Ibotenic acid lesions of the medial septum retard delay eyeblink conditioning in rabbits (Oryctolagus cuniculus).

Abstract

Jersey S. Berry and R. Thompson (1979) reported that electrolytic lesions of the medial septum significantly retard eyeblink conditioning. However, these electrolytic lesions were nonselective and may have also damaged the subcortical inputs to the hippocampus via the fimbria-fornix. In the present study, the medial septum was selectively lesioned with ibotenic acid in rabbits (Oryctolagus cuniculus), whose performance in a delay eyeblink conditioning paradigm was compared with that of intact controls, sham-operated controls, and intact controls given a systemic injection of scopolamine. Rabbits with selective medial septal lesions and rabbits receiving systemic scopolamine were significantly slower to condition than were intact and sham-lesioned rabbits. This finding demonstrates that the selective removal of the medial septum retards delay eyeblink conditioning in a manner similar to the disruption seen after systemic administration of scopolamine.

Selective hippocampal lesions disrupt a novel cue effect but fail to eliminate blocking in rabbit eyeblink conditioning

“…However, prior work in our laboratory on the learned inattention mechanism of blocking in rabbit eyeblink conditioning did not provide any evidence that learned inattention was the mechanism for blocking in eyeblink conditioning (Allen, Padilla, & Gluck, 2002). Normal rabbits that had been previously blocked to a light learned with the light at the same rate as naive controls.…”

“…Recent work in our laboratory has demonstrated the effectiveness of this selective lesion technique in the rabbit (Allen, Chelius, & Gluck, 2002;Allen, Padilla, & Gluck, 2002;Shohamy et al, 2000). This selective lesion technique allowed us to remove the dorsal area of the dorsal hippocampus removed by Solomon (1977), while leaving the overlying cortex and fibers of passage within the hippocampus intact.…”

Parallel acquisition of awareness and differential delay eyeblink conditioning

“…Systemic injection of the cholinergic antagonist scopolamine, which alters hippocampal neuronal activity, severely disrupts delay eyeblink conditioning in rabbits (Moore et al 1976) and in humans (Solomon et al 1993). Lesions of medial septum, which modulates hippocampal activity through cholinergic projections, disrupt the acquisition delay eyeblink conditioning in rabbits (Allen et al 2002). Humans with damage to the basal forebrain structures including the medial septum, as a result of anterior communicating artery aneurism rupture, also show impaired delay eyeblink conditioning compared with matched controls (Myers et al 2001).…”

Hippocampal theta-band activity and trace eyeblink conditioning in rabbits.

“…Moreover, disrupting the functioning of the hippocampus and the associated theta oscillations is more detrimental to eyeblink conditioning than lesioning the hippocampus (Allen, Padilla, & Gluck, 2002;Asaka, Griffin, & Berry, 2002;Salvatierra & Berry, 1989;Solomon, Solomon, Schaaf, & Perry, 1983). It seems that ongoing oscillatory activity in the hippocampus reflects the animal's behavioral and motivational state, determining, for example, the optimal or detrimental conditions for the subsequent acquisition of a conditioned response.…”