limbic system Flashcards
uncus
primary olfactory cortex
input gate to hippocampus
dentate gyrus
functions in LT memory and spatial navigation
hippocampus
limbic func
memory emotion attention feeding mating
stimulation of lateral hypothalamus
Thirst and eating
Also
rage and fightingg
stimulation of VM hypothalamus
satiety and tranquility
olfactory inputs into limbic
- direct input into amygdala (emotions that drives behavior)
- indirect input to hippocampus (olfactory memory)
- input to primary olfactory cortex (uncus)
connection of limbic system that mediates visceral response to odors
- hippocampal to hypothalamic connection
olfactory perception of odors
orbitofrontal cortex
hypothalamus
maintenance of homeostasis
controls several internal conditions, such as control of body weight, drives to eat and drink, temperature regulation and maintenance of body fluids volume.
lateral hypothalamus
- stimulation
- lesions
- stimulation not only causes thirst and eating but also rage and fighting.
- Any lesions in this area will lead to decreased drinking and eating causing lethal starvation.
ventromedial hypothalamus
stimulation provokes a sense of satiety and tranquility.
If damaged, it will result in excessive eating, drinking, and hyperactivity.
Stimulation of periventricular nucleus
The stimulation of the thin zone leads to fear and punishment reactions.
Any lesions in this area will lead to decreased drinking and eating causing lethal starvation.
lateral hypothalamus
major reward centers of hypothalamus
lateral and ventromedial nucleus
mild vs strong stimulation of lateral and ventromedial nucleus of the hypothalamus
Milder stimulation of these areas gives a sense of reward, while stronger stimulation provokes rage and a sense of punishment
‘window’ through which the limbic system sees the place of a person in the world.
amygdala
Amygdala input
bidirectional connection with the hypothalamus. It receives neuronal signals from all portions of the limbic cortex, as well as from the auditory and visual association areas.
The amygdala works in collaboration with the ————. Its stimulation can also provoke feelings of rage, punishment, fear, and escape.
hypothalamus
amygdala outward signals
sends outward signals to the hypothalamus, thalamus, hippocampus, septum and the same cortical areas through which it has received the sensory signals.
structures (limbic system) with processes that impact the episodic autobiographic memory networks
amygdala and hippocampus
Different types of involuntary movements, such as tonic movements, clonic rhythmic movements, and movements associated with eating and olfaction are controlled by the ——-.
amygdala
local epileptic seizures
cause by weak electrical stimulation of the hippocampus may that last for a few seconds, even after the stimulation is over.
During hippocampal seizures, a patient may experience ——— and ——–.
various psychomotor effects and hallucinations.
The memory that remains intact after bilateral hippocampus removal for the treatment of epilepsy
preoperative memory Hippocampus plays an important role in the formation of long-term memory. This is evident by the fact that patients who had undergone bilateral hippocampus removal for the treatment of epilepsy were unable to remember the names of the persons they met after the surgery.
transmission of immediate memory into secondary memory and is also performed by
hippocampus
an example of transmission of immediate memory into secondary memory
the feelings of reward and punishment are the ‘immediate memory’ which needs to be converted into ‘a secondary memory.’ When the same stimulus is given over and over again, a permanent perception is made in the brain regarding that particular stimulus as either ‘a reward’ or ‘a punishment.
functions of the limbic cortex
The cingulate gyrus is responsible for linking the olfactory and visual signals to the previous memories and emotions. It also plays a role in aggression.
bilateral ablation of the posterior portion of the orbital frontal gyrus
it results in severe anosmia and motor restlessness.
Ablation of the cingulate gyri and the subcallosal gyri
release the inhibitory signals on the septum and the hypothalamus and results in extreme rage and aggressive behavior.
components of basal ganglia
It includes the caudate nucleus, the putamen, Globus pallidus, and substancia nigra.
functions of basal ganglia
It is involved in rule-based learning. It also controls the initiation of desired movements while inhibiting the undesired movements at the same time. The working memory andattention span are also under the influence of the basal ganglia.
Wernicke-Korsakoff Syndrome
Wernicke-Korsakoff-Syndrome is a combination of two different medical conditions; namely, Wernicke’s encephalopathy and Korsakoff syndrome.
Both of them result in brain damage due to a deficiency of Vitamin B1 (Thiamine).
In Wernicke’s encephalopathy, the thalamus and the hypothalamus are damaged, while in Korsakoff syndrome, the area of the brain involved in memory is permanently impaired.
causes of WKS
- Chronic alcohol abusers who have altered thiamine absorption and storage capacity as well as disordered activation of thiamine pyrophosphate.
- Individuals suffering from malabsorption syndromes such as post-bariatric surgery patients.
- Starvation.
- Clinical conditions that result in low levels of thiamine, such as AIDS, cancer, hyperemesis gravidarum, long-term dialysis, cardiac failure, thyrotoxicosis and total parenteral nutrition (TPN) for a long time with no thiamine replacement.
Korsakoff syndrome symptoms
loss of memory, hallucinations, and confabulation are the presenting complaints for which the patient is brought for the medical check-up.
