Neuroscience: Brain Anatomy and Function

• The brain's primary function is to produce behavior, integrating information and creating commands for movement.

CNS (Central Nervous System)

• Consists of the brain and spinal cord

PNS (Peripheral Nervous System)

• Sensory neurons gather information from the outside world and send to the spinal cord and brain
• Motor neurons sense external stimuli
• Includes all processes radiating from beyond the brain and spinal cord

Neurons

• The nervous system comprises discrete cells called neurons
• Neurons in the brain communicate with each other, sensory receptors in the skin, muscles, and internal body organs

Cortex

• The heavily folded outer layer of brain tissue is composed of neurons
• Complex thinking capabilities are more present in humans and larger animals
• Known as the cerebrum, forebrain, and cerebral cortex
• Prominent in mammals and birds
• Responsible for most conscious behaviors

Brainstem

• The source of behavior in simpler animals
• Responsible for the majority of unconscious behaviors

Behavior

• Animals produce behaviors through inherited responses or learned experiences
• Human behavior consists of inherited and learned actions
• The complexity of behavior varies among species
• A more complex nervous system allows for a wider range of behavior
• A simpler nervous system implies a narrower range of behavior

Somatic Nervous System

• Soma refers to the body
• Aware of things happening to the body consciously

Autonomic Nervous System

• Automatic
• Not aware of things subconsciously

Enteric Nervous System

• Refers to the gut system

Afferent Information

• Sensory information coming into/towards the CNS (incoming)

Efferent Information

• Information leaving the CNS (outgoing)
• Sensory information must come before motor information

Brain-Body Orientation

• Dorsal: structures atop the brain or within a structure in the brain
• Ventral: Structures towards the bottom of the brain
• Lateral: Structures located towards to the sides
• Medial: Structures towards the brain's midline
• Anterior/rostral: Structures towards the front
• Posterior/caudal: Structures towards the back
• Proximal: Structures towards the center core
• Distal: Structures far away from the center core

Cuts

• Coronal cut: Cuts the face from the head

  • Vertical plane cut
  • Extends from the crown of the head down
  • Yields a frontal view of the brain's internal structures
  • Cannot see structures posterior
  • Can see most dorsal and ventral

• Horizontal cut: Cuts off the top of the head

  • The resulting view falls along the horizon
  • Viewed looking down on the brain from above (dorsal view)
  • Allows visualizing the most lateral or medial structures
  • Shows most rostral (anterior) and caudal (posterior) parts

• Sagittal cut: A cut between the two ears

  • Cut lengthways from front to back and viewed from the side
  • Divides the brain in symmetrical halves (medial view)
  • Shows most dorsal and ventral

Cerebral Cortex

• The brain is split into 2 hemispheres
• Every area of the brain has a mirror of itself in each hemisphere
• It is composed of two sets of four lobes
• Temporal lobe= smell
• Occipital lobe = vision
• Frontal lobe = decision making, personality, motor cortex (in front of the dividing line between frontal and parietal)
• Parietal lobe = sensory cortex

Sulcus (sulci)

• A groove (wrinkle) in brain matter
• Central sulcus extends from the most dorsal to ventral on the lateral side; marking the boundary from the frontal to parietal lobe (RED LINE)
• Parieto-occipital sulcus exists between the boundaries of the parietal and occipital lobes

Gyrus (gyri)

• Protrusion or bump that forms by the folding of the cerebral cortex
• Precentral gyrus is the motor cortex, location of voluntary motor movements
• Postcentral gyrus is the somatosensory cortex; processing touch and pain

Fissure

• A deep sulcus

• Lateral fissure (Sylvian) is on the lateral side, bounded by the frontal and temporal lobes, and the temporal lobe from parietal

• Longitudinal fissure splits into two hemispheres

• Right hemisphere

• Left hemisphere

Terms Regarding Neuron Pathways

• Ipsilateral: Located on the same side
  • Example: Left eye is ipsilateral to the ear
• Contralateral: Located on the opposite side
  • Example: A lesion in the left occipital lobe results in symptoms in the contralateral visual field/right side of vision
• Bilateral: Exists on both sides
• Decussate: Indicates when a neuron or pathway crosses the midline

Ventral View of the Brain

• Olfactory bulbs: Responsible for processing smells
• Optic chiasm: Where visual information decussates
• Pons : Regulates sleep and other processes
• Brainstem (medulla): Controls breathing and heart rate
• Cerebellum: Ballance

Medial View of the Brain

• Central sulcus
• Cingulate gyrus
• Corpus callosum
• Fornix
• Frontal lobe
• Temporal lobe
• Tegmentum
• Midbrain
• Medulla
• Spinal cord
• Calcarine fissure
• Occipital lobe
• Cerebellum

Internal Features of the brain

• Gray matter: Is composed of cell bodies and blood vessels
• Gray matter is gray because of organelles and keeps active due to blood vessels
• Nuclei is in the CNS
• Ganglion is in the PNS
• White matter: Is rich with neural axons - tracts
• Fatty substance = white
• Tract: A bundle of axons in the CNS
• Nerve: A bundle of axons in the PNS
• Corpus Callosum: A white matter structure that connects the two cortical hemispheres
• Contains white matter tracts that connect the two cortical hemispheres for communication
• For the cortex (4 lobes), not brain stem and other structures
• It contains about 200 million axons.
• Each hemisphere acts like their own brain without it
• The biggest tract in the brain

Four ventricles / cavities

• Cavities in the brain that contain cerebrospinal fluid (CSF)
• CSF = Sodium chloride and other sats
• CSF is made by choroid plexus
• Two lateral ventricles (left & right)
• Third ventricles
• Fourth ventricles
• Flow into each other

Ventricular System

• The brain gets rid of ‘trash' accumulated that is from byproducts during the day
• Keeps the brain nourished
• Filled with CSF with and lined with the choroid plexus
• Flow in order: lateral ventricles (make csf) → flow into third ventricle at the midline → flow into cerebral aqueduct → flow into 4th ventricles → down spinal cord

Layers of the brain (In order)

• Dura Mater :Hard mother

  • Outermost layer
  • Tough outer layer of fibrous tissue
  • The thickest Layer

• Arachnoid Layer: Spider web-like

  • A thin sheet of connective tissue
  • Filled up with CSF (protect the brain from hitting the sides of the skull)

• Pia Mater:"Soft mother"

  • Inner layer
  • Surface of the moderately rough layer
  • Single-cell thick, cannot see with eye

• Meningitis: An infection that causes deterioration of pressure on the brain and spinal cord

• The brain requires oxygen from the carotid artery to function

Spinal Cord

• Controls function of the body
• Afferent nerves: Relays sensations from the body to the CNS
• Efferent nerves: Sends out motor commands from the CNS to the body
• Dorsal most half = sensory information
• Ventral most half = motor information

Cranial Nerves

• 12 nerves that enter and leave on the ventral surface of the the brain
• Carries sensory and motor information
• Can carry movement of the eye, tongue, and face
• Vision, hearing, and taste
• Swallowing
• Vagus Nerve = control of organs ; longest autonomic nervous system nerve for relaxing. Mostly somatic as 'mixed somatic and autonomic'

Autonomic Nervous System

• Sympathetic Nervous System
  • Cell bodies located in the middle area of the spinal cord
  • Fight or flight
• Parasympathetic Nervous System
  • Rest and digest
  • Located at the top and bottom cell bodies of the spinal cord

Human Brain Development

• Broke into subdivisions called Encephalon
• Neural tube develops as a ventricle system

Three Major Brain Divisions

• Forebrain: Telencephalon, Diencephalon

• Midbrain: Mesencephalon

• Hindbrain:: Metencephalon, Mylencephalon

• The forebrain consists of the telencephalon (lateral ventricle, cerebral cortex,corpus callosum basal ganglia, limbic system) and the diencephalon (thalamus,hypothalamus)

• The midbrain consist of the tectum (roof over the stem/cerebral aqueduct helps guide sights/sounds tectum) and the tegmentum (input the midbrain into the basal ganglia and limbic system)

• The hindbrain, the oldest part of the brain, consist of pons and cerebellum sensorimotor and balance.Medulla involved in controlling processes ie Essentiall life/heart

• Telencephalon

• Adult brain: Cortex, basal ganglia, limbic system

• Diencephalon:Thalamus, hypothalmus

• Mesencephalon: Tectum, Tegmentum

• Metencephalon:Cerebellum, pons

• Myelencephalon: Medulla

Cells of the Nervous System

• Glial Cells: provide structure and nourishness for neurons; 75% are glial
• Neurons: Communicate with the PNS and CNS; 86 billion is the approximate amount; has 3 structural classes
• Polarity: Refers to amount of processes from the body (including dendrites) of the cell
• Multipolar= greater polarity
• Monopolar= less polarity
• Bipolar= medium polarity

Four Types of Glia

• Astrocytes: CNS-based that's symmetrical and offers structural for the neurons and makes sure the right neuron gets message and transports it; CNS largest glial cell
• Microglia: The CNS's immune cells, found in gray matter (where cell is) protect
  • Drives + Reduces inflammation, attacks infection, activates t-cells .
  • Swells up & attacks bacteria

Neuronal Anatomy

• Neurons are information processors, in charge of collecting, processing, and trasnmitting information to cells
• Dindrites: Collect info from the cell body and integrates it along the axon to terminals to transmit
• Shape and Size can vary from the human brain
• Oligodendrocytes: CNS - Can provide myelin with multiple axons - Nodes of Radvier: - short stretches that contain many axons - Involved in many sclerosis
• Schwann Cells PNS: Same function as the oligodendrocytes; Multiple sclerosis

Neural Communication

• Neurons are information processors, in charge of collecting, processing, and transmitting information to other neurons
• Dendrites collect information
• Cell b body (soma) is in charge of integrating information
• Axons integrate and trasnmit information terminals, they transmit.

Three Functions of Neurons

• Sensory Neurons - collecting information from a bodily source
• Interneurons - collect info, many sources
• Motor - Pass down information to move
• Neuron Doctrine
• Made of discrete of cells and use golgi stain but contiguous

Parts of neuron (yellow Highlight)

• Cell body/soma :Has a new genetic DNA
• Dendrites - input zone. Has recepters and brancheds; where chemical information is processed. Is located in the dendritic spines- protons protrudes to make contact and send chem messages

Axon

• Conduction zones - conducts energy from electrical body to end of cell
• Has a myelin for signal conductance; has axon terms to release neutrons and messages. Neurons can can have axons
• Can make direction control
• Cell is made 2 layers - lipid bilayer and seperate channels to membrane and com outside the cell
• Synapse communicates

Membrane Potential

• Consist of resting and non-resting membrane potentials that enable ions to communication along electrochemicals across
• Has uneventful distribution
• -70 mv with some ranges for electriacl ioni
• Has electircally charged molecules
• can postively and negativity charge for extra cellular fluids

Resting Lon Gradients

• Not firing - at rest inside cell is 70
• Contains more sodium outside of the cell
• More potassium inside cell
• Chlorine outside
• More calcium outside the cell
• Channel - NA open 50. and chlorind open

Concentration Gradients

• Chemical and diffusion which moves from high to low

Electrostatic Pressure

Opposite attracts, like repels, Electro -inside and outside

• only chloride attract outside of cell

Membrane Permeability

• Opens or closes when it reaches its voltage like Potassium

Ion Channels

• Not those passes - its a system that pumps sodium . to pump 3 and 2
• • energy to pump
• Pump keep action running with potassium channels open from rest through resistance -

Neural - Nueron Communication

• Synapse is point where neurons come into contact with one another space separating neurons- synpaticleft
• Neuro transmissions -chemicals - synthesized in the relaeses from terminals of the presnypatric and receptere are on end of post snynapatic

Effects

• Make more insides positive and outides postive with action with EPSPS is make the positive more The really exicted is where the signals cell act with the membrane and pos and neg reach sodium channels
• Has properties by integrating
• -Action potential
• -All or nothing effect
• ---Depolezatrion

Summation

• Spatial - the summation of parts come to ce
• Tempore- which comes up at times that's greator in closeness

•    - Neurontansmission action potentional
  

•    - Longed gated  open for range with molecules bind
  

•    - Mechnicially touch
  

• Potentials are generated is when the membrane 70 or 20
• Voltage- sodium in and make the potantaisl +50
• At that postively channel close and leave - leads to hyperpolizaiton (undershoot phase and understooh phase)
  • Is going back and forth - and not a stable to function
• Sodium pouring cel + potentioan
• Realite- when it so high cant trigger another one unless it high
• Glia swann
• -Myllenation can have an effect can jump from on node in note

Communication

    --Action- a potentiasl 
            - Axenic to a dendite has a close or far of a neuron has  a strong or weak input in a neuron. . with decay neurotransimtters through chamicial

Test your knowledge of brain anatomy, function, and the blood-brain barrier. Questions cover the Circle of Willis, neuronal signaling, and drug delivery to the brain. Explore key concepts in neuroscience.