functional neuroanatomy Flashcards
Outline Cajal and Golgi’s thoughts on the neuron
Golgi and Cajalshared Nobel prize in Physiology or Medicine (1906) even though they had different views on brain structure! − Golgi thought that neurons were continuous,
• i.e. they physically touched each other (reticular theory) − Cajalthought that neurons are contiguous,
• i.e. small gaps between them (Neuron theory/doctrine)
• This means that
− 1) cells/neurons are independent from one another
• Structurally, metabolically, and functionally
− 2) information has to be transmitted over the tiny gaps
Outline the diffrent sites in a neuron
Input zone
i. Dendrites–where neurons collect and integrate information from other cells
2. Integration zone
i. Cell body (soma or somata) –where the decision to produce a neural signal is made
3. Conduction zone i. Axon –where information is transmitted over great distances
4. Output zone i. Axon/synaptic terminal –where the neuron transfers information to the other cells
What are the different types of neuron and their functions?
Multipolar neurons are most common in the brain
• Motor neurons –muscle control
• Interneurons –relay and integrating information for learning and memory
Bipolar –common in sensory systems, such as vision −
Unipolar –also seen in sensory systems, such as touch
What are the glial cells?
glial cell or gilia- non-neuronal cells in the CNS
1. Astrocytes
- Microglia
- Oligodendrocytes
- Schwann cells
what are astrocytes?
Astro means star in Greek
• Diffuse connections
• Each astrocyte can connect with up to 100,000 neurons
• Whilst neurons have stayed the same in evolution, astrocytes have grown more complex
- Forming and modulating neuronal connections during development
- Regulate bloodflow to active neurons
- Create scar tissue stopping spread of damage to neighbouring tissue
what are microglia?
As the name suggests they are very small
• The brain’s clean-up crew
• Travel to injured sites to remove debris • Microglial disfunction in Alzheimer’s disease
bit like WBC
what are Oligodendrocytes and Schwann Cells
Both oligodendrocytes and Schwann cells are involved in myelination − i.e. creating a layer of fat around the axon to speed up neural transmission
• Oligodendrocytes do this in the brain and spinal cord • Schwann cells do this in the rest of the body
outline GBS and MS
Multiple Sclerosis (MS) and Guillain Barre Syndrome (GBS)
• Immune system attacks the myelin produced by oligodendrocytes (MS) and Schwann cells (GBS)
• Probably an autoimmune disease
• Inflammation of CNS nerves
• Affects insulating layer of axons
What is the difference between the CNS and PNS?
Central Nervous System (CNS) • Brain and Spinal cord • Peripheral nervous system (PNS) • All nerves and neurons that reside outside, or extend beyond, the CNS • Nerve = an enclosed bundle of axons
Outline the structural subdivisions of the PNS
structural:
cranial adn spinal nerves
functional:
Functional subdivisions
• Somatic nervous system
• Autonomic nervous system
- Sympathetic nervous system
- Parasympathetic nervous system
Outline the spinal nerves
31 pairs of spinal nerves • One pair for each spinal segment: − 8 cervical nerve pairs (Green) − 12 thoracic nerve pairs (blue) − 5 lumbar nerve pairs (purple) − 5 sacral nerve pairs − 1 coccygeal nerve pair
What does each nerve contain?
Each nerve has a − Ventral (toward front) root • Contains efferentfibres • i.e. projecting away from the brain/CNS − Dorsal (toward back) root • Contains afferentfibres • i.e. projecting towards the brain/CNS
Outline the monosynaptic reflex arc
stimulus hits leg
quadracepts contract
cell body of sensory neuron in dorsal root ganglion
links o grey matter in spinal cord
impulse straight to motor neuron which triggers hamstring to coil.
Outline the SNS and ANS
Somatic nervous system
• Soma is Latin for Body − i.e. the somatic nervous system is part of the PNS that controls voluntary body movements and conducts sensory information
Autonomic nervous system
• Autonomous, i.e. little conscious awareness or control • Part of the PNS that controls homeostasis
• In charge of circulation, breathing, digestion, sexual function
• Usually not subject to voluntary control
− Sympathetic nervous system
− Parasympathetic nervous system
what is the difference betwee parasympathetic and sympathetic nervous systems?
PSNS = rest and digest SNS= fight or flight
what is the physical structue of the human brain?
reflects the neurons cell bodies
White matter reflects the neuron axons
The brain floats in cerebrospinal fluid (CSF)
• Protection
• Nutrition
what is the difference between a sulcus a gyrus and a fissure?
Gyrus (plural gyri)
• ridge
- Sulcus (plural sulci) • groove
- Fissure • deep groove
What are the 3 ways to slice a brain
coronal- width
sagittal- length (right brain and left brain split)
Horizontal
What are the brain and spinal orientations?
Superior (Top) vs Inferior (Bottom)
• Anterior (Front) vs Posterior (Back)
• Medial (Middle) vs Lateral (Left or Right sides
Dorsal (towards back) vs Ventral (towards stomach)
• Rostral (towards nose) vs Caudal (towards tail)
• Different head/spine orientation changes this in bipedal vs quadrupedal
What is it called when brain and space orientations are on the same or different side
Ipsilateral − Same side
− Leftbody/space to leftbrain hemisphere and vice versa
• Contralateral − Switch sides − Leftbody/space to right brain hemisphere and vice versa
Outline the brainstem
Controls vital body functions
− Breathing
− Heartbeat
− Artery dilation
− Salivation
− Vomiting
• Contains the nuclei for cranial nerves III–XII
• The pons is closely connected to the cerebellum
• Important for movement and balance
• The midbrain contains important sensory and motor centres
what does the cerebellum do?
Cerebellum (latinfor ‘Little brain’)
• Own 3-layer cortex with ten ‘lobules’ (gyri)
• Own subcorticalstructures (deep cerebellarnuclei)
• 10% brain volume however, it contains ~50% of the brains 100 billion neurons
Massive computational potential
Receives sensory information directly from brainstem and additional information from isocortex
• Coordinates movement
• Balance
• Motor planning
• Motor learning
• Eye movement control
• Coordinate non-motor function
• Rule learning
• language
what are the 4 main structures of the basal ganglia?
Four main structures − Caudate Nucleus (blue) • Cognitive control
− Putamen (green)
• Motor control
− Nucleus Accumbens(red)
• Reward processing
− Globus Pallidus
• Receives outputs from all three other basal ganglia structures
• Damage leads to basal ganglia leads to: − Parkinson’s Disease − Huntingdon’s Disease
What does the thalamus do?
Complex cluster of nuclei
− Motor nuclei
− Sensory nuclei
• Connected to almost any area of cortex
− The basal ganglia and cerebellum send signals to the isocortexvia the thalamus
- Most important relay station for outputs from and inputs to the cortex
- Involved in regulating sleep and wakefulness
what is the hypothalamus?
• Hypothalamus = “below the thalamus”
• A cluster of LOTS of nuclei • Regulates homeostasis, metabolic processes, autonomic activities − Body temperature − Hunger − Thirst − Circadian cycles − Reproductive behaviour
• Links nervous and endocrine (hormone) systems via pituitary gland
what are the 4 lobes of the cerebral cortex?
The cerebral cortex (or isocortex) splits into 4 lobes:
1) Frontal
2) Parietal
3) Temporal
4) Occipital
what is the occipital lobe?
The smallest of the four lobes • Exclusively concerned with visual processing − Basic visual features − colour − motion
• Separated from parietal lobe by parieto-occipital sulcus
• Calcarine sulcus = primary visual cortex (V1)
− retinotopic organisation
Outline the Pariatal lobe
Parietal lobe
Separated from frontal lobe by central sulcus (fissure)
Important for − Somatosensory perception − Multisensory integration − Spatial attention − Decision making
− If lesioned
• Visual neglect
• Gerstmann’ssyndrome (dysgraphia, dyscalculia, finger agnosia, left-right confusion)
• Bálint’ssyndrome (optic ataxia, optic apraxia, simultaneous agnosia)
Outline the temporal lobe
Separated from frontal lobe by Sylvian fissure (lateral fissure/sulcus)
• Superior temporal gyrus
− Primary auditory cortex
− Speech and language processing (Wernicke’s area)
− Social cognition (Posterior STS)
• Middle temporal gyrus
− Interception
− Distance/time perception
− Language
• Inferior temporal gyrus
− Object recognition
− Face recognition
Prosopagnosia –face blindness • Caused by damage to inferior temporal gyrus
Outline the frontal lobe
Motor, Premotor, and Lateral PFC
• Primary motor cortex (red)
− Anterior to central sulcus
− Action execution
− Direct connections to spinal cord
• Premotor cortex (blue)
− Anterior to primary motor cortex
− Motor preparation
• Prefrontal frontal cortex
− Everything anterior to premotor cortex
− Superior, Middle, Inferior Frontal Gyri
− Functions include working memory, goal-directed action, language
medial prefrontal cortex Regions in the medial PFC important for goal-directed behaviour − Reward/punishment processing − Linking rewards to actions − Tracking expectations and outcomes − Conflict monitoring − Social cognition and emotion
Anterior cingulate cortex
Orbitofrontal cortex
• Reward processing − Linking stimuli to rewards − i.e. Pavlovian/classical conditioning
Frontal lobe ventromedial PFC
• Compares rewards to choose the best action
• i.e. which cereal do I want?
Outline Broddmanns work
Grey matter of isocortex has six layers of cells
• Different brain areas have different cellular profiles (cytoarchitecture
) • Brodmann(1909) mapped brain areas with different cytoarchitecture
• Impossible to see with naked eye
− Don’t conform to sulci and gyri
