Cerebrum Structure and Brain Matter

The Cerebrum

• Divided into 5 anatomical lobes: frontal, parietal, occipital, and insula
• Gyri are separated by depressions called sulci
• Diencephalon: all regions composed of gray matter
• Corpus callosum: facilitates communication between left and right hemispheres

Brain Matter Distribution

• White matter is deep to grey matter in the cerebrum and cerebellum

Embryonic Development of CNS

• Neurulation: formation of the neural tube
• Prosencephalon: gives rise to adult cerebrum
• Mesencephalon: develops into adult brain stem (midbrain)
• Rhombencephalon: develops into adult brain stem (pons and medulla)

Neural Tube Defects

• Spina bifida: incomplete formation of vertebral arches
• Anencephaly: absence of brain

Meninges

• Dura Mater: toughest, most superficial layer
• Arachnoid Mater: subarachnoid space separates it from Pia Mater and circulates CSF
• Pia Mater: delicate layer lying on the brain surface

Formation and Circulation of Cerebrospinal Fluid

• Choroid plexus: spongy mass of capillaries surrounded by ependymal cells
• Interventricular foramen: joins the lateral ventricle to the third ventricle
• Cerebral aqueduct: joins the third ventricle to the fourth ventricle
• Apertures: allow CSF to flow to the subarachnoid spaces
• Central canal: carries CSF to the spinal cord
• Arachnoid granulations: drain CSF

Functions of the Cerebrospinal Fluid

• Buoyancy: supports the brain
• Protection: cushions the brain
• Removal of waste: helps to remove waste products

Blood Brain Barrier

• Regulates exchange of substances from in and out of the brain
• Blood-CSF-barrier: exists in the choroid plexuses
• BBB: exists between capillaries and brain
• Tight junctions of the BBB: found in the linked feet of astrocytes
• Circumventricular organs: lack the BBB and include the medulla and hypothalamus

Pathology

• Stroke: occurs when blood flow to the brain is blocked or if there is bleeding in the brain
• Concussion: altered brain function following a blow to the head
• Encephalitis: inflammation of the brain
• Meningitis: inflammation of the meninges

Brain Stem Regions

• Medulla Oblongata: all nerve fibers connecting the brain and spinal cord pass through this region
• Pons: regulates respiration, sleep, and posture
• Midbrain: substantia nigra contains dopamine-producing neurons; degeneration of these neurons is linked to Parkinson's disease

Cerebellum

• Cognitive function
• Voluntary movement
• Vermis: controls movement of the central body
• Arbor vitae: composed of cerebellar white matter

Thalamus

• Regulates movement
• Contributes to the limbic system
• Relays sensory information; referred to as a "gateway"
• Found on both left and right sides of the brain

Hypothalamus

• Directly connected to the pituitary glands and mammillary bodies
• Functions: thermoregulation, sleep, hormone secretion, autonomic response, food intake, emotional, and memory (remember: ToSHAFEM)

Epithalamus

• Contains the pineal gland which secretes melatonin

Cerebral White Matter

• Commissural tracts: communication between grey matter of left and right hemisphere
• Association tracts: communication between different lobes in the same hemisphere
• Projection tracts: extend out of brain stem and spinal cord

Cerebral Cortex

• Outermost region of the brain
• Made of stellate cells and pyramidal cells
• Stellate cells: receive incoming sensory information
• Pyramidal cells: have to do with outgoing motor information
• Six cellular layers of the neocortex

Limbic System

• Functions associated with memory and learning
• Components: cingulate gyrus, hippocampus, and amygdala
• Most structures in this system have reward centers which explain why we are emotionally influenced to pursue rewarding things (remember: CHA)

Basal Nuclei

• Grey matter region
• Components: putamen, caudate nucleus, and globus pallidus (remember: Paul's crazy gout)

Brain Waves

• Alpha: regular and rhythmic, seen when a person is awake with eyes closed
• Beta: not as regular as alpha waves, seen when a person is concentrated or mentally stimulated
• Theta: normally seen in children or adults who are drowsy or stressed
• Delta: seen in deep sleep, indicates brain damage if found in adults who are awake

Stages of Sleep

• Stage 1: drowsy
• Stage 2: light sleep
• Stage 3: moderate to deep sleep
• Stage 4: deep sleep

Sleep

• Hypothalamus produces increasing levels of orexins which determine when an individual will wake up naturally
• Narcolepsy: can be caused by an immune blockage of orexin receptors
• REM sleep: brain waves are similar to when a person is awake, increased vitals and dreams occur here
• Non-REM sleep: thought to be glucose sparing for whole body restoration, and nightmares usually occur in stage 3 or 4 during non-REM sleep

Cognition

• Range of mental processes by which we acquire and use knowledge
• Brain areas associated with cognition: parietal, frontal, and temporal lobe

Amnesia

• Anterograde: inability to store new memories
• Retrograde: inability to recall past memories

Memory

• Short-term memory is usually stored in the hippocampus
• Long-term memory is usually stored in memory consolidation which involves various regions of the cerebral cortex
• Alzheimer's: death of acetylcholine-releasing neurons

The Cerebrum

• Divided into 5 anatomical lobes: frontal, parietal, occipital, and insula
• Gyri are separated by depressions called sulci
• Diencephalon: all regions composed of gray matter
• Corpus callosum: facilitates communication between left and right hemispheres

Brain Matter Distribution

• White matter is deep to grey matter in the cerebrum and cerebellum

Embryonic Development of CNS

• Neurulation: formation of the neural tube
• Prosencephalon: gives rise to adult cerebrum
• Mesencephalon: develops into adult brain stem (midbrain)
• Rhombencephalon: develops into adult brain stem (pons and medulla)

Neural Tube Defects

• Spina bifida: incomplete formation of vertebral arches
• Anencephaly: absence of brain

Meninges

• Dura Mater: toughest, most superficial layer
• Arachnoid Mater: subarachnoid space separates it from Pia Mater and circulates CSF
• Pia Mater: delicate layer lying on the brain surface

Formation and Circulation of Cerebrospinal Fluid

• Choroid plexus: spongy mass of capillaries surrounded by ependymal cells
• Interventricular foramen: joins the lateral ventricle to the third ventricle
• Cerebral aqueduct: joins the third ventricle to the fourth ventricle
• Apertures: allow CSF to flow to the subarachnoid spaces
• Central canal: carries CSF to the spinal cord
• Arachnoid granulations: drain CSF

Functions of the Cerebrospinal Fluid

• Buoyancy: supports the brain
• Protection: cushions the brain
• Removal of waste: helps to remove waste products

Blood Brain Barrier

• Regulates exchange of substances from in and out of the brain
• Blood-CSF-barrier: exists in the choroid plexuses
• BBB: exists between capillaries and brain
• Tight junctions of the BBB: found in the linked feet of astrocytes
• Circumventricular organs: lack the BBB and include the medulla and hypothalamus

Pathology

• Stroke: occurs when blood flow to the brain is blocked or if there is bleeding in the brain
• Concussion: altered brain function following a blow to the head
• Encephalitis: inflammation of the brain
• Meningitis: inflammation of the meninges

Brain Stem Regions

• Medulla Oblongata: all nerve fibers connecting the brain and spinal cord pass through this region
• Pons: regulates respiration, sleep, and posture
• Midbrain: substantia nigra contains dopamine-producing neurons; degeneration of these neurons is linked to Parkinson's disease

Cerebellum

• Cognitive function
• Voluntary movement
• Vermis: controls movement of the central body
• Arbor vitae: composed of cerebellar white matter

Thalamus

• Regulates movement
• Contributes to the limbic system
• Relays sensory information; referred to as a "gateway"
• Found on both left and right sides of the brain

Hypothalamus

• Directly connected to the pituitary glands and mammillary bodies
• Functions: thermoregulation, sleep, hormone secretion, autonomic response, food intake, emotional, and memory (remember: ToSHAFEM)

Epithalamus

• Contains the pineal gland which secretes melatonin

Cerebral White Matter

• Commissural tracts: communication between grey matter of left and right hemisphere
• Association tracts: communication between different lobes in the same hemisphere
• Projection tracts: extend out of brain stem and spinal cord

Cerebral Cortex

• Outermost region of the brain
• Made of stellate cells and pyramidal cells
• Stellate cells: receive incoming sensory information
• Pyramidal cells: have to do with outgoing motor information
• Six cellular layers of the neocortex

Limbic System

• Functions associated with memory and learning
• Components: cingulate gyrus, hippocampus, and amygdala
• Most structures in this system have reward centers which explain why we are emotionally influenced to pursue rewarding things (remember: CHA)

Basal Nuclei

• Grey matter region
• Components: putamen, caudate nucleus, and globus pallidus (remember: Paul's crazy gout)

Brain Waves

• Alpha: regular and rhythmic, seen when a person is awake with eyes closed
• Beta: not as regular as alpha waves, seen when a person is concentrated or mentally stimulated
• Theta: normally seen in children or adults who are drowsy or stressed
• Delta: seen in deep sleep, indicates brain damage if found in adults who are awake

Stages of Sleep

• Stage 1: drowsy
• Stage 2: light sleep
• Stage 3: moderate to deep sleep
• Stage 4: deep sleep

Sleep

• Hypothalamus produces increasing levels of orexins which determine when an individual will wake up naturally
• Narcolepsy: can be caused by an immune blockage of orexin receptors
• REM sleep: brain waves are similar to when a person is awake, increased vitals and dreams occur here
• Non-REM sleep: thought to be glucose sparing for whole body restoration, and nightmares usually occur in stage 3 or 4 during non-REM sleep

Cognition

• Range of mental processes by which we acquire and use knowledge
• Brain areas associated with cognition: parietal, frontal, and temporal lobe

Amnesia

• Anterograde: inability to store new memories
• Retrograde: inability to recall past memories

Memory

• Short-term memory is usually stored in the hippocampus
• Long-term memory is usually stored in memory consolidation which involves various regions of the cerebral cortex
• Alzheimer's: death of acetylcholine-releasing neurons