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Leo Fowler
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2 Supplemental material Research Article Title: The dorsomedial pathway is not just for reaching: Grasping neurons in the medial parieto-occipital cortex of the macaque monkey Abbreviated title: Authors: Fattori P. 1, Raos V. 2, Breveglieri R. 1, Bosco A. 1, Marzocchi N. 1, Galletti C. 1 1 Dipartimento di Fisiologia Umana e Generale, Universita` di Bologna, I Bologna, Italy 2Department of Basic Sciences, School of Health Sciences, University of Crete, GR Iraklion, Greece Corresponding author: Patrizia Fattori Dipartimento di Fisiologia Umana e Generale, Universita' di Bologna Piazza di Porta San Donato Bologna (Italy) tel: ; Fax: patrizia.fattori@unibo.it 1

3 VISUAL RESPONSES OF V6A NEURONS TO THE PRESENTATION OF OBJECTS TO BE GRASPED. The reach-to-grasp task here presented was performed in darkness with the exception of the 500 ms when the object to be grasped was illuminated well before arm movement (see Fig. 1b). As area V6A contains neurons activated by passive visual stimulations (Galletti et al., 1996; Galletti et al., 1999), and receives a direct visual input from the extrastriate visual area V6 (Galletti et al., 2001) and from many visuomotor areas of the posterior parietal cortex (Gamberini et al., 2009), it is plausible that the visual appearance of the object evokes activations in V6A cells. Fig S1 shows that this is actually the case. The five average spike density functions of Fig. S1, one for each of the 5 objects/grips tested, include the period of object presentation and are aligned twice, once at the object presentation, to appreciate the visual response at the objects appearance (Fig. S1a) the second at the onset of movement, to display the motor responses during the execution of the 5 different grips (Fig. S1b, same data as in Fig. 3). Two peaks of activations are well evident: one during object presentation (left) and one during reach-to-grasp movement (right). The prominent feature of the population as a whole is that the temporal profile and intensity of visual and motor responses is similar for the five objects and for their respective grip types (permutation test, p>0.01). In other words, there was no population bias for a specific object, nor for a specific grip. By looking at single cell responses, we know that individual V6A neurons do show clear visual and motor preferences, but evidently these individual preferences compensate one another at the population level, so that all tested objects/grips are about equally represented. Single cell analysis 2

4 has shown that 93 out of the 111 task-related neurons (84%) displayed visual activity during object presentation (epoch VISUAL: from 40 ms after object illumination till 300 ms after it; t-test, p<0.05). Thirty-seven of them (40%) exhibited visual responses selective for the object shape (ANOVA 1 way, p<0.05). The selectivity of the visual responses was either congruent or incongruent with the neuron s motor response. This activity pattern points to complex neural computations performed to transform the visual features of the object being the target of a grasping action into a grip posture suitable to acquire it with the hand. How visual information is linked to motor performance requires complex work that would be accomplished in future studies. References Galletti C, Fattori P, Kutz DF, Gamberini M (1999) Brain location and visual topography of cortical area V6A in the macaque monkey. Eur J Neurosci 11: Galletti C, Fattori P, Battaglini PP, Shipp S, Zeki S (1996) Functional demarcation of a border between areas V6 and V6A in the superior parietal gyrus of the macaque monkey. Eur J Neurosci 8: Galletti C, Gamberini M, Kutz DF, Fattori P, Luppino G, Matelli M (2001) The cortical connections of area V6: an occipito-parietal network processing visual information. Eur J Neurosci 13: Gamberini M, Passarelli L, Fattori P, Zucchelli M, Bakola S, Luppino G, Galletti C (2009) Cortical connections of the visuomotor parietooccipital area V6Ad of the macaque monkey. J Comp Neurol 513:

5 Supplemental Figure Caption Supplemental Figure 1: Visual and motor encoding of object/grip information in V6A population: The activity of 111 V6A neurons for each tested object (different colors) is expressed as average normalized SDF (thick lines) with variability bands (SEM; light lines). Each cell of the population was taken into account 5 times, once for each grip type. Activity is aligned twice: at the object presentation (a), and at the onset of movement (b). The 5 SDFs are not statistically different (permutation test) during object presentation, nor during reach-tograsp performance. This indicate an absence of a population preference for a specific object or a specific grip. Scale on abscissa: 200 ms/division; vertical scale: 10% of normalized activity/division. 4

The Dorsomedial Pathway Is Not Just for Reaching: Grasping Neurons in the Medial Parieto-Occipital Cortex of the Macaque Monkey

342 The Journal of Neuroscience, January 6, 2010 30(1):342 349 Behavioral/Systems/Cognitive The Dorsomedial Pathway Is Not Just for Reaching: Grasping Neurons in the Medial Parieto-Occipital Cortex of