intro
Charles Bell and Francois Magendie
- used mechanical stimulation to discover the dorsal pathway had no contraction and the ventral pathway had contraction.
- used electrical stimulation to discover the dorsal pathway sometimes had movement, ventral pathway had strong contractions.
Schwann vs. Ogliodendrocyte
Schwann → one portion, single axon (peripheral nervous system)
Oligodendrocyte → several portions, different axons (central nervous system)
Events in chemical transmission:
synthesis, transport to axon terminal, release, receptor binding, inactivation
- release:
voltage gated Ca2+ channels open, Ca2+ enters terminal button, vesicles fuse with membrane through exocytosis
CSF, choroid plexus, syringomyelia, hydrocephalus
CSF: 4 ventricles, central canal, plasma filtered from blood
Choroid plexus: produces CSF
Syringomyelia: spinal cord disruption of CSF
Hydrocephalus: damage to ventricles, skull enlarges and squishes brain tissue
Viktor Hamburger
decrease or increase the size of target for developing spinal motor neurons
Did not manipulate the number of spinal motor neurons
Size and presence of target is critical for development, determines the number of surviving neurons
If neurons serve viable functions, they survive
Key finding of charles and francois
law of roots: dorsal → sensory nerves, ventral → motor nerves
Phrenology
Voltage gated channels:
Nodes of ranvier
Voltage gated channels: transmembrane proteins that open and close in response to changes in membrane potential, allowing specific ions to pass through
Nodes of Ranvier: gaps along the myelin sheath that covers the axon of neuron cells to help recharge the action potential
What would happen if you inhibited AChE after ACh release?
ACh wouldn’t be broken down as quickly → more postsynaptic activity → leads to depression/Parkinson’s, etc.
Limbic System
Limbic system: responsible for learning, memory, emotion, and motivation
Basal ganglia: movement control
Input: Caudate nucleus and putamen
Output: globus pallidus
Animal model of depression- tail suspension test : Role of Neurogenesis & BDNF in Depression Therapy
activity= normal response
immobility= depression
Findings:
Did not show positive response to antidepressants
Decreasing neurogenesis in hippocampus
Neurogenesis may enhance overall brain plasticity → permits positive response to antidepressants
When neurogenesis is prevented (knock out TrkB) → poor response to antidepressants
Basic assumptions:
Functions of the mind are a biological basis
Brain is not a unitary organ - localization of function
Changes in the brain lead to changes in behavior
graded potentials
hort, localized changes in a neuron’s membrane potential caused by ion flow through membrane channels. grant
ACh & AChE
neurotransmitter that plays a role in memory, learning, attention, arousal, and involuntary muscle movement
immediately breaks down acetylcholine (ACh), into acetic acid and choline
cereeeebral cortex
outermost layer of brain, 4 lobes. responsible for vision in primary visual cortex (simple shapes, borders, contrasts, and high cognitive functions
includes the:
- motor cortex: homunculus , somatosensory: parietal lobe, temporal lobe: process complex visual info, leads to prosopagnosia
Tracy Shors
Can learning help keep newly produced neurons alive?
Finding: the brain is continuously changing when we learn which helps to keep cells from dying
Fritsch and Hitzig (1820): discovery of the motor cortex
Made function localization believable, specifically within motor cortex
absolute and relative refractory period
absolute refractory period: first part of the refractory period where there it is impossible to generate another action potential
relative refractory period: second part of the refractory period where an action potential is possible but you need a stronger current to activate it
sets limits on firing rates
MAO
responsible for the degradation of serotonin, dopamine, and norepinephrine in the central nervous system
Hippocampus AND Amygdala
spatial knowledge → cognitive spatial map
Entorhinal cortex: receives information from the neocortex and projects to hippocampus
Grid cells: fire when animals in multiple different places fire from a structured grid plan (forms hexagon with triangles pattern)
Cell migration
In cell migration, each generation of neurons migrates further away from the starting point
Audition procession pathway:
auditory cortex → Wernicke’s area → Broca’s area → motor cortex → speech
temporal and spatial summation
- temporal : each in same place. same toes
-spatial : in different places. different toes
Allosteric drugs
drug attaches to different receptor from neurotransmitter binding site, changing the shape of the receptor and the ability of the neurotransmitter to bind
Hindbrain, Midbrain, Forebrain
Hind:
Medulla: lower part of the brain stem that connects the spine to the brain. Controls life vital functions
Pons: between medulla and midbrain, connects the forebrain and cerebellum
Sensory pathways going up to the brain
Motor pathways come down from the forebrain
Cerebellum “little brain”: motor function, has the most neurons in the brain
Mid:
Tectum: superior colliculus (visual), inferior colliculus (auditory)
Tegmentum: reticular formation (arousal), substantia nigra (DA, Parkinson’s), periaqueductal gray (defensive behavior)
Forebrain
Thalamus: sensory function
Hypothalamus: motivated behavior → hormones
Fight, flight, feed, mating
Telencephalon: limbic system, basal ganglia, cerebral cortex
FAS
Fetal Alcohol Syndrome:
Diagnostic Criteria: Pre and post-natal growth retardation, CNS dysfunction, craniofacial abnormalities, pre-natal alcohol exposure
FAS cognitive impairment overlaps with ADHD -> hyperactivity, low attention/alertness, impaired cognitive function, motor abnormalities; facial features are unique