Context : The formation and evolution of the Milky Way bulge is still largely an unanswered question .
One of the most essential observables needed in its modelling are the metallicity distribution and the trends of the \alpha elements as measured in stars .
While Bulge regions beyond R \gtrsim 50 \mathrm { pc } of the centre has been targeted in several surveys , the central part has escaped detailed study due to the extreme extinction and crowding .
The abundance gradients from the center are , however , of large diagnostic value .

Aims : We aim at investigating the Galactic Centre environment by probing M giants in the field , avoiding supergiants and cluster members .

Methods : For 9 field M-giants in the Galactic Centre region , we have obtained high- and low-resolution spectra observed simultaneously with CRIRES and ISAAC on UT1 and UT3 of the VLT .
The low-resolution spectra provide a means of determining the effective temperatures , and the high-resolution spectra provide detailed abundances of Fe , Mg , Si , and Ca .

Results : We find a metal-rich population at [ Fe/H ] = +0.11 \pm 0.15 and a lack of the metal-poor population , found further out in the Bulge , corroborating earlier studies .
Our [ \alpha /Fe ] element trends , however , show low values , following the outer Bulge trends .
A possible exception of the [ Ca/Fe ] trend is found and needs further investigation .

Conclusions : The results of the analysed field M-giants in the Galactic Centre region , excludes a scenario with rapid formation , in which SNIIe played a dominated role in the chemical enrichment of the gas .
The metal-rich metallicities together with low \alpha -enhancement seems to indicate a bar-like population perhaps related to the nuclear bar .