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Alpha waves

Alpha waves are electromagnetic oscillations in the frequency range of 8–12 Hz arising from synchronous and coherent (in phase / constructive) electrical activity of thalamic pacemaker cells. They are also called Berger's wave in memory of the founder of EEG.

Alpha waves are one type of brain waves detected either by electroencephalography (EEG) or magnetoencephalography (MEG) and predominantly originate from the occipital lobe during wakeful relaxation with closed eyes. Alpha waves are reduced with open eyes and drowsiness and sleep. Historically, they were thought to represent the activity of the visual cortex in an idle state. More recent papers have argued that they inhibit areas of the cortex not in use, or alternatively that they play an active role in network coordination and communication.[1] Occipital alpha waves during periods of eyes closed are the strongest EEG brain signals. They usually can be detected with the naked eye.

An alpha-like variant called mu (μ) can be found over the motor cortex (central scalp) that is reduced with movement, or the intention to move. Alpha waves do not start to appear until three years of age.[2]

Alpha wave intrusion

Alpha wave intrusion occurs when alpha waves appear with non REM sleep when delta activity is expected. It is hypothesized to be associated with fibromyalgia[3], although the study was too small to be conclusive.

References

  1. ^ Palva, S. and Palva, J.M., New vistas for a-frequency band oscillations, Trends Neurosci. (2007), doi:10.1016/j.tins.2007.02.001
  2. ^ Kolev V, Başar-Eroglu C, Aksu F, Başar E. (1994). EEG rhythmicities evoked by visual stimuli in three-year-old children. Int J Neurosci. 75(3-4):257-70. PMID 8050866
  3. ^ Germanowicz D, Lumertz MS, Martinez D, Margarites AF (2006). "Sleep disordered breathing concomitant with fibromyalgia syndrome". J Bras Pneumol 32 (4): 333–8. PMID 17268733. 
  • Brazier, M. A. B. (1970), The Electrical Activity of the Nervous System, London: Pitman 

See also: Binaural beats

External links

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Alpha Waves
Developer(s) Infogrames
Publisher(s) Infogrames (International)/Data East (North America)
Designer(s) Christophe de Dinechin
Platform(s) Amiga, Atari ST, DOS
Release date(s) 1990
Genre(s) Platform game
Mode(s) Single player (DOS), two simultaneous players (Atari ST)
Rating(s) N/A
System requirements

10 MHz processor, CGA, EGA, VGA, or Monochrome graphics (DOS version)

Alpha Waves is an early 3D game that combines labyrinthine exploration with platform gameplay. By most definitions of the genre it could be considered to be the first 3D platform game, released in 1990, 6 years before the genre's seminal classic Super Mario 64. It was released one year before Hovertank 3D, which is sometimes incorrectly credited as being the first 3D game on the PC. It provided the first truly immersive 3D experience, combining for the first time full-screen, six-axis, flat-shaded 3D with 3D object interaction (like bouncing on a platform). Alpha Waves was an abstract game with a moody, artistic presentation, curiously named for its supposed ability to stimulate the different emotional centers of the brain with its use of color and music.

It was developed initially for the Atari ST by Christophe de Dinechin, and later ported to the Amiga and DOS. The DOS port was done by Frédérick Raynal, a notable game designer who would go on to develop Alone in the Dark (often abbreviated AitD), and Little Big Adventure. He has said that his work on Alpha Waves was a major inspiration for AitD.[1][2] The PC version was also localized in North America by Data East, and retitled Continuum. Infogrames may have also published their own version in the US under the original title, and it was also released as a part of no less than two Infogrames compilations, on which it retained its original name.

Contents

Gameplay

Alpha Waves is a simple game. It features two main modes of play: Action and Emotion[3]. The core gameplay in both is the same.

Players guide one of six craft (which are little more than geometric shapes in many cases) onto trampoline-like platforms. On these platforms, the player bounces automatically, higher, with each jump, until he reaches the maximum height possible for that platform (some are stronger than others). Every room in the game is a cube, and the walls contain doorways leading to other rooms. In this way, players have to work their way through the game's rooms, and reach different areas based on different emotions.

In Action Mode, players also work against the clock. Time bonuses are awarded for entering new rooms, and keys can be collected to open new ways. There isn't a particular end to the game, but the goal is simply to last as long and to discover as much as possible before time runs out. Emotion Mode allows players to explore without time constraints, but players are not allowed to cross certain game boundaries.

Emotion mode was not time limited, and allowed players to explore the game environment freely. While completing the game in Action Mode was very difficult, many players simply enjoyed exploring the game territory in Emotion Mode[4].

Version differences

Alpha Waves was initially released on the Atari ST. This version is notable for allowing two players to compete simultaneously. It lacked music entirely on the Atari 520ST, because of insufficient memory to store the music samples. On Atari 1040ST and later models, the theme song played during the intro. The music was stored on the second side of the floppy disk, since any Atari ST with enough memory also had a dual-sided floppy drive. A promotional version of the program was distributed by a french magazine on single-sided floppy disks, crashing any machine with more than 512K of memory.

The Amiga port was second. This version added a theme song at the title screen, but nixed the multiplayer aspect. The interface is similar, but the zone select in Emotion has been redone. Beyond this, it is very similar to the original.

The DOS version was the last one, and contains a number of improvements. This version supported AdLib/SoundBlaster sound cards. Despite the fact that these used the more limited FM synthesis of the Yamaha YM3812, compared to the PCM synthesis of the Amiga, Alpha Waves is one of the rare exceptions where the AdLib sound quality is superior. The soundtrack was also expanded to play in-game, and each zone had its own music. Additionally some of the mobiles have been changed, level layouts tweaked, and the camera tilting toned down for easier viewing. The menus and level selection screen have been redone again, and are noticeably enhanced. The DOS version also includes a two player Action Mode (turn-based as opposed to split-screen).

The DOS version lacks a mechanism to regulate speed when played on systems faster than it was intended for (essentially causing it to play in fast forward on newer hardware). However, when played on a properly configured system or emulator, this can be considered the superior version, for solo play especially.

Technology

Other 3D games of the same era include Falcon (1987), Elite (1984), Starglider 2 (1988), or Hovertank 3D (1991). Alpha-Waves (1990) brought a number of innovations to the 3D gaming experience that make it a significant landmark in 3D gaming[5][6]:

  • No visible depth-of-field clipping (objects disappearing in the distance)
  • True 6-axis motion and rotation (as opposed to simpler movements in Hovertank 3D for example)
  • Large (for the time) number of 3D objects displayed simultaneously
  • First gameplay relying primarily on interaction with 3D objects
  • No bit-mapped graphics, even the player was drawn in 3D
  • Full-screen 3D display, as opposed to 3D occupying a small fraction of the screen.
  • First simultaneous 2-player split-screen mode on a single computer (only on the original Atari ST version)

Alpha-Waves ran on 16-bit microcomputers that did not have hardware floating-point capabilities. For that reason, it performed all perspective and rotation computations using only integer arithmetics. In order to avoid using integer multiplications, which were expensive at the time, it described objects using displacements that were multiples of a base vector. For instance, a square in the Z plane would have been described as "+1X +1Y -1X -1Y". As a result, the vast majority of geometric computations were performed using only additions, not multiplications.

The computation of sine and cosines was similarly done using only integer arithmetic. All angles were represented using not degrees, but 1/256th of a circle. A lookup table contained the value of the sine multiplied by 32767. Multiplying this value by a 16-bit coordinate gave a 32-bit value, and the 16-bit high-half of that result was used.

Another key to performance was a highly optimized polygon-filling routine, which used a number of tricks, including an assembly version of Duff's device to achieve a very high fill rate, besting the in-house self-modifying routine Infogrames was using at the time.

The Atari ST and Amiga versions were written in assembly language. The DOS version was written in C.

References

External links


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