2.4 Limbic-Emotions and Memory Flashcards
Psychology of limbic system
Collectively processes and experiences emotions
Limbic system (physiology) function
Links the somatic (perception of external) & autonomic (internet, visceral) nervous systems
Two-way communication
Hypothalamus (autonomic) to limbic (somatic); limbic channels all somatic perception information to and from the cerebral cortex / diencephalic regions
Hypothalamus provides limbic system with information about…
The state of the INTERNAL body environment..
-Drive or motivational states (physiological reasons for wanting to do things: drink water, eat food, reproduce, etc)
Limbic system sends info about…
State of external environment the body is dealing with (Emotional states of being: fear, anxiety, anger, happy, sad)
Limbic system anatomy
Widespread regions throughout the midbrain, involves both cerebral and diencephalic brain regions
Hypothalamus
Consists of many nuclei that control feeding, drinking, self defense and reproduction
(point between nervous and endocrine)
Arcuate nucleus (hypothalamus)
Has gonadotropes: makes people want to reproduce and controls the actual process
Anterior and Supraoptic nucleus (hypothalamus)
Produce ADH
ADH is potent stimulator of thirst
The hedonic principle
Hypothalamus stimulates behaviors–>those that result in pleasurable sensation in the limbic system are repeated, behaviors that result in painful or unpleasant sensations are avoided
Reward
A stimulus (resulting from a behavior) that results in pleasure ex: you drink water because you are thirsty, positive emotions / associations
Punishment
Stimulus (resulting from a behavior) that results in pain / discomfort
ex: consumption of toxic food, negative emotions / associations with food and venue
Limbic system neurons produce neuropeptides known as…
Endorphins
2 types of endorphins
Enkephalins and dynorphins
Endorphin =
ENDOgenous morphing-like substances
Opiate drugs
Bind to endorphin receptors (morphine, oxycontin, heroin)
Enkephalins
Released following rewarding stimuli, causing pleasurable sensations (euphoria)
When are enkephalins released?
Sexual orgasm, satiety of thirst and hunger
Also during vigorous exercise.. decrease pain sensation(analgesic)
Dynorphins
Released following punishing stimuli, causing unpleasant sensations (dysphoria)
Where do endorphins have a critical role in learning and memory processes?
Hippocampus
What is the first step in detecting / satisfying hunger?
Hypothalamus perceives a caloric deficiency (energy deprivation)
What happens after the hypothalamus perceives energy storage?
Hypothalamus signals limbic system, which results in
a} dynorphin release (dysphoria)
b}a subjective feeling of “hunger” (discomfort) aroused by limbic system
c} Limbic system organizes and initiates feeding behavior
What happens after feeding behavior?
Energy level is normalized
-Both mobilized (blood) and and bodily stores of energy
What happens after normalization of energy level?
Hypothalamus subconsciously detects rise in energy
After the hypothalamus detects rise in energy,
Hypothalamus signals to limbic system which results in
{a} an enkephalin release (euphoria)
{b} Subjective feeling of satiety
{c} You positively associate whatever you just ate, remember the food well (hippocampus) and go back to that food later
Hippocampus
Works with amygdala and cerebral cortex to consolidate information from short-term memory into long-term memory
Short-term memory
Limited to several (about 6) specific pieces of stored information, requires lots of energy to keep things here
What does short term memory require?
Hippocampal attention, subject to distraction and disappear of not reinforced / practiced
What is short-term memory important for?
Short-term planning of behaviors and recalling simple sequences of motor acts
Hippocampus and amygdala assist in…
Formation of long-term, more permanent neuronal networks in the cerebral cortex
Hippocampus (STM–>LTM)
Records context / content of memory ) place and time
Amygdala (STM–>LTM)
Determines object associations (people and positions) and positive / negative emotional impressions
Anterograde amnesia
Transient impairments of reinforcement (black-out drunk) prevents new info storage, yet old memories remain (Ethanol shuts down the function of the hippocampus)
Each region of the cerebral cortex specializes in…
Long-term memory storage
- Highly compartmentalized
- Info stored relates to function of that cortical area
Where is sound remembered?
Wernicke’s area
Where are faces remembered?
Visual association areas of left hemisphere
Amygdala (Emotional side of limbic memory systems)
Association of stimuli with rewards, punishments, severe threats to well-being
- Dynorphins
- Enkephalins
Other functions of amygdala
- Regulates strength and duration of consolidated memories(more emotional will be better remembered)
- Mediates emotions of fear, anger, distress, anxiety
A hypersensitivity in mediation of negative emotions leads to…
Anxiety, PTSD, and OCD
SSRIs
(Selective serotonin repute inhibitors)
Calm things down, allows logic from cerebral cortex to prevail over the primal, irrational fear
Amygdala, if triggered…
Has direct line to sympathetic nervous system.. stress hormones flood the system
Cingulate gyrus
“Gear-shifter”, plays a key role in protecting you from potentially harmful outcomes
Functions of cingulate gyrus
- Key role in decision making since it anticipates possible outcomes
- Talks to the rest of prefrontal cortex involved in the planning of behavior
Functions of cingulate gyrus
- Key role in decision making since it anticipates possible outcomes
- Talks to the rest of prefrontal cortex involved in the planning of behavior
Brainstem Neuromodulatory Systems
-Small populations of neurons that send fibers to large areas of the brain
Function of the Brainstem neuromodulatory systems
Sleep and wake cycle Arousal levels Attention (motor and sensory) Mood Memory
Reticular activating system
Regulates arousal levels (sleep / wake cycles) and attention or alertness when awake
RAS receives inputs from…
- Cerebral (cognitive)
- Limbic (emotional)
- Sensory (external
- Hypothalamic (internal)
…systems
RAS sends..
Outputs to thalamus (sensory pathway arousal) and reticulospinal pathway (motor pathway arousal)
Neurotransmitters involved in sleep / wake cycle and mood
Seratonin, norepinephrine and dopamine
Seratonin
A neurotransmitter derived from the amino acid tryptophan, binds seratonin receptors expressed throughout CNS
Norepinephrine
Neurotransmitter (and hormone in ANS), binds adrenergic receptors expressed within the CNS (not just in the peripheral ANS)
Dopamine
Neurotransmitter produced in a few select (scattered) brain regions (also seen in motor systems)
All receptors of sleep / wake cycle and mood neurotransmitters…
Are G-protein coupled receptors that activate PKA or PKC pathways in target cells
Depression
Pathological feeling of fatigue, helplessness, not alert
-Involves chronic disease in 5-HT (seratonin) or NE
How do anti-depressants work?
Increase brain levels of 5-HT / NE
SSRIs examples
Prozac, zooloft, etc
SNRIs
Seratonin / norepinephrine RIs
Other classes of antidepressants
Electrophalogram (EEG)
Record brain’s electrical activity, electrical potentials sensed by scalp electrodes
What is the sleep / wake cycle regulated by?
Cyclic changes in RAS activity (NE / 5-HT)
Stage 4 (Slow-wave sleep)
Deepest sleep, associated with very low RAS activity
REM
RAS relatively active (particularly motor)
Vivid dreaming occurs..
During REM sleep which is a relatively “alert” state of sleep when people can sleep walk
(Sleep scientists think this helped us from being eaten during sleep)
Prevention of REM sleep can result in..
Psychotic behavior (hallucinations, delusions)
REM sleep (memory consolidation)
Procedural (process) and spatial (environmental) memories
SWS (memory consolidation)
Memory of facts and knowledge
If you truly want to learn something, you need to SW sleep on it
Dopamine (DA) regulates..
Motor behavior
Excessive DA release leads to…
Also cocaine and amphetamines
Hyperactivity
- Cocaine inhibits DA re-uptake
- Amphetamines cause DA release
- Both give perception of physical energy
Decreased DA release leads to…
Also Parkinson’s disease
Death of DA neurons (lack coordination)
Bipolar disorder
Caused by dysregulated DA release
- Excessive DA > Mania!
- Insufficient DA > Depression
“Feel good” drugs all cause ..
Increased DA release which stimulates reward systems
ex: alcohol, nicotine, opiates, cocaine, ecstasy
Summary of dopamine pathway functions and location
Frontal cortex
- Reward (motivation)
- Pleasure
- Motor function
- Compulsion
- Perseveration
Summary of Serotonin pathway functions
- Mood
- Memory processing
- Sleep
- Cognition
