In the lab we study vision in the normal and cortically lesioned human subjects. The major focus of our research has been on the spatial and temporal processing of visual stimuli. We have developed a hypothesis that the right parietal lobe serves a generalized role in visual stimulus timing. These ideas were formulated in studies with parietal lesioned patients. In the lab we use transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), EEG and fMRI in an attempt to examine more in detail the neurobiological processing underlying visual timing as well as other visual functions.
Our TMS and neuropsychological studies have led to an important project on patients affected by chronic cortical lesions. They often fail to recover many cognitive functions even years after the stroke, this is also called maladaptive plasticity. The undamaged cerebral hemisphere takes over functions normally performed by the damaged hemisphere and this could be preventing full recovery. In order to encourage recovery we are using TMS to temporarily suppress activity in the undamaged hemisphere and encourage activity within the damaged cortical areas. We have recently published an important result showing that imbalances in inter-hemispheric competition could be the major cause leading to (chronic) behavioral deficits. Our recent fMRI data will help to figure out how this system works hemodynamically. Our ultimate goal is to design TMS/tDCS approaches for rehabilitation of cerebral lesioned patients.
1. Biological motion perception. We are conducting TMS experiments aiming at determining the role played by functionally different visual areas (namely the posterior Superior Temporal Sulcus –pSTS- and the Extrastriate Body Area –EBA-) in biological motion perception. Dr. Joris Vangeneugden, a former postdoc, has used multivoxel pattern analysis (MVPA) in an fMRI experiment aimed at determining whether pSTS and EBA respond differently to a walker orientation vs walking direction. The subsequent TMS experiment has shown a “direct” involvement of those areas in the two types of motion patterns (orientation vs direction). We are now trying to determine the role of different visual areas in walker orientation discrimination, using more ecological stimuli (3D walkers) (Dr. Nicholas Peatfield, postdoctoral fellow).
2. Relative timing in vision. This project aims at determining the neural as well as behavioural correlates of timing in vision. We have previously shown that higher level visual areas (the inferior parietal lobe) are implicated in the discrimination of relative timing, a fundamental function of our visual system constantly dealing with multiple moving objects in the visual environment. For every day activities it is extremely important to precisely and accurately know which “object” appeared first in our field of view, especially during activities such as driving a car or crossing the street. Dr. Sara Agosta, a postdoc in the lab is now running a TMS experiment and she is also testing neurological patients to determine similarities and differences relative to the normal population. Dr. Peatfield is working on a timing project using an oddball paradigm.
3. Assessment and rehabilitation of neurological patients. We work with neurological patients population. In particular we are now running an experimental project with the “Centro di Riabilitazione Cognitiva (CeRIN)” of the University of Trento, in Rovereto. We have tested few patients and used TMS to rehabilitate their attentional functions in the compromised hemifield. We are also submitting left and right parietal lesion patients to visual timing tasks with the aim of devising a rehabilitation protocol for multiple visual/attentional functions. Finally, in collaboration with a group from the Medical School of the University of Rochester (USA) we are starting to run a direct current stimulation (tDCS) protocol to rehabilitate visual field defects (such hemianopsia and blindsight) caused by lesions to the primary visual areas.
4. Spatial suppression and summation in human MT. We have published a paper in 2011 where we demonstrated that by interfering with the neural activity of visual area MT we reduced spatial suppression (a cortical mechanism likely responsible for our ability to segregate relevant information in the visual field and “ignore/suppress” the background). This reduction caused an improvement in subjects’ ability to detect the direction of motion of large moving stimuli. We have now run a follow up experiment using direct current stimulation (tDCS) and we have demonstrated that we can modulate mechanisms of suppression and summation (the latter having an opposite effect to suppression) using cathodal stimulation simultaneously delivered over left and right MT areas. Our results have important implications in understanding the cortical areas implicated in cognitive decline in the elderly as well as in patients affected by psychopathological syndromes such as schizophrenia.
5. Cortical connectivity. We have recently acquired a TMS-compatible EEG system and our next step will be to study the effect of TMS on multiple brain areas by analyzing the EEG activity during and after stimulation. This will provide new insights into rhythmic brain activity in specific frequency bands and what gets affected after stimulation (local and network effects). Through EEG we will also try to address several questions that have risen through our previous TMS research. In particular we will study the inter-hemispheric interaction during bilateral (presented in both visual field) and unilateral visual stimulus presentation. Finally, Dr.Stefania Ficarella, a graduate student in the lab, is setting up a series of experiments aiming at studying EEG activities or different parts of the brain during decision making and response inhibition tasks.
1. Vangeneugden J., Peelen M., Tadin D. and Battelli L. 2014 Distinct neural mechanisms for body form and body motion discriminations. Journal of Neuroscience, 8; 34(2):574-85.
2. Aghdaee M.S., Battelli L. and Assad J.A. Relative timing: from behavior to neurons. Proceedings of the Royal Society of London: Biological Sciences, in press.
3. Papeo L., Lingnau A., Agosta S., Pascual-Leone A., Battelli L. and Caramazza A. The origin of word-related motor activity. Cerebral Cortex, in press.
4. Tadin D., Silvanto J., Pascual-Leone A. and Battelli L. 2011 Improved motion perception and impaired spatial suppression following disruption of cortical area MT/V5. Journal of Neuroscience, 31(4): 1279-83.
5. Battelli L., Alvarez G., Carlson T. and Pascual-Leone A. The role of the parietal lobe in visual extinction studied with transcranial magnetic stimulation. Journal of Cognitive Neuroscience, 2009, 21(10):1946-55.
6. Merabet L., Battelli L., Obretenova S., Maguire S., Meijer P. and Pascual-Leone A. Functional Recruitment of Visual Cortex for sound encoded object identification in the Blind: A TMS Case Study. NeuroReport, 2009, 28; 20(2):132-8.
7. Cattaneo Z, Silvanto J, Battelli L. and Pascual-Leone A. The mental number line modulates visual cortical excitability. Neurosci Lett., 2009, 25;462(3):253-6.
8. Cattaneo Z., Silvanto J., Pascual-Leone A. and Battelli L. The middle range of the number line orients attention to the left side of visual space. Cogntivie Neuropsychology, 2009, 14:1-12.
9. Cattaneo Z., Silvanto J., Pascual-Leone A. and Battelli L. The role of the angular gyrus in the modulation of visuospatial attention by the mental number line. Neuroimage, 2009, 15; 44(2):563-8.
10. Battelli L., Walsh V., Pascual-Leone A. and Cavanagh P. The ‘when’ parietal pathway explored by lesion studies. Current Opinion in Neurobiology, 2008, 18: 120-26.
11. VanRullen R., Pascual-Leone A. and Battelli L. The Continuous Wagon Wheel Illusion and the ‘When’ pathway of the right parietal lobe: a repetitive transcranial magnetic stimulation study. Plos ONE, 2008, 3(8) e2911.
12. Silvanto J., Cattaneo Z., Battelli L. and Pascual-Leone A. Baseline cortical excitability determines whether TMS disrupts or facilitates behavior. Journal of Neurophysiology, 2008, 99: 2725-30.
13. Battelli L., Pascual-Leone A. and Cavanagh P. The WHEN pathway of the parietal lobe. Trends in Cognitive Sciences, 2007;11(5):204-10.
14. Grossman E., Battelli L. and Pascual-Leone A. 2005 Repetitive TMS over posterior STS disrupts perception of biological motion. Vision Research, 45, 2847-53.
15. Battelli L., Cavanagh P., Martini P. and Barton JJS. 2003 Bilateral deficit of transient visual attention in right parietal patients. Brain, 126: 2164-74.
16. Battelli L., Cavanagh P. and Thornton IM. 2003 Perception of biological motion in parietal patients. Neuropsychologia, 41: 1808-16.
17. Battelli L., Black K. and Wray S.H. 2002 Transcranial magnetic stimulation of visual area V5 in migraine. Neurology, 58: 1066-1069.
18. Battelli L., Cavanagh P., Intriligator J, Tramo M.J., Hénaff M-A, Michèl F. and Barton J. 2001 Unilateral right parietal damage leads to bilateral deficit for high-level motion. Neuron, 32: 985-995.