psyc 211 - research methods

What is the meninges and what are its 3 layers

• the meninges are the three protective layers that are wrapped around the spinal cord and brain

The outer layer is dura mater. It is thick, though, unstretchable tissue

• the middle layer is arachnoid mater. Its web-like extensions create a soft spongy layer that is filled with cerebrospinal fluid

• The third layer is Lia mater. This layer sits closets to the brain and is a bit like Saran-wrap

What is cerebrospinal fluid

• It is made by it is a distinct type of tissue that is located in each of the brain’s ventricles: choriod plexus.

• The two lateral ventricles are the largest. They are underneath the cerebral cortex

• The third ventricle lies between the two thalamic nuclei at the center of the brain

• The fourth ventricle is in the hindbrain, between the pins and cerebellum

• Small canals interconnect each ventricle and bring CSF to the spinal cord

What are the characteristics of CSF

• there are immune system cells in the dura mater that analyze the CSF before it gets returned to the blood supply

• It is made continuously by chronic plexus

• It circulates around and hints the brain providing nutrients and removing waste

• It exits the CNS by passing through holes in the dura mater, where it is absorbed into the blood supply

What are the four primary areas

• Primary motor cortex (frontal lobe): contains motor neurons that Synapse in the spinal cord. Different regions of the primary motor cortex control different parts of the body.

• Somatosensory cortex (parietal lobe): is where touch information enters the cerebral cortex. Different regions of somatosensory cortex receive information from I different parts of the body

• Primary auditory cortex (temporal lobe): is where auditory information enters the cortex

• Primary visual cortex (occipital lobe): is where visual information enters the cerebral cortex

• There is also the insular cortex, where gustatory information enters the cerebral cortex

What is the sensory association cortex

• it is where perception takes place and memories are formed

• A sensory association complex is adjacent to each primary sensory area and receive information only from the nearest one

What is the limbic system

• It is a collection of subcortical brain areas that regulate emotions and the formation of episodic memories

• Its principle areas include the hippocampus, amygdala, and cingulate cortex

Its its

What is the cingulate cortex

• It is a large area that overlies the corpus callosum. This region interconnects many limbic areas of the brain

How does the brain form

• it starts of as a neural tube during the first month of human development in the womb

• The first cells in the tube a neural progenitor cells

• In the 8th week, the cells undergo symmetrical cell division, so each neural progenitor cell becomes two neural progenitor cells

• Over the next 3 months, when a neural progenitor cell divides one of the daughter cells detaches from the center of the neural tube.

• When that cell divides, it will produce two neurons or two glial cells.

What is neurogenesis

• it is the production of new neurons

• Neural progenitor cells produce neurons and glia after they undergo asymmetrical division. Huam neurgofensis largely stops five months after conception when neural progenitor cells start to undergo apoptosis

• There is little neurones is in adult mammals

What is apoptosis

• it is programmed cell death that occurs in multicellular organism

• Human neural progenitor cells undergo apoptosis around t eh fights month of development in the womb. This is when neurogenesis stops

What is computerised Tomography (CT scan)

• It is a machine that takes pictures of the brain

• The resolution is not great for soft brain tissue

• An X-ray beam is projected through the head to an X-ray detector. The X-ray beam is delivered from all angles

• Cheap and fast

What is magnetic resonance imaging (MRI)

• It uses a strong magnetic field and low energy radio waves

• The magnet causes every hydrogen proton in the body to spin in a particular direction

• A pulse of low energy radio waves changes the spin of these protons. Then, each proton flips back to the spin direction determined by the magnet. During this, every proton emits a new radio waves changes, which is detected by the scanner

• The scanner provides an estimate of the relative density of hydrogen atoms

• MRI identifies the density of water molecules and fat molecules

• High resolution three dimensional image

Why is diffusion tensor imaging (DTI)

• it is used to measure the direction and speed of water molecules

• It creates images that show the location and direction of every axon

• It is basically and MRI that is more sensitive to water molecule than to lipid ones

What is functional magnetic resonance imaging (fMRI)

• it is a rapid series of MRI scans that reveal the movement of oxygenated blood

• Ex: when a brain area is active, blood flow to that region increases within 5 seconds. We can then identify changes in neural activity by tracking oxygenated blood

• Doesn’t involve needles, surgery, or radioactivity

• Decent spatial resolution and temporal resolution

what is positron emission tomography (PET)

• it uses 2-DG as a measure of neural activity, but has been replaced by the fMRI

• It is used with other radioactive tracers

• It is uses to medausde changes in the expression levels of neurotransmitter receptors across weeks

What is electroencephalogram (EEG)

• it is a measure of electrical activity in the brain that uses macro electrodes (metal discs) attached to the scalp

• It records the summed up population level activity of millions of neurons

• It can be used as a diagnostic stool

• Specific patterns are associated with consciousness, sleep stages, etc

What is experimental ablation

• it involves the removal or destruction of a portion of the brain. The functions that can no longer be performed following the surgery are probably controlled by that brain area

• Used to know the function of a brain region

What are radio frequency lesions

• they are small lesions made by passing radiofrequency current through a metal wire that is insulated everywhere but the tip

• the electric current produces heat that burns cells around the tip of the wire

• The size and shape of the lesion is determined by the duration and intensity of the current

• Axons that are passing through will also be burned

What is an excitoxic lesion

• it is a brain lesion technique that is selective for cell bodies. It involves micro injections of a glutamate receptor agonist, which causes neurons to spike so much they undergo apoptosis

• Since there are profs on axons, any that are passing thought the area are spared

What is a sham lesion

• it is a placebo procedure that duplicates all steps of producing a brain lesion except die the step that causes extensive brain damage

What is a reversible lesion

• it can be achieved by injecting drugs that temporarily inhibit neuronal spiking, like voltage-gated sodium channel blockers that stop all action potentials

What is chemical stimulation

• it is the infusion of anasthetics which will shut down neural activity (stop all actin potentials)

• The infusion of receptor agonists or antagonists will selectively affect cell bodies and synapses. There are no neurotransmitter receptors on axons, so fiber of passage are not directly affected by drug infusions

What is electrical stimulation

• it is the delivering of electrical current through an implanted metal wire which will stimulate everything in the area (cell bodies and axons passing through)

• Low frequency stimulation → increases spiking activity. Stimulating faster than 10p times per second can produce the same behavioural efffect as lesioning in the brain area

What are micro electrodes

• they are thin metal wires with a fine tip that can record the electrical activity of individual neurons

• They are used during behavioral tests to record every action potential from a given neuron

• It is possible to simultaneously records from hundreds of individual neurons

What are optogenetics

• it is a way to make neurons sensitive to light to depolarize or hyperpolarize collections of them at any moment during a behavioral test

• this foreign DNA provides instructions to make light-sensitive proteins

What is a virus

• it is a DNA delivery system

• they replicate by injecting viral DNA in a host organism

• Its DNA contains instructions on how to make more vireus

What are replication deficient viruses

• they are viruses in which the viral DNA is edited so that they won’t be able to replicate

• They can infect cells, but the DNA they deliver is created by the researchers

What is GFP

• it is a fluorescent protein that is used to shows infected cells in a lab setting

What are mad-made fluorescent receptors

• they are fluorescent proteins that a designed by scientists

• It allows to visualize neurotransmitter release in living brains in real time

What is stereotaxic surgery

• it is a surgical intervention that uses a stereotaxic apparatus

• It is used to infuse drugs in specific parts of the brain

• It is also used to permanently implant metal straws, metal electrodes and fibre optic cables

What is Bregma

• it is the junction where pieces of the skull fuse together.

• Bregma is often used as a reference point for stereotaxic brain surgery

what are the reasons for stereotaxic surgery

it is commonly used for one time injections of a drug or virus to:

• lesion a brain area

• Lesion a specific type of cell in a particular brain area

• To alter gene expression, which typically involves viral-mediated gene delivery