Exam 2 Flashcards
Cognitive Neuroscience
Study of the underlying mechanisms of cognition
Overlaps with cognitive psychology, neurophysiology, psychiatry, neurobiology, neurology, etc.
Anne Greene and Dr. Willis
Accused of murdering her baby, sentenced to death. Hung for 30 minutes and her body was promised to two doctors for autopsy. Within 12 hours she was speaking. Walk talk eat after a week.
Dr. Wilis that was supposed to do the autopsy became famous after this event and began teaching at Oxford, later coined term “neurology”. Performed autopsies on those that he treated and connected individual differences with neuroanatomy
How is neurology studied today
Functional neuroimaging
Electrophysiologic expermients
Cognitive genetics
Traditional clinical studies
Building the brain
genetics and experience help to inform some of the process
Synapses are crucial as they can reversibly connect sets of neurons (neural networks/assemblies)
Networks are composed of neurons that fire together. Building blocks of cognitive function
Neural networks
All cognitive functions are attributed to functioning of neural networks
Synapses are able to wire together large numbers of widespread neurons
Nature with nurture
Genetics:
lays neuronal groundwork
apoptosis
Variability in genomic plan
Experience:
refinement of neural system
Stimuli will alter synapses
“wiring by firing”
Neuronal change over time
Begin with genetics and after birth enter refinement until death
Neural development overview
Embryonic ectoderm gives rise to the nervous system
CNS forms the neural tube
PNS forms the neural crest
Prior to birth neurogenesis is mostly complete
Differentiation of neurons and neuroglial cells begins following development of the neural tube into a rudimentary brain and spinal cord
Neuron differentiation overview
Neurons differentiate first and the neuroglial cells
BEFORE THEY DIFFERENTIATE neurons and glia must travel to their final locations
Reaching their terminal location is necessary for their survival as they must form PARTICULAR synaptic neurons
IF NOT they undergo apoptosis
Migration of neurons
Follow signal transduction molecules and cell surface and extracellular adhesion molecules
Some are chemoattractants and other are chemorepellants
Molecules also guide growing axons
construction of synapses
Appropriate synaptic connections must be made following neurogenesis and migration
Signaling molecules allow the axonal growth cone to correctly identify the path to take
Growth factors assist with the growth of the axon, formation of the synapse and altering the number of connections
Failure to form aan appropriate synapse results in the loss of the axon (trophic nature of the synapse involves growth factors including Protein Nerve Growth Factor
Hebbian Assemblies
Conversion of the growth cone to a presynaptic specialization circuitry can be established
Forming new and modifying existing networks follows the same principles and utilizes the same mechanisms as Hebb’s synaptic plasticity
Long term Potentiation and Long Term Depression
LTP
Requires simultaneous presynaptic and postsynaptic neuronal firing (glutamate and NMDA receptors)
Large amount of Ca ions enter the postsynaptic neuron
Induce LTP by initiating STP and activating protein kinases
NMDA receptors
BOTH ligand gated and charge gated
LTD
Requires asynchronous firing of pre and post-synaptic firing
Requires glutamate and its NMDA receptor
Small influx of Ca ions, initiation of STP, activation of protein phosphatases
LTP vs. LTD
Both require activation of NMDA receptors and entry of Ca into the post-synaptic cell
Main difference is the amount in the post-synaptic neuron
Small influxes = depression
Large influxes = potentiation
LTP relies on the activity of protein kinases
LTD relies on the activity of protein phosphorylases
Often activate and inactivate the same complexes
Types of neural connections
Serial - Arrangement of neurons within an assembly that is linear; Vulnerable to damage
Distributed - Arrangement of neurons within assmebly that contain multiple interconnections. More resilient to damage
Excitatory Connections
Feedforward excitatory connection: low level –> High level
Feedback excitatory connection: Stimulation of postsynaptic neuron (high level –> low level)
Lateral excitatory connection: Stimulates other presynaptic
Inhibitory connections
Feedforward inhibitory - signals one neuron to inhibit another neuron.
Feedback inhibitory - stimulate another neuron that stimulates a neuron that inhibits the original neuron
Lateral inhibitory - similar to other lateral
Produces a signal that causes signaled neuron to release inhibitory signal
Disinhibition
Inhibiton of inhibition leads to excitation
For example: the globus palladus is typically an inhibitor. The caudate nucleus inhibits the globus palladus and leads to an over all stimulatory effect on thalamus)
Divergence stream
One stream to many others
Convergence stream
Severasl neurons to one
convergence and divergence may occur at the same neuron
Lots of convergence of rods, little convergence in cones
Circuit types
Hierarchecal circuit
Local circuit
Hierarchecal circuit
Each level is regulated by local circuits and three types of processing occur in circuits
Serial processing: info flows from one area to another in the sequence
Parallel processing: Info flows side by side
Reciprocal processing: info flows back and forth