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RESULTS: There appears to be a remarkable similarity between (a) the physiological and behavioral consequences of response to a conditioned fear stimulus and (b) a panic attack. In animals, these responses are mediated by a "fear network" in the brain that is centered in the amygdala and involves its interaction with the hippocampus (link) and medial prefrontal cortex (link). Projections from the amygdala to hypothalamic (link) and brainstem sites explain many of the observed signs of conditioned fear responses. It is speculated that a similar network is involved in panic disorder. A convergence of evidence suggests that both inheritable factors and stressful life events, particularly in early childhood, are responsible for the onset of panic disorder. CONCLUSIONS: Medications, particularly those that influence the serotonin system, are hypothesized to desensitize the fear network from the level of the amygdala through its projects to the hypothalamus and the brainstem. Effective psychosocial treatments (i.e. cognitive-behavioral therapy, CBT) may also reduce contextual fear and cognitive misattributions at the level of the prefrontal cortex and hippocampus. Neuroimaging studies should help clarify whether these hypotheses are correct.
(All maroon edits are mine--JP)
Psi and the Temporal Lobes
The two temporal lobes of the brain constitute about 40% of the higher functioning area called the cerebrum; thus, there may be a greater potential for dysfunction or anomalous functioning of the temporal lobes than for other lobes. The temporal lobes are well situated for integrating perceptual stimuli of all kinds as well as for integrating various aspects of such cognitive functions as memory, learning, language, sense of self, in addition to emotional, sexual, and aggressive functions. Because of these capacities, psi experiences could also be integrated in the temporal lobes (Neppe, 1990).
The deep structures of the temporal lobes are the most electrically unstable portions of the human brain, and temporal lobe lability can be modified by such techniques as meditation. The contribution of temporal lobe processes to psi phenomena have two important implications. First, the phenomenological characteristics of psi experiences, especially spontaneous ones, could well be dominated by the functions of the temporal lobes. Such evidence is clearly seen in the propensity for spontaneous psi experiences to involve dreams, waking imagery, and intense affect that attributes the experience with intense personal meaningfulness (Persinger, 1974). Secondly, the electrical lability of the temporal lobes means that many other stimuli could both compete for neural substrates that facilitate psi experiences as well as simulating experiences resembling psi.
Well...since you mentioned it, a related report about being decapitated and being able to see themselves as such for a few seconds has been reported, or theorized.
The principle of fMRI imaging is to take a series of images of the brain in quick succession and to statistically analyze the images for differences among them. For example, in the blood-oxygen level dependent method (Ogawa, et al., 1990), the fact that hemoglobin and deoxyhemoglobin are magnetically different is exploited. Hemoglobin shows up better on MRI images than deoxyhemoglobin; thus, oxygenated blood shows up better. Brain areas with more blood flow have been shown to have better visibility on MRI images (Cohen & Bookheimer, 1994). Therefore, better visibility is thought to be correlated with brain activation. This has been exploited in the following type of procedure: a series of baseline images are taken of the brain region of interest when the subject is at rest; the subject performs a task and a second series is taken; then the first set of images is subtracted from the second, and the areas that are most visible in the resulting image are presumed to have been activated by the task. Other fMRI methods exploit the fact that the bulk movement of hydrogen nuclei causes changes in the MRI signal. Such methods could image CSF flow, blood flow, or diffusion of water through tissue. Care must be taken not to move the head, since spurious results could occur due to movement artifacts (Cohen & Bookheimer, 1994).www.neuroguide.com...
Magnetic resonance can be adequately understood in terms of electromagnetic theory, as follows. All atomic nuclei spin on their axes; nuclei have a positive electronic charge; and any spinning charged particle will act as a magnet with north and south poles located on the axis of spin. In magnetic resonance studies, an object is put in a strong, externally-imposed magnetic field ("main magnetic field"); the spin-axes of all the nuclei in the object line up with the field, with the north poles of the nuclei pointing in the "southward" direction of the field. This creates an average vector of magnetization of the object that points parallel to the magnetic field (the main magnetic field is conventionally referred to as pointing along the z-axis) (Horowitz, 1995).
Then a radiofrequency (RF) pulse is broadcast toward the object in a line perpendicular to the magnetization vector. The RF pulse causes the axes of the nuclei to tilt with respect to the main magnetic field, thus causing the net magnetization vector to deviate from the main magnetic field by a certain angle. However, only those nuclei which precess about their axes at the RF pulse frequency will be affected by the pulse; in other words, the nuclei that "resonate" to that frequency will be affected (Horowitz, 1995).
The net magnetization vector gradually (over 20-300 msec) returns to the state of being parallel with the external magnetic field, and the time that this takes is called the T2 relaxation time or "spin-spin relaxation time" after deactivation of the RF pulse. The amount by which the magnetization vector tilts away from the z-axis is controlled by the intensity and duration of the RF pulse; for example, if a 5 msec pulse at a certain intensity caused it to deviate 90 degrees from the z-axis, then a 10 msec pulse would cause a 180 degree deviation. In MRI studies on biological tissue, hydrogen nuclei are examined; T2 relaxation time of these nuclei differs from tissue to tissue (Horowitz, 1995). www.neuroguide.com...
Originally posted by semperfortis
If an action is performed enough times, does the brain create "pathways" for this particular action to facilitate the execution, thereby reducing the response time?