[MOD15C - ANATOMY] Olfaction and Limbic System_2028

What is induced from lesions in the lateral amygdala?

Unrestrained eating (bulimia)

What is induced from lesions in the medial amygdala?

Anorexia, accompanied by hypersexuality

Electrical stimulation of the amygdala in humans may produce _

fear, anxiety, or rage and aggression

Performed to suppress these antisocial traits in patients, and has sometimes been followed by hypersexuality

Amygdalectomy

Three type of memory

immediate recall, short-term memory, and long-term memory

Involved in converting short-term memory (up to 60 minutes) to long-term memory (several days or more)

hippocampus

Patients with bilateral damage to the hippocampus and bilateral interruption of the fornices (e.g, by removal of a colloid cyst at the interventricular foramen) can demonstrate _, in which no new long-term memories can be established

anterograde amnesia

A process whereby synaptic strength is increased when specific efferent inputs to the hippocampus are excited in a paired manner

long-term potentiation

Encodes spatial memory in the hippocampus for navigation and spatial problem-solving

place cells

This refers to the production of new neurosis and it continues to occur throughout adulthood in the dentate gyrus

Neurogenesis

True or False: There is a reduced rate of neurogenesis in the dentate gyrus in association with depression; while there is an increase in neurogenesis with use antidepressant medications (such as selective serotonin reuptake inhibitors, or SSRIs)

TRUE

This disturbance of the limbic system activity occurs in patients with bilateral temporal lobe lesions

Kluver-Bucy Syndrome

Results from damage to the amygdala when visual stimuli can no longer be paired with affective (pleasurable or unpleasant responses); Objects are no longer visually recognizable

Psychic blindness/Visual agnosia

May include abnormal sensations, especially bizarre olfactory sensations, sometimes called uncinate fits, as well as repeated involuntary movements such as chewing, swallowing, and lip smacking; disorders of consciousness; memory loss; hallucinations; and disorders of recall and recognition

Temporal lobe epilepsy

Seizure control for Temporal lobe epilepsy

neurosurgical removal of the seizure focused in the temporal lobe

Carries out basic survival functions that include feeding behavior, "Fight-or-flight" responses, aggression, expressions of emotion and of the autonomic, behavioral, and endocrine aspects of the sexual response

Limbic system

What are the three main components of the limbic system from oldest to newest (phylogenetically)?

1. Hippocampal formation (archicortex)

2. Limbic lobe (mesocortex)

3. Neocortex (isocortex)

What is the main input to the dentate gyrus?

Entorhinal cortex via the perforant pathway.

Name five output targets of the hippocampus

Mammillary bodies, anterior thalamus, septal area, tuber cinereum (via fornix), and subcallosal area (via longitudinal striae).

List three input sources to the septal area.

Olfactory bulb, amygdala, and fornix.

Name other output targets of the amygdala aside from the hypothalamus

Septal area

Why is the limbic lobe called "limbic"?

Because it forms a "limbus" or border between the diencephalon and the neocortex of the telencephalon.

Which gyri make up the limbic lobe?

Subcallosal gyrus, cingulate gyrus, and parahippocampal gyrus.

True or False: The fornix and medial forebrain bundle are considered components of the limbic system.

TRUE

True or False: The amygdala lies in the lateral temporal pole of the brain.

False - It lies in the medial temporal pole.

True or False: The basolateral nuclear group of the amygdala receives higher-order sensory information from association cortices.

TRUE

True or False: The corticomedial group is located near the visual cortex.

False - It is located near the olfactory cortex.

True or False: Activity in the amygdala increases during states of apprehension, such as in response to frightening stimuli.

TRUE

True or False: The stria terminalis courses along the lateral horn of the lateral ventricle.

False - It courses along the inferior horn and body of the lateral ventricle.

What is the gray matter structure in the medial temporal lobe involved in emotion and sensory association.

Amygdala

What is the nuclear group in the amygdala that is strongly associated with olfactory connections.

Corticomedial nuclear group

What is the limbic structure that animals will self-stimulate for pleasurable sensations.

Septal area

What is the pathway that carries amygdala fibers to the septal area and hypothalamus.

Stria terminalis

What is the pathway that directly connects the amygdala to the hypothalamus.

Amygdalofugal pathway

What are the two main nuclear groups of the amygdala:

Basolateral nuclear group and Corticomedial nuclear group

Enumerate at least three functions associated with the amygdala's influence on the hypothalamus:

1. Regulation of endocrine activity

2. Modulation of sexual behavior

3. Control of food and water intake

The amygdala is situated just anterior to the tip of the __________ horn of the lateral ventricle.

Anterior

The basolateral nuclear group is primarily involved in processing higher-order __________ information.

Sensory

The corticomedial group is interconnected with the __________ bulb and olfactory cortex.

Olfactory

The limbic system influences both somatic motor and __________ responses, including cardiovascular changes.

Autonomic

The septal area receives afferent input from both the olfactory system and the __________ system.

Limbic

What is the limbic pathway that some fibers of the amygdala cross to reach the opposite amygdala.

Anterior Commissure

Stimulation of the limbic system can lead to bizarre eating and drinking habits, as well as changes in __________ and grooming behavior.

Sexual

What are the two brainstem or midbrain areas influenced by the limbic system via efferent fibers from the septal area?

Hypothalamus and Epithalamus

What are specialized neurons in the olfactory mucous membranes that respond to depolarizations when confronted with odor-producing molecules?

olfactory receptor neurons (ORNs)

How many odorant receptor genes are there?

1000 odorant receptor genes

True or false: Each olfactory receptor expresses only one or few and thus responds to only one or a few odoriferous molecules.

TRUE

Which glands are responsible for producing the mucus that covers the olfactory receptors?

Bowman's glands

Which enzyme generates cyclic adenosine monophosphate (cAMP) when the G-protein is activated by the binding of specific odoriferous molecule to the appropriate olfactory receptor?

Adenylate cyclase

What structures carry the axons of olfactory receptors to the olfactory bulb?

Olfactory nerves (10-15 in number)

Through which structure do the olfactory nerves pass to reach the olfactory bulb?

Cribriform plate

Where is the olfactory bulb located in the brain?

In the olfactory sulcus on the orbital surface of the frontal lobe

Where does the olfactory tract divide into as it passes posteriorly?

Lateral olfactory striae and medial olfactory striae

What type of cells receive input from olfactory receptor axons in the olfactory bulb?

Mitral cells

What is the specialized synaptic arrangement where the olfactory axons terminate called?

Glomeruli

Which component of the primary olfactory pathway sends their axons posteriorly via the olfactory tracts to reach the olfactory projection area in the cortex

Mitral cells

Which component of the primary olfactory pathway is a fiber bundle that projects laterally along the floor of the lateral fissure and enters the olfactory projection area?

Lateral olfactory stria

Which component of the primary olfactory pathway passes medially and ascends toward the subcallosal gyrus near the inferior part of the corpus callosum to carry the axons of some mitral cells to the anterior olfactory nucleus?

Medial olfactory stria

Which component of the primary olfactory pathway sends its axons back to the olfactory bulbs on both sides, presumably as part of a feedback circuit that modulates the sensitivity of olfactory sensation?

Anterior olfactory nucleus

Which component of the primary olfactory pathway is a thin of gray matter with many openings that permit the small lenticulostriate arteries to enter the brain?

Anterior perforated substance

Which component of the primary olfactory pathway serves a role in olfactory reflex reactions together with the medial stria?

Anterior perforated substance

Provides an antomic substrate for the convergence of cognitive activities, emotional experience, and expression

Papez Circuit

The portion of gray matter that covers the inferior aspect of the rostrum of the corpus callosum

Subcallosal gyrus

A thin layer of gray matter that extends from the subcallosal gyrus and covers the upper surface of the corpus callosum

Supracallosal gyrus or Indusium griseum

Delicate strands that extend along the upper surface of the corpus callosum to and from the hippocampal formation

Medial and Lateral longitudinal striae

Band-like tract of white fibers that crosses the midline to join both cerebral hemispheres

Anterior commisure

Joins both anterior olfactory nuclei near the olfactory bulbs

Interbulbar system

Connects the temporal lobe areas of both cerebral hemispheres

Intertemporal system

True or False: Septal area is an area of gray matter lying superior to the lamina terminalis and inferior to the rostrum of the corpus callosum

TRUE

Pleasue center in the brain

Septal nuclei

Double sheet of gray matter below the genu of the corpus callosum

Septum lucidum

What is the primitive cortical structure that is folded and rolled up, submerged deep into the parahippocampal gyrus?

Hippocampal formation

Name the gyrus that serves as the input station for the hippocampal formation.

Dentate gyrus

What is the major outflow tract from the hippocampus?

Fornix

Identify the white layer on the ventricular surface of the hippocampus that contains fibers from the dentate gyrus and hippocampus.

Alveus

What is the name of the structure that connects the 2 crura of the fornix

Hippocampal commissure

The _______ gyrus is the gray matter on top of the corpus callosum, also known as the indusium griseum.

Supracallosal

The _______ pathway relays input from the entorhinal cortex to the dentate gyrus.

Perforant

The _______ is a primitive precommissural area that is part of the hippocampal formation.

Septal area

The _______ of the dentate gyrus send axons (mossy fibers) that terminate on pyramidal neurons in the CA4 region of the hippocampus.

Granule cells

The _______ is the transitional cortex from the archicortex of the hippocampal formation to the six-layered neocortex.

Subiculum