The inferior longitudinal fasciculus is commonly considered to be a long association fiber bundle interconnecting the occipital and temporal lobes. Based on blunt dissections of human and monkey brains, we have found that the only long fiber bundle common to both the occipital and temporal lobes is the geniculostriate pathway (i.e., optic radiations), located within the external sagittal stratum. In addition, our autoradiographic experiments indicate that the pathway from the occipital to the temporal cortex in monkeys consists of a series of U fibers that course beneath the cortical mantle to connect adjacent regions in striate, prestriate, and inferior temporal cortex. We suggest that the occipital and temporal lobes in human beings are similarly connected by a series of U fibers and that the term inferior longitudinal fascicubs be replaced with the term occipitotemporal projection system. Different clinical syndromes attributed to lesions of the inferior longitudinal fasciculus, including visual agnosia, prosopagnosia, and impaired visual recent memory, are probably due to interruption of fibers at different points along this projection system. Tusa RJ, Ungerleider LG: The inferior longitudinal fasciculus: a reexamination in humans and monkeys.
Ann Neurol 18:583-591. 1985 Current neuroanatomical textbooks refer to the inferior longitudinal fasciculus (ILF) as a long association fiber bundle interconnecting the occipital and temporal lobes 15, 6, 10, 11, 213. As visual perception and recognition of objects depend on the relay of visual information from occipital to temporal cortex, the ILF is considered to be a major pathway mediating these functions 1301. Several different clinical syndromes, including visual agnosia, prosopagnosia, visual hypoemotionality, and impaired visual recent memory, have been attributed to disruption of the ILF in patients with lesions of the white matter underlying occipitotemporal cortex 11-4, 261. Despite these references to the ILF in the neurological literature, the precise location of this fiber bundle remains unclear. The history of the identification of From the "