<prompt> A patient has a right homonymous hemianopia with saccadic pursuit movements and defective optokinetic nystagmus. The lesion is most likely to be in theFrontal lobeOccipital lobeParietal lobeTemporal lobe  <response>: Right nomonymous hemianopia with saccadic pursuit movements and detective optokinetic nystagmus confirms the diagnosis of perietal lobe lesion.Optokinetic Nystagmus: - It can be elicited in all normal individuals.Defect in optokinetic nystagmus and lesions of brain associated with it.In a case of hemianopia due to lesions of the parietal lobe optokinetic nystagmus is absent.Other lesions where optokinetic Nystagmus is defective:-Frontal lobe lesions - it inhibits this response only temporarily.Brainstem lesions - it results in asymmetry of this response in vertical plane. 