A report on Amnesia and Memory

Amnesie
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

Amnesia is a 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.

- Amnesia

Memory loss is usually described as forgetfulness or amnesia.

- Memory
Amnesie

6 related topics with Alpha

Overall

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.

Rats exposed to an intense learning event may retain a life-long memory of the event, even after a single training session.

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

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

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

Retrograde amnesia

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In neurology, retrograde amnesia (RA) is a loss of memory-access to events that occurred or information that was learned in the past.

This would resemble generic amnesia.

Episodic memory

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Episodic memory is the memory of everyday events (such as times, location geography, associated emotions, and other contextual information) that can be explicitly stated or conjured.

The label "amnesia" is most often given to patients with deficits in episodic memory.

Short-term memory

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Capacity for holding a small amount of information in an active, readily available state for a short interval.

Capacity for holding a small amount of information in an active, readily available state for a short interval.

The duration of short-term memory (absent rehearsal or active maintenance) is estimated to be on the order of seconds.

Patients with this form of amnesia have an intact ability to retain small amounts of information over short time scales (up to 30 seconds) but have little ability to form longer-term memories (illustrated by patient HM).

This image shows a priming web built from different types of priming. The lines in this web indicate associations that an individual might have. If two words are more closely linked in the web, then they are more likely to be more quickly recognized when primed with a nearby word. The dotted lines indicate morpheme primes, or primes from words that sound similar to each other, while the straight lines indicate semantic primes or words that have meanings or associations that relate to each other.

Priming (psychology)

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Phenomenon whereby exposure to one stimulus influences a response to a subsequent stimulus, without conscious guidance or intention.

Phenomenon whereby exposure to one stimulus influences a response to a subsequent stimulus, without conscious guidance or intention.

This image shows a priming web built from different types of priming. The lines in this web indicate associations that an individual might have. If two words are more closely linked in the web, then they are more likely to be more quickly recognized when primed with a nearby word. The dotted lines indicate morpheme primes, or primes from words that sound similar to each other, while the straight lines indicate semantic primes or words that have meanings or associations that relate to each other.
The extrastriate cortex (shown in orange and red) is believed to be involved in perceptual priming

This means that the first stimulus activates parts of a particular representation or association in memory just before carrying out an action or task.

Patients with amnesia are described as those who have suffered damage to their medial temporal lobe, resulting in the impairment of explicit recollection of everyday facts and events.