Specific Roles Of Macaque Parietal Regions In Making Saccades And Reaches

A principle task of our brain is to guide movements, includng saccade: fast eye movements) and reaches towards things that we see. Regions in the parietal cortex such as LIP and PRR are active during visually-guided movements. Neurons in these areas respond differentially for saccades versus reaches, but in most parietal areas there is some response: in single unit recording as well as in fMRI imaging) with either type of movement. This raises an important question. What is the functional significance of the neuronal activity in parietal areas? Recording and imaging studies can only show correlations; causal roles must be inferred. The activity in any particular area could reflect where the subject\u27s spatial attention is directed, without regard for what behavior the subject will perform. Stronger activity in one task compared to another could reflect differential allocation of attention. For example, we might attend more strongly to a target for an eye movement than to a target for an arm movement, or vice versa. Alternatively, might play a causal role in driving only one type of movement. In this case, the weaker activity evoked during a different type of movement might serve no purpose at all; it might represent a contingency plan to perform the non-selected movement; or it might be serve some other function unrelated to the specific movement - for example, weak saccade-related activity in an area with strong arm movement related signals might support play no role in driving eye movements, but instead provide timing information to the reaching system to support eye-hand coordination. To help resolve this mystery, we used an interventional approach. We asked what happens to reaches and saccades when we reversibly lesioned specific areas in the monkey parietal cortex. In order to establish what brain regions were affected in each inactivation experiment, we developed a novel technique to image the location of the lesions in vivo. The results of this causal manipulation were clear: LIP lesions delay the initiation of saccades and have no effect on reaches, while PRR lesions delay the initiation of reaches and have no effect on saccades. We obtained further evidence for a more motoric role for parietal areas than previously suspected. PRR was active for reaches of only the contralateral arm, aimed at targets in either hemisphere - similar to the typical profiles of motor but not visual sensory areas. Interestingly, LIP lesions did influence reaches, but only when the animals were allowed to first look at the target before reaching for it. We believe that in this case, the reaching movement waits for the saccade system, and so the direct effect of the lesion on the saccades has an indirect effect on the reaches. These results are important for several reasons. First, they resolve a long-standing debate regarding the functional specificity of parietal areas with regard to particular movements and attention. They provide new information on the circuits guiding eye movements, arm movements and eye-hand coordination. Finally, our results underscore the fact that measurements of neuronal activity can be misleading, and are only one of several tools that must be used in order to understand brain function

Contralateral limb specificity for movement preparation in the parietal reach region

The canonical view of motor control is that distal musculature is controlled primarily by the contralateral cerebral hemisphere; unilateral brain lesions typically affect contralateral but not ipsilateral musculature. Contralateral-only limb deficits following a unilateral lesion suggest but do not prove that control is strictly contralateral: the loss of a contribution of the lesioned hemisphere to the control of the ipsilesional limb could be masked by the intact contralateral drive from the nonlesioned hemisphere. To distinguish between these possibilities, we serially inactivated the parietal reach region, comprising the posterior portion of medial intraparietal area, the anterior portion of V6a, and portions of the lateral occipital parietal area, in each hemisphere of 2 monkeys (23 experimental sessions, 46 injections total) to evaluate parietal reach region\u27s contribution to the contralateral reaching deficits observed following lateralized brain lesions. Following unilateral inactivation, reach reaction times with the contralesional limb were slowed compared with matched blocks of control behavioral data; there was no effect of unilateral inactivation on the reaction time of either ipsilesional limb reaches or saccadic eye movements. Following bilateral inactivation, reaching was slowed in both limbs, with an effect size in each no different from that produced by unilateral inactivation. These findings indicate contralateral organization of reach preparation in posterior parietal cortex

Open-source tools for behavioral video analysis: Setup, methods, and best practices

Recently developed methods for video analysis, especially models for pose estimation and behavior classification, are transforming behavioral quantification to be more precise, scalable, and reproducible in fields such as neuroscience and ethology. These tools overcome long-standing limitations of manual scoring of video frames and traditional 'center of mass' tracking algorithms to enable video analysis at scale. The expansion of open-source tools for video acquisition and analysis has led to new experimental approaches to understand behavior. Here, we review currently available open-source tools for video analysis and discuss how to set up these methods for labs new to video recording. We also discuss best practices for developing and using video analysis methods, including community-wide standards and critical needs for the open sharing of datasets and code, more widespread comparisons of video analysis methods, and better documentation for these methods especially for new users. We encourage broader adoption and continued development of these tools, which have tremendous potential for accelerating scientific progress in understanding the brain and behavior

Open-Source Tools for Behavioral Video Analysis: Setup, Methods, and Development

Recently developed methods for video analysis, especially models for pose estimation and behavior classification, are transforming behavioral quantification to be more precise, scalable, and reproducible in fields such as neuroscience and ethology. These tools overcome long-standing limitations of manual scoring of video frames and traditional "center of mass" tracking algorithms to enable video analysis at scale. The expansion of open-source tools for video acquisition and analysis has led to new experimental approaches to understand behavior. Here, we review currently available open source tools for video analysis, how to set them up in a lab that is new to video recording methods, and some issues that should be addressed by developers and advanced users, including the need to openly share datasets and code, how to compare algorithms and their parameters, and the need for documentation and community-wide standards. We hope to encourage more widespread use and continued development of the tools. They have tremendous potential for accelerating scientific progress for understanding the brain and behavior.Comment: 20 pages, 2 figures, 2 tables; this is a commentary on video methods for analyzing behavior in animals that emerged from a working group organized by the OpenBehavior project (openbehavior.com

Mapping the neuroethological signatures of pain, analgesia, and recovery in mice.

Ongoing pain is driven by the activation and modulation of pain-sensing neurons, affecting physiology, motor function, and motivation to engage in certain behaviors. The complexity of the pain state has evaded a comprehensive definition, especially in non-verbal animals. Here, in mice, we used site-specific electrophysiology to define key time points corresponding to peripheral sensitivity in acute paw inflammation and chronic knee pain models. Using supervised and unsupervised machine learning tools, we uncovered sensory-evoked coping postures unique to each model. Through 3D pose analytics, we identified movement sequences that robustly represent different pain states and found that commonly used analgesics do not return an animal's behavior to a pre-injury state. Instead, these analgesics induce a novel set of spontaneous behaviors that are maintained even after resolution of evoked pain behaviors. Together, these findings reveal previously unidentified neuroethological signatures of pain and analgesia at heightened pain states and during recovery