Download File - Wk 1-2

Week 30 Learning Objectives
Memory
1. Describe basic concepts of memory, including retrograde and anterograde amnesia,
short-term versus long-term memory, classical conditioning, and the possible molecular
basis of synaptic changes in conditioning
There are two general types of memory:


Declarative – Explicit factual information. Conscious recollection of facts. This type
of memory has two subcategories.
o Semantic – General knowledge, stored undated (personally so you have no
“sense” of when it happened)
o Episodic – Personal experiences, stored dated (you know when these
personal experiences happened)
Non Declarative – Also known as “Procedural Memory”. Actions, motor skills,
conditioned behaviour and emotional memories. Subconscious memory expressed
through actions or performance.
Amnesia is the condition of the loss of memory. This loss can be caused by physiological or
psychological factors. Physiological causes include damage to the brain or the effects of
certain drugs. Psychological causes include self defence mechanisms that can result from
conditions such as post-traumatic stress. There are two types of amnesia:

Retrograde – A loss of the memory which precedes the development of amnesia.
The affected person will not be able to recall events that happen before the onset of
amnesia. They will be able to remember anything that happens after the onset.

Anterograde – A loss of the memory that succeeds the development of amnesia. The
affected person will not be able to recall events that happen after the onset of
amnesia. They will be able to remember anything that happens before the onset.
These two types of amnesia do not always happen separately and can happen together.
With regards to longevity, there are also two types of memory; Short Term and Long Term
Short Term Memory
Lasts for Seconds to Hours
Retained for reasons of interest, relevance
or random catchability
Can be attained completely by random
observation
Unknown storage site
Long Term Memory
Can be recalled years afterwards
Retained from consolidation of short term
memory
Can be attained without short term memory
Temporal lobe is suspected storage site for
long term memory
The memories which are most viable (able to be recalled) are the ones that were
experienced with multiple senses and also with great intensity.
Classical conditioning is a type of behavioral conditioning that pairs a neutral stimulus with a
stimulus that evokes a reflex; the stimulus that evokes the reflex is given whether or not the
conditioned response occurs until eventually the neutral stimulus comes to evoke the reflex.
UCS - Unconditioned Stimulus / UCR – Unconditioned response / CS – Conditioned Stimulus
CR – Conditioned Response
In essence, classical conditioning is the learning of certain behaviour by manipulating the
effects of events with associated responses. In this example, teaching the dog to salivate to
the sound of the bell by associating the sound of the bell with food.
2. Outline the features of the brain pathology (location and mechanism of lesions) and
memory loss in Wernicke- Korsakoff syndrome
Memory impairment in Wernicke - Korsakoff Syndrome is the result of damage in the
diencephalon, including the medial thalamus, and connections with the medial temporal
lobes andamygdala.
Additionally, damage to the diencephalon is associated with markedly decreased release of
acetylcholine from the hippocampus. Acetylcholine is important for memory activation so
impairment to its normal physiological release would affect memory as well.
(Additional Notes of Interest – Not Part of LO)
Extensive research has indicated that the crucial structures for incorporating and storing
sensory perceptions in fact memory are the hippocampus and the amydala (both part of the
limbic system), the diencephalon (specific areas of teh thalamus and hypothalamus), the
ventromedial prefontal cortex ( a cortical region tucked beneath the front of the brain), and
basal forebrain (a cluster of ACh-secreting neurons anterior to the hypothalamus)
Ataxia: damage to the cerebellum, particularly the superiorvermis. The loss of neurons leads
to persistent ataxia of gait and stance. In addition tocerebellardysfunction,
thevestibularapparatus also is affected.
Ocular motor signs: lesions in the brainstem affecting theabducensnuclei and eye movement
centers in theponsand midbrain.
3. Briefly outline the clinical features of Wernicke-Korsakoff syndrome, and compare with
temporal lobe amnesia.
Wernicke's encephalopathy is a degenerative brain disorder caused by the lack of thiamine
(vitamin B1). It may result from alcohol abuse, dietary deficiencies, prolonged vomiting,
eating disorders, or the effects of chemotherapy. Symptoms include mental confusion,
vision impairment, stupor, coma, hypothermia, hypotension, and ataxia. Korsakoff's amnesic
syndrome-a memory disorder-also results from a deficiency of thiamine, and is associated
with alcoholism. The heart, vascular, and nervous system are involved. Symptoms include
amnesia, confabulation, attention deficit, disorientation, and vision impairment. The main
features of Korsakoff's amnesic syndrome are the impairments in acquiring new information
or establishing new memories, and in retrieving previous memories. Although Wernicke's
and Korsakoff's may appear to be two different disorders, they are generally considered to
be different stages of the same disorder, which is called Wernicke-Korsakoff syndrome.
Wernicke's encephalopathy represents the "acute" phase of the disorder, and Korsakoff's
amnesic syndrome represents the "chronic" phase.
Most amnesic patients with damage to the medial temporal lobe retain some capacity to
learn new information about facts and events. In many cases, the learning appears to
depend on a residual ability to acquire conscious (declarative) knowledge. An important
finding in amnesic patients with MTL damage is the impairment of memory in all sensory
modalities – sound, feeling, smell, touch, sight. This reflects the fact that the MTL is a
processor for all of the sensory modalities, and helps store these kinds of thoughts into
memory. In addition, subjects can often remember how to perform relatively simple tasks
immediately (on the order of 10 seconds), but when the task becomes more difficult, even
on the same time scale, subjects tend to forget. This demonstrates the difficulty of
separating procedural memory tasks from declarative memory; some elements of
declarative memory may be used in learning procedural tasks.
4. Identify the differences between amnesia and dementia.
Dementia is not a specific disorder or disease. It is a syndrome (group of symptoms)
associated with a progressive loss of memory and other intellectual functions that is serious
enough to interfere with performing the tasks of daily life. Dementia can occur to anyone at
any age from an injury or from oxygen deprivation, although it is most commonly associated
with aging. Dementia can be defined as an overall decline in intellectual function, including
difficulties with language, simple calculations, planning and judgment, and motor (muscular
movement) skills as well as loss of memory.
Amnesia is the condition of a partial or total loss of memory. Like dementia it can happen as
a result from a massive array of causes. Unlike dementia which affects other neurological
elements, amnesia only affects memory. Dementia is a broad cognitive disorder that may
include amnesia.
(Additional Information – Not Part of LO)
Dementia can be caused by nearly forty different diseases and conditions, ranging from
dietary deficiencies and metabolic disorders to head injuries and inherited diseases. The
possible causes of dementia can be categorized as follows:


Primary dementia. These dementias are characterized by damage to or wasting
away of the brain tissue itself. They include Alzheimer's disease (AD), frontal lobe
dementia (FLD), and Pick's disease. FLD is dementia caused by a disorder (usually
genetic) that affects the front portion of the brain, and Pick's disease is a rare type of
primary dementia that is characterized by a progressive loss of social skills, language,
and memory, leading to personality changes and sometimes loss of moral judgment.
Multi-infarct dementia (MID). Sometimes called vascular dementia , this type is
caused by blood clots in the small blood vessels of the brain. When the clots cut off
the blood supply to the brain tissue, the brain cells are damaged and may die. (An
infarct is an area of dead tissue caused by obstruction of the circulation.)




Lewy body dementia. Lewy bodies are areas of injury found on damaged nerve cells
in certain parts of the brain. They are associated with Alzheimer's and Parkinson's
disease, but researchers do not yet know whether dementia with Lewy bodies is a
distinct type of dementia or a variation of Alzheimer's or Parkinson's disease.
Dementia related to alcoholism or exposure to heavy metals (arsenic, antimony,
bismuth).
Dementia related to infectious diseases. These infections may be caused by viruses
(HIV, viral encephalitis); spirochetes (Lyme disease, syphilis); or prions (CreutzfeldtJakob disease). Spirochetes are certain kinds of bacteria, and prions are protein
particles that lack nucleic acid.
Dementia related to abnormalities in the structure of the brain. These may include a
buildup of spinal fluid in the brain (hydrocephalus); tumors; or blood collecting
beneath the membrane that covers the brain (subdural hematoma).
Dementia may also be associated with depression, low levels of thyroid hormone, or niacin
or vitamin B 12 deficiency. Dementia related to these conditions is often reversible.