Lecture 2: Neuropsychology- The Limbic and Executive Systems Flashcards
PET and fMRI studies also suggest the _____ and _____ lobes are strongly connected
- frontal
- temporal
The limbic system includes the ____ areas surrounding the ____
- forebrain
- thalamus
Traditionally regarded as critical for emotion
What are the functions of the limbic system (6)?
- Pavlovian learning or classical conditioning = stimulus-response learning
- Spatial and temporal learning
- Learning about emotional stimuli
- Affective state = 1) personality = semi-permanent, 2) mood/affective = short term
- Responding to stress
- Vigilance/attention
List key structures of the limbic system (4)
- Hippocampus
- Amygdala
- Hypothalamus
- Prefrontal cortex
What cortical sites are used for the long-term storage of declarative information (2)? What are their functions?
- Wernicke’s area = meaning of words (language comprehension)
- Temporal cortex = memories of objects, faces, et.
What is the function of the hippocampus and where is it located?
- Responsible for “amplifying information” to learn and store new memories
- Located in the medial temporal lobe
What are the two types of memory systems present in our brains?
- Declarative Memory
- Nondeclarative Memory
What is declarative memory and how is it sent through the brain?
HIGH yield
- Anything you can describe to someone in words
- Projections from the hippocampus are sent to varying cortical/sensory regions associated w/ specific memories ( i.e. auditory cortex for auditory memories)
What is Nondeclarative memory (4)?
Motor learning, habits, bias and prejudice
What brain structures are used for long-term memory of declarative information?
A variety of cortical sites (e.g. Wernicke’s area for the meaning of words, temporal cortex for the memories of objects and faces, etc.)
What brain structures are used for short-term memory of declarative information?
hippocampus and related structures
What brain structures (4) are used for Long-term storage of Nondeclarative information?
Low yield
- cerebellum
- basal ganglia
- premotor cortex
- other sites related to motor behavior
What brain structures are used for Short-term memory of Nondeclarative storage?
Low yield
sites unknown but presumbly widespread
What does damage to the hippocampus lead to?
Deficits in memory formation
Explain the hippocampus cortical interactions
Declarative information no matter the sensory system it is coming from, will go back to the hippocampus where it will be “amplified” and made into memory and stored back into the cortices (initial site of processing)
What is Long Term Potentiation (LTP)?
A process involving persistent strengthing of synapses that lead to a long-lasting increase in signal transmission between neurons
What are the key receptors that are needed for memory formation?
Glutamate Receptors
- AMPA receptors- Activated by glutamate, moves Na+ into the neuron
- NMDA receptors (silent activators)- Mg2+ blocks channel so it can NOT be activated by glutamate
What structure in the limbic system plays a role in emotion?
Amygdala
Explain the location and function of the amygdala
- A bilateral structure from the medial temporal lobe
- Main function: Related to emotion, particularly in the processing of aversive information
- Other roles
1. Associating emotions with memories
2. Activation associated w/the presence of pheromones (i.e. sexual attraction)
The Circuit of the Amygdala
What is the main learning and emotional control center of the amygdala?
Basal-lateral nuclei
Explain the pathway from the amygdala to the prefrontal cortex
- The basal-lateral nuclei of the amygdala connect to various reward areas (i.e. ventral basal ganglia) into the mediodorsal nucleus of the thalamus
- From the thalamus information is sent to the orbital and medial prefrontal cortex
Review Slide 16
The circuit between the prefrontal cortex and amygdala is an essential factor in diagnosing depression. Explain what is seen in a healthy individual vs a depressed individual.
- Healthy Individual: Lots of inhibition from the PFC to amygdala (b/c the amygdala tends to mediate negative emotion)
- Depressive Individual: Inhibition is less b/w PFC and amygdala. Low activity of PFC, high activity of amygdala
Explain the connection between the amygdala and the hippocampus and how it affects learning.
- Amygdala connects directly to the hippocampus to enhance our learning process
- Emotionally relevant info is much easier to remember than neutral stimuli
- Amgydala directs its own boost to the hippocampus if the stimuli has some kind of emotinal component (doubling up on activation)
Explain the Judgement of Trustworthiness
Example of Amygdala Activation
The amygdala is activated by potentially negative stimuli (i.e. untrustworthy person) regardless of whether you’re conscious of the stimulus or not (explicit vs implicit)
Review Slide 18
What other circuits are affected by mood disorders (e.g. depression, bipolar, post-partum, etc)?
- Mediodorsal nucleus of the thalamus
- Orbital and medial prefrontal cortex
The __________ is a major output pathway of the limbic system.
Hypothalamus
What are some functions of the hypothalamus (4)?
- Autonomic Motor Function→”Fight of Flight”
- drive toward reward pathways
- hunger pathways
- Mediates a lot of behavioral responses to emotional and memory cues
Explain the mechanism of the Sham Rage Experiments and what was discovered by the results.
Sham Rage Experiment
- Done on cats who expressed aggressive responses in absense of stimuli
- Two lesions were performed with different outcomes:
1. Lesion posterior to hypothalamus→connection to brainstem and body LOST→Sham rage LOST
2. Lesion through the hypothalamus→connection to brainstem and body INTACT→Sham rage INTACT - These results illustrate that the hypothalamus is the relay station sending averse stimuli to the rest of the body to elicit a response
What is the function of the Prefrontal cortex and Cingulate gyrus (cortical areas)?
Provide executive (aka top-down) control but also process emotions
_______ is strongest for the emotion of disgust
Localization
When is the insular cortex strongly activated?
during exposure to stimuli perceived as “disgusting”
Also the primary taste cortex
The insular cortex reacts to ______ stimuli and is _____ in drug addiction so not completely dedicated to disgust.
- frightening
- active
The ______ hemisphere seems to be more responsive to emotional stimuli than the ______.
- right
- left
Ex. Asymmetrical smiles
What is the result of damage to the right temporal cortex?
difficultly identifying emotions of others (facial expressions)
What is the result of damage to the left temporal cortex?
unable to recognize who people are