A spatial memory signal shows that the parietal cortex has access to a craniotopic representation of space

Humans effortlessly establish a gist-like memory of their environment whenever they enter a new place. They can then use this memory to guide action even in the absence of vision. Neurons in the lateral intraparietal area (LIP) of the monkey exhibit a form of this environmental memory, responding when a monkey makes a saccade that brings the spatial location of a stimulus that appeared on a number of prior trials, but not on the present trial into their receptive fields. The stimulus need never have appeared in the receptive field of the neuron. This response is usually weaker with a longer latency than the neuron9s visual response. We suggest that these results demonstrate that LIP has access to a craniotopic memory of space, which is activated when the spatial location of the vanished stimulus can be described by a retinotopic vector from the center of gaze to the stimulus.