Memory means the conservation of certain conditions,
their reproduction and their localisation in the past. The
three elements are of unequal values; The first two are
necessary , indispensible ; The third , what in the
language of the school is called “Recollection” ,
completes the act of memory but does not constitute it.
In neuropsychology amnesia is most commonly used to
describe a patient suffering from what is called as
Amnesic syndrome , which can be defined as permanent
global disorder of memory following brain damage.
Amnesia is a topic that is of high importance in
Indian scenario as the number of cases on it are
increasing and the awareness of this disease is
My aim is to study the screening procedures for
amnesia and giving a brief account of drug therapy
It is an organic brain syndrome, caused by head
Includes: Korsakov's syndrome or psychosis
Results from a psychological cause.
loss of short-term memory, the loss or impairment of the ability
to form new memories through memorization.
loss of pre-existing memories to conscious
recollection, beyond an ordinary degree of forgetfulness.
The most well-described regions indicated in this
disorder are the medial temporal lobe (MTL), basal
forebrain, and fornix.
Hypertensive surge is hypothesised as one of the
cause for amnesia .
excessive glucocorticoid stimulation has been
shown to induce loss of dentritic spines &
synapse, Shrink the hippocampus and impair
cognition in both animal models and humans.
MANAGMENT OF AMNESIA
The primary goal in the management of amnesia is
to treat the underlying cause.
A regimen of anticancer drugs (chemotherapy)
along with radiation treatments (radiation therapy)
may be indicated for individuals with cancerous
Behavioral models for studying drugs or conditions
that affect cognitive processes rely on a stimuli to
induce an aversive state within the organism.
Once an animal has learned to escape from
aversive events, the next favourable strategy is to
try to avoid those aversive events totally.
1.MORRIS WATER MAZE
A task was developed where rats learn to swim in a
water tank to find an escape platform hidden under
the water (Morris 1984).
As there are no proximal cues to mark the position
of the platform, the ability to locate it efficiently will
depend on the use of a configuration of the cues
outside the tank.
Learning is reflected on the shorter latencies to
escape and the decrease on the length of the path
to find the platform.
2.RADIAL ARM MAZE
The rat uses spatial information provided by the
distal cues in the room to efficiently locate the
The radial arm-maze allows the study of spatial
reference and working memory processes in the
working memory procedures have a major temporal
component as the information resented in the
maze (arms baited) is useful for one session but not
for subsequent ones.
Correct choices in the radial arm-maze are
rewarded by food.
A variety of Y-maze task paradigms are available
for the evaluation of spatial working and long-term
memory in rodents.
Using food or sweetened water as an incentive to
reach the goal, animals are either required to
execute a specific search sequence or minimize
time/errors in the quest for a reward.
The spontaneous alteration task paradigm is the
simplest version of Y-maze task used to measure
the spatial working memory in rats.
4.FIGURE 8 MAZE
Figure 8 maze, used to measure spatial ability of
animals, is a unique task paradigm designed
basically to provide a classic common ‘choice point’
(Figure 4) with gated entry and exit points.
It may also be equipped with photo-cell detection
system for automatic recording of the animal
However, this task is not being used
currently, except for supportive information.
These mazes are built on the concept of construction
complex mazes with simple maze segments. Using the
six basic segments (Figure 8) a number of complex
mazes can be constructed by adjoining and increasing
numbers and variations in the basic segments.
Each basic segment comprises a specific maze
pathway constructed on a one square foot platform or in
any other required dimension. Platforms may be
mechanically joined to complete the maze.
Further, the junction of platforms may be demarcated
with photocell sensors that defined specific maze
sections for automated monitoring studies using
commercially available photo-cell monitors or video
It is complex modular maze used to assess the
mixed spatial workin, cue and taxon learning
skills in rats.
The maze has only one correct route. A
delicious food was placed in the goal box at the
end of the maze.
A trial started when the rat had moved both
forelimbs, snout, and upper body out of the start
box. The trial ended when the rat reached the
goal box and made contact with the food reward
or after 5 min had elapsed.
7.THREE-PANEL RUNWAY APPARATUS
A straightforward avoidance situation features a
fixed aversive gradient which can be traversed by
The shock can be avoided when the safe area is
reached within the time allocated.
The time the animal needs to reach the safe area
on both days is measured. In addition, the number
of errors (not reaching the safe area) is recorded.
elevated plus-maze has been recently extended to
measure the spatial long-term memory in animals.
It is based on the apparent natural aversion of
rodents to open and high spaces .Animals spend
more time in the enclosed arms because they
dislike the open arms.
transfer latency (the time in which the animal
moves from the open arms to the enclosed arms)
was markedly shortened if the animal has
previously experienced entering the open arms.
9.TWO-WAY SHUTTLE BOX
Compared to runway avoidance, shuttle box
avoidance (two-way-shuttle-box) is a more difficult
Since the animal is not handled between trials, the
shuttleboxcan be easily automated.
The time the animal needs to reach the safe area
on both days is measured.
In addition, the number of errors (not reaching the
safe area) are recorded.
INDUCTION OF AMNESIA IN LABORATORY
Drug-induced state dependent learning
Animals trained on a task under some drugs often
show a failure of learning performance when they
are tested in the absence of the drugs. The failure,
however, is ameliorated when the drugs are
Amnesia can also be induced in experimental
animals by electroshock (ES) stimulation.
Presentation of electroshock by silvercorneal
electrodes induces clonic-tonic seizures and impair
BRAIN LESION-INDUCED COGNITIVE DYSFUNCTION
Lesions have been produced with several different
neurotoxic and electrolytic techniques and several
cholinergic agents have been utilized to reverse the
A selective cholinergic neurotoxin, ethylcholine
mustard aziridinium ion (AF64A) has been widely
used for the experimental induction of cognitive
Novel drug Approach
Aim Materials &
stevioside The present
i.p.) in animals.
The results are
The data of
analyzed by one-
way analysis of
post hoc Tukey‟s
test using Sigma
induced rise in
It may be
stevioside exerts a
of rats possibly
Aim Materials &
The learning and
All results were
(SEM). All the
ß-alanine at both
the doses (10 and
young- and aged-
ethanol (1.0 g/kg
mg/kg i.p.) -
in young mice.
appears to be
related to its
Brahmi Identify the
days 1 to 15.
trained in a T-
maze using a
Brahmi do not in
amnestic effects of
Aim Materials &
Linn. as a
paradigm served as
can be employed
in the treatment of
disorders such as
claim of the
as elevated plus
maze and Water
maze were used to
assess the short-term
amnesia served as
The data were
EAAS (100 and 200
kg, p.o.) significantly
amnesia.[ The ethyl
acetate and ethanolic
fractions (EAAS) of
roots were selected
for the study]
The results indicate
that A. speciosa has
traditional use in
Although a wide variety of behavioural models for the
evaluation of learning and memory processes are currently
being used, the interpretation of behavioural parameters in
many of these tasks is still ambiguous.
Drug effects should be tested in different types of tasks that tap
different aspects of behaviour to exclude alternative
explanations for the performance in a cognitive task.
Rapid developments in the field of neurobiology of learning
and memory processes may hopefully lead to an improved
understanding of the pathophysiology of several disorders that
are associated with cognitive dysfunction.
1. Theodule armand ribot, Diseases of memory , an essay in the
positive psychology. page no. 10-25
2. H. Gerhard vogel , drug discovery and evaluation pharmacological
assays second edition page no. 624-634
3. WHO bluebook -The icd-10 classification of mental and
4. Assessment of nootropic and amnestic activity of centrally acting
agents by d.S. Reddy[department of pharmacology, university
institute of pharmaceutical sciences, punjab university.Chandigarh.]
5. Antiamnesic effect of stevioside in scopolamine-treated rats deepika
sharma1, munish puri, ashok k. Tiwary, nirmal singh, amteshwar
singh jaggi ijp
6. anti-amnestic properties of brahmi and mandookaparni in a rat
model chittaranjan andrade, j. Suresh chandra indian journal of