9. Limbic System Flashcards
(60 cards)
1
Q
what aspects of human behavior are associated with the
limbic system?
A
- emotions
- learning
- memory
2
Q
reward:
define
A
positive reinforcer; something for which we will work to approach and contact
3
Q
punisher:
define
A
negative reinforcer; something we will work to avoid
4
Q
emotion:
define
A
state elicited by rewards or punishers
5
Q
motivation:
define
A
state in which reward is being sought OR punisher is being avoided
6
Q
feelings:
define
A
conscious awareness of emotional state
7
Q
mood:
define
A
predominant emotional state over time
8
Q
primary reinforcer:
define
A
a reinforcer that an animal is born needing such as food, water, shelter.
9
Q
secondary reinforcer:
define
A
or conditioned, reinforcers are stimuli, objects, or events that become reinforcing based on their association with a primary reinforcer
10
Q
positive primary reinforcers
(examples)
A
- light touch,
- food,
- water
all are unconditioned reinforcers
11
Q
positive secondary reinforcer
A
a secondary reward because she learned the associations with the image/person and makes him a secondary reinforcer
(example given was a picture of her grandfather)
12
Q
negative primary reinforcers
A
those that threaten our survival;
e.g. pain and hunger
13
Q
negative secondary reinforcer
A
something you may associate w/ pain and threat to survival;
such as warfare
14
Q
emotions are produced by…
A
delivery, omission, or termination of a reward or punisher
15
Q
2 critical anatomical structures for emotions, learning, and memory?
where are these found?
A
- amygdala (sl more anterior) & hippocampus
- can be seen on medial surface of temporal lobe (you can’t see them on external surface of the brain)
16
Q
parahippocampal gyrus:
define and fxn
A
- grey matter cortical region of the brain surrounding hippocampus
- part of the limbic system
- fxn: important role in memory encoding and retrieval
17
Q
cortical association areas involved in memory
A
- temporal
- parietal
- cingulate
- olfactory
- prefrontal
18
Q
procedural (implicit) memory:
define and assoc. anatomical structures
A
- habits, skills, sensorimotor adaptations
- cerebellum and neostriatum –> brainstem and spinal motor outlets
19
Q
emotional memory:
define and assoc. anatomical structures
A
- conditioned preferences or aversions; memory modulation
- amygdala –> hypothalamus, autonomic, & hormonal inputs
20
Q
declarative (explicit) memory:
define and assoc. anatomical structures
A
- episodic and semantic;
- conscious recollection of facts, flexible expression
- new learning
- spatial memory
- parahippocampal region <–> hippocampus
21
Q
working memory:
define and assoc. anatomical structures
A
- brief memory, capacity 7-10, e.g. reading phone # and punching it into a phone
- prefrontal cortex –> prefrontal (lateral aspect)
22
Q
what aspect of memory takes place in hippocampus?
A
memory consolidation:
processes whereby initially labile memories become “permanent”
23
Q
case of H.M.
procedure and outcomes
A
- suffered from epilepsy
- surgery to both medial and temporal lobes
- lost ability to take short term memories and consolidate them to long term memory; but could still retain previous memories
24
Q
what aspects of HM’s memory remained in tact?
A
- could still retain previous memories
- *IMPLICIT MEMORY (non-declarative) remained largely in tact:
- can learn motor skills (e.g. mirror drawing)
- simple learning
- short-term memory okay (time-dependent)
25
knocking out hippocampus or related structures --\>
has what effect?
causes **anterograde amnesia**
26
**CC: anterograde amnesia**
define
* loss of semantic memory (and loss of ability to form new memories)
* knowledge of:
* facts
* people
* objects
* new word meaning
27
location and processing of long term memory
* resides in higher-order association areas of cerebral cortex
* processed by hippocampus (encodes the memories and sends them off to be stored; associations in the cerebral cortex)
28
Papez circuit:
define
circuit is involved in learning and memory;
◦ damage to this circuit --\> memory problems
29
CC: Korsakoff syndrome
* Results from alcohol abuse, thiamine deficiency
* (nutrient deficiency secondary to alcoholism)
* Sxs: memory loss due to destruction of mammillary bodies or thalamus
30
**Intracranial self-stimulation in rodents**
1. implant electrode in live rodent brain
2. link electrode stimulation w/ lever pressing
3. If electrical stimulation of brain region is rewarding, the rodent will press the lever vigorously --\> may even ignore food/ other survival instincts
This indicates that the electrical current is an extremely rewarding sensation
31
**reward circuit**: encoding
* all rewards are encoded the same way --\>
1. rewarding stimuli --\> causes release of NT **dopamine** in **nucleus accumbens**
2. **hippocampus** lays down **memories** of pleasurable sensation
3. **amygdala** creates a **conditioned response** to rewarding stimuli
32
33
reward circuit and addictive drugs
* addictive drugs hijack the reward circuit
* by flooding the nucleus accumbens w/ dopamine
34
**mesocorticolimbic dopamine system**:
define and components
* aka mesolimbic system, the reward system
* connects the **_ventral tegmental area_ (VTA)** in the midbrain, --\> to the ventral striatum of the basal ganglia in the forebrain.
* (The ventral striatum includes the **_nucleus accumbens_** and the olfactory tubercle)
35
where is the **nucleus accumbens** found?
important connections?
* found in the ventral striatum
* reciprocal connections w/ orbitofrontal cortex and anterior cingulate cortex
* part of mesolimbic dopamine circuit
36
**ventral tegmental area**:
define and location
* **origin of the dopaminergic cell bodies** of the mesolimbic system
* may be involved in **drug and natural reward circuitry** of the brain
* important role in: cognition, motivation, orgasm, & intense emotions relating to love, as well as several psychiatric disorders.
* neurons in the VTA project to multiple areas of the brain: prefrontal cortex, caudal brainstem, etc.
* location: VTA is close to midline in floor of the **midbrain**
37
**amygdala**:
function & structure
* emotions and behavioral expressions
* contains multiple different nuclei:
* **basolateral** nucleus (input to amygdala)
* **central** nucleus (outputs from amygdala)
38
**fast** route and **slow** route of input to amygdala
* **fast** route: is from **thalamus --\> directly to basolateral nucleus** of amygdala
* **long** route: is from the thalmus --\> **\*sensory and association cortex\*** --\> then to basolat. nucl of amygdala
39
flow of info w/in the amygdala
input to **basolateral nucleus** of amygdala --\> **central nucleus** of amygdala
40
four different output pathways from amygdala,
and respective functions
From central nucleus of amygdala --\>
* **prefrontal, cingulate cortex:** decision making
* **hypothalamus:** autonomic & endocrine response
* **PAG:** pain modulation, defensive behavior
* **LC (NE), Raphe (5-HT), VTA (DA):** attention, sensory perception
41
function of amygdala circuit & example:
## Footnote
**prefrontal, cingulate cortex**
* decision making
* e.g. behavioral response to remove yourself from the situation
42
function of amygdala circuit & example:
## Footnote
**hypothalamus**
* autonomic & endocrine response
* (e.g. inc HR & inc CRH--\>ACTH--\>cortical response)
43
function of amygdala circuit & example:
## Footnote
**periaqueductal gray**
* (PAG): pain modulation, defensive behavior
* e.g. due to adrenaline; one's own pain is modulated to be able to mobilize in stressful situations
44
function of amygdala circuit & example:
## Footnote
**Locus ceruleus (NE), Raphe (5-HT), VTA (DA)**
* attention, sensory perception
e. g. attention is focused on emotional stimulus/senses may tune into the stimulus to better pay attention
45
primary sensory stimuli:
general pathway organization
**DRTC (A/O)**
1. detection
2. relay
3. thalamus
4. cortex
5. amygdala OR orbitofrontal cortex
46
**taste receptor:**
pathway
1. **taste receptor** (detection)
2. **nucleus of solitary tract** (relay)
3. **ventroposteromedial** (VPM) (thalamus)
4. **fronto-parietal operculum insula** (cortex)
5. amydgala or orbitofrontal cortex
47
**touch** (primary sensory stimuli):
pathway
1. **touch (A-delta, C fibers)** (detection)
2. **Dorsal horn and spinal n. nuclei** (relay)
3. **ventral posteromedial nucleus or ventral posterolateral nucleus** (VPM & VPL) of thalamus
4. **Somatosensory cortex** (of cortex)
5. amygdala or orbitofrontal cortex
48
**olfactory** (primary sensory stimuli):
pathway
1. **olfactory neurons (**detection)
2. **olfactory bulb** (relay)
3. **medial temporal lobe cortex (**cortex)
49
key inputs to the learning centers?
1. visual and auditory cortex unimodal association cortex
2. primary reinforcers
50
key center(s) for **learning associations**?
key center(s) for **explicit memory?**
* **amygdala & orbitofrontal** for learning associations
* **hippocampus** for explicit memory
51
outputs from learning centers?
* **autonomic and endocrine**
* **implicit actions** (basal ganglia, emotional memory, conditioning)
* **explicit actions**, language systems
52
function of amygdala w/ regards to **emotional experiences**
* determines which stimuli are responded to
* how overt responses to stimuli are organized
* internal responses of the body's organs
53
damage to amygdala results in:
1. inability to recognize facial expressions (esp. fear)
2. generalized reduction in fear responses (can be dangerous)
3. inability to recognize the emotional content of speech
54
which brain structure lights up on functional imaging studies if looking at a
fearful facial expression?
a healthy amygdala should light up bilaterally upon seeing an expression of fear
55
where do **conditioned responses** occur?
* amygdala --\> **hypothalamus and periaqueductal gray (PAG)**
* conditioned responses to rewards/punishers; automatic and unconscious
56
where does **memory modulation** occur?
* amygdala --\> **hippocampus**
* declarative memory of emotional situations; conscious memories of situations with emotional content
57
where are **unconscious/automatic** responses found?
where are **conscious** memories of situations w/ emotional content found?
* unconscious/automatic: **hypothalamus & periaqueductal grey**
* conscious emotional memory: **hippocampus**
58
based on MRI studies, which type of image has the strongest MRI stimulation of amygdala?
* **frightening images stimulate most activity of amygdala**
* \*memory for the dangerous dog was much stronger than for the pleasant image
* there is little to no response to a neutral stimulus
59
association center for emotion?
what is the output?
* **amygdala** associates the image with an emotion (e.g. fear or behavior)
* **output** is via the **hypothalamus and frontal lobes**
60
which region relates image to the environment?
what is its output?
* **hippocampus** relates image to the environment, context, and modifies behavior
* Places the information in context; (e.g. rattling, triangular head of a snake) and relating the emotional stimulus to the context
* Freeze --\> contextualize --\> then frontal cortex helps w/ decision-making (fight or flight)
* output is through **frontal lobes**
