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Spatial Cues (spatial + cue)
Selected AbstractsDifferential involvement of the dorsal hippocampus in passive avoidance in C57bl/6J and DBA/2J miceHIPPOCAMPUS, Issue 1 2008Petra J.J. Baarendse Abstract The inferior performance of DBA/2 mice when compared to C57BL/6 mice in hippocampus-dependent behavioral tasks including contextual fear conditioning has been attributed to impaired hippocampal function. However, DBA/2J mice have been reported to perform similarly or even better than C57BL/6J mice in the passive avoidance (PA) task that most likely also depends on hippocampal function. The apparent discrepancy in PA versus fear conditioning performance in these two strains of mice was investigated using an automated PA system. The aim was to determine whether these two mouse strains utilize different strategies involving a different contribution of hippocampal mechanisms to encode PA. C57BL/6J mice exhibited significantly longer retention latencies than DBA/2J mice when tested 24 h after training irrespective of the circadian cycle. Dorsohippocampal NMDA receptor inhibition by local injection of the selective antagonist DL -2-amino-5-phosphonovaleric acid (AP5, 3.2 ,g/mouse) before training resulted in impaired PA retention in C57BL/6J but not in DBA/2J mice. Furthermore, nonreinforced pre-exposure to the PA system before training caused a latent inhibition-like reduction of retention latencies in C57BL/6J, whereas it improved PA retention in DBA/2J mice. These pre-exposure experiments facilitated the discrimination of hippocampal involvement without local pharmacological intervention. The results indicate differences in PA learning between these two strains based on a different NMDA receptor involvement in the dorsal hippocampus in this emotional learning task. We hypothesize that mouse strains can differ in their PA learning performance based on their relative ability to form associations on the basis of unisensory versus multisensory contextual/spatial cues that involve hippocampal processing. © 2007 Wiley-Liss, Inc. [source] The effect of spatial cues on infants' responses in the AB task, with and without a hidden objectDEVELOPMENTAL SCIENCE, Issue 4 2001Andrew Bremner The errors made by infants in the AB task were taken by Piaget as an indication of an inability to update their representations of the spatial location of a hidden object. This paper presents an experiment designed to further investigate the role of spatial representations in the production of the error. The introduction of strong visual cues to spatial location was found to reduce the traditional A-not-B search error. However, it also increased perseveration when a ,lids-only' analogue of the AB task was used, in which infants are simply cued to pick up lids rather than encouraged to search for a hidden object. These results present a challenge to the dynamic systems account of the error given by Smith, Thelen, Titzer and McLin (Psychological Review, 106 (1999), 235,260), and indicate that the traditional A-not-B search error arises from a difficulty in updating representations of the spatial location of hidden objects. The relation of these results to Munakata's PDP model (Developmental Science, 1 (1998), 161,211) and Thelen, Schöner, Scheier and Smith's (Behavioural and Brain Sciences, 24 (2001), 1--86) most recent dynamic systems model of the A-not-B error is also discussed. [source] Dissociation of function between the dorsal and the ventral hippocampus in spatial learning abilities of the rat: a within-subject, within-task comparison of reference and working spatial memoryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2004Helen H. J. Pothuizen Abstract Lesions restricted to the dorsal, but not the ventral, hippocampus severely impair the formation of spatial memory. This dissociation was first demonstrated using the water maze task. The present study investigated whether the dorsal and the ventral hippocampus are involved differentially in spatial reference and spatial working memory using a four-baited/four-unbaited version of the eight-arm radial maze task. This test allows the concurrent evaluation of reference and working memory with respect to the same set of spatial cues, and thereby enables a within-subjects within-task comparison between the two forms of memory functions. Rats with N -methyl- d -aspartic acid-induced excitotoxic lesions of the dorsal hippocampus, ventral hippocampus or both were compared with sham and unoperated controls. We showed that dorsal lesions were as effective as complete lesions in severely disrupting both reference and working spatial memory, whereas rats with ventral lesions performed at a level comparable with controls. These results lend further support to the existence of a functional dissociation between the dorsal and the ventral hippocampus, with the former being preferentially involved in spatial learning. [source] The essential role of Broca's area in imitationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2003Marc Heiser Abstract The posterior sector of Broca's area (Brodmann area 44), a brain region critical for language, may have evolved from neurons active during observation and execution of manual movements. Imaging studies showing increased Broca's activity during execution, imagination, imitation and observation of hand movements support this hypothesis. Increased Broca's activity in motor task, however, may simply be due to inner speech. To test whether Broca's area is essential to imitation, we used repetitive transcranial magnetic stimulation (rTMS), which is known to transiently disrupt functions in stimulated areas. Subjects imitated finger key presses (imitation) or executed finger key presses in response to spatial cues (control task). While performing the tasks, subjects received rTMS over the left and right pars opercularis of the inferior frontal gyrus (where Brodmann area 44 is probabilistically located) and over the occipital cortex. There was significant impairment in imitation, but not in the control task, during rTMS over left and right pars opercularis compared to rTMS over the occipital cortex. This suggests that Broca's area is a premotor region essential to finger movement imitation. [source] The effect of whole-body tilt on sound lateralizationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2002Jörg Lewald Abstract The effect of passive whole-body tilt in the frontal plane on the lateralization of dichotic sound was investigated in human subjects. Pure-tone pulses (1 kHz, 100 ms duration) with various interaural time differences were presented via headphones while the subject was in an upright position or tilted 45° or 90° to the left or right. Subjects made two-alternative forced-choice (left/right) judgements on the intracranial sound image. During body tilt, the auditory median plane of the head, computed from the resulting psychometric functions, was always shifted to the upward ear, indicating a shift of the auditory percept to the downward ear, that is, in the direction of gravitational linear acceleration. The mean maximum magnitude of the auditory shift obtained with 90° body tilt was 25 µs. On the one hand, these findings suggest a certain influence of the otolith information about body position relative to the direction of gravity on the representation of auditory space. However, in partial contradiction to previous work, which had assumed existence of a significant ,audiogravic illusion', the very slight magnitude of the present effect rather reflects the excellent stability in the neural processing of auditory spatial cues in humans. Thus, it might be misleading to use the term ,illusion' for this quite marginal effect. [source] Guided Cell Migration on Microtextured Substrates with Variable Local Density and AnisotropyADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Deok-Ho Kim Abstract This work reports the design of and experimentation with a topographically patterned cell culture substrate of variable local density and anisotropy as a facile and efficient platform to guide the organization and migration of cells in spatially desirable patterns. Using UV-assisted capillary force lithography, an optically transparent microstructured layer of a UV curable poly(urethane acrylate) resin is fabricated and employed as a cell-culture substrate after coating with fibronectin. With variable local pattern density and anisotropy present in a single cell-culture substrate, the differential polarization of cell morphology and movement in a single experiment is quantitatively characterized. It is found that cell shape and velocity are exquisitely sensitive to variation in the local anisotropy of the two-dimensional rectangular lattice arrays, with cell elongation and speed decreasing on symmetric lattice patterns. It is also found that cells could integrate orthogonal spatial cues when determining the direction of cell orientation and movement. Furthermore, cells preferentially migrate toward the topographically denser areas from sparser ones. Consistent with these results, it is demonstrated that systematic variation of local densities of rectangular lattice arrays enable a planar assembly of cells into a specified location. It is envisioned that lithographically defined substrates of variable local density and anisotropy not only provide a new route to tailoring the cell-material interface but could serve as a template for advanced tissue engineering. [source] Learning associations between places and visual cues without learning to navigate: Neither fornix nor entorhinal cortex is requiredHIPPOCAMPUS, Issue 4 2003E.A. Gaffan Abstract Rats with fornix transection, or with cytotoxic retrohippocampal lesions that removed entorhinal cortex plus ventral subiculum, performed a task that permits incidental learning about either allocentric (Allo) or egocentric (Ego) spatial cues without the need to navigate by them. Rats learned eight visual discriminations among computer-displayed scenes in a Y-maze, using the constant-negative paradigm. Every discrimination problem included two familiar scenes (constants) and many less familiar scenes (variables). On each trial, the rats chose between a constant and a variable scene, with the choice of the variable rewarded. In six problems, the two constant scenes had correlated spatial properties, either Allo (each constant appeared always in the same maze arm) or Ego (each constant always appeared in a fixed direction from the start arm) or both (Allo + Ego). In two No-Cue (NC) problems, the two constants appeared in randomly determined arms and directions. Intact rats learn problems with an added Allo or Ego cue faster than NC problems; this facilitation provides indirect evidence that they learn the associations between scenes and spatial cues, even though that is not required for problem solution. Fornix and retrohippocampal-lesioned groups learned NC problems at a similar rate to sham-operated controls and showed as much facilitation of learning by added spatial cues as did the controls; therefore, both lesion groups must have encoded the spatial cues and have incidentally learned their associations with particular constant scenes. Similar facilitation was seen in subgroups that had short or long prior experience with the apparatus and task. Therefore, neither major hippocampal input,output system is crucial for learning about allocentric or egocentric cues in this paradigm, which does not require rats to control their choices or navigation directly by spatial cues. Hippocampus 2003;13:445,460. © 2003 Wiley-Liss, Inc. [source] When and where to fuel before crossing the Sahara desert , extended stopover and migratory fuelling in first-year garden warblers Sylvia borinJOURNAL OF AVIAN BIOLOGY, Issue 2 2008Thord Fransson Large numbers of passerine migrants cross the Sahara desert every year on their way to-and-from wintering areas in tropical Africa. In the desert, hardly any fuelling opportunities exist and most migrants have to prepare in advance. A central question is how inexperienced birds know where to fuel. Inexperienced garden warblers Sylvia borin were studied in Greece just before the desert crossing in autumn. Body mass data collected at two sites indicate that most birds do not fuel for the desert crossing further north. For the first time, detailed information about stopover duration close to the Sahara desert was studied by using light weight radio-transmitters. Results from Crete show that most first-year garden warblers arrive with relatively small fuel loads in relation to lean body mass (<30%), stay for 13,20 d and depart with an average fuel load of about 100%. Radio-tagged birds performed small scale movements initially and took advantage of fig fruits. Birds trapped at fig trees were heavier than birds trapped with tape lures, showing that tape lures can bias the sample of migrants trapped. The precise fuelling pattern found indicates that first-year migrants must also include external spatial cues to make the preparation for crossing the desert in the right area. [source] Acute Ethanol Potentiates the Clock-Speed Enhancing Effects of Nicotine on Timing and Temporal MemoryALCOHOLISM, Issue 12 2007Warren H. Meck Background:, Acute ethanol administration potentiates some of the behavioral effects of nicotine, although the extent of this effect is unknown. The present investigation assessed the ability of ethanol to potentiate nicotine's effect on the overestimation of multisecond durations as a result of an increase in the speed of an internal clock. Methods:, Adult male rats were exposed to the acute effects of ethanol (0.0, 0.5, 1.5, and 3.0 g/kg; IG) which was given 10 minutes prior to the administration of nicotine (0.0, 0.3, 0.6, and 1.0 mg/kg; IP). The effects of these combined treatments on timing and temporal memory were assessed using 18- and 36-second peak-interval procedures with separate visual/spatial cues for responding. Results:, When administered alone, ethanol had no consistent effect on peak time, but decreased peak rate, and increased peak spread as a function of dose. In contrast, nicotine alone shifted the peak times of the response distributions leftward in a proportional manner as a function of dose. When administered after pretreatment with ethanol, nicotine's effect on the horizontal placement of the peak functions was potentiated. Conclusions:, The observation that ethanol pretreatment potentiates the clock-speed enhancing effects of subsequently administered nicotine is discussed in terms of the role of ,7-nicotinic acetylcholine receptors and dopamine,glutamate interactions in cortico-striatal circuits thought to subserve interval timing. [source] | ||||||||||