After bilateral circumscribed lesions in the region of the dorsomedial and anterior thalamic nuclei, transitory confusion for time (chronotaraxis), frequently alone and sometimes combined with disorientation for place, was found. As a rule this disturbance lasted only a few days or weeks, but in one case half a year. The patients were confused regarding date, season of the year, and time of day. They misstated their age and that of their children. There was, in some instances, a tendency to overestimate, in others to underestimate, duration of time, such as the patient's stay in hospital or in his home. Usually the disturbances were associated with memory defects affecting recent as well as remote events. A combination with anosognosia or emotional changes occurred in some instances only. Sometimes, there was a discrepancy between the patient's feeling as to the passage of time and his judgment of it as obtained by intellectual processes. These latter observations seem to support the view that isolated disturbances of the immediate perception of duration do exist. Various circuits participate in the mechanism of temporal orientation, particularly connections of the dorsomedial nuclei with the frontal lobe and of the anterior nuclei with the mammillary body, and perhaps of the lateral nuclei with the parietal lobe. The significance of the connections of the anterior nuclei with the gyrus cinguli and of the intralaminar nuclei is doubtful. The multiplicity of the participating circuits explains that circumscribed lesions of single thalamic nuclei produce only transitory temporal disturbances.Abstract Teaser