Tj. Kornecook et al., Rhinal cortex, but not medial thalamic, lesions cause retrograde amnesia for objects in rats, NEUROREPORT, 10(13), 1999, pp. 2853-2858
MALE Long-Evans rats were trained on five separate object discrimination pr
oblems at different times prior to surgery. Following surgery, retrograde a
mnesia was assessed by measuring retention of the preoperatively learned di
scrimination problems in lesioned rats and controls. Rats with rhinal corte
x lesions displayed temporally graded retrograde amnesia; retention of obje
ct discriminations acquired in the recent past (i.e. 2 or 9 days prior to s
urgery) was significantly impaired, whereas retention of object discriminat
ions acquired more remotely (i.e. 16, 37, or 58 days prior to surgery) was
not. In contrast, rats with mediodorsal thalamic lesions exhibited normal s
avings of all discrimination problems. These results suggest that the rhina
l cortex, but not the mediodorsal thalamus, plays a time-limited role in th
e consolidation of object memory. (C) 1999 Lippincott Williams & Wilkins.