Patients with early Alzheimer's disease (AD) exhibit impaired declarative memory although some forms of nondeclarative memory are intact. Performance on perceptual nondeclarative memory tasks is often preserved in AD, whereas conceptual nondeclarative memory is often impaired. A conceptual nondeclarative learning task that has been studied in amnesic patients is the artificial grammar learning ...

We assessed the role of the hippocampus in anterograde memory, using the shock-probe test. Rats with sham or neurotoxic lesions of the hippocampus were given a shock-probe acquisition session during which each time they contacted a probe they received a shock; 24 h later, the rats were given a second shock-probe session to test their retention, but in this instance the probe was not electrified...

The amnesic patient H.M. has been solving crossword puzzles nearly all his life. Here, we analysed the linguistic content of 277 of H.M.'s crossword-puzzle solutions. H.M. did not have any unusual difficulties with the orthographic and grammatical components inherent to the puzzles. He exhibited few spelling errors, responded with appropriate parts of speech, and provided answers that were, at ...

Habit learning has been defined as an association between a stimulus and a response that develops slowly and automatically through repeated reinforcement. Concurrent discrimination (CD) learning, in which subjects learn to choose the rewarded objects in a series of pairs, is believed to be an example of habit learning in monkeys. Studies of human amnesic subjects, however, have produced equivoc...

HOW DOES MEMORY WORK? It turns out that there is one brain structure that appears to be a ‘memory maker’. Without it, we cannot remember anything that has happened to us, even from only a few minutes ago, let alone from last summer. Indeed, there was a very famous case of a patient named Henry Molaison (often referred to as H.M.), who had damage to his brain and was completely unable to form ne...

Sildenafil (Viagra) has been introduced recently in market to correct male impotency and has gained immense popularity for its dramatic effects all over the world. The present study was designed to investigate the effect of sildenafil on learning and memory in mice using elevated plus maze. A total of XV groups of animals were employed in the present study. Central cholinergic pathways play a c...

We describe a mathematical model of learning and memory and apply it to the dynamics of forgetting and amnesia. The model is based on the hypothesis that the neural systems involved in memory at different time scales share two fundamental properties: (1) representations in a store decline in strength (2) while trying to induce new representations in higher-level more permanent stores. This pape...

Malingering amnesia is a phenomenon in which patients simulate or exaggerate their symptoms of memory loss. The purpose behind faking amnesia is usually for financial gain through insurance fraud or avoiding criminal punishment. This essay outlines various tests that are available to detect patients who may be simulating anterograde amnesia (inability to learn new information) and retrograde am...

The anterior thalamic (AT) nuclei constitute an important component of an extended hippocampal-diencephalic system, and severe persisting memory deficits are normally found after AT damage. This study examined whether postoperative enrichment promotes the recovery of the flexible use of spatial representations in rats with AT lesions. After training to swim from a single constant start position...

Anexate (Ro 15-1788) a specific benzodiazepine antagonist, was assessed for its action in reversing midazolam-induced sedation. Sixty-five patients undergoing prostatic surgery under subarachnoid anaesthesia received midazolam for intraoperative sedation (mean dose 16 mg) followed by either active drug (anexate) or placebo given as a randomized, double-blind i.v. injection. The anexate dose suf...