In monkeys, only studies relevant to the issue of directional motor components of neglect will be discussed here. Both inactivation (Stein, 1976) and unilateral lesion (Faugier-Grimaud et al., 1985) of area 7 lead to increased inaccuracy of reaching and to longer reaction times for reaches to contralateral visual targets. In the first study, this effect was reported for both arms. In the latter, it was observed for monkeys using the contralesional

arm, and was more severe for movements toward contralateral rather than ipsilateral space. In one animal, an increase in RT was also observed for the ipsilesional arm, especially for movements directed to targets in the contralateral space. In this latter study (Faugier-Grimaud et al., 1985) the two limbs were tested each in NU7441 ic50 only one direction of movement, i.e., the right arm for leftward movements and the left arm for rightward ones. Therefore, it is difficult to conclude whether the prolongation of reaction time was related to the arm used or to the ALK inhibitor direction of movement (toward or away from the side of the lesion). In any case, the impaired movements were mainly those directed to the target located in the contralesional space. An additional study (LaMotte & Acuña, 1978) reported a directional impairment of reaches to visual targets performed with the contralesional arm, in either

the presence or absence of visual guidance of movement. In fact, reaches towards targets in contralesional space were consistently hypometric as they were systematically misdirected toward the midline, as if the contralateral space was somehow ‘compressed’ or under-represented.

In this experiment, the lesion included both SPL and IPL. Finally, monkeys with unilateral lesions confined to area 7a (Deuel & Farrar, 1993) were observed to be reluctant, slow and inaccurate when reaching to moving targets only in the contralesional space, although they were able to detect and glance at them. Therefore, in both monkeys and humans Myosin IPL lesions severely impair the representation of directional motor information concerning action space. Understanding such representations was a necessary step toward understanding the directional movement disorders of neglect from a neurophysiological perspective. To this end, we will refer to recent studies of the dynamic properties of neurons in area 7a of the IPL of monkeys examined during the performance of several tasks aimed at assessing the relationships between neural activity and the direction of visually- and memory-guided eye–hand movements (Battaglia-Mayer et al., 2005, 2007). The tasks adopted in these studies were designed to reproduce in the laboratory set-up the forms of behaviour that are compromised by IPL lesions in neglect patients.