Suppression of saccades and response properties of fixation neurons in the monkey frontal eye field

Abstracts Evans) rats (n = 2) were used. Flickers of the LEDs or sinusoidal moving gratings were presented as visual stimuli. The electrode array was attached onto the dura mater covering the visual cortical areas. Visually evoked intracortical unit activities were simultaneously recorded by a tungsten microelectrode inserted into the cortex through the spaces between the mesh. Comparable to the simultaneously recorded intracortical LFPs, the visually evoked changes were distinguished by the mesh electrode array during 50 to 300 ms after the onset of the stimuli for more than three weeks. These results indicate the feasibility of chronic cortical recordings by using the mesh electrode array. doi:10.1016/j.neures.2009.09.170

O2-I5-2 Subcellular-resolution electronic recording and stimulation of cultured cortical networks using an 11,011 electrode CMOS array Douglas Bakkum 1 , Urs Frey 2 , Andreas Hierlemann 2 , Hirokazu Takahashi 1 1

Dept. Mechano-Informatics, Univ. of Tokyo, Japan; Biosystems Science and Engr., Switzerland

2

ETH Zurich, Dept.

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O2-J1-1 Function of primary visual cortex in compensatory control of saccadic eye movement Takuro Ikeda 1,2 , Masatoshi Yoshida 1,3 , Tadashi Isa 1,2,3 1

National Institute for Physiological Sciences, Japan; Graduate University for Advanced Studies, Japan

2

CREST, Japan;

3

The

Saccades are fast movements of eyes by which animals can search visual scene efficiently. Saccades are known to be quite accurate in spite of their rapid and fast nature, although the neural mechanisms underlying the accurate control of saccades are still unclear. We have reported that saccadic motor control was impaired after lesion of primary visual cortex (V1) (Yoshida et al., J. Neurosci., 2008). Here, we further analyzed velocity profiles of saccades in monkeys with unilateral lesions in V1. We found that saccades tended to be more “ballistic” in the affected field (contralateral to the lesion), while saccades were more “guided” to compensate the variation of initial velocity in the normal field (ipsilateral to the lesion). This result suggests that saccades are controlled by at least two components: a driving signal which may be generated by the superior colliculus (SC) and a compensatory signal which requires visual information via the geniculostriatal pathway. doi:10.1016/j.neures.2009.09.174

A brain’s unique abilities emerge from the processing of information by networks of neurons. Multiunit recording techniques, typically multielectrode arrays and imaging using Ca++ or voltage sensitive dyes, were created to investigate such dynamics. However, these methods are not ideal. Accessible neurons are limited by number and spatial resolution of electrodes, and imaging techniques have poor signal-to-noise ratios or low temporal resolution along with phototoxicity and photobleaching. To overcome these limitations, we grew networks of neurons and glia over a CMOS integrated array (11,011 electrodes in 3.4 mm2 ). Within a few ms, 126 arbitrary electrodes can be configured to sample activity. Nearby electrodes can record the same soma with signals up to 140 times rms. Spike-triggered averaging enabled propagating axonal APs to be observed. Likewise, each electrode can deliver stimuli to evoke activity, with artifacts localized within 80 ␮m. doi:10.1016/j.neures.2009.09.171

O2-I5-3 An accretion based data mining algorithm for assembly identification Sonja Gruen 1,2 , Denise Berger 2,3 , Christian Borgelt 4 , George Gerstein 5 RIKEN Brain Science Institute, Japan; 2 BCCN, Berlin, Germany; 3 Freie Univ., Berlin, Germany; 4 European Center for Soft Computing, Mieres (Asturias), Spain; 5 Univ. of Pennsilvania, Philadelphia, USA

O2-J1-2 Reduction of motor variability by a possible patternclassifier function of the cerebellum: saccade case Masahiko Fujita Fac. Eng., Hosei. Univ., Tokyo, Japan Saccades to a single target vary in amplitude and direction. Monkeys recover saccade amplitude some months after an oculomotor vermis lesion. However, variations in amplitude remain as large as during the early postlesion period (Takagi et al., 1998; Barash et al., 1999). Reduction of the variability is likely a cerebellar cortex process; learning speed itself does not reduce variability. Here I propose a model Golgi-granule cell system with a preprocessing ability for characterizing mossy fiber inputs such that Purkinje cells can impinge upon nuclear activity with the amount of inhibition necessary to reduce variability in the saccade amplitude. The strength of inhibition in response to each mossy fiber input pattern is learned during erroneous trials as adaptation. The proposed Golgi-granule cell system extends the capability of feed-forward place-code associative learning of the cerebellum (Fujita, 2005) and reduces motor variability in general. doi:10.1016/j.neures.2009.09.175

1

We present a new method which identifies neurons participating in assemblies by combining the accretion method with data mining approaches (frequent item set mining, FIM). Spike synchrony among groups of neurons is detected by the accretion approach: pairs of spike trains are tested for significant correlation and then reduced to new point processes containing only synchronized spikes. These processes are in turn merged with correlated spike trains until the maximal order of correlation is found. FIM algorithms help to efficiently search the space of all neuronal subsets. Using simulations of massively parallel spike processes that contain various constellations of correlated activity we illustrate that our algorithm is well suited for identifying neuronal groups exhibiting higher order correlations. The approach is able to separate neuronal groups of overlapping assemblies, irrespective of the number of assemblies individual neurons are participating in. doi:10.1016/j.neures.2009.09.172

O2-I5-4 Correlation between output spike trains of feed forward network receiving common input Yasuhiro Nishigaki 1 , Jun-nosuke Teramae 2 , Tomoki Fukai 1,2 1

Dept. Complexity, The University of Tokyo, Tokyo, Japan; Wako, Japan

2

BSI, RIKEN,

Neuron in the brain have two ways of information coding by spike trains. One is rate coding and another is temporal coding. Recent study suggests that the existence of the neural circuit which can convert rate coding to temporal coding. In this study we propose the neural circuit model which can convert input firing rate to correlation of output spike trains. We show that output correlation can be independently controlled from output firing rate. doi:10.1016/j.neures.2009.09.173

O2-J1-3 Properties of input–output organization of INC neurons as a counterpart of IBNs in the horizontal saccade system Yuriko Sugiuchi, Yoshiko Izawa, Mayu Takahashi, Yoshikazu Shinoda Dept. Systems Neurophysiol., Tokyo Medical and Dental University, Tokyo, Japan The interstitial nucleus of Cajal (INC) has been known to contain burst neurons related to vertical (V) saccades. Our previous study showed that inhibitory burst neurons (IBNs) existed in the V saccade system, and they were located in the INC. The present study was aimed at characterizing the input–output organization of INC neurons for generation of V saccades using an intracellular recording technique in anesthetized cats. INC neurons were identified by their antidromic responses to stimulation of the contralateral (contra-) trochlear (IV) nucleus, INC or FFH. INC neurons projecting to the contra-IV nucleus received monosynaptic excitation and disynaptic inhibition from the ipsi- and contra-SC, respectively. These INC neurons also projected to the contra-INC and FFH simultaneously. Stimulation of the OPN area and contra-INC evoked monosynaptic IPSPs. These findings support the idea that INC neurons that mediate inhibition from the SC to contra-IV motoneurons are a counterpart of IBNs in the horizontal saccade system. doi:10.1016/j.neures.2009.09.176

O2-J1-4 Suppression of saccades and response properties of fixation neurons in the monkey frontal eye field Yoshiko Izawa, Hisao Suzuki, Yoshikazu Shinoda Dept. Systems Neurophysiol., Tokyo Medical and Dental Univ., Tokyo, Japan We have shown previously that electrical stimulation of the frontal eye field (FEF) suppressed the generation of saccades supporting the idea that the FEF has a role in maintaining attentive fixation. The present study analyzed the activity of fixation neurons discharging during fixation in the FEF in trained monkeys. The neural activity of fixation neurons increased at the start of fixation and was maintained during fixation. When a fixation spot disappeared during steady fixation, different fixation neurons exhibited different categories of response ranging from activity reduction to activity increase. Fixation neurons usually decreased their firing rate before the

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Abstracts

onset of saccades. The activity reduction of fixation neurons almost coincided with, or occurred slightly before, activity increase of saccade-related movement neurons in the FEF in the same monkey. The present results suggest that fixation neurons in the FEF form suppression mechanism that could control the maintenance of fixation and the initiation of saccades. doi:10.1016/j.neures.2009.09.177

O2-J1-5 Mechanism of visual motion detection in the MST area of monkey cortex Kenichiro Miura, Naoko Inaba, Kenji Kawano Grad. Schl. Med., Kyoto Univ., Kyoto, Japan Visual motion can be sensed by low-level (energy-based) and/or high-level (featurebased) mechanisms. To understand the neural mechanism sensing visual motion in the MST area, single unit activities were recorded from two monkeys while they were exposed to motion of square wave gratings lacking the fundamental (“missing fundamental (mf) stimulus”). Motion consisted of successive 1/4 wavelength steps, so the overall pattern (feature) shifted in the direction of the steps, whereas the major Fourier component (the 3rd harmonic) shifted in the reverse direction because of spatial aliasing. The direction-selective MST neurons, whose preferred directions were determined by responses to a moving random-dot pattern, generally showed larger responses when the mf stimulus shifted in the opposite to their preferred directions than shifted in their preferred directions. The result suggests that the MST neurons are sensitive to the motion of the major Fourier component rather than the feature, consistent with the low-level, energy-based mechanism.

O2-J1-6 Entrainment of neuronal activity to periodic stimuli in the primate deep cerebellar nuclei Masaki Tanaka 1,2 , Shogo Ohmae 1 , Akiko Uematsu 1 Dept. Physiol, Hokkaido Univ. Sch. Med., Sapporo, Japan; Tokyo, Japan

2

PRESTO, JST,

Accumulating evidence suggests that the cerebellum is involved in temporal processing in the range of several hundreds of milliseconds. To explore the underlying neural mechanisms, we examined single neuron activity in the deep cerebellar nuclei. In the oddball paradigm, visual stimuli appeared periodically at a fixed interval (200–800 ms) around the fixation point. Monkeys were required to make a saccade to a peripheral target as soon as they detected either the changes in stimulus color (deviant condition) or the absence of the expected stimulus (missing condition). A subset of neurons in the dentate nucleus of the cerebellum exhibited firing modulation that gradually increased as the repetition of the stimuli progressed in each trial. Most of them showed greater firing modulation for longer inter-stimulus interval, and responded differently to the deviant and the missing oddballs. These results suggest that neurons in the dentate nucleus might represent internal rhythms, which are necessary to predict the timing of upcoming stimulus and to detect a missing oddball. doi:10.1016/j.neures.2009.09.179

O2-J2-1 Differences in binocular responsiveness and ocular dominance plasticity between excitatory and GABAergic neurons in the mouse visual cortex Kazuhiro Sohya 1 , Katsuro Kameyama 1,2 , Teppei Ebina 1,3 , Yuchio Yanagawa 4 , Tadaharu Tsumoto 1 1

Brain Science Institute, RIKEN, Wako, Japan; 2 Tottori University, Yonago, Japan; 3 TUAT, Tokyo, Japan; 4 Gunma University, Maebashi, Japan

In visual cortex, the binocular responsiveness of neurons is modified by a monocular visual deprivation during the critical period of postnatal development. Although this was established more than four decades age, excitatory and GABAergic neurons have not been separately studied so far. Because GABAergic neurons were proposed to play an important role in the expression of such plasticity during the critical period, we examined differences in ocular dominance plasticity between excitatory and GABAergic neurons by applying in vivo two-photon functional Ca2+ imaging to the visual cortex of VGAT-Venus transgenic mouse, in which GABAergic neurons express Venus fluorescence protein. We found that the binocularity of visual responses of GABAergic neurons is higher than that of excitatory neurons in normally reared mice and the ocular dominance plasticity of GABAergic neurons is higher than that of excitatory neurons after the end of the critical period. doi:10.1016/j.neures.2009.09.180

1

Osaka University, Toyonaka, Japan; sciences, Japan

2

Graduate School of Frontier Bio-

In neurons of the lateral geniculate nucleus (LGN), response to a stimulation of the classical center-surround receptive field (CRF) is suppressed by a stimulation of the extraclassical receptive field (ECRF) (surround suppression, SS). To study how intrathalamic GABAergic inhibition is responsible for SS, we performed exracellular single-unit recordings from LGN neurons of anesthetized and paralyzed cats, and examined effects of a blockade of GABAergic inhibition with a microiontophoresis of bicuculline (BIC) on stimulus-size tuning property of response to drifting sinusoidal gratings. Stimuli larger than CRF caused a reduction of response (SS), and BIC antagonized the SS induced by a stimulation of narrow ECRF near CRF more strongly than the SS induced by a stimulation of wide and distal area of ECRF. These results suggest that there are two types of SS; (1) GABA-mediated and elicited from near the CRF, and (2) non-GABA-mediated and induced from distal area in ECRF. doi:10.1016/j.neures.2009.09.181

O2-J2-3 Natural image statistics predicts the orientation tuning properties of simple cells in the early visual cortex Kota S. Sasaki 1 , Izumi Ohzawa 1,2 1 2

doi:10.1016/j.neures.2009.09.178

1

O2-J2-2 Mechanisms underlying surround suppression in the cat lateral geniculate nucleus Satoshi Shimegi 1,2 , Masahiro Okamoto 2 , Shin-ichiro Hara 2 , Akihiro Kimura 1 , Hiromichi Sato 1,2

Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan; Japan Science and Technology Agency, Tokyo, Japan

Sensory information processing in the brain is assumed to have evolved to represent naturally occurring stimuli efficiently. Therefore, it is worth examining a relationship between statistics inherent of natural images and cellular functions in the visual system. From a publicly available image database, we analyzed 1000 images that did not include artificial objects by filtering them with Gabor filters. We found that local image features tend to be elongated more along the orientation axis in high spatial frequency components than in low spatial frequency components, meaning that detailed features have narrower bandwidth than coarse ones in natural scenes. This bias was also found in the receptive fields and orientation tuning properties of simple cells, but not in those of complex cells, in the early visual cortex when their responses were examined with dynamic 2D noise and drifting gratings. doi:10.1016/j.neures.2009.09.182

O2-J2-4 Arrangement of orientation selective neurons in monkey V1 revealed by in vivo 2-photon calcium imaging Koji Ikezoe 1 , Yoshiya Mori 1 , Kazuo Kitamura 2,3 , Hiroshi Tamura 1,3 , Ichiro Fujita 1,3 1

Grad. Sch. Frontier Biosci., Osaka Univ., Toyonaka, Japan; 2 Grad. Sch. Med., Univ. of Tokyo, Tokyo, Japan; 3 CREST, JST, Toyonaka, Japan

At the macroscopic level, the preferred orientation of neurons in the monkey primary visual cortex (V1) is systematically mapped across the cortical surface around pinwheel centers. However, how smoothly preferred orientation shifts across the map at the cellular level, which is necessary to consider the function and development of the map. Here, we describe the orientation map at the single-cell level by using in vivo 2-photon calcium imaging in monkey V1. We found that nearby neurons preferred a similar orientation in all 8 recorded regions (<250 ␮m × 250 ␮m) and that the preferred orientation difference increased with distance between neurons. However, a significant fraction of nearby neurons preferred different orientations by more than 60◦ in 6 of the 8 regions. This additional point argues that orientation map in monkey V1 can also has coarse transitions at the cellular level, meaning that the location and preferred orientation of neurons are less correlative than previously thought. doi:10.1016/j.neures.2009.09.183

O2-J3-1 Periodic microcolumns in neocortical layer V Toshihiko Hosoya, Kazumasa Kubota, Hisato Maruoka, Rumi Kurokawa, Tomonori Manabe RIKEN BSI, Japan The complexity of the mammalian neocortex has hampered functional analyses. Analysis could be simplified, however, if the neocortical circuit had a repeated structure composed of specific neuronal types. Our previous study demonstrated that layer V of the mouse neocortex has a periodically repeated structure composed of microcolumns of a major type of pyramidal neurons, i.e. subcerebral projection