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Methods

Submitted by kmydosh on Wed, 12/13/2017 - 13:33

The overall methodlogical approach of this study was to place mice in different contexts and measure their fear response. Mice respond to fearful situations by freezing. This is a measurable behavior, since mice cannot verbally communicate that they are afraid. One aspect of emotion is that it is filtered through emotional expression. They are using an emotional response, a fear memory. In this case the fear memory is the room that the mice were shocked in. In this case the researchers used the protien c-fos. When neurons are really active they turn on c-fos. The researchers make use of c-fos by putting the promoter for c-fos downstream of the promoter. For th two contexts they had mice in room A. Room A is essentially a chamber with no smells. Context B is room B. This chamber is similar to room A but it has different color walls, different scents, ect. They let the mice explore room A. Then they let the mice explore room B. In room B the mice are shocked. The researchers turn on the neurons using c-fos when they put the mice back in room A. They can then measure the mouses response. This way they can ask if the mice remember being in room B. This is synthetic because they are forcing neurons to be on when they normally wouldn't be. In this way they are able to ask what does the mouse remember? 

Young's double slit

Submitted by kmydosh on Tue, 12/12/2017 - 13:57

Young's double slit experiment is a demonstration that light can display characteristics of both waves and particals. In this basic experiment, a light source, such as a laser beam, is shone through two slits. The nature of light to act as a wave causes the light to appear on a screen in a pattern. The pattern is repeating light and dark bands. The laser must hit both slits so they are very close together. The slits are roughly the same distance as the wavelength of the light from the laser. When the light hits the slits not all of the light gets through. When the light wave encounter the slit they spread out. This phenomanom is call diffraction. These two light wave overlap. Where they overlap constructivly there is a light spot and where they overlap destructively there is a dark spot. The light waves align constructivly in a line and this is what creates the diffraction pattern. At the center bright spot the path length of the light is 0. This is because the light traveled the same distance to the center from the two slits. At the next bright spot the light waves are traveling one wavelength further from one slit so x is equal to lambda. At the third bright spot, the distance in pathlength is 2 lambda. This continues so on and so forth until the spots of light are too far from the source of the light and the light particles are too dispersed to be seen. 

Generation of Synthetic Memory Trace

Submitted by kmydosh on Mon, 12/11/2017 - 13:36

In this paper researchers examined the effect of activation a competing, artificially generated, neutral representation on encoding of contextual fear memory in mice. They used a transgenic approach to induce the hM3Dq DREADD receptor. This is a designer receptor exclusively activated by a designer drug. Neural activity could then be specifically and inducibly increased in the hM3Dq expressing neurons by an exogenous ligand. Figure 1 of the study shows the two transgenes encoded in the mice. The figure showed the distribution of the gene in the hippocampus from immunofluorescence. Figure 2 showed the incorporation of synthetic neural activity in a 24 hour representation. Figure 3 showed the distribution of memory retrieval by synthetic neural activation.  Finally figure 4 showed that memory performance during synthetic reactivation is network specific. The results of this study infer that learning new memories are not produced de novo. But instead, new memories form based on old ones. New information coded is based on pre-existing circuit activity. One drawback of the study was that stimulation of the artificial gene does not replicate the temporal dynamics of this naturally occurring phenomenon. However the results do support the idea that the internal dynamic of the brain at the time of learning contribute to memory encoding. 

RC Circuits

Submitted by kmydosh on Fri, 12/08/2017 - 09:24

Resistors and capacitors work in combination to create a circut. The process of gainging and losing charge is not instantanous. It does not happen immeadiately. A simple circuit conatins a battery, one resistor, and one capacitor. The charge leaves the postive end and flows through to the negative end. The charge cannot move through the capacitor. For example, the charge starts off at zero. Eventually it will reach a maximum. As you have less energy to move around it will eventually reach a maximum value. As the current is going to zero the charge is going to the maximum. The inital value of the current is V=Q/C. The inital value of the charge is zero. In one microsecond you will reach a percentage of the maximum charge. This is for a charging circuit. For a discharging current, the charge and current decay at the same rate. 

Basal Ganglia

Submitted by kmydosh on Wed, 12/06/2017 - 11:44

There are two loops in the basal ganglia that focus activation onto specific areas of the motor cortex. The direct loop and the indirect loop function in different ways to regulate movement. In the direct loop  neurons of the globus are sponaneously active. These neurons are inhibitory. They keep the break on signals moving from the thalamus to the cortex. The globus neurons are constantly active and constantly keeping signals from traveling. The frontal cortex neuron is activating the globus neuron. In this way an inbibitor is inhibiting another neuron. This allows signals to pass trhough the cortex to a specific part of the cortex. The direct loop is essential for movement. The direct pathway through the basal ganglia activates the thalamus to initiate willed movements. In contrast, the indirect pathway inhibits the thalamus to supress unwanted movements. 

Luminol

Submitted by kmydosh on Mon, 12/04/2017 - 19:13

Bioluminesence is observed in many different organisms. These include fungi, algea, and many other marine organsims. Most commonly it is observed in fireflys. When the reaction is of chemical origin, it is called chemiluminescence. In chemiluminescense changes in chemical reactions sometimes result in the release of heat. This energy change can also be accompanied by the emission of light. One example of chemiluniescense is the oxidation of luminol. Luminol can be sythnesized via reduction of 3- nitrophthalhydrazide and sodium hydrosulfite. It is then oxidated with potassium ferricyanide and hydrogen peroxide. It's chemiluminescence properties can then be observed in dark conditions. 

Chapter 15

Submitted by kmydosh on Thu, 11/30/2017 - 10:50
  • The basal ganglia
    • Deep various components
    • Striatum
    • Globus pallidus
  • The basal ganglia focuses activation onto specific area of motor cortex
    • The direct loop is illustrated here
    • The inhibitory neuron inhibiting another inhibitory neuron allows the signal to proceed
    • Indirect pathway blocks movements that are unwanted
        • Substantia nigra
          • This neuron activates and inhibitor. This inhibitor then inhibits another inhibitor
          • Decreased output of VL resulting in hypoactivity
          • If you don’t have this then signals will have more difficulty relseasing the brake.
          • Means there’s less activity through, means there’s less movement.
        • Subthalamus
          • You will have more activity and more movement
          • You have a less active brake
          • Less able to inhibit the thalamus
          • You will have too much movement
  • Parkinsons disease
    • A selective and mysterious death in the substania nigra
      • The inability to initiate movement
    • Hypokinesia
      • 1% of people over 50 get it
      • Less than 10% get it genetically
    • Treatment
      • We don’t know why these neurons selectively die
      • Drug L-Dopa
        • Precursor to dopamine
        • You can give people L-Dopa and only the neurons that use dopamine take this up
        • The neurons are still dying but the remaining neurons have more dopamine to work with
        • Its unfortunately only temporary because the neurons continue to die
    • Balastic movements
      • Unwanted shaking movement
      • Normally this is surpassed
      • Results in hyperkenisia
  • Huntington’s disease
    • Caused by a dominant mutation of the huntingtons gene
    • Its dominant and often only appears in the late 30s after they’ve had children
    • Its invariably fatal
    • More common in people with European ancestry
    • No cure

Atomic Spectrum

Submitted by kmydosh on Thu, 11/30/2017 - 10:49

This experiment explored the continuous spectrum of colors the rainbow made when white light decomposes into its various colors. The spectrum of various color was observed using with light from an incandescent bulb or tube passing through a slit and then through a diffraction grating or prism. Various line colors were observed for lamps containing the different elements: hydrogen, mercury, sodium. A continuous spectrum was observed as well. Different elements each emit their own light at specific wave lengths. The distance of these lines of light from the center of the aperture were measured and then the wavelengths based on this information was then calculated.

 

Procedure

Submitted by kmydosh on Wed, 11/29/2017 - 11:21

Propanoic acid (0.97mL, 13mmol) and 3-methylbutanol (1.185mL, 11mmol) was added to a round bottom flask (5mL) containing three boiling chips. Sulfuric acid (4 drops) was added to the flask and the contents were mixed by expelling the solution with a pipet. The mixture was then refluxed for a total of 45 minutes. Every fifteen minutes, the top layer containing organic product and a lower water phase that was collected in the side arm was tilted back so that the upper organic phase dripped back into the flask. After 45 minutes, the entire contents of the side arm were tilted back into the flask. The mixture was allowed to cool for 10 minutes. The cooled mixture was then transferred to a centrifuge tube containing water (1 mL) and the aqueous layer was extracted after being mixed thoroughly. The extraction of the aqueous layer was repeated twice, first after the addition of sodium bicarbonate (1 mL) and then again with sodium chloride (1 mL). Each time the mixture was expelled thoroughly before the lower aqueous layer was removed. The product was then dried with three anhydrous calcium chloride spheres, before then undergoing analysis by infrared spectroscopy.

Esterification

Submitted by kmydosh on Tue, 11/28/2017 - 15:36

In this experiment, Isopentyl propionate was synthesized from propanoic acid and 3-methyl-1-butanol using refluxing for 45 minutes. The product was then cooled and washed with water, aqueous sodium bicarbonate, and then saturated aqueous sodium chloride. Then the product was dried with CaCl2 spheres and analyzed with infrared spectroscopy. The final product had a fruity smell like bananas or strawberries. The reactants, 3-methyl-1-butanol smelled rancid and the propanoic acid smelled like vinegar. The percent yield was calculated to be 53.2%. The low yield could have been due to water dripping back into the round bottom flask when the side arm was being titled. The infrared spectroscopy showed a strong peak at about 2900cm-1 to 3000cm-1. This is due to the C-H stretching vibration of an alkyl C-H bond. There is also another strong peak at about 1700cm-1 which is consistent with a C=O stretching vibration. The lack of any more significant peaks greater than 3000cm-1 indicates an absence of an OH group, thus excludes possibility that the product contains a carboxylic acid. The peaks shown in the infrared spectroscopy supports that the product successfully formed was an ester. 

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