Visual Discrimination Impaired by Cutting Temporal Lobe Connections

Abstract

An attempt was made to transect the white matter that connects the anterior temporal lobe with dorsal and medial brain areas. Eight monkeys were trained preoperatively on a visual discrimination and tested postoperatively for retention and relearning of the task. They were also tested for Klüver-Bucy symptoms. The two animals that had complete lesions were unable to relearn the visual discrimination. It is suggested that human medial temporal lesions may produce their effects on learning and retention by damage to temporal white matter rather than by destruction of hippocampus.

Visual recognition in monkeys following rhinal cortical ablations combined with either amygdalectomy or hippocampectomy

“…This dissociation resembles that reported by ZolaMorgan et al (1982), who found that lesions of the temporal stem disrupted visual pattern discrimination learning but not recognition memory, whereas combined ablations of the amygdala and hippocampus had the opposite effect. The available data suggest that the substrate for the acquisition of pattern discriminations includes the following temporal-lobe components: the posterior inferior temporal cortex (Cowey and Gross, 1970;Iwai and Mishkin, 1968), the white matter ofthe temporal stem (Horel and Misantone, 1976;Zola-Morgan et al, 1982) and temporal-lobe portions of the striatum (Buerger et al, 1974;Divac et al, 1967; and the present results). The evidence thus points to the existence of a corticostriatal pathway for pattern discrimination learning that is partially independent of the corticolimbic pathway for recognition memory (cf.…”

The Neurology of Memory: The Case for Correspondence Between the Findings for Human and Nonhuman Primate

“…One (Douglas & Pribram, 1966) required monkeys to discriminate between two circles (diameters of 3 A versus Vi inch). Nevertheless, it is known that lesions of temporal white matter, including temporal stem, can impair visual discrimination performance (Horel & Misantone, 1976). In the other two positive studies the lesions were larger than those in the nine negative studies, and included damage to structures other than amygdala.…”

“…Evidence of the second kind comes from two studies, which have assessed the behavioral effects of selective damage to temporal stem (Horel & Misantone, 1976;Zola-Morgan, Squire, & Miskin, 1982). In the first study lesions of the stem, without accompanying damage to hippocampus, severely impaired the ability of monkeys to relearn a preoperatively acquired visual discrimination, and the degree of impairment correlated with the extent of the lesion (Figure 6.18).…”

Memory: Anatomical Organization of Candidate Brain Regions

“…The probe was "inserted into the hole about 12 to 15 mm and moved in a medial and lateral direction. The intention was to make a horizontal slit dorsal to the anterior temporal lobe, above the amygdala and laterally up to the insula" (215). In these cases, the extents of the lesions were plotted on representative coronal sections.…”