Abstract
The inferior part of the parietal lobe (IPL) is known to play a very important role in sensorimotor integration. Neurons in this region code goal-related motor acts performed with the mouth, with the hand and with the arm. It has been demonstrated that most IPL motor neurons coding a specific motor act (e.g., grasping) show markedly different activation patterns according to the final goal of the action sequence in which the act is embedded (grasping for eating or grasping for placing). Some of these neurons (parietal mirror neurons) show a similar selectivity also during the observation of the same action sequences when executed by others. Thus, it appears that the neuronal response occurring during the execution and the observation of a specific grasping act codes not only the executed motor act, but also the agent's final goal (intention).In this work we present a biologically inspired neural network architecture that models mechanisms of motor sequences execution and recognition. In this network, pools composed of motor and mirror neurons that encode motor acts of a sequence are arranged in form of action goal-specific neuronal chains. The execution and the recognition of actions is achieved through the propagation of activity bursts along specific chains modulated by visual and somatosensory inputs.The implemented spiking neuron network is able to reproduce the results found in neurophysiological recordings of parietal neurons during task performance and provides a biologically plausible implementation of the action selection and recognition process.Finally, the present paper proposes a mechanism for the formation of new neural chains by linking together in a sequential manner neurons that represent subsequent motor acts, thus producing goal-directed sequences.
Highlights
The inferior parietal cortex has been traditionally conceived as a typical association cortex [1,2], because of its polymodal neuronal properties and of the occurrence of spatial deficits after its damage in humans
An example of parietal neurons integrating sensory and motor properties is represented by mirror neurons [5,13,14,15] that, to those previously found in ventral premotor cortex (PMv), are active during execution of goal-related motor acts and during observation of similar motor acts performed by another individual
The results showed that, to motor neurons, the great majority of mirror neurons was differentially activated during the visual task depending on whether the observed grasping was followed by bringing to the mouth or by placing (Figure 2, left)
Summary
The inferior parietal cortex has been traditionally conceived as a typical association cortex [1,2], because of its polymodal neuronal properties and of the occurrence of spatial deficits after its damage in humans. Neurons of the inferior parietal lobule (IPL) are active during execution of several types of goal-related motor acts, such as reaching, grasping, bringing to the mouth or during eye movements and many of them integrate sensory and motor properties [3,5,9]. This integration subserves several types of sensorimotor transformations for reaching, grasping, oculomotion [10,11,12]. It has been proposed that this matching mechanism underpins understanding of the observed motor acts
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