Memory retrieval

Block RI and Wittenborn JR (1986). Marijuana effects on the speed of memory retrieval in the letter-matching task. International Journal of Addictions, 21, 281-285. 

Popik P. (1996). Facilitation of memory retrieval by the "anti-addictive" alkaloid, ibogaine. Life Sci. 59(24) PL37945. 

Evidence of central nervous system toxicity in animals includes disturbed equilibrium in cats exposed to 7,200 ppm chloroform for 5 minutes, deep narcosis in cats exposed to 21,500 ppm for 13 minutes, deep narcosis in mice exposed to 4,000 ppm for 30 minutes, slight narcosis in mice exposed to 3,100 ppm for 1 hour, and no obvious effects in mice exposed to 2,500 ppm for 2 hours (Lehmann and Flury 1943). Memory retrieval was affected in mice exposed to chloroform via anesthesia (concentration not specified) (Valzelli et al. 1988). The amnesic effect was not long-lasting. 

Inhalation exposure to high chloroform concentrations induced narcosis (Lehmann and Flury 1943 Sax 1979) and reversible impairment of memory retrieval in animals. High, single, oral doses of chloroform caused ataxia, incoordination, anesthesia, and brain hemorrhage in mice (Balster and Borzelleca 1982 Bowman et al. 1978). Behavioral effects were observed at lower oral doses. 

For human beings, two different memory categories have been introduced. According to Schacter, imphcit (or unconscious/unaware) memory is revealed when previous experiences facilitate performance on a task that does not require conscious or intentional recollection of those experiences. Explicit memory, in turn, is revealed when the performance of a task requires conscious recollection of previous experiences. These are descriptive concepts that are primarily concerned with a person s psychological experience at the time of memory retrieval. Accordingly, the concepts of implicit and expUcit memory neither refer to nor imply the existence of two independent or separate memory systems (Schacter 1987). As these two memory categories cannot be easily appHed to the situation in animals, they will not be further considered in this chapter. 

Hall J, Thomas KL, Everitt BJ (2001a) Cellular imaging of zif268 expression in the hippocampus and amygdala during contextual and cued fear memory retrieval selective activation of hippocampal CAl neurons during the recall of contextual memories. J Neurosci 21 2186-2193... 

Hall J, Thomas KL, Everitt BJ (200 lb) Fear memory retrieval induces CREB phosphorylation and Fos expression within the amygdala. Eur J Neurosci 13 1453-1458... 

Levy BJ, Anderson MC (2002) Inhibitory processes and the control of memory retrieval. 

Manahan-Vaughan D, Braunewell KH (1999) Novelty acquisition is associated with induction of hippocampal long-term depression. Proc Natl Acad Sci U S A 96 8739-8744 Maren S (2001) Neurobiology of Pavlovian fear conditioning. Annu Rev Neimosci 24 897-931 Maren S, Holt W (2000) The hippocampus and contextual memory retrieval in Pavlovian conditioning. Behav Brain Res 110 97-108... 

Improve the aversive memory retrieval in rats conditioned in a T maze with appetitive and aversive events [Kumar et al. 1995]... 

Chuang DM, Gao X-M, Paul SM N-methyl-D-aspartate exposure blocks glutamate toxicity in cultured cerebellar granule cells. Mol Pharmacol 42 210-216, 1992 Chugh Y, Saha N, Sankaranarayanan A, et al Enhancement of memory retrieval and attenuation of scopolamine-induced amnesia following administration of S-HTj antagonist ICS 205-930. Pharmacol Toxicol 69 105-106, 1991 Ciraulo DA, Jaffe JH Tricyclic antidepressants in the treatment of depression associated with alcoholism. Clin Psychopharmacol 1 146, 1981 Ciraulo DA, Barnhill JG, Jaffe JH Clinical pharmacokinetics of imipramine and desipramine in alcoholics and normal volunteers. Pharmacol Ther 43 539-548, 1988... 

Ouyang, M. Thomas, S. A. (2005). A requirement for memory retrieval during and after long-term extinction learning. Proc. Natl. Acad. Sci., U. S. A., 102, 9347-9352. 

This initial finding of abnormal hippocampal function during memory retrieval in schizophrenia has been clarified by several subsequent studies. First, patients with schizophrenia rely less on the recruitment of the hippocampus and show more widespread activation of the prefrontal cortex during the retrieval of previously learned information (Weiss et al., 2003). Second, the ability to classify new items as previously not experienced is impaired in schizophrenia and is associated with decreased activation and smaller volume of the hippocampus (Weiss et al., 2004). Third, hippocampal recruitment in schizophrenia is impaired specifically during a relational, but not during a nonrelational memory task (Ongur et al., 2006). 

Abnormal recruitment of the hippocampus during memory retrieval in schizophrenia. The right hippocampal region indicated in red in (a) showed increased relative cerebral blood flow (rCBF) during high accuracy recall when compared with both lexical retrieval at baseline and low accuracy recall in healthy control subjects ("controls" in (b)). This normal pattern was absent in the schizophrenia group and all three recall conditions were associated with higher rCBF in the hippocampus ("schizophrenics" in (b))... 

These findings of impaired hippocampal activation during memory retrieval in chronic patients with schizophrenia have now been complemented by a study of hippocampal-based encoding of memory in first-episode psychosis (FEP) patients (Achim et al., 2007). While some hippocampal functions remained intact, the FEP patients demonstrated a selective deficit to engage hippocampal-dependent relational binding when presented with arbitrary stimulus pairs, resulting in poorer subsequent recognition performance. 

Heckers S, Goff D, Schacter DL, Savage CR, Fischman AJ, et al. 1999. Functional imaging of memory retrieval in deficit vs nondeficit schizophrenia. Arch Gen Psychiatry 56 1117-1123. 

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