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Environmental memory in the lateral intraparietal area
e6
Abstracts / Neuroscience Research 68S (2010) e4–e52
S1-1-2-5 The neuroethics of neurotrauma Sarah A Dunlop School of Animal Biology, University of Western Australia Neurotrauma is a traumatic injury to the nervous system. It is sudden, unexpected and, for the CNS, includes spinal cord injury (SCI). In Australia (population 21m), approximately 1 person every day has a SCI; the prevalence is 10,000. Despite the small numbers, costs in 2009 were $2bn. SCI primarily affects young males (18–25 yo), but falls in the elderly are an increasing cause. SCI is for a lifetime and involves significant, often distressing, secondary progressive complications. Despite significant pre-clinical advances in cellular and molecular-based therapies, there is no cure. Current treatments involve surgery, drugs, prostheses and rehabilitation. Mounting pre-clinical and clinical evidence points to the beneficial effects of exercise after SCI which translate into improved function. There has also been a paradigm shift from teaching compensatory rehabilitation strategies to exercising the paralysed limbs to help drive remaining circuits and promote neurological recovery. In contrast to “tablet trials” involving one drug for one disease state, randomised controlled trials (RCTs) for SCI and rehabilitation are inherently more complex due to the variable nature of the injury, wide range of sequelae and multimodal nature of the intervention. Ethical challenges are significant and include the highly vulnerable nature of this population and the large numbers of patients that need to be recruited. Randomisation to control groups as well as the possibility of increased burden in terms of time and effort due to the intervention itself must also be considered. Safety is paramount, as is giving hope but not false hope. Expense needs to be considered and inclusion and exclusion criteria must be sufficiently strict to enable appropriate power yet broad enough to ensure utility. Although RCTs are the gold standard for evidence-based practice, rigorous debate around practice-based evidence for complex injuries involving multimodal interventions is now timely. doi:10.1016/j.neures.2010.07.252
S1-2-1-1 Introduction: Coding of high-order cognition grounded onto spatial representation Atsushi Iriki Laboratory for Symbolic Cognitive Development, RIKEN BSI The primate posterior parietal cortex (PPC) processes information related to environmental physical space. The human PPC has apparently expanded not only in size but also in its functional range to encompass certain abstract and higher-order conceptual spaces. Review of various forms of non-spatial representation in the PPC revealed that various kinds of non-spatial cognition can be grouped and ordered based on the levels of abstraction of the ‘objects’ and ideally defined spatial relations represented. Assumed coordinate systems for such ‘spaces’ vary depending on the abstraction level. These pseudo-spatial nature of the high-order cognition supported by the PPC may derive from the essential characteristics of the objects represented but alternatively may derive from the nature of the PPC’s pre-existing information-processing mechanisms, namely as a hub for multisensory integration and representing physical environmental space. The meta-analysis illustrates that the PPC areas responsible for these novel forms of cognition are not necessarily clearly segregated, either in monkeys or humans, but does suggest a trend of gradual expansion toward the IPL as the level of abstraction proceeds. Thus, it seems that the PPC gradually incorporated high-order cognition as it expanded during hominid evolution while preserving its original principles of operation. doi:10.1016/j.neures.2010.07.253
S1-2-1-2 Environmental memory in the lateral intraparietal area Michael E. Goldberg , Sara C. Steenrod Columbia University College of Physicians and Surgeons The lateral intraparietal area (LIP) maintains a priority map of space in gazecentered oordinates which can be used by the oculomotor system to choose the goal of saccads and the visual system to determine the locus of attention (Bisley and Goldberg). This map is predominantly determined by vision, but neurons in LIP have been shown also to respond to significant auditory stimuli (Linden, Grunwald and Andersen). Once a location has been established as important, for example as the target of a memory-guided delayed saccade, LIP neurons maintain the location of the important spatial object without requiring further visual stimulation (Gnadt and Andersen). Here we show that this memory continues beyond the confines a single trial. We trained
monkeys to make a saccade to a given location which did not excite an LIP neuron. On the next block of trials that saccade brought a recently appeared task-irrelevant stimulus into the receptive field of the neuron; not unexpectedly the cell fired around the beginning of the saccade. After a number of such trials we intermixed trials in which the task-irrelevant stimulus appeared, and trials in which it did not. On the trials in which the stimulus did not appear, the cell fired, albeit with a lower intensity and a longer postsaccadic latency. After a block of trials in which the stimulus was never brought into the receptive field by the saccade the response dissipated. This environmental memory response often required 10 trials to dissipate. We suggest that it represents a spatial memory of an environmental event, which lasts across trials. Control experiments show that the memory could be established without ever stimulating the cell’s receptive field as long as the stimulus appeared in a consistent spatial location, nor was the activity dependent on association with a given saccade. Thus the parietal cortex has access to a supraretinal representation of space, which is gated by the appropriate saccade. doi:10.1016/j.neures.2010.07.254
S1-2-1-3 Cognitive set-shifting macaque parietal cortex
mechanisms
in
the
Tsukasa Kamigaki , Yasushi Miyashita Department of Physiology, The University of Tokyo School of Medicine Humans are able to flexibly change patterns of thought or internal “cognitive sets” to find adequate solutions when faced with problems. Cognitive flexibility underlies the ability to act adaptively in changing environments. Accumulating evidence from functional magnetic resonance imaging (fMRI) investigations in humans suggests that functional networks of prefrontal and posterior parietal cortices (PPC) may be critical for such cognitive flexibility. To assess the single-cell level dynamics underlying these cortical processes, we recorded neuronal activity from the PPC of monkeys performing an analog of the Wisconsin Card Sorting Test (WCST). The WCST was originally devised to probe cognitive flexibility in humans. We modified the test for monkeys, providing a task requiring flexible shifting between color-matching and shape-matching behavior. The results revealed a group of PPC neurons whose activity signaled the direction in which monkeys would shift their cognitive set, i.e., from shape to color or from color to shape. These neurons were activated in preparatory processes preceding the actual behavioral output by about 4 s, and the firing significantly predicted the success/failure of monkeys’ set shifting. Our analyses further demonstrated that another neuronal group was involved in transforming such preparatory processes into behavioral output (i.e., execution processes), by exhibiting shift-selective activity modulation both in preparation and execution processes. These cells still exhibited activity when the monkeys spontaneously performed set shifting without any external cues, which may reflect set-shifting mechanisms that can be driven by either internal or external triggers. Our results suggest that distinct neuronal groups are dynamically recruited for the different subprocesses involved in cognitive set shifting. doi:10.1016/j.neures.2010.07.255
S1-2-1-4 The role of the parietal cortex in movement intention and awareness Angela Sirigu Center for Cognitive Neuroscience, CNRS I will focus on the role of parietal and premotor regions for movement representation and movement prediction. I will present findings obtained in patients with selective lesions in the parietal or premotor cortex using task requiring “preparing to move” or “preparing to observe another’s movement”. I will also show how direct cortical stimulation (during surgery for the removal of a tumor) of the inferior parietal regions produces the ‘desire to move’ or perception of movement even when no motor act actually occurred, as shown by EMG recording. The opposite patterns will be described during stimulation of the premotor cortex where patients did in fact move but the experience of movement did not reach consciousness. I will argue that the inferior parietal regions play a key role in anticipating the future states of our own movements and for bringing them to awareness. doi:10.1016/j.neures.2010.07.256
Abstracts / Neuroscience Research 68S (2010) e4–e52
S1-1-2-5 The neuroethics of neurotrauma Sarah A Dunlop School of Animal Biology, University of Western Australia Neurotrauma is a traumatic injury to the nervous system. It is sudden, unexpected and, for the CNS, includes spinal cord injury (SCI). In Australia (population 21m), approximately 1 person every day has a SCI; the prevalence is 10,000. Despite the small numbers, costs in 2009 were $2bn. SCI primarily affects young males (18–25 yo), but falls in the elderly are an increasing cause. SCI is for a lifetime and involves significant, often distressing, secondary progressive complications. Despite significant pre-clinical advances in cellular and molecular-based therapies, there is no cure. Current treatments involve surgery, drugs, prostheses and rehabilitation. Mounting pre-clinical and clinical evidence points to the beneficial effects of exercise after SCI which translate into improved function. There has also been a paradigm shift from teaching compensatory rehabilitation strategies to exercising the paralysed limbs to help drive remaining circuits and promote neurological recovery. In contrast to “tablet trials” involving one drug for one disease state, randomised controlled trials (RCTs) for SCI and rehabilitation are inherently more complex due to the variable nature of the injury, wide range of sequelae and multimodal nature of the intervention. Ethical challenges are significant and include the highly vulnerable nature of this population and the large numbers of patients that need to be recruited. Randomisation to control groups as well as the possibility of increased burden in terms of time and effort due to the intervention itself must also be considered. Safety is paramount, as is giving hope but not false hope. Expense needs to be considered and inclusion and exclusion criteria must be sufficiently strict to enable appropriate power yet broad enough to ensure utility. Although RCTs are the gold standard for evidence-based practice, rigorous debate around practice-based evidence for complex injuries involving multimodal interventions is now timely. doi:10.1016/j.neures.2010.07.252
S1-2-1-1 Introduction: Coding of high-order cognition grounded onto spatial representation Atsushi Iriki Laboratory for Symbolic Cognitive Development, RIKEN BSI The primate posterior parietal cortex (PPC) processes information related to environmental physical space. The human PPC has apparently expanded not only in size but also in its functional range to encompass certain abstract and higher-order conceptual spaces. Review of various forms of non-spatial representation in the PPC revealed that various kinds of non-spatial cognition can be grouped and ordered based on the levels of abstraction of the ‘objects’ and ideally defined spatial relations represented. Assumed coordinate systems for such ‘spaces’ vary depending on the abstraction level. These pseudo-spatial nature of the high-order cognition supported by the PPC may derive from the essential characteristics of the objects represented but alternatively may derive from the nature of the PPC’s pre-existing information-processing mechanisms, namely as a hub for multisensory integration and representing physical environmental space. The meta-analysis illustrates that the PPC areas responsible for these novel forms of cognition are not necessarily clearly segregated, either in monkeys or humans, but does suggest a trend of gradual expansion toward the IPL as the level of abstraction proceeds. Thus, it seems that the PPC gradually incorporated high-order cognition as it expanded during hominid evolution while preserving its original principles of operation. doi:10.1016/j.neures.2010.07.253
S1-2-1-2 Environmental memory in the lateral intraparietal area Michael E. Goldberg , Sara C. Steenrod Columbia University College of Physicians and Surgeons The lateral intraparietal area (LIP) maintains a priority map of space in gazecentered oordinates which can be used by the oculomotor system to choose the goal of saccads and the visual system to determine the locus of attention (Bisley and Goldberg). This map is predominantly determined by vision, but neurons in LIP have been shown also to respond to significant auditory stimuli (Linden, Grunwald and Andersen). Once a location has been established as important, for example as the target of a memory-guided delayed saccade, LIP neurons maintain the location of the important spatial object without requiring further visual stimulation (Gnadt and Andersen). Here we show that this memory continues beyond the confines a single trial. We trained
monkeys to make a saccade to a given location which did not excite an LIP neuron. On the next block of trials that saccade brought a recently appeared task-irrelevant stimulus into the receptive field of the neuron; not unexpectedly the cell fired around the beginning of the saccade. After a number of such trials we intermixed trials in which the task-irrelevant stimulus appeared, and trials in which it did not. On the trials in which the stimulus did not appear, the cell fired, albeit with a lower intensity and a longer postsaccadic latency. After a block of trials in which the stimulus was never brought into the receptive field by the saccade the response dissipated. This environmental memory response often required 10 trials to dissipate. We suggest that it represents a spatial memory of an environmental event, which lasts across trials. Control experiments show that the memory could be established without ever stimulating the cell’s receptive field as long as the stimulus appeared in a consistent spatial location, nor was the activity dependent on association with a given saccade. Thus the parietal cortex has access to a supraretinal representation of space, which is gated by the appropriate saccade. doi:10.1016/j.neures.2010.07.254
S1-2-1-3 Cognitive set-shifting macaque parietal cortex
mechanisms
in
the
Tsukasa Kamigaki , Yasushi Miyashita Department of Physiology, The University of Tokyo School of Medicine Humans are able to flexibly change patterns of thought or internal “cognitive sets” to find adequate solutions when faced with problems. Cognitive flexibility underlies the ability to act adaptively in changing environments. Accumulating evidence from functional magnetic resonance imaging (fMRI) investigations in humans suggests that functional networks of prefrontal and posterior parietal cortices (PPC) may be critical for such cognitive flexibility. To assess the single-cell level dynamics underlying these cortical processes, we recorded neuronal activity from the PPC of monkeys performing an analog of the Wisconsin Card Sorting Test (WCST). The WCST was originally devised to probe cognitive flexibility in humans. We modified the test for monkeys, providing a task requiring flexible shifting between color-matching and shape-matching behavior. The results revealed a group of PPC neurons whose activity signaled the direction in which monkeys would shift their cognitive set, i.e., from shape to color or from color to shape. These neurons were activated in preparatory processes preceding the actual behavioral output by about 4 s, and the firing significantly predicted the success/failure of monkeys’ set shifting. Our analyses further demonstrated that another neuronal group was involved in transforming such preparatory processes into behavioral output (i.e., execution processes), by exhibiting shift-selective activity modulation both in preparation and execution processes. These cells still exhibited activity when the monkeys spontaneously performed set shifting without any external cues, which may reflect set-shifting mechanisms that can be driven by either internal or external triggers. Our results suggest that distinct neuronal groups are dynamically recruited for the different subprocesses involved in cognitive set shifting. doi:10.1016/j.neures.2010.07.255
S1-2-1-4 The role of the parietal cortex in movement intention and awareness Angela Sirigu Center for Cognitive Neuroscience, CNRS I will focus on the role of parietal and premotor regions for movement representation and movement prediction. I will present findings obtained in patients with selective lesions in the parietal or premotor cortex using task requiring “preparing to move” or “preparing to observe another’s movement”. I will also show how direct cortical stimulation (during surgery for the removal of a tumor) of the inferior parietal regions produces the ‘desire to move’ or perception of movement even when no motor act actually occurred, as shown by EMG recording. The opposite patterns will be described during stimulation of the premotor cortex where patients did in fact move but the experience of movement did not reach consciousness. I will argue that the inferior parietal regions play a key role in anticipating the future states of our own movements and for bringing them to awareness. doi:10.1016/j.neures.2010.07.256