3 - Integrated Systems: Limbic System

Question 1

Four major functions of Limbic System?

Answer 1

HOME

H - Homeostasis (hypothalamus)

O - Olfaction (olfactory cortex)

M - Memory (hippocampal formation)

E - Emotion and Drive (amygdala)

Question 2

What areas does the hippocampus receive direct input from?

Answer 2

1. Cingulate Gyrus
2. Amygdala
3. Septal Nuclei
4. Hypothalamus

Question 3

Corticolimbic Areas: Insular Cortex

Answer 3

Buried within the Sylvian Fissure

Involved in empathy

Can be affected in Autism Spectrum Disorder

Question 4

Corticolimbic Areas: Orbitofrontal Association Cortex

Answer 4

Integration of personality and emotional behavior

Conscious perception of smell

Question 5

Corticolimbic Areas: Prefrontal Association Cortex

Answer 5

Involved in executive function, memory, and risk taking

Internal cognition, self-referential processes–more activity in this area when at rest

Question 6

Cingulate Gyrus

Answer 6

Surrounds corpus callosum

Integration of emotion, pain, and memory

Dysfunction: Pain, Social inderrence

Impacted rgreating in Alzheimer’s Disease

Question 7

Parahippocampal Gyrus

Answer 7

Part of telencephalon

Entorhinal cortex, Hippocampal Formation

Major efferents and afferents with the polymodal association cortex

Learning and Memory Process

Question 8

Entorhinal Cortex (Area 28)

Clinical?

Answer 8

Anterior portion of the parahippocampal gyrus

Major relay hub between the association cortex and hippocampal formation

***The first cortical area to degenerate in Alzheimers***

Question 9

Hippocampal Formation

Answer 9

Adj. to temporal horn of the lateral ventricle

Ouput: Fornix

Function: Regulates memory encoding; storing and processing spatial information, formation of episodic memory

Question 10

Fornix (Meaning Arch)

Answer 10

Travels inferior to the corpus callosum

Major Output

Projects to: Mammillary Bodies, Anterior Thalamic Nucleus, Septal Nuclei

**Connects Hippocampus to Mammillary Body**

Question 11

Papez Circuit

Answer 11

Limbic Circuit (Loop)

Play role in memory

Question 12

Septal Nuclei location

Answer 12

***ADD PICTURE***

Question 13

Septal Nuclei input?

Answer 13

Ventral Tegmental Area

Hippocampal Formation

Amygdala

Hypothalamus

Question 14

Amygdala

Answer 14

Corticoid Structure

3 Sets of Nuclei: Basolateral, Corticomedial, Central

Input: Highly processed sensory stimuli, Autonomic Input

*Direct olfactory information

Combines emotional interpretation of environmental with internal stimuli relating fear and anger; recall emotional content

Fight or Flight, Mood, Emotion

Question 15

Brainstem Nuclei

Answer 15

Interpeduncular

Superior Central

Dorsal Tegmental

Ventral Tegmental Nucleus (VTA) - Reward system

Reticular FOrmation

Question 16

Basal Ganglia Limbic Loop

Answer 16

Regulation of emotion and motivational drive; central role in many neurobehavioral and psychiatric disorders

Question 17

Medial Diencephalic Structure (MDS)

Medial Temporal Lobe Structures (MTLS)

Clinical: Bilateral Damage

Answer 17

Consists of the anterior nuclei, the mediodorsal nucleus of the thalamus and the mammillary bodies of hypothalamus

Reciprocal connectiosn b/t the multimodal association, entohinal cortex, and hippocampal formation

Critical for Memory Processes

Damage to either results in loss of declarative or explicit memory; anterograde amnesia, forgetting daily events which involve conscious recollection, inabiliy to make NEW memories

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Question 18

Clinical Correlate: HM

Answer 18

Medial Temporal Lobe (MTL) Resection

Anterograd amnesia

Question 19

Clinical: Kluver-Bucy Syndrome

Answer 19

Ablation of anterior temporal lobes (amygdala, hippocampal formations, anterior temporal cortex)

Surgery for epilepsy, viral encephalitis can also destroy

Symptoms:

Hypersexuality, Hyperphagia (eating), Loss of fear and reduced anger/aggression, dementia like symptoms

Question 20

Clinical: Amygdala Hyperactivation

Hormone release?

Therapy?

Answer 20

Anxiety, Panic Attacks, PTSD, OCD

Chronic activation of HPA axis increases cortisol release; impaired learning and memory, decrease neurogenesis

Cognitive Behavioral Therapies work to increase prefrontal control dampening amygdala activation

Question 21

Clinical: Hippocampus Hypoxia

Major Blood Supply

Answer 21

Posterior Cerebral Artery supplies MTLS / MDS

Stroke here can result in memory loss

Bilateral infarction of the superior portion of the basilar artery can cause memory loss

Question 22

Clinical: Contusion / Concussion

Answer 22

Concussion memory loss can be temporary

Contusion more likely to cause permanent damage and possibly seizure activiyt

Question 23

Clinical: Seizures

Answer 23

Often originate from hippocampal formation

Can induce memory loss following events

Severe seizure activity can result in Hippocampal clerosis (Asrocytic Scar Formation); memory loss can persist during seizure free episodes

Question 24

Clinical: Wenicke Korsakoff

Answer 24

Degeneration of MDS / MTLS

Anterograde and Retrograde Amnesia, impulse control, and confabulation (patients provide random answers to questions w/out conscious attempt to deceive)

Question 25

Clinical: What do psychiatric disorders such as Schizophrenia, PTSD, Anxiety, Depression, and Bipolar disorder have in common?

Answer 25

Can reduce brain volume and impair memory

Some drugs can worsen conditions

Question 26

Clinical: Electroconvulsive Therapy (ECT)

Answer 26

Short seizure induced under anesthesia

Can cause amnesia which usually resolves

Can be lifechanging/saving for some patients

Question 27

Clinical: Deep Brain Stimulation (DBS)

Answer 27

Electrodes in brain

Question 28

Clinical: Wernick-Korsakoff classic triad?

Answer 28

Ataxia

Nystagmus

Altered mental status