Layered control architectures in robots and vertebrates

We revieiv recent research in robotics, neuroscience, evolutionary neurobiology, and ethology with the aim of highlighting some points of agreement and convergence. Specifically, we com pare Brooks' (1986) subsumption architecture for robot control with research in neuroscience demonstrating layered control systems in vertebrate brains, and with research in ethology that emphasizes the decomposition of control into multiple, intertwined behavior systems. From this perspective we then describe interesting parallels between the subsumption architecture and the natural layered behavior system that determines defense reactions in the rat. We then consider the action selection problem for robots and vertebrates and argue that, in addition to subsumption- like conflict resolution mechanisms, the vertebrate nervous system employs specialized selection mechanisms located in a group of central brain structures termed the basal ganglia. We suggest that similar specialized switching mechanisms might be employed in layered robot control archi tectures to provide effective and flexible action selection

Behavioral deficits revealed by multiple tests in rats with ischemie damage limited to half of the CA1 sector of the hippocampus

Ischemia causes neuronal necrosis in the septal half of the CA1 sector of the hippocampus in rats and produces deficits in spatial and other tasks, but the impairments are not severe. CA1 -damaged rats may perform at control levels on some tests and may overlap the performance of control animals on other tests. The present study examined the performance of CA1-damaged rats on a range of tests known to be sensitive to hippocampal damage and evaluated the size of the deficit using a composite test-battery score. The rats with CA1 damage were impaired on learning set, matching to place, and latent-learning spatial navigation in a swimming pool, delayed alternation, and pattern alternation on dry land, but not on amphetamine-induced locomotion or on negative patterning. The CA1damaged rats' impairments were mild, characterized by behavioral strategies similar to those of control rats, and their test scores overlapped those of control rats. Nevertheless, a composite profile derived from the measures obtained from the different tests revealed a large overall impairment. The results confirm that rats with partial damage to CA1 display impairments, especially on tests that demand working memory, and suggest that the test-battery approach can be used to enhance group differences

Tongue protrusions modify the syntax of skilled reaching for food by the mouse: Evidence for flexibility in action selection and shared hand/mouth central modulation of action

Skilled reaching for food by the laboratory mouse has the appearance of an action pattern with a distinctive syntax in which ten submovements occur in an orderly sequence. A mouse locates the food by Sniffing, Lifts, Aims, Advances, and Shapes the hand to Pronate it over a food target that it Grasps, Retracts, and Withdraws to Release to its mouth for eating. The structure of the individual actions in the chain are useful for the study of the mouse motor system and contribute to the use of the mouse as a model of human neurological conditions. The present study describes tongue protrusions that modify the syntax of reaching by occurring at the point of the reaching action at which the hand is at the Aim position. Tongue protrusions were not related to reaching success and were not influenced by training. Tongue protrusions were more likely to occur in the presence of a food target than with reaches made when food was absent. There were vast individual differences; some mice always make tongue protrusions while other mice never make tongue protrusions. That the syntax of reaching can be altered by the insertion of a surrogate (co-occurring) movement adds to a growing body of evidence that skilled reaching is assembled from a number of relatively independent actions, each with its own sensorimotor control that are subject to central modulation. That tongue and hand reaching movements can co-occur suggests a privileged relation between neural mechanisms that control movements of the tongue and hand. © 2017 Elsevier B.V

The relationship of structural ischemic brain damage to neurobehavioural deficit: the effect of postischemic MK-801.

Global cerebral ischemia is well known to cause neuronal necrosis in selectively vulnerable sectors of the hippocampus. Since the hippocampus of the rat is involved in spatial navigation, learning, and memory, selective deficits in these abilities may arise from ischemic brain damage. Previous studies have shown (a) a detectable neurobehavioural deficit due to ischemic brain damage limited to half of the CA1 sector of the hippocampus and (b) a reduction of ischemic neuronal necrosis with the noncompetitive N-methyl-D-Aspartate (NMDA) antagonist MK-801. This study was designed to determine the relationship between the improvement in structural brain damage in postischemically treated rats and any improvement in neurobehavioural performance, using a learning-set water task. Seventeen male Wistar rats received 10.5 min of forebrain ischemia induced by carotid clamping and hypotension. Brain temperature was estimated with probes in the temporalis muscle. Ten of these animals received no therapy (controls), and seven animals received 5 mg/kg MK-801 iv, 20 min postischemia. Six additional rats underwent a sham operation. Postischemic hypothermia was prevented with heating lamps. Four controls and one MK-801 treated animal died. The survivors were then tested on a place learning-set task in a swimming pool paradigm, and quantitative histopathologic analysis of their entire brains was done. The learning-set task revealed defects in spatial navigation, reflected as increased errors and latency in the performance of the untreated control rats. The performance of the MK-801 treated group progressively approached that of sham-operated rats over the course of testing and was significantly better than controls. Importantly, no long-term detrimental effect of MK-801 on the learning-set task performance was seen. Quantitative neuropathology revealed significantly less damage in the MK-801 treated group in all major brain regions. In the hippocampus, MK-801 treated animals showed hippocampal damage limited to the vulnerable portion of the pyramidal cell band comprising 48.8% of the CA1 pyramidal cells, as opposed to 72.4% in untreated controls. Extra-hippocampal damage was evident only in untreated control animals. MK-801 totally prevented neuronal necrosis in both the cerebral cortex and striatum and also prevented infarction in the neocortex and thalamus. Three conclusions emerge from the study. First, postischemic MK-801 mitigates structural brain damage in several brain

The syntactic organization of pasta-eating and the structure of reach movements in the head-fixed mouse

Mice are adept in the use of their hands for activities such as feeding, which has led to their use in investigations of the neural basis of skilled-movements. We describe the syntactic organization of pasta-eating and the structure of hand movements used for pasta manipulation by the head-fixed mouse. An ethogram of mice consuming pieces of spaghetti reveals that they eat in bite/chew bouts. A bout begins with pasta lifted to the mouth and then manipulated with hand movements into a preferred orientation for biting. Manipulation involves many hand release-reach movements, each with a similar structure. A hand is advanced from a digit closed and flexed (collect) position to a digit extended and open position (overgrasp) and then to a digit closed and flexed (grasp) position. Reach distance, hand shaping, and grasp patterns featuring precision grasps or whole hand grasps are related. To bite, mice display hand preference and asymmetric grasps; one hand (guide grasp) directs food into the mouth and the other stabilizes the pasta for biting. When chewing after biting, the hands hold the pasta in a symmetric resting position. Pasta-eating is organized and features structured hand movements and so lends itself to the neural investigation of skilled-movements. © 2017 The Author(s)

A mouse's spontaneous eating repertoire aids performance on laboratory skilled reaching tasks: A motoric example of instinctual drift with an ethological description of the withdraw movements in freely-moving and head-fixed mice

Rodents display a spontaneous “order-common” pattern of food eating: they pick up food using the mouth, sit on their haunches, and transfer the food to the hands for handling/chewing. The present study examines how this pattern of behaviour influences performance on “skilled-reaching” tasks, in which mice purchase food with a single hand. Here five types of withdraw movement, the retraction of the hand, in three reaching tasks: freely-moving single-pellet, head-fixed single-pellet, and head-fixed pasta-eating is described. The withdraw movement varied depending upon whether a reach was anticipatory, no food present, or was unsuccessful or successful with food present. Ease of withdraw is dependent upon the extent to which animals used order-common movements. For freely-moving mice, a hand-to-mouth movement was assisted by a mouth-to-hand movement and food transfer to the mouth depended upon a sitting posture and using the other hand to assist food holding, both order-common movements. In the head-fixed single-pellet task, with postural and head movements prevented, withdraw was made with difficulty and tongue protrude movements assisted food transfer to the mouth once the hand reached the mouth. Only when a head-fixed mouse made a bilateral hand-to-mouth movement, a component of order-common eating, was the withdraw movement made with ease. The results are discussed with respect to the use of order-common movements in skilled-reaching tasks and with respect to the optimal design of tasks used to assess rodent skilled hand movement. © 201

Organization of the reach and grasp in head-fixed vs freely-moving mice provides support for multiple motor channel theory of neocortical organization

Multiple motor channel (MMC) theory of neocortical organization proposes that complex movements, such as reaching for a food item to eat, are produced by the coordinated action of separate neural channels. For example, the human reach-to-grasp act is mediated by two visuo-parieto-motor cortex channels, one for the reach and one for the grasp. The present analysis asked whether there is a similar organization of reach-and-grasp movements in the mouse. The reach-to-eat movements of the same mice were examined from high-shutter speed, frame-by-frame video analysis in three tasks in which the mice obtained equivalent success scores: when freely-moving reaching for food pellets, when head-fixed reaching for food pellets, and when head-fixed reaching for pieces of pasta. To reach, the mice used egocentric cues to vary upper arm movements in a task-appropriate manner to place an open hand on the food or to locate the food using a “touch-release-grasp” strategy. Although mice could not hand-shape offline when reaching, they could hand-shape using online touch-related cues from the mouth to manipulate the food at the mouth. That the reach can be performed offline in relation to egocentric cues whereas hand shaping for the grasp requires online cues supports the idea that for the mouse, as for primates, the reach and grasp are separate acts. The results are further discussed in relation to the use of the head-fixed behavioral procedure to identify the independent neural substrates of the reach and the grasp using mesoscale stimulation/imaging methods. © 2017, Springer-Verlag Berlin Heidelberg