what is “Le Grade Lobe Limbique”?
the initial components of the limbic lobe for emotions
-cortical area forming rim around diencephalon on medial surface of brain (cingulate cortex, parahippocampal gyrus, olfactory cortex)
what did the Papez circuit hypothesize?
hippocampus is connected to mammillary bodies (hypothalamus) to the anterior nucleus of the thalamus to the cingulate cortex to the hippocampus (and neocortex)
-proven via rabies spread synaptically
does NOT include amygdala
what is the Kluever-Bucy experiment?
removing temporal lobes of aggressive monkeys caused them to become docile, over-eat, eat inappropriate things, hyperoral, hypersexual
-originally agreed with Papez, but then disproved b/c could recapitulate symptoms by removing/damaging amygdala
what are the limbic system and downstream targets known today?
- anterior and mid-cingulate cortex (ACC and MCC)
- amygdala
- hypothalamus
- periaqueductal gray (PAG) matter
- autonomic nervous system
- dorsal raphe nucleus (DRN; serotonin) and locus coeruleus (LC; norepinephrine)
what does the anterior cingulate cortex do?
- store emotional/valenced (emotional weight)information
- recode amygdala (so no primary fear response)
what does the mid-cingulate cortex do?
- select responses (mental or motor)
- predict outcomes and resolve ambiguity
- improvise new behaviors for new problems
what does the amygdala do?
- invests sensory experience with emotional significance (valence)
- most prominently involved in fear
what does the hypothalamus do?
autonomic/hormonal control
what does the periaqueductal gray do?
coordinate autonomic/skeletal behaviors
-surrounds aqueduct in midbrain between 3rd and 4th ventricles
what does the autonomic nervous system do?
skeletal motor output and memory enhancement
what does the locus coeruleus do?
- coordinates responses for fight/flight
- enhances storage of emotional memories
what does the dorsal raphe nucleus do?
regulate mood
what is “emotion”, and the difference between primary and secondary emotions? what are brain structures involved?
emotion = weighting (valencing) object and events with positive or negative responses
primary = reflexive emotions (implicit, don’t need to think about it); linked with autonomic reflexes
- fear is most well-studied
- amygdala, hypothalamus, PAG
secondary = conscious emotions; object and context-dependent
-cortical limbic structures
what mediates the fear response in the amygdala?
the basal-lateral nucleus connects to the central nucleus
what happened to SM, the patient with Urbach-Wiethe disease?
loss of amygdalas bilaterally (due to calcification), but hippocampus intact
- inability to experience fear or recognize fear in faces
- -excessive risk taking, odd relations and financial decisions
- no motor or sensory defects; no intelligence, memory, or language deficits
why would the fear response be intact if the connection between the auditory cortex and amygdala was cut?
amygdala gets input from both auditory cortex (which gets it from medial geniculate nucleus), and directly from MGN
-since the thalamic message has no cortical processing, thus dominating initial primary response to fear
steps in how amygdala is involved in fear perceptions, ANS responses, and memory
- fear-invoking stimulus from any sensory modality (visual, auditory, touch, etc.)
- stimulus is perceived
- input goes directly from LGN to amygdala (and visual cortex), activating fear response
- activates both cortex and output pathways - expression of fear somatic and viscerally (fight or flight response)
- memory gets encoded in amygdala and cortex
- memory is dramatically enhanced in presence of NE for LC
what does electrical stimulation of PAG (or hypothalamic nuclei that project to it) do? how are responses organized? does it have memory?
evoke complex and fully integrated behaviors
- stimulating different parts of PAG makes different classes of behaviors
- responses are organized by PAG projections into different parts of ANS and skeletomotor systems to produce fully coordinated outputs
- PAG has no memory, since it’s controlled by higher brain regions
what would tumors to the lateral hypothalamus cause emotion-wise?
affective defense is projected to PAG
what would tumors to the ventral medial hypothalamus cause emotion-wise?
quiet biting/quiescence is projected to PAG
what is sham rage and how is it produced?
fully integrated rage w/o external control
-can be produced by stroke/tumors to hypothalamus/PAG
how does the PAG regulate ANS?
projections to the nucleus of solitary tract, dorsal motor nucleus of vagus, and intermediolateral nucleus
-circuit produces ANS sensory input during arousal via somatic markers
what is the HPAA?
hypothalmic control of hormone response via pituitary, adrenals, and amygdala
what does amgydala and limbic cortex do in HPAA?
drives PVN of hypothalamus to secrete CRH into portal veins
- evokes release of ACTH from pituitary to evoke release of cortisol from adrenal cortex
- cortisol binds glucocorticoid receptors to
- -increase glucose levels/metabolism
- -increase AA metabolism
- -increase fat breakdown
- -increase memory
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Unit 1 - Introduction to Neuroscience18
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Unit 1 - Early Development of Nervous System42
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Unit 1 - Axonal Growth, Synaptogenesis, and Tropism37
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Week 1 - Channels and Transporters36
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Week 1 - CNS Neurotransmitters66
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Week 1 - Synaptic Transmission26
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Week 1 - Role of ion channels in epilepsy31
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Lab - External Anatomy and Blood Supply of the Brain73
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Week 1 - Cellular mechanisms of learning and memory34
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Week 1 - Memory Disorders19
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Week 1 - Olfaction and Taste35
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Week 1 - Brain Imaging35
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Lab 2 - Internal Anatomy of the Brain and Ventricles45
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Week 2 - Early Recognition of Stroke24
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Case Study Notes70
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Brain MRI5
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Week 2 - Retinal Phototransduction and Signal Processing84
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Week 2 - Perimetry and Clinical Correlation of Visual Field Defects48
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Lab 3 - Sensory and Motor Circuits69
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Week 2 - Central Visual Processing I43
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Week 2 - Visual Development and Neural Plasticity25
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Week 2 - Somesthesis30
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Week 3 - Nociception35
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Week 3 - Limbic Systems45
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Week 3 - The Medial Pain System and Limbic-Motor Interactions25
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Lab 4 - Internal Anatomy of the Spinal Cord and Peripheral Nerves45
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Week 3 - Spinal Cord and Movement Control: Motor Unit and Spinal Reflexes22
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Week 3 - Spinal Reflexes and Electromyogram21
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Week 3 - Spinal Cord Injuries22
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Week 3 - Nerve Regeneration and Repair23
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Week 4 - Upper Motor Neurons and Cortical Control of Movement39
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Week 4 - The Basal Ganglia and Movement Disorders43
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Week 4 - The Cerebellum38
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Week 4 - Vestibular Function18
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Week 4 - Audition33
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Week 4 - Clinical Correlation: Coma11
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Week 4 - Oculomotor and Motor Learning19
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Week 4 - Chronobiology56
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Week 4 - Association Cortex66
