the limbic system and memory
____ & ____can also produce anoxia of this region.
head trauma & cerebral edema
The amygdala itself also has properties suggesting
"learning" or modification with experience.
The amygdala appears to add a _____ component to memory as part of formation and recall
"sympathetic" autonomic
Limbic Subcortical components Subcortical components (nuclei) that are primary contributors to limbic system function include:
- Hippocampus - Amygdala - Septal nuclei
While the circuit appears to go in a circle, in fact there are many points at which information enters and leaves the circuit to include wide areas of cerebral cortex. ______ in particular and pathway under it, the cingulum bundle, provide a mechanism for the diffusion of information from Papez's circuit.
Cingulate cortex This area of cortex has broad two-way communication with areas including prefrontal areas, premotor areas, visual, auditory and somatosensory association cortex. -This communication forms the basis for certain types of memory
Immediate memory: working memory: long term memory:
IM : fractions of a sec Wrking M: sec-min LTM: days-yrs
_______is the ability to hold ongoing experiences in mind for fractions of a second. It is very large, and each sensory modality (visual, tactile, verbal) appears to have its own register.
Immediate memory
is a primary pathway that links together the major limbic system components.
The Circuit of Papez
In this example, tasks of identifying a face is compared with remembering where an object is in space.
The blue areas were associated with a facial identity; the red for spatial memory. The green areas were activated during both.
consolidation is
The process of converting information in working memory to long term memory It is not entirely clear if the process of consolidation may occur in sequence or in parallel with short term memory.
ability to hold information in mind for access for seconds to minutes after the present.
Working memory (aka-short term memory)
anterior nuclear group part of the thalamus then sends
broad projections (thalamic radiations) to the cingulate gyrus and other cortical areas associated with the limbic system.
The nucleus accumbens or nucleus accumbens septi contains receptors for
a variety of neurotransmitters including endogenous opioids.
pathological memory loss.
amnesia
The emotional affect and rewarding nature of behaviors that are involved in memories and remembered actions also involve some subcortical structures. Among the most important of these are the
amygdala, septal nuclei, the nucleus accumbens and the ventral tegmental area of the brainstem.
The nucleus accumbens or nucleus accumbens septi receives input from the
amygdaloid complex, the hippocampal formation, and the substantial nigra and ventral tegmental area (dopaminergic) via the medial forebrain bundle (around the hypothalamus).
The CA 1 area of the hippocampus is particularly sensitive to
anoxia
The amygdaloid complex is located in the
anterior and medial portion of temporal horn under the uncus with which part of it blends.
The inability to form new memories results in ____ whereas difficult in retrieving memories already established is ____
anterograde amnesia retrograde amnesia
Forgetting may occur at
any stage of memory formation
Memories that are "significant" usually have intense ______ responses and affect associated with them.
autonomic
Electrical stimulation of the amygdala is ____ and can produce feelings of
aversive fear or anxiousness
Diseases in which the _____ are damaged are typically accompanied by the ______
basal nuclei (Huntington's disease, Parkinson's) inability to learn motor skills (as opposed to performance) -This might include mirror drawing or tracking a spot of light
The most likely substrates for procedural memory are the
basal nuclei loops involved in the performance and integration of motor tasks.
These circuits involve the
basal nuclei, prefrontal cortex, amygdala, sensory association cortex and cerebellum (but not those of the temporal lobe or midline thalamic nuclei.)
As might be suspected by the patterns of brain activation in recall, the substrates for long term memory or its retrieval can be shown to be ______ distributed.
broadly
_____ damage can also interfere with some types of conditioned reflex learning
cerebellar (blink reflex to a tone and puff of air).
Priming is particularly noted for the
creation of associational biasing or creating false memories.
These loops have some of the same characteristics of ____ systems
declarative (loop, tonic activity, modulation with activity).
For working memory, the regions of cerebral cortex involved in the memory appear to This can be demonstrated by
depend upon the type of task. functional MRI, which can show increases in blood flow with cortical activation during a task
Only ___ or ___ will produce appreciable deficits in long term memory.
diffuse damage or overactivation (epilepsy, or using electroconvulsive therapy)
Its basic connections suggest that a primary function is involved in
feeding and defensive bxs. it receives cortical connections as well
One important mechanism to add significance to memory is
emotional affect
Circuit of Papez originally described as part of a collection of structures as involved in ____, it also describes a set structures that when damaged
emotional affect (usually bilaterally) can disrupt memory processing.
This suggests the modulation of behavior through
endogenous reward mechanisms
In declarative memory, priming is usually demonstrated by
exposing subjects to a list of words or objects (without a request to remember them) and then some time later, testing to see if memory of the list has been retained
Priming is usually demonstrated by
exposing subjects to items in their environment without an effort to remember them and then showing that this exposure affects recall.
T/F The two primary types of memory are associated with the same circuitry.
false § Declarative memory § Nondeclarative (procedural) memory These primary types of memory are associated with two different circuitries that can be distinguished by different types of damage.
The normal inability to convert memories from one form to another, loss of memory, or inability to recall is
forgetting
Anoxia related memory loss can become evident in cases where
general body oxygen levels drop as in heart attacks or cardiac surgery.
Some of working memory is contributed by the _____, however, more recent studies suggest that _____ & _____ are associated with the more complex tasks of working memory, particularly ___ & ___ - The difference may be the inclusion of being able to use the items as well as remembering them.
hippocampus, prefrontal cortex and other neocortical areas problem solving and behavioral planning.
Outgoing connections (efferents) are to the
hypothalamus, brainstem and the globus pallidus as part access to the basal nuclei.
Patients with isolated lesions of the Declarative Memory system/Circuit of Papez have
immediate and some short term memory, but cannot consolidate information into long term memory.
1. a pathway to the hypothalamus (the part that goes 2. a major projection to the
in front of the anterior commissure (precommissural) mammillary bodies (postcommissural).
Working memory is
information held for a short period of time in order to accomplish a task.
The nucleus accumbens or nucleus accumbens septi lies at the
junction of the caudate nucleus and the putamen and next to the septal nuclei.
The cortical structures form a ring around the ____ the primary parts include:
medial aspect of the brain. the cingulate gyrus, the parahippocampal gyrus, the uncus, and small cortical areas included in hippocampal formation.
Nondeclarative (procedural) memory
memories that largely cannot be retrieved at a conscious level; how to perform tasks (e.g., riding a bicycle, gymnastic maneuvers).
The limbic system contains several cortical and subcortical structures that are interconnected for the processing of
memory and the expression of related emotions.
Amygdala's connections with the hypothalamus are believed to be the mechanism for
memory associated autonomic responses.
The neural circuitry involved in the incorporation of STM to LTM has been revealed primarily through the study of cases where lesions have produced
memory deficits
To actually confirm forgetting, it must be clear that a
memory has been formed.
A major function of limbic system circuitry is
memory processing
Association is important to enhance _____, particularly if the association is perceived as ____ for the individual
memory storage "significant" The association of random objects, words, or numbers with objects significant to the individual can dramatically increase particularly declarative memory, but also non-declarative aspects.
Long term memory is the
more permanent storage of information for periods of days, weeks, months, or years.
the _____ appears to play a role in addiction though the moderation of the rewarding nature of behavior.
nucleus accumbens
Immediate memory is required to be ___ & ____ in an environment. ___ & their connections contribute to this. It is evaluated clinically as
oriented and responsive Broad areas of cerebral cortex general orientation to environment.
Circuit of Papez Basic Pathway- extends sequentially from the ____ to the _____ to the _____ via the fornix (post commissural) to the _____ (via the mammillothalamic fasciculus) to the ______ back to the ______ via a pathway called the _____ that runs just under the cingulate gyrus.
parahippocampal gyrus (entorhinal area) hippocampus mammillary bodies anterior thalamic nuclei cingulate gyrus parahippocampal gyrus (entorhinal area) cingulum bundle
This suggests that at least image recall involves a process of the reactivation of similar brain regions to those involved in
perception
_____ is a phenomenon that demonstrates the continual transfer of information from working memory into long term memory whether or not there is an intent to remember it.
priming
In such patients, ____ memory is often intact, and intelligence testing may indicate ______ In general, _____ injury is required to produce appreciable deficits in this system (but not always).
procedural normal or even above normal. bilateral
The consolidation process is particularly sensitive to
processes which damage or interfere with the hippocampus.
patterns of brain activation involved in perception are similar to those activated in the process of
recall
Electrical stimulation of this area is
rewarding, and it may be responsible for the for addictive or compulsive behaviors by attaching a positive affect to them.
forgetting is an important process in the
selectivity of information that is incorporated
The amygdaloid complex connects directly and indirectly to the _____ It has large input from areas associated with
septal area (nuclei), the hypothalamus, the nucleus accumbens, and rostral areas of the caudate nucleus & putamen taste & olfaction
The fornix- contains two major pathways that interconnect the hippocampus to the
septal area, hypothalamus, and mammillary bodies
There is also some evidence that some disruption of ____ can be achieved by manipulation during recall.
specific long term memories
Declarative memory is
storage and retrieval that is available to consciousness and can be expressed by language (e.g., remembering a telephone number or images of events that have happened).
Non-declarative Memory Substrates The fact that patients with memory consolidation deficits can be shown to retain the ability to acquire procedures or non-declarative memory indicates that these memories have a different
substrates
Declarative memory is generally associated with
the circuit of Papez
Papez's circuit appears to be most closely associated with
the formation of new memories, primarily of the type that can be stated (declarative memory). In particular, it is associated with the transition between short term memory and long term memory.
Long term memory is the general model studied to identify
the incorporation of a piece of information (in the form of afferent action potentials) into a physical embodiment of neuronal change (engram).
The Mammillothalamic tract connects
the mammillary bodies with the thalamus (anterior nuclear group).
These forms may occur
together, but also apart and can give a clinical picture of the severity of brain trauma after brain injury. (e.g., the extent of amnesia after head trauma, memory of the accident, before and after can indicate the severity of injury).
The amygdala uses ______ sensory inputs to coordinate emotional responses to ____ stimuli
visceral and somatic pleasurable, fearful, and visceral stimuli
Clinical test is to remember a span of digits presented; 7-9 is normal. § Another is a list of several words to be recalled later in an interview. are examples for which type of memory?
working memory (STM)
Although there are many neural pathways that interconnect the structures of the limbic system, the two major ones are the
§ Fornix § Mammillothalamic tract.
temporal aspects of these two memory types:
§ Immediate memory § Working memory § Long term memory