Anterograde amnesia and Related Topics

Midazolam

Benzodiazepine medication used for anesthesia, procedural sedation, trouble sleeping, and severe agitation.

Injectable midazolam in 1 and 5 mg/ml strengths

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It works by inducing sleepiness, decreasing anxiety, and causing a loss of ability to create new memories.

Lorazepam

Benzodiazepine medication.

1987 advertisement. "In a world where certainties are few...no wonder Ativan is prescribed by so many caring clinicians."

It is also used during surgery to interfere with memory formation and to sedate those who are being mechanically ventilated.

Humans have two hippocampi, one in each hemisphere of the brain. They are located in the medial temporal lobes of the cerebrum. In this lateral view of the human brain, the frontal lobe is at the left, the occipital lobe at the right, and the temporal and parietal lobes have largely been removed to reveal one of the hippocampi underneath.

Hippocampus

Major component of the brain of humans and other vertebrates.

Image 1: The human hippocampus and fornix (left) compared with a seahorse (right)

Image 2: Cross-section of cerebral hemisphere showing structure and location of hippocampus

Image 3: Coronal section of the brain of a macaque monkey, showing hippocampus (circled)

Image 4: Basic circuit of the hippocampus, as drawn by Cajal DG: dentate gyrus. Sub: subiculum. EC: entorhinal cortex

Image 5: Hippocampal location and regions

Image 6: Spatial firing patterns of 8 place cells recorded from the CA1 layer of a rat. The rat ran back and forth along an elevated track, stopping at each end to eat a small food reward. Dots indicate positions where action potentials were recorded, with color indicating which neuron emitted that action potential.

Image 7: Examples of rat hippocampal EEG and CA1 neural activity in the theta (awake/behaving) and LIA (slow-wave sleep) modes. Each plot shows 20 seconds of data, with a hippocampal EEG trace at the top, spike rasters from 40 simultaneously recorded CA1 pyramidal cells in the middle (each raster line represents a different cell), and a plot of running speed at the bottom. The top plot represents a time period during which the rat was actively searching for scattered food pellets. For the bottom plot the rat was asleep.

Image 9: An EEG showing epilepsy right-hippocampal seizure onset

Image 10: An EEG showing epilepsy left-hippocampal seizure onset

Image 11: Drawing by Italian pathologist Camillo Golgi of a hippocampus stained using the silver nitrate method

thumb|Hippocampus highlighted in green on coronal T1 MRI images

thumb|Hippocampus highlighted in green on sagittal T1 MRI images

thumb|Hippocampus highlighted in green on transversal T1 MRI images

People with extensive, bilateral hippocampal damage may experience anterograde amnesia: the inability to form and retain new memories.

Benzodiazepine

Fusion of a benzene ring and a diazepine ring.

Midazolam 1 & 5 mg/mL injections (Canada)

Addiction experts in psychiatry, chemistry, pharmacology, forensic science, epidemiology, and the police and legal services engaged in delphic analysis regarding 20 popular recreational drugs. Benzodiazepines were ranked in this graph 7th in dependence, physical harm, and social harm.

Diazepam 2 mg and 5 mg diazepam tablets, which are commonly used in the treatment of benzodiazepine withdrawal.

Chlordiazepoxide 5 mg capsules, which are sometimes used as an alternative to diazepam for benzodiazepine withdrawal. Like diazepam it has a long elimination half-life and long-acting active metabolites.

Schematic diagram of the (α1)2(β2)2(γ2) GABAA receptor complex that depicts the five-protein subunits that form the receptor, the chloride (Cl−) ion channel pore at the center, the two GABA active binding sites at the α1 and β2 interfaces and the benzodiazepine (BZD) allosteric binding site at the α1 and γ2 interface.

Left: The 1,4-benzodiazepine ring system. Right: 5-phenyl-1H-benzo[e] [1,4]diazepin-2(3H)-one forms the skeleton of many of the most common benzodiazepine pharmaceuticals, such as diazepam (7-chloro-1-methyl substituted).

A pharmacophore model of the benzodiazepine binding site on the GABAA receptor. White sticks represent the carbon atoms of the benzodiazepine diazepam, while green represents carbon atoms of the nonbenzodiazepine CGS-9896. Red and blue sticks are oxygen and nitrogen atoms that are present in both structures. The red spheres labeled H1 and H2/A3 are, respectively, hydrogen bond donating and accepting sites in the receptor, while L1, L2, and L3 denote lipophilic binding sites.

The molecular structure of chlordiazepoxide, the first benzodiazepine. It was marketed by Hoffmann–La Roche from 1960 branded as Librium.

Xanax (alprazolam) 2 mg tri-score tablets

High doses of many shorter-acting benzodiazepines may also cause anterograde amnesia and dissociation.

Temporal lobe

One of the four major lobes of the cerebral cortex in the brain of mammals.

Animation showing the position of the human left temporal lobe

The medial temporal lobes include the hippocampi, which are essential for memory storage, therefore damage to this area can result in impairment in new memory formation leading to permanent or temporary anterograde amnesia.

Amnesia

Deficit in memory caused by brain damage or disease, but it can also be caused temporarily by the use of various sedatives and hypnotic drugs.

There are two main types of amnesia: retrograde amnesia and anterograde amnesia.

Flunitrazepam

Benzodiazepine used to treat severe insomnia and assist with anesthesia.

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This may appear as lack of concentration, confusion and anterograde amnesia—the inability to create memories while under the influence.

Alprazolam

Fast-acting tranquilizer of medium duration in the triazolobenzodiazepine class, which are benzodiazepines (BZDs) fused with a triazole ring.

Alprazolam pills in boxes, as sold in France. Both Xanax (original Pfizer alprazolam product) and various generic forms of alprazolam are depicted here.

Binding at the α1β3γ2 GABAA receptor. Alprazolam with red space-filling carbon atoms. γ2 receptor subunit in mint green. The α1' subunit is hidden.

Alprazolam is metabolized into 4-hydroxyalprazolam (top) and α-hydroxyalprazolam (bottom).

Anterograde amnesia and concentration problems

The line processes to make information memory

Memory consolidation

Category of processes that stabilize a memory trace after its initial acquisition.

Systematic studies of anterograde amnesia started to emerge in the 1960s and 1970s.

Overview of the forms and functions of memory.

Episodic memory

Memory of everyday events that can be explicitly stated or conjured.

For example, anterograde amnesia, from damage of the medial temporal lobe, is an impairment of declarative memory that affects both episodic and semantic memory operations.