PSYC 301 Neuroanatomy

what is the basic structure of the brain?

• cerebral cortex

• diencephalon

• midbrain

• pons

• medulla

• cerebellum

• spinal cord

what are the divisions of the NS & what it a part of them?

• CNS located skull & spine

  • brain & spinal cord

• PNS located outside skull & spine

what are the divisions of the PNS & describe them?

• somatic nervous system: interacts w/ environment

• autonomic nervous system: regulates body’s internal environment

what is the role of afferent & efferent nerves in the somatic nervous system?

• afferent nerves carry sensory signals from the skin, skeletal muscles, joints, eyes, ears to the CNS

• efferent nerves carry motor signals from the CNS to the skeletal muscles

what is the role of afferent & efferent nerves in the ANS?

• Afferent nerves that carry sensory signals from internal organs to CNS

  • see’s bear & send’s to brain=> danger

• Efferent nerves that carry motor signals from the CNS to internal organs

  • heart rate increases

what are the 2 kinds of efferent nerves in the ANS & describe them?

• Sympathetic nerves: mobilize energy in threatening situations (e.g., via adrenal glands)

• Parasympathetic nerves: act to conserve energy or “rest and digest” (e.g.,

stimulate gut motility)

how are neurons 2-stage?

• Neurons project from CNS go part of the way then synapse on other neurons that carry the signal the rest of the way

• Sympathetic neurons synapse on 2^nd-stage neurons further away from target organs

• Parasympathetic neurons synapse closer to targeted organs

what are the 3 principles of the conventional view of sympathetic & parasympathetic nerves?

1) sympathetic nerves stimulate, organize, mobilize energy resources in threatening situations & parasympathetic acts to conserve energy

2) each autonomic target organ receives opposing sympathetic & parasympathetic & activity is controlled relative to both activity input ex: symp increases HR while para decreases it

3) sympathetic changes relate to psyc arousal & parasympathetic relate to psyc relaxation

=> Exception: Most nerves in the PNS project from the spinal cord but…

=> 12 pairs of cranial nerves – project from brain

·       Sensory nerves: brain - olfactory (I), optic (II), vagus (x – to & from gut)

in the CNS, what is a nucleus & tract?

• nucleus: a cluster of cell bodies

• tract: a bundle of axons

in the PNS, what is a ganglion & nerves?

• ganglion: cluster of cell bodies

• nerve (fibres): bundle of axons

what are meninges?

brain & spinal cord are encased in bone & covered by 3 protective membranes (protect CNS)

what are the 3 meninges & explain them?

• dura mater: tough, thick, protective layer

• arachnoid membrane: middle layer, delicate, web-like

• contains the subarachnoid space where CSF circulates

• pia matter: innermost layer, thin layer that covers brain & spinal cord

what does the spinal cord consist of?

• inner H-shaped core of gray matter: cell bodies and unmyelinated axons

• surrounding area of white matter: myelinated axons

what does a cross section of the spinal cord look like & where are the dorsal & ventral roots?

where is cerebrospinal fluid produced?

cerebrospinal fluid is produced by the choroid plexuses (network of capillaries, or small blood vessels that protrude into the ventricles from the pia mater)

where does the cerebrospinal fluid flow?

excess cerebrospinal fluid is absorbed from the subarachnoid space into dural sinuses (large blood-filled spaces) which runs through the dura mater & drain into the large jugular veins of the neck

what are the functions of CSF?

• cushions the brain

• provides nutrients

• removes waste

• protects against physical injury

what is gray matter & white matter made of?

• gray: cell bodies & capillary blood vessels

• white: myelinated axons

what are the directions of a mouse body?

• dorsal towards the top

• ventral towards the bottom

• rostral toward the nose

• caudal towards the tail

• anterior towards the front

• posterior towards the back

what are the directions of a human brain?

what are the 4 different types of laterality?

• unilateral: one side

• bilateral: both sides

• ipsilateral: on the same side

• contralateral: on opposite sides

what is the blood-brain barrier?

impedes the passage of many toxic substances from the blood into the brain

what are the functions in the body & brain?

• body: cell that make up the walls of blood vessels are loosely packed so nutrients can easily pass

• brain: cells of blood vessels are tightly packed, affecting the degree to which drugs/recreational drugs can influence brain activity

what are the external features of a multipolar neuron?

• cell membrane: semipermeable membrane that encloses the neuron

• dendrites: short processes emanating from the cell body, which receives most of the synaptic contacts from other neurons

• cell body: metabolic center of the neuron (soma)

• axon hillock: cone-shaped region at the junction between the axon & the cell body

• axon: long, narrow process that projects from the cell body

• myelin: fatty insulation around axons

• nodes of ranvier: gaps between sections of myelin

what makes up a neuron’s cell membrane?

• composed of lipid bilayer (2 layers of fat molecules)

• protein molecules forming the basis of cell membrane functional properties

• channel proteins: certain molecules may pass

• signal proteins: transfer signal to the inside of the neurons when particular molecules bind to them on the outside of the membrane         

what are the classes of neurons?

• multipolar: more than 2 processes extending from its cell body

• unipolar: neuron w/ 1 process extending from its cell body

• bipolar: neuron w/ 2 processes extending from its cell body

what are the 4 kinds of glial cells?

• oligodendrocytes

• schwann cells

• microglia

• astrocytes

what are oligodendrocytes?

• glial cells w/ extension that wrap around the axons of some neurons of the CNS

• extensions are rich in myelin & myelin sheath to increase the speed & efficiency of axonal conduction

what are schwann cells?

• function similarly to oligodendrocytes but on the PNS

• only 1 myelin segment

  • guide axonal regeneration (regrowth) after damage

what is the 3rd class of glial cells?

• microglia respond to injury/ disease by multiplying, engulfing cellular debris or even entire cells, & triggering inflammatory responses

• shown to play a role in regulation of cell death, synapse formation, & synapse elimination

what are the 4th class of glial cells?

• astrocytes are the largest

• some extensions outer surfaces of blood vessels in the brain & make contact w/ neurons

• play a role in allowing some chemicals from the blood into CNS neurons & blocking other chemicals & have the ability to contract or relax blood vessels based on blood flow demands of certain brain regions

• control establishment & maintenance of synapses between neurons, to modulate neural activity, to form functional networks w/ neurons & other astrocytes, to control blood-brain barrier, & to respond to brain injury

what are the 5 major divisions of the brain?

• telencephalon

• diencephalon

• mesencephalon

• metencephalon

• myelencephalon

what is the brain made up of?

• 2-3% of body weight, ~3 lbs

• Consumes ~20% of body’s energy

• Made up of neurons, neural stem cells, glia, blood vessels

• 60-100 billion neurons; ~half in cerebellum

• Brain size is weakly related to

body height

what are the components of the myelencephalon?

• Composed largely of tracts carrying

  signals between the rest of the

  brain and the body

what are the components of the metencephalon?

• Pons: houses many fibre tracts and part of reticular formation

• Cerebellum:50% of all neurons in the

brain!

• Massively connected to cortex -- multiple cerebro-cerebellar systems

• Involved in movement & timing

what are the components of the mesencephalon?

Composed of:

• the tectum (“roof”), which contains

nuclei that receive and relay: visual information (superior colliculi) & auditory info (inferior colliculi)

• the tegmentum (“floor”), which

contains nuclei related to: motor function (substantia nigra & red nucleus) & pain-reducing effect of opiods - analgesic (periaqueductal grey)

what is the reticular formation?

• In the myel-, met- and mesencephalon (midbrain + hindbrain)

• Many nuclei that play roles in arousal, attention, cardiac and respiratory reflexes, and other jobs

what are disorders of the midbrain & hindbrain?

• dejerine syndrome (bilateral medial medullary stroke)

• chiari malformation

• pontine tegmental cap dysplasia

what are symptoms of dejerine syndrome?

• Respiratory failure

• Paralysis of all four limbs

• Tongue dysfunction

what is chiari malformation & its symptoms?

Compression & distortion of cerebellum due to skull shape

• Headache

• Neck pain

• Coordination issues

• Swallowing issues

what is pontine tegmental cap dysplasia & symptoms affected?

A rare genetic disorder of pons & cerebellum formation due to a developmental error in axon growth & guidance

• Hearing, gaze, swallowing, facial

  movements

what are the components of the diencephalon?

• thalamus

• hypothalamus

what is the role of the thalamus?

2-lobed structure @ top of brainstem

• Many different types of nuclei – some process & relay info between receptors & cortex

• Nuclei may be specific to one sense or non-specific & involved in multimodal integration

how does the thalamus play a role in general anesthetics?

• tend to act upon the nonspecific nuclei of the thalamus (as well as other structures)

• Abnormal synchronization in the thalamo-cortical network can cause absence seizures

what is the role of the hypothalamus?

below anterior thalamus

• Plays an important role in behaviours such as feeding, sex, sleeping, temperature, emotion, & movement

• Acts upon the body’s endocrine (hormone) system via the pituitary gland

what are symptoms of hypothalamic & pituitary tumours?

• Headache, seizures

• Feeding & weight changes: Failure to thrive, loss of appetite, weight gain or loss

• Energy and mood changes: euphoria, hyperactivity, fatigue, aggression

• Cognitive changes: disrupted attention, memory problems

• Hormonal changes like early puberty, sexual problems

where is the brainstem?

• mesencephalon to myelencephalon

• sometimes diencephalon is included

• cerebellum isn’t a part of the brainstem

what are the components of the telencephalon?

is the cerebrum

• basal ganglia

• limbic system

• cerebral cortex

what are the functions of the telencephalon?

largest division of the brain

• mediates complex functions

• initiates voluntary movement

• interprets sensory input

• mediates complex cognitive processes ex: learning, speaking, & problem solving