Application of floating silicon-based linear multielectrode arrays for acute recording of single neuron activity in awake behaving monkeys

Abstract

One of the fundamental challenges in behavioral neurophysiology in awake animals is the steady recording of action potentials of many single neurons for as long as possible. Here, we present single neuron data obtained during acute recordings mainly from premotor cortices of three macaque monkeys using a silicon-based linear multielectrode array. The most important aspect of these probes, compared with similar models commercially available, is that, once inserted into the brain using a dedicated insertion device providing an intermediate probe fixation by means of vacuum, they can be released and left floating in the brain. On the basis of our data, these features appear to provide (i) optimal physiological conditions for extracellular recordings, (ii) good or even excellent signal-to-noise ratio depending on the recorded brain area and cortical layer, and (iii) extreme stability of the signal over relatively long periods. The quality of the recorded signal did not change significantly after several penetrations into the same restricted cortical sector, suggesting limited tissue damage due to probe insertion. These results indicate that these probes offer several advantages for acute neurophysiological experiments in awake monkeys, and suggest the possibility to employ them for semichronic or even chronic studies.

Space-Dependent Representation of Objects and Other's Action in Monkey Ventral Premotor Grasping Neurons

“…It is clear that the strongest modulations of multiunit activity occurred in the deepest sites, whereas in the most superficial ones the activity was weaker. This pattern most likely derives from recordings performed in the crown and the upper part of the posterior bank of inferior arcuate sulcus (Belmalih et al, 2009). The exact location of this penetration in the recorded region is indicated with the asterisk in Figure 2 (M1).…”

“…Figure 5 shows the depth distribution of all the recorded neurons classified as mirror (orange), canonical (blue), canonicalmirror (red), and purely motor (gray) neurons. Because this region has been defined as "poorly laminated" (Belmalih et al, 2009, their Fig. 2 A), we could only analyze the distribution along the probe shaft (in depth) of the recorded neurons, with no relationship to cortical laminae.…”

“…), followed by postsurgical pain medications. Surgical procedures were the same as previously described Bonini et al, 2010). All the experimental protocols were approved by the Veterinarian Animal Care and Use Committee of the University of Parma and complied with the European law on the humane care and use of laboratory animals.…”

“…To better understand the relevance of space-constrained coding of objects in F5 grasping neurons, in a subset of penetrations (3 in M1 and 6 in M2), we tested neurons in a paradigm previously used to study metric or pragmatic space coding in area F5 mirror neurons (Caggiano et al, 2009). In particular, 22 canonical neurons and 16 canonical-mirror neurons (all showing significant responses to object presentation during the VMT) were also studied during the visual presentation of the three different objects (in a randomized fashion) in a modified condition of the VMT.…”

“…Some evidence has suggested that canonical and mirror neurons could be anatomically segregated in different sectors of area F5 Raos et al, 2006): the former mostly buried in the posterior bank of the arcuate sulcus (area F5p) and the latter hosted in the adjacent convexity of area F5 (area F5c) (Belmalih et al, 2009;Maranesi et al, 2012). However, previous studies mainly focused on the neuronal coding of either objects or observed actions.…”