Limbic System Flashcards
what are the core structures of the limbic system?
hippocampus
amygdala
cingulate gyrus
fornix
mamillary bodies
what are additional structures often included in the limbic system?
hypothalamus
anterior nucleus thalamus
which structures connect to the limbic system?
frontal cortex
basal forebrain
septal nuclei
nucleus accumbens
what is the mesolimbic dopamine system?
Connects the limbic system to the nucleus accumbens that is responsible for the brain’s reward center that releases dopamine when we experience pleasure and regulates what is real and worth reacting to versus what is irrelevant or imagined
what can too much dopamine in the temporal gyrus lead to?
Too much dopamine can cause misinterpretation of neutral stimuli, leading to delusions or hallucinations
what is the papez circuit?
loop-like pathway that connects structures in the limbic system, allowing information to flow between areas involved in memory, learning, and emotion
Hippocampus→Fornix→Mammillary Bodies (in Hypothalamus)→Anterior Nucleus of the Thalamus→Cingulate Gyrus→Back to the Hippocampus
what can disruptions in the papez circuit cause?
amnesia
what does the hypothalamus coordinate?
hormonal, autonomic responses and stress responses related to reward and motivation
what is the function of the Hippocampus?
Located in the temporal lobe, helps convert short-term memories into long-term memories and encodes and retrieves personal (episodic) and pattern-based memories
***(Long-term memories are not stored in the hippocampus but distributed across different parts of the cortex)
what is the function of the anterior nucleus of the thalamus?
acts as a relay hub, passing memory-related signals between the mammillary bodies and cingulate gyrus
what is the function of the cingulate gyrus?
- connects the limbic system (emotion) to higher cognitive functions (thinking, awareness)
- role in the conscious experience of emotions and how we process pain perception
- helps us assign emotional significance to memories
what is the function of the amygdala?
strongly connected to the hippocampus, links emotions to memories, helps store emotionally charged memories, such as those related to fear, trauma, or pleasure and establishes emotional associations with pain (unconscious bias)
what is the function of the parietal lobe?
process new sensory information and connects it with retrieved memories
** integrate old memories with new experiences
what is the role of the Prefrontal Cortex?
directs attention to important information decides what is worth remembering (factual information, events, experiences) but without attention new information is not stored properly
declarative (explicit) vs non-declarative memory (implicit)
- declarative: episodic and semantic memory (events and facts)
- nondeclarative: skills, habits, emotional memory, conditioned reflexes
what is the CA1 region of the hippocampus sensitive to?
O2 deprivation and is critical to memory consolidation
what is the primary site of Long Term Potentiation?
Hippocampus
what is Long Term Potentiation?
strengthens the connections between neurons (synaptic plasticity), allowing short-term memories to be consolidated into long-term memories
how does repeated stimulation in a presynaptic neuron cause Long Term Potentiation?
- presynaptic neurons release a lot of glutamate which binds AMPA and NMDA receptors allowing more Na⁺ and Ca2+ in
- Increased calcium activates the CREB which promotes the production of more AMPA & NMDA receptors
- Stronger synapses = More efficient signal transmission = Long-term memory formation
how does CREB organize how memories are stored?
based on context, time, or categories (“chunking”)
where does the mammillothalmic tract project to?
anterior nucleus of the thalamus
what is Wernicke’s encephalopathy?
neurological disorder caused by thiamine (Vitamin B1) deficiency, most commonly seen in chronic alcohol use disorder (AUD). It primarily affects the mammillary bodies, thalamus, and temporal lobe, leading to memory impairment (anterograde amnesia) and confusion.
why is it imporant to catch Wernicke’s Encephalopathy early?
it is reversible with thiamine treatment (Vitamin B1) but if untreated, it progresses to Korsakoff’s syndrome, a more severe, irreversible memory disorder
what is the function of the Frontal Cortex?
Deliberate retrieval of factual (semantic) memory and storage of facts, knowledge, and general information