BIOPSYCH: Major structures of the brain

Nucleus

Cluster of neurons in the central nervous system

Tracts

Bundle of nerve fibers (axons)

Peduncle

Stem-like connector

Gyrus

A ridge on the cerebral cortex

1. Forebrain
2. Midbrain
3. Hindbrain

Main divisions of the brain

1. Prosencephalon (Forward brain)
2. Diencephalon (Between-brain)
3. Telencephalon (End-brain)

What consists the forebrain?

Mesencephalon (Middle brain)

What consists the midbrain?

1. Rhombencephalon (Parallelogram-brain)
2.Metencepalon (Afterbrain)
3. Myelencephalon (Marrow-brain)

What consists the hindbrain?

Thalamus, hypothalamus

What are the major structures of diencephalon?

Cerebral cortex, hippocampus, basal ganglia

What are the major structures of telencephalon?

Tectum, tegmentum, superior colliculus, inferior colliculus, substantia nigra

What are the major structures of mesencephalon?

Hindbrain

- Both the myelencephalon and the metencephalon form the hindbrain
- Consists of the medulla, pons, and cerebellum
- Located at the posterior portion of the brain

Brainstem

It is made up by the hindbrain structures, the midbrain and other central structures of the brain

Myelencephalon

- Sometimes called the medulla or medulla oblongata
- Basic life support
- Situation between the pons and the brainstem
- Composed largely of tracts carrying signals between the rest of the brain and the body
- Contains the reticular formation

Reticular formation

Plays a role in arousal, attention, movement, maintenance of muscle tone, various cardiac, respiratory, and circulatory reflexes

1. Parvocellular Reticular nuclei (Lateral zone)
2. Gigantocellular reticular nuclei (Medial zone)
3. Raphe nuclei (Median)
4. Somatic motor control

Division of the reticular formation

Parvocellular Reticular nuclei (Lateral zone)

Division of the reticular formation that regulate exhalation

Gigantocellular reticular nuclei (Medial zone)

Division of the reticular formation that is responsible for motor coordination

Raphe nuclei (Median)

Division of the reticular formation where serotonin (5-HT) is synthesized which affects mood regulation

Somatic motor control

Division of the reticular formation that is responsible for tone, balance, and posture during body movements.

Relays eye and ear signals to the cerebellum so that the cerebellum can integrate visual, auditory and motor coordination

Medullary pyramids

Bundle of fibers (Pyramid tracts) that decussate and continue down the spinal cord on the contralateral side

1. Corticospinal tract
2. Corticobulbar tract

Two kinds of pyramidal tracts

Olivary bodies

- Medullary olives or Olives
- Pair of prominent oval structures that contain the olivary nuclei

Cerebral

Learning

Cerebellar

Learned/Muscle memory

1. Inferior Olivary nucleus
2. Superior Olivary nucleus

What consists olivary bodies?

Inferior Olivary nucleus

Part of the olivo-cerebellar system and is mainly involved in cerebellar motor-learning and function

Superior Olivary nucleus

Part of the pons and part of the auditory system, aiding in the perception of sound

Metencephalon

Houses many ascending and descending tracts and parts of the reticular formation

Bridge

What does Latin pons mean?

Pons

- Regulation of breathing (pneumotaxic center) and involved in the transmission of to and from other areas of the brain (Cerebrum to the cerebellum)
- Lies on each side of the medulla (ventral and anterior)
- Along with the medulla, contains the reticular formation and raphe system

1. Descending portion
2. Ascending portion

Portions of the reticular formation

Descending portion

Portion of the reticular formation that control the motor areas of the spinal cord

Ascending portion

Portion of the reticular formation that sends output to much of the cerebral cortex and selectively increasing arousal and attention

Raphe system

Sends axons to much of the forebrain, modifying the brain's readiness to respond to stimuli

Cerebellum

- Coordinate muscle movements, posture, and integrate sensory formation from the inner ear and proprioception in the muscles and joints
- Helps regulate motor movement, balance and coordination
- Important for shifting attention between auditory and visual stimuli

Proprioception

Sense of one's position and strength of effort

Compress brain size as it contains a large size of information

What is the purpose of the folds in the brain?

Tectum

- Roof of the midbrain
- Responsible for auditory and visual reflexes

Superior colliculus and inferior colliculus

Located on each side of the tectum and processes sensory information

Hill

Meaning of colliculi

Tegmentum

The intermediate level of the midbrain containing nuclei for cranial nerves and part of the reticular formation

Tegmentum

Floor of the midbrain

Substantia nigra

Gives rise to the dopamine-containing pathway facilitating readiness for movement

1. Tectum
2. Tegmentum (contains superior colliculus and inferior colliculus)

Divisions of mesencephalon

Superior colliculus

Responsible for visual

Inferior colliculus

Responsible for auditory

1. Periaqueductal gray
2. Substantia nigra
3. Red nucleus

Colorful structures of the tegmentum

Periaqueductal gray

A colorful structure of Tegmentum with a gray matter situated around the cerebral aqueduct. It mediates the analgesic effect of opiate drugs and acts as pain-receiver

Substantia nigra

A part of the tegmentum's colorful structure that is responsible for eye-movement, motor planning, reward-seeking, learning, and addiction and mediated by the striatum

Red nucleus

A part of the tegmentum's colorful structures that is vestigial in primate brains and is responsible for motor coordination (crawling in babies and arm swinging in walking)

Vestigial

A part that is evolutionary present but with unknown function; An evolutionary remnant

Diencephalon

Thalamus + Hypothalamus

Thalamus

A large, two-lobed structure that constitutes the top of the brain stem that both sit on each side of the third ventricle. A sensory "way-station" and is composed of many different pairs of nuclei which project to the cortex

Massa intermedia

Joins both lobes

Lamina

Screen/Surface

Internal capsule

Fibers (Corticospinal tracts) that join the telencephalon to the diencephalon. It carries motor information from the motor cortex downward.

Sensory relay nuclei

Most understood thalamic nuclei that receives signals from sensory receptors, process them, and then transmit them to appropriate areas of sensory cortex

Lateral geniculate nuclei, medial geniculate nuclei, and the ventral posterior nuclei

Relay stations in the visual, auditory, and somatosensory systems

Hypothalamus

Below the anterior thalamus where all senses get terminated and regulated sleeping, eating, and sexual behavior and hormones released by the pituitary gland

Hyperthyroidism

Release too much thyroid hormones that can cause anxiety like symptoms

Hypothyroidism

Release too few thyroid hormones that can cause depression like symptoms

Optic chiasm

It is where the nerves from the eyes decussate

Mamillary bodies

Spherical nuclei which has a role in recollective memory

Limbic system and the basal ganglia

Circuit of midline structures that circle thalamus

Fight, flight, feeding, and sexual intercourse

Four F's of behavior

Basal forebrain

Comprised of several structures that lie on the dorsal surface of the forebrain and contains the nucleus basalis

Nucleus basalis

Receives input from the hypothalamus and basal ganglia that sends axons that release acetylcholine to the cerebral cortex
and is responsible for arousal, wakefulness, and attention

Amygdala

Enhances emotional memory and does not store memory; Emotional memory and fear

Cingulate cortex

Linking motivational outcomes to behavior; Important for schizophrenia and depression

Fornix

Function is not entirely sure but correlates well with recall memory

Septum pellucidum

Anatomical barrier yet real function remains unclear, however it is associated with motivation, emotion, drives, and aggression. This part includes the olfactory bulb, hypothalamus, amygdala, and cingulate gyrus of the cerebral cortex.

Hippocampus

A large structure located between the thalamus and cerebral cortex and is critical for storing certain types of memory

Basal ganglia

Plays a role in the performance of voluntary motor responses

Putamen

Responsible for planning, learning (Reinforcement learning, implicit learning, category learning, hate circuit (with insula)) and execution, motor preparation, specifying of amplitudes of movement, and movement sequences

Globus pallidus

Regulates movement at the subconscious level

Pallidoctomy

Damage is cause in order to reduce involuntary muscle tremors

Central canal, ventricles

Parts of the canal system

Central canal

A fluid-filled channel in the center of the spinal cord

Ventricles

Four-fluid filled cavities within the brain containing cerebrospinal fluid

Telencephalon

Largest division of the human brain and mediates the brains most complex functions
as it initiates voluntary movements, interprets sensory input, and mediates complex cognitive processes such as learning, speaking, and problem solving

Cerebral cortex

The most prominent part of the mammalian brain and consists of the cellular layers on the outer surface of the cerebral hemisphere and is more highly developed in humans than other species

Corpus callosum and anterior commissure

Two halves of the cerebral cortex

Frontal lobe, parietal lobe, temporal lobes, and occipital lobe

Four lobes of the brain

Fissures

Large furrows in the brain

Longitudinal fissure

Divides both (cerebral) hemisphere

Cerebral commissures

Connect both hemisphere

Corpus callosum

Largest commissure

Sulci

Small furrows

Gyri

Ridges between fissures and sulci

Precentral gyri, postcentral gyri, and the superior temporal gyri

Largest gyri

Neocortex (New cortex)

Six layers of recent evolution

Pyramidal and stellate

Two types of cells which abound from cortices I to VI

Hippocampus

Memory specifically for spatial locations

1. Contains up to six distinct laminae (layers) that are parallel to the surface of the cortex
2. Cells of the cortex are also divided into columns that lie perpendicular to the laminae
3. Divided into four lobes: Occipital, parietal, temporal and frontal

Organization of the cerebral cortex

Postcentral gyrus

Analyze sensations of the body

Precentral gyrus

Motor function

Gyrus rectus/orbital gyri

Function is unclear and is viewed as primitive development but is linked with personality and hypersexuality with men

Inferior frontal gyrus

Speech production

Superior temporal gyrus

Auditory processing and social cognition