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A seguito della lunga esperienza maturata con il prodotto MRI Devices per la risonanza magnetica funzionale ed a seguito delle richieste dei nostri clienti Alpa ha deciso di iniziare la progettazione di un nuovo pacchetto software per la gestione degli stimoli per la risonanza magnetica funzionale.<\/p>\n
Attualmente, il pacchetto pi\u00f9 usato \u00e8 uno strumento di vecchia concezione, per altro estremamente complesso nella generazione degli stimoli.<\/p>\n
il nuovo pacchetto software comprende un tool di edit dello stimolo di facile e contemporanea gestione ed un software di presentazione che si occupa di effettuare la somministrazione dello stimolo stesso.<\/p>\n
Le particolari peculiarit\u00e0 del nuovo sistema di disegno dello stimolo lo rendono un prodotto attuale e di semplice utilizzo, sono chiaramente presenti funzioni avanzate di programmazione, ma la base \u00e8 uno trumento solido dotato della gastione, ad esempio, di un database delle immagini – video – audio files.<\/p>\n
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fMRI technique is based on reaction of the patient to some stimuli. During the stimulation, images of the patient\u2019s brain are continuously acquired to produce a complete data set. After really complex pre and post processing it is possible to recognize which area of the brain are used to do something like to move the finger (Finger Tapping), to make association between a listened word and a verb, between a seen image and a word and so on. During this stimuli some small changes into MRI signal occur in synchronized manner with stimulation. To achieve sufficient statistic consistency the condition rest (no one stimulation) and task (stimulation) is repeated some times. The modality in stimuli delivery is called paradigm.<\/p>\n
There are two main stimuli modality: the first one, called block design, is the most used. It consists in alternating rest periods to task periods a precise number of time as shown in figure 1-1. The need of block design is because of statistic: blocks work as multiple experiments.<\/p>\n
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Otherwise there is another modality to delivery stimulate to the patient called event related. This delivering modality is quite precise but has a minor statistic evidence and is used only in special cases or particular studies. An example of event related stimulation is shown in figure 1-2: the stimuli delivery is activated only in particular moment (give TR) of experiment without any repetition.<\/p>\n
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Alpa fMRI Soft Suite is a complete software system to delivery audio and video stimuli to the patient inside a MRI bore.
\nThe appearance of a general stimuli presentation is be quite similar to a MS PowerPoint presentation, in order to delivery to the patient (by the way of an Audio-Video system) sounds, images and written indications.
\nThe main keypoint is timing precision and flexibility. The system deliver sounds, video written phrases, images with really precise timing.
\nThere are two main procedures in build and execute an fMRI stimuli session:
\nthe first one is about authoring and the second one is about the real stimuli delivery.
\nThe second one (Delivery of the Stimuli) is a player which must be very precise without any delay.
\nThe first one is the more complex part of the Alpa fMRI Soft Suite.<\/p>\n
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The authoring program enables the end user in building stimuli delivery (paradigm) in the simplest possible way. Regarding fMRI field, the timing is decided by a gap called TR (Time of Repetition) in order of about 2000 ms. This TR is the main clock of fMRI experiments. Generally (but not mandatory) the time gap between an audio-video event and the subsequent must be an integer multiple of TR. The value of TR is not a priori fixed, so the end user has to specify this value.<\/p>\n
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