BCSC 240 Basic Neurobiology Exam 1 - Structure-Function

What are the major divisions of the brain?

Telencephalon, Diencephalon, Mesencephalon, Metencephalon, Myelencephalon

Which major division(s) of the brain is the cerebrum found in?

Telencephalon

Which major division(s) of the brain is the cerebellum found in?

Metencephalon

Which major divison(s) of the brain is the brain stem found in?

Diencephalon, Mesencephalon, Metencephalon, Myelencenphalon

What does the telecenphalon (cerebrum) surround?

Paired lateral ventricles

What does the diencephalon surround?

The third ventricle

The cerebrum is comprised of what main areas?

• Outer area of neural cell bodies (called gray matter or cerebral cortex)

• Inner area of myelinated axons (called white matter)

• Subcortical areas of gray matter (gray matter floating in the white matter)

What is the neocortex

Many areas of the cerebral cortex that are organized in a similar manner. It is six layers deep and 2-4 mm thick

What is the main function of layer 1 in the neocortex?

Synaptic integration - local processing

What is the main function of layers 2-3 in the neocortex (they do the same thing)?

input/output to other cortical areas

• Both layers 2 and 3 comprise of this

What is the main function of layer 4 in the neocortex?

Input from the thalamus - gateway to the cortex

What is the main function of layer 5 in the neocortex?

Output to the brainstem/spinal cord

What is the main function of layer 6 in the neocortex?

Output to the thalamus - feedback back to the thalamus

What is the majority of cells in the cortex comprised of?

Pyramidal cells (projection cells), elongated

What is the role of stellate cells in the neocortex?

They provide the local structural organization since they are circular and not very long

What is the role of pyramidal cells in the neocortex?

They span across all layers and often serve as communicators between different layers. The axons of pyramidal cells also leave the column

What is the significance that Brodmann contributed to the neocortex?

This person came up with upwards of 50 distinct regions of the neocortex. He observed that distinct regions have different thickness and structure and therefore serve a different function

What of Brodmann’s areas are we supposed to memorize?

• Sensory (5)

  • 1-3: Primary Somatosensory

  • 17: Primary Visual

  • 34: Part of primary olfactory (most olfactory cortex is not neocortex)

  • 41-42: Primary Auditory

  • 43: Primary Taste (gustatory)

• Motor (2)

  • 4: Primary Motor

  • 6: Supplementary motor

• Association (2)

  • 39-40: Language Comprehension (Wernicke’s Area)

  • 44-45: Speech Production (Broca’s Area)

What is white matter and what are their primary function?

White matter is composed of bundles of myelinated nerve cell axons that serve to connect various gray matter areas of the CNS to each other

List the white matter fiber tracts?

Association, Commissural, Projection

What is the main role of the Association white matter fiber tract?

Connects gyri in the same hemisphere together

What is the main role of the Commissural white matter fiber tract?

Connect corresponding gyri in opposite hemispheres

What is the main role of the Projection white matter fiber tract?

Connect cerebrum with other parts of brain and spinal cord

Within the Association white matter fiber tract are what main types of tracts?

• Arcuate (short) fibers:

  • connects Primary Somatosensory with Primary Motor

• Fascicules (long) fibers:

  • connect Wernicke’s and Broca’s areas

What are important structures that are related to the Commissural white matter tracks?

Corpus Callosum and anterior

• Commissural fibers serve to connect like things to the opposite side

What are important structures that are related to the Projection white matter tracks?

• Corona Radiata

  • Kinda grabbing everything (includes everything else)

• Internal capsule

  • Sensory input from thalamus

  • motor output to spinal cord

What are subcortical areas?

Areas and structures underneath the cerebral cortex

What are the main groups of the subcortical areas?

Roughly going from anterior to posterior

• Basal forebrain

• Basal ganglia

• Limbic system

  • Amygdala - emotions

  • Hippocampus - memory and learning

What is the basal forebrain?

The basal forebrain is a subcortical structure that is composed of many structures

What two main things are comprised of the basal forebrain?

the nucleus accumbens and the nucleus basalis

What is the role of the nucleus accumbens?

Cognitive processing of motivation and reward learning, and in addiction

What is the role of the nucleus basalis?

Primarily involved in the sleep-wake cycle and learning and memory (undergoes damage when someone has Alzheimer’s disease

What is the basal ganglia and its primary function?

The basal ganglia is a subcortical structure that is composed to many things. Its main role is in the selection of which several motor actions to execute at any given time. Damage to the basal ganglia can lead to Parkinson’s or Huntington’s disease

What are the main structures of the basal ganglia?

• Striatum (caudate and putamen put together)

• Globus Pallidus

• Subthalamus (diencephalon)

• Substantial Nigra (mesencephalon)

What is the limbic system?

A set of brain structures that are located in the subcortical areas

What main structures are in the limbic system?

• Hippocampus

  • learning and memory

• Amygdala

  • processing emotions

What main structures are composed of the diencephalon?

• Thalamus (most important)

  • Largest structure

• Hypothalamus (most important)

• Epithalamus

  • Pineal gland

• Subthalamus

What is the main role of the thalamus? (Diencephalon)

The thalamus is known as the gateway to the cortex and serves to communicate with the cortex to accomplish many goals.

• It also processes/relays somatic system information to the cerebral cortex

• Sleep/wake states

• Consciousness

If sending information up to the cerebral cortex, it must past through the thalamus. Going down does not need to pass through the thalamus

What distinct components are part of the thalamus? (Diencephalon)

• Medial Geniculate Body (MGB)

• Lateral Geniculate Body (LGB)

• Ventral Posterolateral Nucleus (VPN)

• Ventral Lateral Nucleus (VLN)

• Ventral Anterior Nucleus (VAN)

What is the Medial Geniculate Body (MGN) known for? (Diencephalon)

Ascending auditory system

What is the Lateral Geniculate Body (LGN) known for? (Diencephalon)

Receives Retina Information (Visual System)

What is the Ventral Posterolateral Nucleus (VPN) known for? (Diencephalon)

Somotasensory system: touch, skin (post central gyrus)

What is the Ventral Lateral Nucleus (VLN) known for? (Diencephalon)

This component is used when the cerebellum wants to talk to the primary motor complex

What is the Ventral Anterior Nucleus (VAN) known for? (Diencephalon)

This component is know for aiding the secondary motor complex and helping the basal ganglia with motor selection and motor decision

What are the main functions of the hypothalamus? (Diencephalon)

• Motivates the search for food, drink, sleep, temperature, mates

• Controls activities of the autonomic nervous system

  • Heart rate, blood pressure, breath rate

• Links the nervous system to the endocrine system by synthesizing and secreting hormones (some into systemic circulation, others to stimulate/inhibit secretion of hormones from the pituitary)

What are the main components of the mesencephalon?

• The tectum (roof) is the dorsal surface

• The tegmentum (floor) is ventral to the tectum

  • Also called the cerebral peduncles

What initiates the division of the forebrain into two separate hemispheres?

The tegmentum (also called the cerebral peduncles)

What are the main parts of the tectum? (Mesencephalon)

Colliculi

• Superior colliculi

• Inferior colliculi

What is the main role of the superior colliculi? (Mesencephalon)

The superior colliculi has a visual-motor function that specifically directs the body’s orientation towards or away from a visual stimulus

What is the main role of the inferior colliculi? (Mesencephalon)

The inferior colliculi are part of the auditory system (sends output to MGB of thalamus). Part of the ascending auditory system.

• Inferior colliculi —→ MGM —-→ Gyrus

What are the main parts of the tegmentum? (Mesencephalon)

• 3 colorful nuclei:

  • periaqueductal gray (cell bodies)

  • red nucleus

  • substantia nigra

• 2 major fiber tracts:

  • Medial lemniscus

  • Pyramidal tract

What are colorful nuclei in the tegmentum? (Mesencephalon)

• Periquadecutal gray (cell bodies)

• Red nucleus (iron)

• Substantia nigra (melanin)

What is the main function of the periaqueductal gray? (Mesencephalon)

Pain modulation, defensive behavior

What is the main function of the red nucleus? (Mesencephalon)

Motor coordination: it is where cerebellum sends output, where it tries to fix the problem

What is the main function of the substantia nigra? (Mesencephalon)

Movement selection (part of basal ganglia)

What is the primary function of the Medial Lemniscus major fiber tract? (Mesencephalon)

This fiber tract serves the somatosensory fibers ascending to VPN of thalamus

What is the primary function of the Pyramidal major fiber tract? (Mesencephalon)

This fiber tract serves the motor axons from primary motor cortex descending towards spinal cord

• Interacts with layer 5 of the neocortex

• Not seen in the thalamus

• Mainly uses pyramidal cells

What are the main structures of the Metencephalon?

• The Pons

• The Cerebellum

Where are the pons located? (Metencephalon)

The pones is part of the brain stem, and in humans lies between the medulla oblongata (below) and the midbrain (above) and in front of the cerebellum

What are the main component of the pons?

• Dorsal pons

• Ventral pons

What are the main functions of the dorsal pons?

The dorsal pons contains the nuclei for four cranial nerves (V-VIII), which serve both sensory and motor functions. Cranial five is the most important

What are the main roles of the ventral pons?

The ventral pons contains pontine nuclei scattered among, and receiving input from, the descending fibers of the pyramidal tract. The pontine nuclei then project their axons into the cerebellum via the middle cerebellar peduncle

• The primary motor cortex moves down. This relays the neurons which goes into the cerebellum