Richard Andersen

..Data obtained in the adjacent parietal reach region (PRR) indicate that this transformation may be achieved by vectorially subtracting hand location from target location, with both locations represented in eye-centred coordinates...

..We will create computational models of the nervous system embodying this insight and explain a variety of clinically observed neurological deficits in human subjects using these models...

..These two perceptual functions are mediated by different parts of the posterior parietal cortex, the former in the dorsal aspect of the medial superior temporal area (MSTd) and the latter in area 7a...

..The decode performances of LFPs and spike signals are comparable and, because LFP recordings are more long lasting, they might help to increase the lifetime of the prosthetics...

..Finally, new movable probe technologies will enable recording electrodes to seek out automatically the best signals for decoding cognitive variables...

..The CNP approach relies on scientific understanding of the neural processes involved in cognition, and many of the decoding algorithms it uses also have parallels to underlying neural circuit functions...

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..Attention and learning effects are also evident in the PPC. However, these effects may be general to cortex and operate in the PPC in the context of sensory-motor transformations...

..e., increased tuning depth and coverage of encoding parameter space) as well as an increase in off-line decoding performance of the PPC ensemble...

..We interpret these data to suggest that the type of information that PRR neurons encode evolves throughout a task...

..These results cannot be explained in terms of an attention effect and support the idea of two segregated populations in the posterior parietal cortex, PRR and LIP, that are involved in different movement plans...

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..However, because the activity is gain modulated by vergence angle, the absolute depth can be decoded from the population activity...

..This similarity may be indicative of a common spatial framework for hand-eye coordination...

..We conclude that LIP uses the same retinotopic coding of saccade target whether the target is specified as an absolute point in space or as a location on a moving object...

..These findings suggest that PRR is involved in decision making for reach movements and that separate cortical networks exist for target selection of different types of action...

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..Together, these results suggest that V1 is not directly involved in the generation of the SFM percept, whereas MT is. The perceptual modulation in V1 may be attributable to top-down feedback from MT...

..These results indicate that many MSTd neurons compensate for pursuit velocity, pursuit direction as previously reported and pursuit speed, and further implicate MSTd as a critical stage in the computation of egomotion...

..This new evidence provides further support for a role of the parietal cortex in movement planning and the potential application of LFP signals for a brain-machine interface...

..This finding could accelerate the development of a cortical neural prosthesis...

..Thus, posterior parietal cortex has prospective plans for upcoming behaviors while considering both types of targets relevant for action: those to be acquired and those to be avoided...

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..Such differential activity associated with effector choice under identical stimulus conditions provides definitive evidence that the PPC is prospectively involved in action selection and movement preparation...

..In addition, we found that the space-time tuning functions of these neurons were largely separable in the angle-time plane, suggesting that they mostly encode straight and approximately instantaneous trajectories...

..The results indicate that the posterior parietal cortex is involved in the spatial planning of more complex action patterns and represents immediate and subsequent movement goals...

..We conclude that LFPs vary with the stimulation condition and that the LFP-spike relationship depends on a given neuron's connectivity to the dominant input sources in a particular stimulation condition...

..The results corroborate that the LFP spectrum change in PRR is a robust indicator for the movement onset and can be used for control of execution onset in a cortical prosthesis...

..These results suggest that the neural activity preceding goal-directed actions incorporates the absolute value of that action, predicated upon subjective, rather than objective, estimates of one's performance...

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..These results, together with our previous findings, suggest that a single decoder based on both spikes and LFPs in PRR can robustly provide the subjects' motor intent under varying contexts for neural prosthetic applications...

..Our results also indicate that prefrontal cortex may be a source of control signals for neuroprosthetic applications...

..This system is shown to be capable of autonomous operation in monkey cortical tissue...

..We implanted the FMA in rats and show that the FMA is capable of recording both spikes and local field potentials...

..We employed maximum likelihood decoders to estimate movement direction and to drive finite state machines governing when to move. Performance exceeded 90% with as few as 40 neurons...

..Such a relative position code may play an important role in coordinating hand and eye movements by computing their relative position...

..This finding reflects the fact that the response fields were generated by the same neural network and encode the same underlying process...

..The results provide strong evidence for (a) gaze modulation of aftereffects, (b) generality of gaze modulation across two visual attributes, and (c) perceptual correlates of the modulation of neural activity by gaze direction...

..We describe the measured performance of initial micropower low-noise CMOS preamplifiers for the neuroprosthetic...

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..Differences in the temporal-related parameters across time provided a clear distinction between learning and automatic behavior...

..With the parylene flexible cables, the probes can be easily assembled to a high density 3-D array for chronic implantation...

..We also found that area MSTd demonstrates significant eye position gain modulation of response fields much like its posterior parietal neighbors...

..These results suggest that MSTd neurons are sensitive to stimulus features specific to the perceived 3D orientation of the rotating plane stimuli and suggest that area MSTd is involved in SFM processing...

..It might also be an efficient way to represent the locations of different sensory targets in the world...

..The gaze modulation of visual aftereffects provides a useful psychophysical tool to analyze human cortical processes for coordinate transformations of visual space...

..This finding indicates that PRR represents integrated knowledge on spatial sensory information combined with abstract behavioral rules to encode the desired movement goal...

..The method should find application in the development of neural prosthetics based on the LFP signal. Our approach uses a new feature vector, which we call the 2d cepstrum...

..We therefore conclude that activation in this region is related to specific motor intent; i.e. it encodes information related to the subject's intention to make a specific movement to a particular spatial location...

..Cells participating in this decision circuit may influence movement choices by providing a common bias to the selection of movement goals...

..Critically, this state estimate appears to be encoded in an eye-centered frame of reference...

..The clinical trials are designed to help patients with severe paralysis, which can result from spinal cord lesion and other traumatic accidents, peripheral neuropathies, amyotrophic lateral sclerosis, multiple sclerosis, and stroke. ..

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..These studies are designed to gain knowledge of how the brain processes information, and will help to understand neurological deficits that occur with brain diseases. ..

..These experiments are designed to determine the stage in auditory processing pathway where head-centered auditory fields are converted into eye-centered auditory fields similar to those encountered in the PPC. ..

..abstract_text> ..

..They will help in understanding deficits that result from neurological diseases that effect cortical functioning, and can guide the diagnoses and treatments for these diseases. ..

..Knowledge from this work will be applied to brain- control tasks involving the continuous, sequential determination of goals. ..

..Knowledge from this work will be applied to brain- control tasks involving the continuous, sequential determination of goals. ..

..They will help in understanding deficits that result from neurological diseases that effect cortical functioning, and can guide the diagnoses and treatments for these diseases. ..

..is done in human patients and healthy subjects, will facilitate the understanding of normal cortical functions and deficits that result from neurological diseases, and can guide the diagnoses and treatments for these diseases ..

..By determining the types of signals that can be obtained from different brain regions, neural implants can be made to read out these signals in order to control assistive external devices for paralyzed patients. ..

..This hypothesis will be tested initially with cortical recordings in anesthetized rats followed by recordings from visual cortical areas in behaving monkeys. ..

..They will also determine if monkeys perceive SFM and the role of V1, MT, and MST in this important perceptual process. ..

..Overall these experiments will significantly further our understanding of how perceptions are transformed into actions. ..