limbic system Flashcards
roll of the limbic system
generate feelings and emotion from sensory inputs
evolved to promote survival
what does limbic system activity depend on
physiologic needs
parts of the limbic system
Cingulate and parahippocampal gyrus(limbic lobe, amygdala, hippocampus etc
what does the limbic system involve in response to envirnomnetal change
autonomic/voluntary response
also hypothalamus and cerebral cortex
what makes up the limbic system
Limbic cortex
Subcortical nuclei
what makes up the limbic cortex
3 layered allocortex
mesocortex
where is the allocortex of the limbic cortex
hippocampus and septal area
where is the mesocortex of the limbic cortex
parahippocampal gyrus, cingulate, and insula
what makes up the subcortical nuclei
Amygdala, hypothalamus
Nucleus accumbens
reticular formation
roll of the amygdala in the limbic system
emotional responses
roll of the hippocampus in the limbic system
learning and memory
where do some afferents go first to project to the hipocampus
Entorhinal cortex
the entorhinal cortex gets info from what
olfactory areas(minor) many other areas (major)
what afferents project to the hippocampus
Entorhinal cortex
Input from septal nuclei
what is the nature of input from spetal nuclei
modulatory in nature
what does input from septal nuclei affect
chance that info in hippocampus will be retained
the 3 zones of the hippocampus
dentate gyrus
Hippocampus proper(cornu ammonis)
Subiculum
The transition between hippocampus proper and adjacent parahippocampus cortex
Subiculum
Afferent hippocampal connections
Afferent fibers from sensory cortex
Entorhinal cortex projects to dentate gyrus
The pathway from the entorhinal cortex to the dentate gyus
Perforant pathway
Dentate neuron project to what
CA3
CA# neurons project into
fimbria and CA1
Pathway of afferent hippocampal connections
- afferent fibers from sensory cortex
- entorhinal cortex projects to dentate gyrus
- Dentate nuerons projects to CA3
- CA3 neuron projects into fimbria and CA1
- CA1 neuron projects to subiculum
- Subiculum projects to fimbria
- subiculuar neurons projects to entorhinal cortex
- entorhinal neuron projects to sensory cortex
CA1 neuron projects to what
subiculum
subiculum proejcts toL
fimbria
entorhinal cortex
when the subiculum projects to fimbria
alvear pathway
entorhinal neurons project to
sensory cortex
the 2 big hippocampal efferents
the alveolar pathway into the fornix
from the entorhinal cortex into the cerebral cortex
efferent outputs from hippocampus
subiculum and entorhinal cortex
what is the fornix a direct continuation of
the fimbria
the fornix has a long course under what
the corpus callosum
where does the crus arch
up beneath the corpus callosum
how is the trunk formed
joining of the crus’s
where is the trunk formed
near hippocampal commissure
what does the trunk devide into near the anterior commissure
precommissural fibers
Postcommisural fibers
where are the precommissural fibers
septal area
where are the postcommisural fibers
hypothalamus, mammilary body
papez circuit
- neurons in cingulate gyrus project back
- cingulate gyrus projects into the entorhinal cortex
- entorhinal cortex projects into the hippocampus
- hippocampus sends out projects via the fornix
- fornix eventually reaches the mammillary bodies
to begin the mammillothalamic tract - projectsions from the mammillary bodies begin the mammillothalamic tract to go to the anterior nucleus of the thalamus to cingulate cortex
6.5 whole thing repeats itself
short term
hold information briefly in mind while you need it
long term
stored information, can be retrieved
Explicit long term
recall of facts/ events, aka declarative memory or spisodic memory
semantic memory
pertains to spoken/written words, extended to knowledge of facts/concepts
Implicit memory
performed a leaned motor fucntion, riding a bike
working memory
memory needed for task at hand, like driving along a known route
consolidation
process of storing new information in long term memory
how are novel facts relayed
from sensory association areas to hippocampus for encoding, processed, encoded info sent beack to association area it came from and does not dpeend on hippocampus for retrieval
Bilateral removal of hippocampi leads to
impaired declarative memory, and new could not be formed:
episodic memories
semantic memories
but working memory is intact and HM could learn new skills
Episodic memories
past personal experices
semantic memories
ideas and concepts not related to personal experinces
location of the amygdala
in anterior, medial temporal lobe
the amygdala mergeis with
periamygdaloid cortex as part of uncus
nuclear groups as part of amygdala
Basolateral
Central
Medial
Basolateral Amygdala nuclear group
Cortex
Central nuclei
Emotional response
Central Amygdala nuclear group
hypothalamus
PAG
Emotional responses
MEdial Amygdala nuclear group
Olfaction
what is the amygdala primary associated with
emotion of fear
Afferents to the Amygdala
All sensory association areas directly to the lateral nucleus
prefrontal cortex iva association fibers
Visual areas
why the prefrontal cortex sends association fibers to the amygdala
sensation can be cognitively evaluated
visual areas project to amygdala because of
phobias, anxiety states
where are most nuclei reeiving afferents situated in the amygdala
laterally situated (lateral nucleus)
Amygdala afferents come from
Orbital cortex and Cingulate
Brainstem and PAG, other sites
Cortex and Thalamus
Olfactory bulb
what does the orbital cortex and cingulate send to the amygdala
General sense of emotional and physical discomfort/comfort
what does the Brainstem and PAG send to the Amygdala
Visceral sensory
what does the cortex and thalamus send to the Amygdala
Vision, taste, hearing, somatosensory
what does the olfactory bulb and cortex send to the amygdala
olfaction
the fibers pathwyas of the Amygdala
Stria terminalis
Ventral amygdalofugal pathwya
the stria terminalis is from
hypothalamus and septal nuclei
the ventral amygdalofugal pathway is from
the thalamus, hypothalamus, orbtial and anterior cingulate cortex
how do fibers leaves the amygdala
via stria terminalis and VAG pathway
Amydgala output to vventral striatum is supposed to be a means for
drive-related information to influence decisions about movemtn
travel of stria terminalis
emerges from central nucleus
follows curve of caudate
fibers go to septal area and hypothalamus
then medial forebrain bundlea and central tegmental tract
the bed nucleus is regarded as
the extended amygdala
what is more active then amygdala in anxiety
bed nucleus
function of amygdala efferent to the periaqueductal gray (medulla and raphespinal tract)
antinociception
function of amygdala efferent to the periaqueductal gray (to medullary rectulopinal tract)
freezing
function of amygdala efferent to the norepinephrine medullary neurons (project to lateral gray horn)
increase heart rate and blood pressure
function of amygdala efferent to the hypothalamus/dorsal nucleus of Vagus (heart0
decrease heart rate, fainting
function of amygdala efferent to the Hypothalamus (release corticotropin RH)
stress hormone secretion
function of amygdala efferent to the parabrachial nucleus to medullary respiratory nuclei
Hyperventilation (panic attacks)
what is injurted in kluver-bucy syndrome
Bilateral temporal lobe injury, involving the amygdala, parahippocampal gyrus
symptomes of Kluver-Bucy Syndrome
Fearless, Placid, no emotion reaction, don’t respond to threats, don’t flee threates
males become hyperxexual, indiscriminate, seeking sexual stimulation from inanimate or inappropriate objection
inordinate attention to all sensory stimuli, sniff and examine everythin orally, will eat if can be eaten
may pick up the sam object repeatedly as they seem to recognize nothing (visual agnoia
stimulation of nucleus accumbens leads to
sense of well-being “high af”
why do you feel a sense of well being due to stimulation of the nucleus accumbens
doapmine release in NA (and medial prefrontal cortex) from ventral tegmental area
Ventral striatal dopamine release is from
ventral tegmental area in midbrain
Limic loop in basal ganglia is related to
drive-related info to influence movement/behavior
associate stimuli with rewards
limbic loop in basal ganglia
Amygdala hypocampus and limbic cortex project to Ventral striatum
Ventral striatum projects to Ventral Palotum
Ventral palotum projects to Thalamus
Thalamus projects to LImbic cortex repeat
