Class 1,2,3,4 Flashcards
Why does philosophy matter?
- It predates the establishment of modern science as we know it
- The first people to consider questions of the mind were philosophers
- When we make inferences about natural phenomena based on the empirical data we collect, we are using logic to do so
REDUCTIVE PHYSICALISM
Mind is Brain
CARTESIAN DUALISM
Mind it totally different from the brain
Aristotle
the heart as the seat of the rational soul
Idea behind phrenology
Increased usage of a brain region leading to growth of it (Gall & Spurzheim)
mainstreamed phrenology
The idea that measuring one’s skull could result in knowledge of an individual’s character led to phrenology’s application in:
- Job interviews
- Marriage compatibility tests
- Arguments against (and also for!) abolitionism
Localization of function found by
Paul Broca & Carl Wernicke
Brodmann areas
(BAs): cytoarchitectonics
the study of the cellular composition of the central nervous system’s tissues under the microscope.
Empiricism
knowledge is gained through sensory experience
rationalism
knowledge is gained through reason
Behaviourism
(& its problem)
the only objective measurements made are behavioral
Issue with this — we know that some complex mental structures already exist! - “Cells that fire together, wire together”
Modern-day phrenology?
- Without a more rigorous understanding of the methods, it is possible to conceive of what neuroimaging tells us as a ‘new phrenology’
- However, we also have many different mechanisms in the scientific community to protect against this
Neuroimaging to disprove phrenology
No connection between scalp curvature and brain gyrification
Soma
Contains essentials for cellular function
- Nucleus, mitochondria, DNA, ribosomes, enzymes
- Forms most of grey matter
Dendrites
- Receives signals
- Many different kinds for making different types of connections
Axon
• Carries electrical information along its length
- Forms most of white matter
- Sheathed in myelin via glia
Glia (types)
4 (main) types
PNS - Schwinn Cell
CNS - Microglia, astrocytes, oligodendrocytes
Astrocytes
• Star-like shape
- Form the blood-brain barrier
- Protect CNS
- Role in healing from stroke and spinal cord injuries
- Supply nutrients to neurons
- Influence neurochemical communications
Oligodendrocytes and Schwann cells
- Responsible for myelination of axons (white matter)
- Oligodendrocytes in CNS, Schwann cells in PNS
Microglia
- Immune system of the brain
- Monitors for signals from CNS to be activated
- Cleans up dead cells
- Helps with regulation of CNS
Action potential (AP)
Fast shift in the membrane potential of a neuron that begins once a certain threshold potential is passed and propagates down the axon
Resting membrane potential
Inside of the neuron is maintained at a negative potential compared to the outside
Difference maintained by Na+/K+ pumps in the membrane
Resting State (AP)
• Inputs from dendrites raise or lower the potential
• When sum of inputs increases potential to -55 mV (threshold
potential), AP occurs
• Potential needed for voltagegated Na+ channels to open
Depolarization (AP)
Voltage-gated Na+ channels open, Na+ enters, cell depolarizes
As cell depolarizes, voltage-gated K+ channels open, K+ leaves cell
Repolarization (AP)
At around +40 mV, the Na+ channels close
• This causes the polarity of the membrane to reverse
• But since the K+ channels are still open, the gradient overshoots -70
Hyperpolarization (AP)
The gradient overshoots
• K+ channels close at this point, stopping the flow of K+ outward
• Na+/K+ pump restores membrane potential back to -70 mV
Adding up all the PSPs collected from dendrites in the axon and summed at the
axon hillock
Neurotransmitter types
Amino acids:
• Glutamate (CNS)
• GABA (CNS)
“System” neurotransmitters:
• Acetylcholine
• Dopamine
• Noradrenaline / norepinephrine
• Serotonin
Directions for the brain
Contralateral
Opposite side
Ipsilateral
Same Side
Unilateral
one side
Bilateral
both sides
Proximal
closer to body center
Distal
further from body center
Spinal Cord is the ___
Interface of the PNS/CNS
tetraplegia
cervical area damage causes - (quadriplegia): loss of function in all four limbs
Cranial Nerves
(and where they origonate)
- Nerves that directly come out of the brain (as opposed to spinal cord)
- 12 in total
- Olfactory and optic (I and II) originate in cerebrum
- All other cranial nerves originate in brainstem
Medulla
- Part of hindbrain portion of brainstem
- Contains many cell bodies of cranial nerves (involved in head-related motor and sensory signals)
- Cranial nerves IX – XII (9-11)originate here
- Most motor fibers cross from one side of the body to the other at the medulla
- Contralateral organization of motor
- Includes neurons that are part of reticular activating system
- Arousal, attention, sleep-wake cycle
Pons
Lies superior to medulla and anterior to cerebellum; also part of hindbrain
- Main connection between cortex and cerebellum
- Diverse functions, including roles in eye movements, vestibular function (balance)
- Cranial nerves V – VIII (4-7) originate here
Midbrain
(Brainstem)
• Part of reticular activating system
• Contains superior and inferior colliculi
- Inferior colliculus: sound localization
- Reflexive orienting of attention to sound events
- Superior colliculus: foveation (focusing of vision)
- Cranial nerves III and IV (3-4) originate here
Cerebellum
- Voluntary movement
- Coordinated movement
- Ipsilateral organization with respect to motor control
- Higher cognitive functions
- Timing
- Working memory
Case study: No cerebellum?
• Damage to or absence of cerebellum interferes with
fine motor skills, coordinated movements like walking: cerebellar ataxia
• Does not mean complete loss of motor movement; slowed development of walking reported
Thalamus
Diencephalon
• Large bilateral mass of grey matter deep in the brain
• Axons from almost every sensory modality innervate the thalamus
- Medial geniculate nuclei (audition)
- Lateral geniculate nuclei (vision)
- Sensory relay to cortex:
- Allows for reorganization and fine-tuning of afferent inputs
Hypothalamus
Diencephalon
- Ventral to thalamus (hypo = ‘under’)
- Controls the ANS and endocrine system
- Hormone release
- Function: regulation of homeostasis
- Eating, drinking, sexual behaviors
- Fight-or-flight response
- Light-dark cycles, circadian rhythms
Basal Ganglia
• Multiple subcortical structures
• Striatum: Caudate, putamen, nucleus
accumbens
• Globus pallidus
• Substantia nigra
• Subthalamic nuclei
• Functions
• Preparation and termination of actions
• Motivation and reward
Hippocampus
- Located in medial temporal lobes (MTL)
- Some main functions:
- Memory consolidation
- Spatial navigation
Amygdala
- Sits above hippocampus in the MTL and made of multiple nuclei
- Function:
- Emotion processing
- Memory modulation
- Decision-making
- Fear / reward learning
- Damage results in impairments in decision-making and emotional processing
Amygdala
- Sits above hippocampus in the MTL and made of multiple nuclei
- Function:
- Emotion processing
- Memory modulation
- Decision-making
- Fear / reward learning
- Damage results in impairments in decision-making and emotional processing
Cerebral Cortex
• Most recent evolutionary expansion of the brain
- Made of up to 6 layers of cells, depending on the area of the cortex
- Neocortex (6 layers)
- Allocortex (3-4 layers)
- 1.5 to 4.5 mm thick
- Very wrinkled and convoluted
- Divided into two halves
- Communicate with each other through:
- Corpus callosum
- Anterior commissure
Insula
Deep within lateral sulcus
- Primary gustatory cortex (for taste)
- Also processes feeling of disgust (both physical and moral)
Fissure
Very deep sulcus
• Sulcus (pl. sulci): valley between gyri
Planes
Neocortex
has 6 layers, outermost
two sides of the cerebral cortex communicate by
- Corpus callosum
- Anterior commissure
Allocortex
3-4 layers
Inferior colliculus
sound localization
• Reflexive orienting of attention to sound events
Superior colliculus
foveation (focusing of vision)
Dorsal
Top
Supperior
top/dorsal
anterior
left/to nose
rostral
Left/to nose
Posterior
R/Back of head
caudal
R/back of head
Ventral
bottom
inferrior
bottom
Sagital/Coronal/Horzontal planes
PNS divisoins
Dorsal: Sensory / afferent
Ventral: Motor / efferent
Outputs from dorsal horn come together to form __
dorsal root, same for ventral
Cell bodies of dorsal root sensory neurons form
dorsal root ganglion
paraplegia
Damage below the cervical area preserves arm function, resulting in paraplegia
