Transcript Consciousness, Thought, and Memory

Consciousness, Thought, and
Memory
Cristina Krage, Anthony Kurland,
and Malynda Clark
What is Consciousness?
Consciousness is a difficult concept to define. Even
today, not everything regarding its complexities is fully
understood. However, we do know that it is graded on a
continuum, ranging from alertness at the highest state,
through drowsiness/lethargy, stupor, and coma at the
lowest state. It involves the voluntary initiation and
control of movement, the perception of sensation, and
higher mental processing (memory, logic, judgment, etc).
To be functional, simultaneous stimulation of large areas
of the cerebral cortex must occur. This activity is
superimposed on other types of neuronal activity. This
activity can be both regional and/or involved in cognition.
In any case, the idea of consciousness is holistic and
totally interconnected within the cerebrum.
What is Memory?
Memory is the storage and retrieval of information. The
two stages of memory are short term (STM) and long
term (LTM). STM is the first step, and is limited to seven
or eight chunks of information. Some 5% of sensory
input is transferred to the STM. The LTM is of limitless
capacity, but its ability to store and retrieve information
declines with aging. The transfer of information from
STM to LTM is affected by emotional state, rehearsal
(repetition), association (tying new information to old),
and automatic memory (memory that is not consciously
formed). The consolidation of memory involves fitting
new facts into various categories of knowledge already
stored in the cerebral cortex. These newly stored
memories are usually filed along with the context in
which they were learned.
Categories of Memory
Declarative (fact) memory- learning specific
information (names, faces, words, and dates)
related to conscious thought and the ability to
manipulate symbols and language.
Nondeclarative memory- less conscious or
unconscious learning. This type of memory
contains 3 subcategories: procedural (skills)
memory, motor memory, and emotional memory.
These are acquired through experience and
repetition, and do not preserve the circumstance
of learning.
Brain Structures involved in
Memory
Specific pieces of memory are stored near
regions of the brain that need them.
Pathway of Memory Storage: Association
cortices -> medial temporal lobe (hippocampus
and temporal cortical areas) -> thalmus and
prefrontal cortex <-basal forebrain
Memories are retrieved when the same sets of
neurons that were initially involved in memory
formation are stimulated.
Mechanisms of Memory
During learning:
1. Neuronal RNA content is altered and
newly synthesized mRNAs are delivered to
axons and dendrites
2. Dendritic spines change shape.
3. Unique extracellular proteins are
depositited at synapses involved in LTM
4. The number and size of pre-synaptic
terminals may increase
5. More neurotransmitters are released by
pre-synaptic neurons.
Alzheimer’s Disease
In this disease, normal storage and retrieval of memory
is disrupted by plaques, which accumulates between
neurons, and tangles, twisted sections of the protein tau
(which normally supports neuronal structure), causing
cell damage and death. People afflicted with this disease
present all the symptoms one would expect from a
disorder of its nature; forgetfulness, personality changes,
poor judgment, etc. These symptoms demonstrate the
complexity of the nervous system, particularly the
cerebrum as it pertains to consciousness and memory.
If the slightest element should become ineffective, the
entire system often follows soon after.
Thought
The phenomena of thought has been puzzled
over by philosophers, scientists, and other men
of great learning for thousands of years. Despite
the great advances we have made in technology
and available data, exactly how and why we
think is mostly still a mystery. However, it is often
equated to awareness of the subconscious,
which encompasses all actions performed
without the conscious decision to do so, and
conscious mind.
Sources
• Human Anatomy and Physiology, Seventh
Edition. Marieb, Elaine N. and Hoehn,
Katja. 2007.
• Pukamble.tripod.com
• MayoClinic.com