Neuroanatomy of Memory and Emotion Flashcards
What is the LIMBIC LOBE?
ring-shaped convolution
encircles the medial border of the cerebral hemisphere
functions:
- emotion
- mood
- pain perception
- motivation
- behaviour
- memory
- olfaction
What is the function of the HIPPOCAMPUS?
central part of the limbic lobe
- memory
- spatial navigation
not so much mood or emotion
What does damage to the hippocampus cause?
anterograde amnesia
inability to make new memories
What are the main regions of the limbic lobe?
- hypothalamus
- cingulate gyrus
- parahippocampal gyrus
- hippocampus
- amygdala
- septal area (small, in front of the hypothalamus - associated with mating/sexual behaviour)
What is the CINGULATE GYRUS?
portion of limbic lobe
lies in the medial, frontal and parietal regions
C-shaped convolution wraps around the corpus callosum
separated from the frontal and parietal lobes by the cingulate and sub-parietal sulci
What is the SUBGENUAL AREA?
part of cingulate gyrus which lies below the gene of the corpus callosum
often underactive in patients with major depressive disorder
What is the RETROSPLENIAL AREA?
part of cingulate gyrus
portion that lies behind the splenium of the corpus callosum
involved in the recall of personal/episodic memories
What is the PARAHIPPOCAMPAL GYRUS?
part of the limbic lobe which sits on the medial temporal region
lateral boundary: collateral sulcus
anterior part of gyrus folds back on itself to form the UNCUS - resembles a hook or bend finger
What is the structure of the HIPPOCAMPUS?
medial temporal cortex which rolls on itself
forming a longitudinal bulge in the floor of the temporal horn of the lateral ventricle
it sits submerged under a layer of CSF
cortical fold: thinner (3-layer) cortex
What is the neocortex?
used to describe the cortical structures of the cerebral hemispheres
here, the cortex is thicker (6-layers)
neocortex is found in 90% of the cerebral hemispheres
How is the HIPPOCAMPAL CORTEX arranged?
into an S-shaped fold
occupies the medial temporal region
What are the main parts of the hippocampal cortex?
3 parts:
- dentate gyrus
- Ammon’s horn
- subiculum
What is the ENTORHINAL CORTEX?
=> interface between the hippocampus and neocortex
=> allows hippocampus to create and store personal (episodic) memories
e.g. maps to allow spatial navigation
most anterior part of the parahippocampal gyrus
lies medial to the rhinal sulcus
What is the RHINAL SULCUS?
a short furrow that can be separate or continuous with the COLLATERAL SULCUS
What happens in Alzheimer’s and how does this affect hippocampal function?
earliest and most severe changes often in entorhinal cortex
hippocampus is functionally disconnected from rest of cortex
interferes in formation of new memories (anterograde amnesia)
also why day-to-day episodic memories are most severely affected
=> patients with Alzheimer’s can often get lost in familiar places
What is SHORT TERM MEMORY?
aka working memory
used for holding several pieces of info in mind for the duration of a particular task
working memory overlaps with attention and the ‘central executive’ functions of the FRONTAL LOBE
allows organising and planning of actions
DORSOLATERAL PRE-FRONAL REGION is important in this type of memory
What is LONG TERM MEMORY
3 stages:
- encoding
- storage
- retrieval
What is the anatomic basis of HUMAN MEMORY FORMATION?
not fully understood
memory traces are initially represented by electrochemical changes in existing synapses
long term potentiation: synaptic strengthening mechanisms where the same stimuli may result in a most tightly powered response if conditioned to do so
protein synthesis is required for more permanent memory storage
new growth of dendrites and synapses may occur
memory CONSOLIDATION
What is memory CONSOLIDATION?
process of converting a temporary memory trace into a long term permanent store
What are the types of long term (consolidated) memories?
DECLARATIVE (explicit)
consciously recalled and can be put into words
e.g. verbal description of an event
NON-DECLARATIVE (implicit)
cannot be put into words but have to be demonstrated in some way
e.g. a skill or competency that has been learnt
What are the 2 main types of DECLARATIVE memory?
- semantic
- episodic
What is SEMANTIC memory?
long term memory
involved in the knowledge of facts and info
e.g, capital cities etc
affected by damage/disease in the LATERAL temporal lobe
What is EPISODIC memory?
long term memory, involved with day-to-day personal memories that can be recalled
affected by damage in the MEDIAL temporal lobe
What is non-declarative/implicit memory?
several types, e.g. PROCEDURAL (‘how to do’)
often called ‘muscle memory’
required for gradual acquisition of motor skills
e.g. touch typing, clutch control
will probably involve the basal ganglia and/or cerebellum
What is the AMYGDALA?
large, almond shaped nuclear mass
in the anterior part of the medial temporal lobe
lies just in front of the hippocampus
composed of numerous sub-nuclei (like the thalamus)
involved with emotional responses and learning
How are the nuclei in the amygdala arranged?
into medial, lateral and central groups
MEDIAL NUCLEI
receive smell-related projections from the olfactory bulb and tract
LATERAL NUCLEI
receive primarily visual and auditory info from the lateral temporal lobe
CENTRAL NUCLEI
main outflow structure of amygdala
projects to the hypothalamus and brain stem
via the STRIA TERMINALIS
can trigger coordinated emotional responses
e.g. fight/flight response
What is the STRIA TERMINALIS?
a thin white matter pathway
carries info from the amygdala to the hypothalamus and brain stem
What is the function of the amygdala?
collects info about what is happening
integrates the info
and determines the emotional significance of ongoing events
particularly sensitive to fearful or threatening stimuli
described “danger detector”
therefore associated with
- anxiety
- fear
- rage
How do patients with damage to the amygdala present?
become fearless and engage in risky activities which may put them in danger
