demand of the 40Hz-ASSR task is much lower than in the visual grating task. Overall, MPH can improve the efficiency of attentional processing and increase gamma-band power over brain regions implicated in sustained visual attention. Since dopamine activation can enhance gamma-band oscillations (9), one hypothesis is that the observed action of MPH exerted on gamma power is mediated by the increased availability of dopamine at the level of synaptic cleft.
Disorders of the Nervous System:
Neurodevelopmental/ Early Life (eg. ADHD, autism) 2
Psychiatric (eg. Depression, Anxiety, Schizophrenia)
Modeling and Analysis Methods:
EEG/MEG Modeling and Analysis
Perception, Attention and Motor Behavior:
Attention: Auditory/Tactile/Motor
Attention: Visual 1
Keywords:
Attention Deficit Disorder
Electroencephaolography (EEG)
Other - Gamma band oscillations
1|2Indicates the priority used for review
Provide references using author date format
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