&p.1:Abstract The prefrontal cortex is involved in many pro- cesses, some of which are related to motor activity such eye movements and speech. Experimental data exist that suggest that prefrontal cortical activity occurs in relation to attention, short-term memory, affective discrimination, and complex forms of motor behaviour, i.e. anticipatory preparation, motor sequences, programming of speech, etc. We were interested in studying participation of this cortical region in locomotion. For this purpose, record- ings were made of unitary activity in the prefrontal cor- tex of chronically prepared cats walking on an exercise belt that was moving at a speed of 0.1 m/s. From a total of 63 neurones in the prefrontal area from which record- ings were made, 37 (59%) changed their activity during locomotion, 28 of which (76%) increased and 9 of which (24%) decreased their frequency of discharge; the re- maining 26 units (41%) showed no locomotor-related change in activity. The results obtained show that 59% of prefrontal units are involved in the locomotor process and it is reasonable to assume that their activity contrib- utes to the control of the movements. &kwd:Key words Unitary activity · Prefrontal cortex · Locomotion · Cats · Dorsomedial thalamic nucleus · Posterior parietal cortex&bdy: Introduction The prefrontal cortex is defined anatomically as a neo- cortical target of the dorsomedial thalamic nucleus. This nucleus relays neuronal influences from several struc- tures to the prefrontal cortex and is considered to be an association nucleus, receiving from and projecting to the frontal, motor and premotor cortex. Experimental data support the idea that the prefrontal cortex is involved in attention, short-term memory, affective discrimination and other processes such as motor activity [3, 10, 16, 21]. This area is endowed with a great variety of connec- tions that allow it to integrate information from different sectors of the sensorium and the internal environment. Its diverse efferent projections provide the anatomical basis for a high level of contribution by the prefrontal cortex to the execution of movements. It is not possible, however, to deduce either functional significance or control mech- anisms solely from the evidence of anatomical connec- tions. Experimental data obtained from monkeys support the idea that some prefrontal units are involved in senso- ry and motor coupling during the execution of visual tasks [10, 21]. As regards the role of the prefrontal cor- tex in locomotion, there have been, to our knowledge, no previous electrophysiological studies of this region. Investigations of mechanisms in the central nervous system that contribute to locomotor control in cats have demonstrated that neural circuits or “pattern generators” capable of maintaining movements of the limbs exist within the spinal cord [12, 13]. However, several lines of evidence show that there are different hierarchical levels which modulate the activity of the spinal cord in loco- motion, such as: the MLR-reticulo-spinal system [8, 17], Deiter’s and red nucleus [18–20, 24], the cerebellum [4, 5, 19], and the motor cortex [3, 18]. On the other hand, the posterior parietal “association” cortex is of major im- portance for accurate visual guidance of reaching move- ments in primates. Posterior parietal cortical neurones receive visual, auditory, somatosensory and vestibular sensory inputs, as well as information relating to eye, head, limb and whole-body movements and strong moti- vational projections from the limbic system [27]. Al- though homologous structures are well developed in cats, their neuronal activity during motor activity has not been investigated. The aims of this study are firstly to provide evidence from single unitary activity recorded from the prefrontal cortex that is supportive of its suggested participation in motor control; secondly to characterize the patterns of J.M. Criado ( ✉ ) · A.J. Fuente · M. Heredia · A.S. Riolobos J. Yajeya Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad de Salamanca, Av. Campo Charro s/n, E-37007 Salamanca, Spain&/fn-block: Pflügers Arch – Eur J Physiol (1997) 434:91–96 © Springer-Verlag 1997 ORIGINAL ARTICLE &roles:José María Criado · Antonio de la Fuente Margarita Heredia · Adelaida Sánchez Riolobos Javier Yajeya Electrophysiological study of prefrontal neurones of cats during a motor task &misc:Received: 24 October 1996 / Received after revision: 23 January 1997 / Accepted: 4 February 1997