dating moldavie - Memory consolidation or updating consolidation

This early critical review rapidly raised a polemic public debate, the flavor of which can be gleaned from notes published in (Lewis and Maher 1965; Mc Gaugh and Petrinovich 1965; Lewis and Maher 1966).

Subsequent to this debate, scores of papers appeared from many different laboratories questioning the interpretation of experimental amnesia studies in terms of blockade of memory consolidation.

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Much of this work was done in collaboration with D. Lewis, who later turned a critical eye on his mentor’s work, to suggest initially, after careful behavioral analysis, that the performance deficit after ECS treatment was not necessarily due to amnesia, but to “competing responses” elicited by the treatment.

In 1965, Lewis published a review of the ECS-induced amnesia literature, containing already at this early date over 40 references, concluding that they do not provide unequivocal support for the consolidation hypothesis.

For more general reviews, refer to Mc Gaugh (2000) and Dudai (2004).

Scientific investigation of memory processes was initiated at the end of the 19th century by psychologists in Germany, Ebbinghaus (1885) and then Müeller and Pilzecker (1900).

In his 1949 paper he concluded that his experiments provided direct evidence for Müeller and Pilzecker’s hypothesis stating that post-learning neural perseveration was necessary for consolidating memory.

ECS disrupted this activity, thereby preventing post-acquisition memory consolidation.

This was followed in 1948 by “Habit reversal deficit induced by electroshock in the rat” (Duncan 1948), culminating with “The retroactive effect of electroshock on learning” (Duncan 1949).

In his first studies, Duncan administered an electroconvulsive shock (ECS) after each daily trial in a complex maze and showed an inverse relationship between the speed of learning and the delay between the trial and the amnestic treatment.

The protocol of retrograde amnesia, indeed, opened a door on a neurobiological approach to the study of memory, evaluating the efficacy and temporal dynamics of diverse physiological treatments without interfering with acquisition.

In general, the rationale for these experiments was that treatments that disrupt on-going brain activity (ECS, anesthesia, hypothermia) disturb memory. On the other side of the coin, treatments that enhance brain function such as psycho stimulant drugs (Mc Gaugh 1966), or mild stimulation of the ascending reticular activation system (Bloch et al. The common feature of these experiments is that both promnesic and amnesic agents lose their ability to respectively enhance or impair memory as the interval between memory acquisition and the treatment is increased, defining a temporal gradient of efficacy.

From his studies of amnesic patients, he formulated “La loi de regression,” which simply notes that, as memories age, they become more resistant to trauma-induced amnesia.

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