Spatiotemporal tuning of short-latency manual and ocular following responses associated with sudden visual motion in monkeys

s / Neuroscience Research 58S (2007) S1–S244 S213 P3-e39 Gain modulation of manual following response associated with galvanic vestibular stimulation Koji Kadota1, Hiroaki Gomi1,2 1 JST-ERATO, Shimojo Implicit Brain Function Project, Kanagawa, Japan; 2 NTT Communication Science Laboratories, Kanagawa, Japan In order to make stable interactions with various environments, our motor system is required to provide quick processing for sensory inputs. Recently, we found that a sudden motion of the visual background during target reaching induces change of hand trajectory with an ultra short latency (manual following response: MFR). This is considered as a compensatory response for online control of hand trajectory when having a postural imbalance. However, this idea has yet to be directly verified. If the MFR plays an important role for maintaining reaching performance while less postural stability, we would expect an increase in the MFR gain against the visual motion in order to achieve the reaching task. To test this idea, we examined whether or not perception of unstable postural condition motivated by frequently applied galvanic vestibular stimulation (GVS) during experiment would cause a gain modulation of the MFR. In the results, we found evidence that a perception of instability can affect the MFR gain. P3-e40 Do the similar quick visuomotor controls of arm and eye share a gain modulation caused by the spatial dissociation of gaze and pointing? Naotoshi Abekawa1, Hiroaki Gomi1,2 1 NTT CS Labs, Kanagawa, Japan; 2 ERATO Shimojo Implicit Brain Function Proj., JST, Kanagawa, Japan Background visual motion induces reflexive manual (MFR) and ocular (OFR) responses. We recently revealed that the MFR is modulated by the spatial relationship between reaching target and gaze point. To explore its mechanism, we here examined whether or not the OFR share this spatialdependent modulation. In the experiment, participants were asked to hit the NEAR (placed at same horizontal direction to the gaze point) or FAR (different direction) target by index finger while looking at the center of the screen placed in front of the face. In the FAR condition, participants rotated their body without change of the face-screen configuration in order to keep reaching kinematics. Upward or downward visual motion was given on the screen during arm movement to induce MFR and OFR. The results show that the OFR did not change for the NEAR and FAR, whereas the MFR was greater for the NEAR than for the FAR. This suggests that the MFR gain was modulated after the common visual motion processing for MFR and OFR. P3-e41 Spatiotemporal tuning of short-latency manual and ocular following responses associated with sudden visual motion in monkeys Aya Takemura1,5, Naotoshi Abekawa2, Shigeru Yamane3, Kenji Kawano4, Hiroaki Gomi2,5 1 Neurosci. Res. Inst., AIST, Tsukuba, Japan; 2 NTT Communication Sci. Lab., NTT, Atsugi, Japan; 3 Maebashi Inst. Tech., Maebashi, Japan; 4 Grad. Sch. Med., Kyoto Univ., Kyoto, Japan; 5 ERATO Shimojo Project, JST, Atsugi, Japan A sudden drifting movement of a visual stimulus evokes short latency manual following response (MFR) in both humans and monkeys. It helps to adjust an arm movement during body movement accompanied by visual motion. The same visual motion also evokes ocular-following response (OFR), which helps to stabilize gaze. To clarify whether a common visual processing pathway provides inputs to both manual and oculo-motor systems, the manual and ocular responses were simultaneously recorded in arm reaching tasks in monkeys. The spatiotemporal tuning characteristics of the OFR were similar to those of the MFR: the amplitude of both MFR and OFR increased markedly with temporal frequency, generally reaching a peak at 10 m 20 Hz. This result suggests that the early visual processing pathway in monkey may be shared in generating the MFR and OFR. P3-e42 Localization of V-ATPase in the retina: Evidence for proton feedback hypothesis H. Jouhou1, K. Nakano2, S. Ishikawa2, K. Sano2, T. Shishido2, A. Kaneko3, M. Yamada1 1 Tokyo Metropol. Univ., Japan; 2 Astellas Pharma Inc., Japan; 3 Kio Univ., Japan In order to interpret the formation of receptive field surround in retinae, Hirasawa and Kaneko (2003) proposed a pH-mediated mechanism to substitute for GABA-mediated feedback hypothesis from horizontal cells (HCs) to cones. To verify the idea that the depolarized HCs release protons, we measured, by a fluorescence ratio imaging method, pH of the immediate external surface (pH0) of isolated HCs of goldfish. Bafilomycin A1, a specific inhibitor of V-ATPase, suppressed depolarization-induced acidification of HC pH0, suggesting the existence of V-ATPase on HC membranes. Anti-V-ATPase immunoreactivity (IR) was found at the cone terminals and on the surface of GAD-positive external HCs in retinal slices. In ribbon synapses, anti-V-ATPase IR was found in lateral elements of dendrites (post-synapse) wrapped in anti-V-ATPase IR cones. These results suggest that pH0 reduction at the narrow invaginating synaptic cleft would suppress Ca2+ channels at the cone terminals, resulting in suppression of release of glutamatergic synaptic vesicles from cones to the second neurons. Research funds: 18500313, 17657051 P3-e43 A retinal circuit model accounting for functions of amacrine cells Yuki Hayashida, Murat Saglam, Nobuki Murayama Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan Recent studies have demonstrated the higher-level functions of visual processing, such as object motion sensitivity and spatio-temporal pattern adaptation, in vertebrate retinas. In those visual processing, diverse types of retinal third-order interneurons, amacrine cells are believed to play essential roles by integrating excitatory and inhibitory signals on their dendrites to shape the ganglion cell responses. Previously, a simple ‘linear–nonlinear’ model was utilized to explain a specific function of the retina, and could capture the spiking behavior of retinal output, although each class of the retinal neurons were largely omitted in it. In the present study, to reveal the cellular mechanisms underlying the retinal functions, we developed a circuit model based on the response function for each class of the retinal neurons and the anatomical wirings between them. By this model, not only the spatio-temporal filtering properties of outer retina but also the higher-order nonlinear computations in the inner retinal circuitry involving amacrine cells could be realized. Research funds: KAKENHI 17700398 P3-e44 Motion picture effects to eye movement and cerebral blood flow Atsuhiko Iijima1,2, Tohru Kiryu3, Kazuhiko Ukai2, Haruo Toda1, Takehiko Bando1 1 Div. Integrative Physiol., Grad. Sch. Med., Niigata University, Niigata, Japan; 2 Department of Appl. Phys., Sch. Sci. & Tech., Waseda University, Tokyo, Japan; 3 Div. Inform. Sci., Grad. Sch. Sci. & Tech., Niigata University, Niigata, Japan We presented that motion pictures representing rider’s view of motocross bike elicited two types of horizontal eye movements; coherent or noncoherent to the motion vectors in the movie, while those representing passenger’s view of roller coaster evoked similar eye movements in all subjects (29th JNS, 2006). We investigated the relationship between their eye movements and cerebral blood flow (CBF) while watching these vehicle type movies on 10 subjects. Eye movements were measured by a binocular video oculography (Newopto), and head movements were measured by a magnetic motion sensor (Polhemus). CBF was simultaneously monitored with a near infrared spectroscopy (Shimadzu). Both the eye movements and the CBF variation had relevance to the motion components. It might depend on the differences in the strategies for the recognition of these movies. Research funds: Tsukada Medical Foundation, NS Promotion Foundation for Science of Perception