Overlapping representations of numerical magnitude and motion direction in the posterior parietal cortex: A TMS-adaptation study

The human posterior parietal cortex (PPC) is involved in the encoding of both visual motion and numerical magnitude. In non human primates, neurons have been found in PPC that are selective for both motion direction and magnitude. Whether such neurons also exist in human PPC is not known. Here we investigated this hypothesis using state-dependent transcranial magnetic stimulation (TMS). Participants were adapted to a specific motion direction (either leftward or rightward), after which they performed a magnitude comparison task, with TMS applied at the onset of each trial. Our hypothesis was that neurons tuned to leftward motion may also be sensitive to small magnitudes and neurons tuned to rightward motion may also be sensitive to large magnitudes, a mapping that may have developed via spatial attentional mechanisms. Our results supported this view by showing that the effect of PPC TMS on small and large numbers depended on the motion direction being adapted, thus suggesting that there may be a functional overlap in neuronal representations of motion direction and numerical magnitude in human PPC.

[1]  Neil G. Muggleton,et al.  New light through old windows: Moving beyond the “virtual lesion” approach to transcranial magnetic stimulation , 2008, NeuroImage.

[2]  Masako Okamoto,et al.  Three-dimensional probabilistic anatomical cranio-cerebral correlation via the international 10–20 system oriented for transcranial functional brain mapping , 2004, NeuroImage.

[3]  J M Zanker,et al.  Mechanisms of human motion perception: combining evidence from evoked potentials, behavioural performance and computational modelling , 2000, The European journal of neuroscience.

[4]  J. Mattingley,et al.  Fast and slow parietal pathways mediate spatial attention , 2004, Nature Neuroscience.

[5]  Giacomo Koch,et al.  Focal Stimulation of the Posterior Parietal Cortex Increases the Excitability of the Ipsilateral Motor Cortex , 2007, The Journal of Neuroscience.

[6]  Neil G. Muggleton,et al.  Testing the validity of the TMS state-dependency approach: Targeting functionally distinct motion-selective neural populations in visual areas V1/V2 and V5/MT+ , 2008, NeuroImage.

[7]  Uwe Herwig,et al.  Using the International 10-20 EEG System for Positioning of Transcranial Magnetic Stimulation , 2004, Brain Topography.

[8]  J. Schwarzbach,et al.  State-dependent TMS reveals a hierarchical representation of observed acts in the temporal, parietal, and premotor cortices. , 2010, Cerebral cortex.

[9]  M. Goldberg,et al.  Ventral intraparietal area of the macaque: anatomic location and visual response properties. , 1993, Journal of neurophysiology.

[10]  Guy A. Orban,et al.  Similarities and differences in motion processing between the human and macaque brain: evidence from fMRI , 2003, Neuropsychologia.

[11]  S. Dehaene,et al.  The mental representation of parity and number magnitude. , 1993 .

[12]  M. Carrasco,et al.  How do attention and adaptation affect contrast sensitivity? , 2007, Journal of vision.

[13]  V. Walsh,et al.  The parietal cortex and the representation of time, space, number and other magnitudes , 2009, Philosophical Transactions of the Royal Society B: Biological Sciences.

[14]  W Fias,et al.  Irrelevant digits affect feature-based attention depending on the overlap of neural circuits. , 2001, Brain research. Cognitive brain research.

[15]  Juha Silvanto,et al.  Double Dissociation of Format-Dependent and Number-Specific Neurons in Human Parietal Cortex , 2010, Cerebral cortex.

[16]  Juha Silvanto,et al.  TMS-adaptation reveals abstract letter selectivity in the left posterior parietal cortex. , 2009, Cerebral cortex.

[17]  Michael Andres,et al.  Number magnitude and grip aperture interaction , 2004, Neuroreport.

[18]  D. Siddle,et al.  Orienting and habituation : perspectives in human research , 1983 .

[19]  Demis Basso,et al.  Motion on Numbers: Transcranial Magnetic Stimulation on the Ventral Intraparietal Sulcus Alters Both Numerical and Motion Processes , 2009, Journal of Cognitive Neuroscience.

[20]  S. Dehaene,et al.  THREE PARIETAL CIRCUITS FOR NUMBER PROCESSING , 2003, Cognitive neuropsychology.

[21]  Andreas Nieder,et al.  Temporal and Spatial Enumeration Processes in the Primate Parietal Cortex , 2006, Science.

[22]  Z. Cattaneo,et al.  Investigating visual motion perception using the transcranial magnetic stimulation-adaptation paradigm , 2008, Neuroreport.

[23]  Carmel Mevorach,et al.  Opposite biases in salience-based selection for the left and right posterior parietal cortex , 2006, Nature Neuroscience.

[24]  Juha Silvanto,et al.  Neural adaptation reveals state‐dependent effects of transcranial magnetic stimulation , 2007, The European journal of neuroscience.

[25]  T. Kitama,et al.  Vertical eye movement-related secondary vestibular neurons ascending in medial longitudinal fasciculus in cat I. Firing properties and projection pathways. , 1990, Journal of neurophysiology.

[26]  C. A. Marzi,et al.  Transcranial magnetic stimulation selectively impairs interhemispheric transfer of visuo-motor information in humans , 1998, Experimental Brain Research.

[27]  ROBERT S. MOYER,et al.  Time required for Judgements of Numerical Inequality , 1967, Nature.

[28]  C Caltagirone,et al.  Overestimation of numerical distances in the left side of space , 2004, Neurology.

[29]  Andreas Nieder,et al.  Neuronal population coding of continuous and discrete quantity in the primate posterior parietal cortex , 2007, Proceedings of the National Academy of Sciences.

[30]  Marisa Carrasco,et al.  When sustained attention impairs perception , 2006, Nature Neuroscience.

[31]  Harold Bekkering,et al.  Getting a grip on numbers: numerical magnitude priming in object grasping. , 2007, Journal of experimental psychology. Human perception and performance.

[32]  A. Kohn.  Visual adaptation: physiology, mechanisms, and functional benefits. , 2007, Journal of neurophysiology.