A report on Amnesia and Retrograde amnesia

Amnesie

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

- Amnesia

This would resemble generic amnesia.

- Retrograde amnesia
Amnesie

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Hippocampus (brain)

Anterograde amnesia

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Hippocampus (brain)

In neurology, anterograde amnesia is a loss of the ability to create new memories after the event that caused amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact.

This is in contrast to retrograde amnesia, where memories created prior to the event are lost while new memories can still be created.

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

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Major component of the brain of humans and other vertebrates.

Major component of the brain of humans and other vertebrates.

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.
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
Rats and cognitive maps
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.
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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

It is apparent that complete amnesia occurs only when both the hippocampus and the parahippocampus are damaged.

The unexpected outcome of the surgery was severe anterograde and partial retrograde amnesia; Molaison was unable to form new episodic memories after his surgery and could not remember any events that occurred just before his surgery, but he did retain memories of events that occurred many years earlier extending back into his childhood.

Long-term memory

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Stage of the Atkinson–Shiffrin memory model in which informative knowledge is held indefinitely.

Stage of the Atkinson–Shiffrin memory model in which informative knowledge is held indefinitely.

Research by Meulemans and Van der Linden (2003) found that amnesiac patients with damage to the medial temporal lobe performed more poorly on explicit learning tests than did healthy controls.

His subsequent total anterograde amnesia and partial retrograde amnesia provided the first evidence for the localization of memory function, and further clarified the differences between declarative and procedural memory.

Overview of the forms and functions of memory.

Memory

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Faculty of the mind by which data or information is encoded, stored, and retrieved when needed.

Faculty of the mind by which data or information is encoded, stored, and retrieved when needed.

Overview of the forms and functions of memory.
Olin Levi Warner, Memory (1896). Library of Congress Thomas Jefferson Building, Washington, D.C.
The working memory model
The garden of oblivion, illustration by Ephraim Moses Lilien.
Regulatory sequence in a promoter at a transcription start site with a paused RNA polymerase and a TOP2B-induced double-strand break
Brain regions involved in memory formation including medial prefrontal cortex (mPFC)
Regulatory sequence in a promoter at a transcription start site with a paused RNA polymerase and a TOP2B-induced double-strand break

Memory loss is usually described as forgetfulness or amnesia.

This memory loss includes retrograde amnesia which is the loss of memory for events that occurred shortly before the time of brain damage.

Psychogenic amnesia

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Memory disorder characterized by sudden retrograde episodic memory loss, said to occur for a period of time ranging from hours to years to decades.

Memory disorder characterized by sudden retrograde episodic memory loss, said to occur for a period of time ranging from hours to years to decades.

Psychogenic amnesia is distinguished from organic amnesia in that it is supposed to result from a nonorganic cause: no structural brain damage or brain lesion should be evident but some form of psychological stress should precipitate the amnesia, however psychogenic amnesia as a memory disorder is controversial.

Psychogenic amnesia is the presence of retrograde amnesia (the inability to retrieve stored memories leading up to the onset of amnesia), and an absence of anterograde amnesia (the inability to form new long term memories).

Thiamine

Korsakoff syndrome

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Thiamine

Korsakoff syndrome (KS) is a disorder of the central nervous system characterized by amnesia, deficits in explicit memory, and confabulation.

2) retrograde amnesia, memory loss extends back for some time before the onset of the syndrome

Fugue state

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Mental and behavioral disorder that is classified variously as a dissociative disorder, a conversion disorder, and a somatic symptom disorder.

Mental and behavioral disorder that is classified variously as a dissociative disorder, a conversion disorder, and a somatic symptom disorder.

The disorder is a rare psychiatric phenomenon characterized by reversible amnesia for one's identity, including the memories, personality, and other identifying characteristics of individuality.

Unlike retrograde amnesia (which is popularly referred to simply as "amnesia", the state where someone forgets events before brain damage), dissociative amnesia is not due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication, DSM-IV Codes 291.1 & 292.83) or a neurological or other general medical condition (e.g., amnestic disorder due to a head trauma, DSM-IV Code 294.0).

Figure 1. Depiction of standard model

Ribot's law

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Figure 1. Depiction of standard model

Ribot's law of retrograde amnesia was hypothesized in 1881 by Théodule Ribot.

Patients who incurred amnesia from a specific event such as an accident often also lost memory of the events leading up to the incident as well.

A common symptom of PTA is confusion.

Post-traumatic amnesia

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State of confusion that occurs immediately following a traumatic brain injury (TBI) in which the injured person is disoriented and unable to remember events that occur after the injury.

State of confusion that occurs immediately following a traumatic brain injury (TBI) in which the injured person is disoriented and unable to remember events that occur after the injury.

A common symptom of PTA is confusion.
Hippocampus (animation)
A Vasopressin molecule
Image from WWI, taken in an Australian dressing station near Ypres in 1917. The wounded soldier in the lower left of the photo has a dazed stare, a frequent symptom of "shell shock".
An elderly woman

There are two types of amnesia: retrograde amnesia (loss of memories that were formed shortly before the injury) and anterograde amnesia (problems with creating new memories after the injury has taken place).

MECTA spECTrum 5000Q with electroencephalography (EEG) in a modern ECT suite

Electroconvulsive therapy

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Psychiatric treatment where a generalized seizure (without muscular convulsions) is electrically induced to manage refractory mental disorders.

Psychiatric treatment where a generalized seizure (without muscular convulsions) is electrically induced to manage refractory mental disorders.

MECTA spECTrum 5000Q with electroencephalography (EEG) in a modern ECT suite
Electroconvulsive therapy machine on display at Glenside Museum in Bristol, England
ECT device produced by Siemens and used for example at the Asyl psychiatric hospital in Kristiansand, Norway from the 1960s to the 1980s
An illustration depicting electroconvulsive therapy
ECT machine from before 1960.
A Bergonic chair, a device "for giving general electric treatment for psychological effect, in psycho-neurotic cases", according to original photo description. World War I era.

It has been claimed by some non-medical authors that retrograde amnesia occurs to some extent in almost all patients receiving ECT.

The acute effects of ECT can include amnesia, both retrograde (for events occurring before the treatment) and anterograde (for events occurring after the treatment).