LIMBIC SYSTEM

AND

MEMORY

CSMU Anatomy Department

By

Caleb Tinashe Munikwa

Group 214

The limbic system is composed of structures in

the brain that deal with Emotions(such as anger ,

happiness and fear) as well as Memory

It supports a variety of functions including adrenaline flow, emotion,

behavior, motivation, long-term memory, and olfaction. Emotional life is

largely housed in the limbic system, and it has a great deal to do with

the formation of memories.

The limbic system (or paleomammalian brain) is a complex set of

brain structures located on both sides of the thalamus, right under the

cerebrum. It’s a collection of structures from the telencephalon,

diencephalon, and mesencephalon. It includes the olfactory bulbs,

hippocampus, amygdala, anterior thalamic nuclei, fornix, columns of

fornix, mammillary body, septum pellucidum, habenular commissure,

cingulate gyrus, parahippocampal gyrus, limbic cortex, and limbic

midbrain areas ass shown in the above slide.

MEMORY

Memory is a process in which information is encoded , stored

and retrieved

Memory is a complex relationship between brain neurons

The major parts of the Limbic System involved in Memory are

: Amygdala

: Hippocampus

: cingulate gyrus

Information flows from the outside world through our sight

, hearing , smelling , testing and touch sensors

Therefore memory is simply ways we store and recall

things we have sensed

We store memory in areas located throughout the cortex ,

some data moves into short term memory and finally into

long term memory

AMYGDALA

AMYGDALA

Almond shaped masses of neurons on

either side of the thalamus at the lower end of

the hippocampus

It is for emotion , arousal , storing of

memory and stimulation of the hippocampus

in remembering of events for future

recognition

LONG TERM POTENTIATION

LONG TERM

POTENTIATIONS

Connections of neurons that fire repeatedly

again and again in a particular pattern, archive long

term potentiation (LTP) becoming more and more

sensitive

Hence creating memory and ready to fire the

exact same way in the future

LTP firing makes it more easy to remember as a

result of a particular strengthened pattern of firing

neurons

FIRING NEURONS CREATE

MEMORY (LTP)

Memory is not stored in one combination of LTP but in

numerous combinations of neurons like in the above

picture

The mesh of neurons in the above slide might be the

memory of your first kiss

It is stored in various networks, the events leading to

your 1st kiss are stored in another network, the way it felt

in another network , the way it smelled in another

network

Hence all added up making up the memory of your first

kiss

YOUR FIRST KISS

AMYGDALA RESPONSIBLE FOR

RECOGNITION(MEMORY)LEADING

TO AROUSAL & EMOTIONS

The amygdala is responsible for recognition/ distinguishing

male from female and in turn feeling aroused by the opposite

gender

Females have a larger amygdala than males hence are

more emotional and tend to remember the finest details of

events than males e.g they can link the color red to their

break up memory because the first thing she saw

immediately after her break up was a red car.

On the same note males have smaller amygdala

compared to that of the opposite gender and tend to be less

emotional

Homosexuals have a larger than amygdala compared to

that of heterosexuals whose memory recognizes people of

the same gender as arousing.

Damage to the amygdala causes individual to have an

impaired ability to interpret emotional aspect of facial

expressions

CINGULATE GYRUS

The cingulate gyrus provides a pathway

from the thalamus to the hippocampus and is

responsible for associating memories of smell

with pain or pleasant memories

HIPPOCAMPUS

HIPPOCAMPUS

Consist of two horns that curve back from the amygdala

Responsible for converting short term memories into long

termed memories, works with the amygdala for storage

Damage couples to every day memory fades away ( A

condition depicted in the films [ Memento and 50 1st

dates ]

PAPEZ CIRCUIT

PAPEZ’S CIRCUT

The hippocampus consolidates new memories in an event

that creates temporally links among cortex neurons e.g ‘’red’’

gets stored in the visual area of the cortex and the sound of

the bitten apple gets stored in the auditory area

When one remembers the new fact ‘’delicious apple’’ the

new memory converges on the hippocampus , which sends

them along the same path several times to strengthen the

links(LTP)

The information follows a pathway called the papez

circuit starting at the hippocampus , circulating through

more of the limbic system (to pick up any emotional

associations like ‘’happy warm day’’ and spatial

associations like ‘’apple orchard’’

Then to various parts of the cortex and back to the

hippocampus ,making the information flow around the

circuit many times strengthens the links(LTP) enough that

they stabilize and no longer need the hippocampus to

bring the data together therefore becoming long term

memory

SHORT TERM MEMORY

SHORT TERM MEMORY

Short term memory is the type of memory that

enables you to speak back the last sentence of a

conversation when someone accuses you of not

listening

It stores only data that catches your attention like a

police car behind you or following direction

STM is small it holds about 7 independent items at

one time such as carrying numbers when calculating

arithmetic

LONG TERM MEMORY

Long term memory has a large capacity and contains

memories that are decades old in addition to memories that

arrived several minutes ago.

Memories of LTM are relatively permanent are not likely

to be lost and can be divided into two Explicit and Implicit

Explicit memory measures requires a participant to

remember information e.g in exam

Implicit memory measure requires the participants to

perform a task without making a conscious effort to recall

the past because of previous experiences e.g playing music

or tennis.

SPATIAL MEMORY

spatial memory is the part of memory

responsible for recording information about

one's environment and its spatial orientation.

For example, a person's spatial memory is

required in order to navigate around a familiar

city

AMNESIA

Amnesia can also be caused temporarily by the use of various

sedatives and hypnotic drugs. Essentially, amnesia is loss of memory.

The memory can be either wholly or partially lost due to the extent of

damage that was caused. There are two main types of amnesia:

retrograde amnesia and anterograde amnesia. Retrograde amnesia is

the inability to retrieve information that was acquired before a

particular date, usually the date of an accident or operation. In some

cases the memory loss can extend back decades, while in others the

person may lose only a few months of memory. Anterograde amnesia

is the inability to transfer new information from the short-term store

into the long-term store. People with this type of amnesia cannot

remember things for long periods of time. These two types are not

mutually exclusive. Both can occur within a patient at one time.

Storage capacity of a human brain is 2,5 petabytes

{Paul Reber} of information .Equivalence of recording a

TV channel continuously for 300 years. That is a lot of

information that we have learned , seen ,experienced

e.t.c