“Transfer of learning” by injection of brain RNA: A replication

Abstract

Brain RNA was extracted from two groups of rats one of which had learned a passive avoidance of a dark chamber previously preferred by both groups. Recipient groups received the two kinds of RNA extract via intraperitoneal injection. The group injected with the extract from the brains of the conditioned animals showed significantly greater avoidance of the preferred chamber.Recent research has reported beneficial effects on memory due to ribonucleic acid (RNA) administration (Cameron & Solyom, 1961; Cameron et aI, 1963;Cook et al, 1963;Wagner et al, 1966;Corson & Enesco, 1966). There have also been reports of "transfer" effects accomplished through RNA extraction from the brains of trained animals and its injection into naive animals (Babich et aI, 1965;Jacobson et al. 1965; Fjerdingstad et al, 1965). These results are especially significant since they provide evidence of a direct relationship between nucleic acid and memory. Recently the generality of these findings has been seriously questioned (Luttges et al, 1966;Graves & Carey, 1965; Gordon et aI, 1966; Byrne et al, 1966). These negative findings have weighed heavily against the RNA molecular theory of memory.As Byrne et al point out, "failure to reproduce results is not after all, unusual in the early phase of research when all the relevant variables are as yet unspecified" (1966). In hopes of contributing toward the eventual uncovering of the significant variables involved in the "memory-transfer" phenomenon, the following experiments which obtained positive results are reported. Subjects Experiment 1. Ss (19 male hooded rats, approximately 65 days of age) were divided into four groups: Learned-Donors (N= 7); Control-Donors (N =4); Learned-Recipients (N=4); Control-Recipients (N=4).Experiment 2. Sa (22 female hooded rats, 100 days of age) were divided into four groups: Learned-Donors (N = 7); Control-Donors (N = 7); Learned-Recipients (N = 4); Control-Recipients (N=4). The test trials were carried out by an assistant who did not know the designation of the individual Ss nor the purpose of the experiment. In all other respects the two experiments were similar. ApparatusA maze was constructed in which three boxes (11 in. x 12 in.) were connected by two runways, 24 in. x 6 in. The boxes were arranged with a white one in the middle of the runway which served as the start box (SB). A second white box (WB) was connected to Psychon. Sci., 1967, Vol. 8 (9) RIC HARD GAY 1 AND ALFRED RAPHELSON UNIVERSITY OF MICHIGAN, FLINT COLLEGESB by the left runway (LRW), and a third box, painted black, connected to the SB by the right runway (RRW) served as the goal box (GB). The whole apparatus, with the exception of GB, was covered by clear Plexiglas. A 25 W light was placed directly over WB. The GB was covered with a wooden top with a small dark blue Plexiglas window. The floor of GB contained a grid, and a guillotine door controlled the entrance.Preliminary work demonstrated that rats would, when allowed to freely explore, show a definite preference for the darkest area...

Chemical transfer of learned behavior

“…This was in contradiction with the majority of workers who believed that the transfer factors were RNA sequences [11,12,14,26,31] and there was no doubt that certain types of RNA extracts were active. To resolve this controversy, I took advantage of the presence in my laboratory of Dr. Fjerdingstad, one of the early exponents of the RNA hypothesis.…”

“…Since the fall of 1967 work in my laboratory was concentrated on a passive avoidance paradigm, first transferred successfullyby GAY and RaPHELSON [31]. It is based on the innate preference of rodents for dark enclosures.…”

Synthetic Rat Scotophobin Induces Dark Avoidance in Mice

“…The importance of independent replication of the scotophobin studies has been emphasized in a summary on -the state of the art by the Psychopharmacology Research Branch of the National Institute of Mental Health (5). Transfer of learned dark avoidance by means of crude or partially purified brain extracts has already been reported by six groups of workers (6). The groups, however, reported negative results (7) .…”

RNA induced enhancement of a simple discrimination task

“…Thus, the shock avoidance task provided no evidence that this active-avoidance task was transferred. Some success, however, has been found with a passive-avoidance task (Gay & Raphelson, 1967). It may be that due to the wide variety of responses available in the active-avoidance proce~ure (e.g., crouching in corner, biting grid), that bar-pressing is not necessarily the response of primary intensity.…”