Abstract
Stress is an integral part of modern life. Although there is a large body of literature regarding the harmful effects of chronic stress on different aspects of human life, acute stress is the most common form of stress, resulting from the demands and pressures of the recent past and the anticipated demands and pressures of the near future. In spite of its pervasive nature, less attention has been paid to the impact of acute stress on sensory processing than to the consequences of chronic stress, particularly concerning auditory processing. In this systematic review, the impact of experimental acute stress on the auditory processing of healthy adults was investigated. The results revealed the adverse effects of acute physical and psychological stresses on auditory processing. According to the open field of research on stress and the auditory system and the high possibility of experiencing different types of acute stresses in various life environments, including testing places, it seems that more investigations are needed to identify and manage different types of acute stresses in both clinical and research situations.
Acknowledgments
This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant #40352, Campus Alberta for Innovation Program Chair, Alberta Alzheimer Research Program to M.H.M. This study was part of a postdoctoral fellowship to Z.J. in the Canadian Center for Behavioral Neuroscience (CCBN) at Lethbridge University, Alberta, Canada. Z.J. would like to thank the Iran University of Medical Sciences (IUMS) Sabbatical Leave Committee for their approval on her study leave. We would especially like to acknowledge Drs. Sergio and Vivien Pellis (CCBN) for reading and improving this paper.
Disclosure statement: The authors declare that they have no competing interests.
References
Adler, L.E., Hoffer, L., Nagamoto, H.T., Waldo, M.C., Kisley, M.A., and Giffith, J.M. (1994). Yohimbine impairs P50 auditory sensory gating in normal subjects. Neuropsychopharmacology 10, 249–257.10.1038/npp.1994.28Search in Google Scholar
al’Absi, M., Hugdahl, K., and Lovallo, W.R. (2002). Adrenocortical stress responses and altered working memory performance. Psychophysiology 39, 95–99.10.1111/1469-8986.3910095Search in Google Scholar
Allen, A.P., Kennedy, P.J., Cryan, J.F., Dinan, T.G., and Clarke, G. (2014). Biological and psychological markers of stress in humans: focus on the trier social stress test. Neurosci. Biobehav. Rev. 38, 94–124.10.1016/j.neubiorev.2013.11.005Search in Google Scholar
Al-Mana, D., Ceranic, B., Djahanbakhch, O., and Luxon, L.M. (2008). Hormones and the auditory system: a review of physiology and pathophysiology. Neuroscience 153, 881–900.10.1016/j.neuroscience.2008.02.077Search in Google Scholar
Asbjornsen, A., Hugdahl, K., and Bryden, M.P. (1992). Manipulations of subjects’ level of arousal in dichotic listening. Brain Cogn. 19, 183–194.10.1016/0278-2626(92)90044-MSearch in Google Scholar
Bairey Merz, C.N., Dwyer, J., Nordstrom, C.K., Walton, K.G., Salerno, J.W., and Schneider, R.H. (2002). Psychosocial stress and cardiovascular disease: pathophysiological links. Behav. Med. 27, 141–147.10.1080/08964280209596039Search in Google Scholar
Bali, A. and Jaggi, A.S. (2015). Clinical experimental stress studies: methods and assessment. Rev. Neurosci. 26, 555–579.10.1515/revneuro-2015-0004Search in Google Scholar
Basner, M., Babisch, W., Davis, A., Brink, M., Clark, C., Janssen, S., and Stansfeld, S. (2014). Auditory and non-auditory effects of noise on health. Lancet 383, 1325–1332.10.1016/S0140-6736(13)61613-XSearch in Google Scholar
Beckwith, B.E., Lerud, K., Antes, J.R., and Reynolds, B.W. (1983). Hydrocortisone reduces auditory sensitivity at high tonal frequencies in adult males. Pharmacol. Biochem. Behav. 19, 431–433.10.1016/0091-3057(83)90115-6Search in Google Scholar
Boutros, N.N. and Belger, A. (1999). Midlatency evoked potentials attenuation and augmentation reflect different aspects of sensory gating. Biol. Psychiatry 45, 917–922.10.1016/S0006-3223(98)00253-4Search in Google Scholar
Boutros, N.N., Torello, M.W., Barker, B.A., Tueting, P.A., Wu, S.C., and Nasrallah, H.A. (1995). The P50 evoked potential component and mismatch detection in normal volunteers: implications for the study of sensory gating. Psychiatry Res. 57, 83–88.10.1016/0165-1781(95)02637-CSearch in Google Scholar
Braff, D.L. and Geyer, M.A. (1990). Sensorimotor gating and schizophrenia. Human and animal model studies. Arch. Gen. Psychiatry 47, 181–188.10.1001/archpsyc.1990.01810140081011Search in Google Scholar PubMed
Burns, M.N., Nawacki, E., Kwasny, M.J., Pelletier, D., and Mohr, D.C. (2014). Do positive or negative stressful events predict the development of new brain lesions in people with multiple sclerosis? Psychol. Med. 44, 349–359.10.1017/S0033291713000755Search in Google Scholar PubMed PubMed Central
Centre for Reviews and Dissemination (CRD). (2009). Systematic Reviews: CRD’s Guidance for Undertaking Reviews in Health Care (York: University of York).Search in Google Scholar
Chatkoff, D.K., Maier, K.J., and Klein, C. (2010). Nonlinear associations between chronic stress and cardiovascular reactivity and recovery. Int. J. Psychophysiol. 77, 150–156.10.1016/j.ijpsycho.2010.05.008Search in Google Scholar PubMed
Checkley, S. (1992). Neuroendocrine mechanisms and the precipitation of depression by life events. Br. J. Psychiatry (Suppl.) 160, 7–17.10.1192/S0007125000296633Search in Google Scholar
Choi, S.H. and Choi, C.H. (2015). Noise-induced neural degeneration and therapeutic effect of antioxidant drugs. J. Audiol. Otol. 19, 111–119.10.7874/jao.2015.19.3.111Search in Google Scholar PubMed PubMed Central
Cornwell, B.R., Baas, J.M., Johnson, L., Holroyd, T., Carver, F.W., Lissek, S., and Grillon, C. (2007). Neural responses to auditory stimulus deviance under threat of electric shock revealed by spatially-filtered magnetoencephalography. Neuroimage 37, 282–289.10.1016/j.neuroimage.2007.04.055Search in Google Scholar PubMed PubMed Central
Dagnino-Subiabre, A. (2013). Effects of chronic stress on the auditory system and fear learning: an evolutionary approach. Rev. Neurosci. 24, 227–237.10.1515/revneuro-2012-0079Search in Google Scholar PubMed
Dietl, T., Vogl, L., and Dirlich, G. (2004). Auditory information processing is altered in novelty stress conditions: first session effects in auditory-evoked potentials. Int. J. Neurosci. 114, 131–142.10.1080/00207450490249437Search in Google Scholar PubMed
Drabant, E.M., Kuo, J.R., Ramel, W., Blechert, J., Edge, M.D., Cooper, J.R., Goldin, P.R., Hariri, A.R., and Gross, J.J. (2011). Experiential, autonomic, and neural responses during threat anticipation vary as a function of threat intensity and neuroticism. Neuroimage 55, 401–410.10.1016/j.neuroimage.2010.11.040Search in Google Scholar PubMed PubMed Central
Elling, L., Steinberg, C., Brockelmann, A.K., Dobel, C., Bolte, J., and Junghofer, M. (2011). Acute stress alters auditory selective attention in humans independent of HPA: a study of evoked potentials. PLoS One 6, e18009.10.1371/journal.pone.0018009Search in Google Scholar
Ermutlu, M.N., Karamursel, S., Ugur, E.H., Senturk, L., and Gokhan, N. (2005). Effects of cold stress on early and late stimulus gating. Psychiatry Res. 136, 201–209.10.1016/j.psychres.2003.03.002Search in Google Scholar
Fasano, M.L., Sand, T., Brubakk, A.O., Kruszewski, P., Bordini, C., and Sjaastad, O. (1996). Reproducibility of the cold pressor test: studies in normal subjects. Clin. Auton. Res. 6, 249–253.10.1007/BF02556295Search in Google Scholar
Freedman, R., Waldo, M., Bickford-Wimer, P., and Nagamoto, H. (1991). Elementary neuronal dysfunctions in schizophrenia. Schizophr. Res. 4, 233–243.10.1016/0920-9964(91)90035-PSearch in Google Scholar
Fuerst, D.R., Gallinat, J., and Boutros, N.N. (2007). Range of sensory gating values and test-retest reliability in normal subjects. Psychophysiology 44, 620–626.10.1111/j.1469-8986.2007.00524.xSearch in Google Scholar PubMed
Gadea, M., Gomez, C., Gonzalez-Bono, E., Espert, R., and Salvador, A. (2005). Increased cortisol and decreased right ear advantage (REA) in dichotic listening following a negative mood induction. Psychoneuroendocrinology 30, 129–138.10.1016/j.psyneuen.2004.06.005Search in Google Scholar PubMed
Gandhi, P.H., Gokhale, P.A., Mehta, H.B., and Shah, C.J. (2013). A comparative study of simple auditory reaction time in blind (congenitally) and sighted subjects. Ind. J. Psychol. Med. 35, 273–277.10.4103/0253-7176.119486Search in Google Scholar PubMed PubMed Central
Griffith, J., Hoffer, L. D., Adler, L. E., Zerbe, G. O., and Freedman, R. (1995). Effects of sound intensity on a midlatency evoked response to repeated auditory stimuli in schizophrenic and normal subjects. Psychophysiology 32, 460–46610.1111/j.1469-8986.1995.tb02097.xSearch in Google Scholar PubMed
Hall, J.W. 3rd (2007). New Handbook of Auditory Evoked Responses. 4th ed. (Boston, MA, USA: Pearson).Search in Google Scholar
Hasson, D., Theorell, T., Bergquist, J., and Canlon, B. (2013). Acute stress induces hyperacusis in women with high levels of emotional exhaustion. PLoS One 8, e52945.10.1371/journal.pone.0052945Search in Google Scholar PubMed PubMed Central
Heinecke, K., Weise, C., Schwarz, K., and Rief, W. (2008). Physiological and psychological stress reactivity in chronic tinnitus. J. Behav. Med. 31, 179–188.10.1007/s10865-007-9145-0Search in Google Scholar PubMed
Hemmerle, A.M., Herman, J.P., and Seroogy, K.B. (2012). Stress, depression and Parkinson’s disease. Exp. Neurol. 233, 79–86.10.1016/j.expneurol.2011.09.035Search in Google Scholar
Henkin, R.I. and Daly, R.L. (1968). Auditory detection and perception in normal man and in patients with adrenal cortical insufficiency: effect of adrenal cortical steroids. J. Clin. Invest. 47, 1269–1280.10.1172/JCI105819Search in Google Scholar
Hetrick, W.P., Sandman, C.A., Bunney, W.E., Jr., Jin, Y., Potkin, S.G., and White, M.H. (1996). Gender differences in gating of the auditory evoked potential in normal subjects. Biol. Psychiatry 39, 51–58.10.1016/0006-3223(95)00067-4Search in Google Scholar
Holgers, K.M., Erlandsson, S.I., and Barrenas, M.L. (2000). Predictive factors for the severity of tinnitus. Audiology 39, 284–291.10.3109/00206090009073093Search in Google Scholar
Horner, K.C. (2003). The emotional ear in stress. Neurosci. Biobehav. Rev. 27, 437–446.10.1016/S0149-7634(03)00071-XSearch in Google Scholar
Hsieh, M.H., Liu, K., Liu, S.K., Chiu, M.J., Hwu, H.G., and Chen, A.C. (2004). Memory impairment and auditory evoked potential gating deficit in schizophrenia. Psychiatry Res. 130, 161–169.10.1016/j.pscychresns.2002.12.001Search in Google Scholar
Hunter, R.G., Gagnidze, K., McEwen, B.S., and Pfaff, D.W. (2015). Stress and the dynamic genome: steroids, epigenetics, and the transposome. Proc. Natl. Acad. Sci. U. S. A. 112, 6828–6833.10.1073/pnas.1411260111Search in Google Scholar
Jerger, K., Biggins, C., and Fein, G. (1992). P50 suppression is not affected by attentional manipulations. Biol. Psychiatry 31, 365–377.10.1016/0006-3223(92)90230-WSearch in Google Scholar
Joels, M. and Baram, T.Z. (2009). The neuro-symphony of stress. Nat. Rev. Neurosci. 10, 459–466.10.1038/nrn2632Search in Google Scholar
Johnson, M.R. and Adler, L.E. (1993). Transient impairment in P50 auditory sensory gating induced by a cold-pressor test. Biol. Psychiatry 33, 380–387.10.1016/0006-3223(93)90328-BSearch in Google Scholar
Juruena, M.F. (2014). Early-life stress and HPA axis trigger recurrent adulthood depression. Epilepsy Behav. 38, 148–159.10.1016/j.yebeh.2013.10.020Search in Google Scholar
Katzenell, U. and Segal, S. (2001). Hyperacusis: review and clinical guidelines. Otol. Neurotol. 22, 321–326.10.1097/00129492-200105000-00009Search in Google Scholar
Kirschbaum, C. and Hellhammer, D.H. (1994). Salivary cortisol in psychoneuroendocrine research: recent developments and applications. Psychoneuroendocrinology 19, 313–333.10.1016/0306-4530(94)90013-2Search in Google Scholar
Knipper, M., Van Dijk, P., Nunes, I., Ruttiger, L., and Zimmermann, U. (2013). Advances in the neurobiology of hearing disorders: recent developments regarding the basis of tinnitus and hyperacusis. Prog. Neurobiol. 111, 17–33.10.1016/j.pneurobio.2013.08.002Search in Google Scholar
Koenen, K.C., Moffitt, T.E., Poulton, R., Martin, J., and Caspi, A. (2007). Early childhood factors associated with the development of post-traumatic stress disorder: results from a longitudinal birth cohort. Psychol. Med. 37, 181–192.10.1017/S0033291706009019Search in Google Scholar
Kolb, B. and Gibb, R. (2015). Plasticity in the prefrontal cortex of adult rats. Front. Cell. Neurosci. 9, 15.10.3389/fncel.2015.00015Search in Google Scholar
Kolb, B., Mychasiuk, R., Muhammad, A., and Gibb, R. (2013). Brain plasticity in the developing brain. Prog. Brain Res. 207, 35–64.10.1016/B978-0-444-63327-9.00005-9Search in Google Scholar
Kudielka, B.M., Buske-Kirschbaum, A., Hellhammer, D.H., and Kirschbaum, C. (2004). HPA axis responses to laboratory psychosocial stress in healthy elderly adults, younger adults, and children: impact of age and gender. Psychoneuroendocrinology 29, 83–98.10.1016/S0306-4530(02)00146-4Search in Google Scholar
Lazarus, R.S. (1993). From psychological stress to the emotions: a history of changing outlooks. Annu. Rev. Psychol. 44, 1–21.10.1146/annurev.ps.44.020193.000245Search in Google Scholar PubMed
Liberati, A., Altman, D.G., Tetzlaff, J., Mulrow, C., Gotzsche, P.C., Ioannidis, J.P., Devereaux, P.J., Kleijnen, J., and Moher, D. (2009). The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. J. Clin. Epidemiol. 62, e1–e34.10.1016/j.jclinepi.2009.06.006Search in Google Scholar PubMed
Lovallo, W. (1975). The cold pressor test and autonomic function: a review and integration. Psychophysiology 12, 268–282.10.1111/j.1469-8986.1975.tb01289.xSearch in Google Scholar PubMed
Low, C.A., Salomon, K., and Matthews, K.A. (2009). Chronic life stress, cardiovascular reactivity, and subclinical cardiovascular disease in adolescents. Psychosom. Med. 71, 927–931.10.1097/PSY.0b013e3181ba18edSearch in Google Scholar PubMed PubMed Central
Lupien, S.J., Maheu, F., Tu, M., Fiocco, A., and Schramek, T.E. (2007). The effects of stress and stress hormones on human cognition: implications for the field of brain and cognition. Brain Cogn. 65, 209–237.10.1016/j.bandc.2007.02.007Search in Google Scholar PubMed
Lupien, S.J., McEwen, B.S., Gunnar, M.R., and Heim, C. (2009). Effects of stress throughout the lifespan on the brain, behaviour and cognition. Nat. Rev. Neurosci. 10, 434–445.10.1038/nrn2639Search in Google Scholar PubMed
Maddock, C. and Pariante, C.M. (2001). How does stress affect you? An overview of stress, immunity, depression and disease. Epidemiol. Psychiatr. Soc. 10, 153–162.10.1017/S1121189X00005285Search in Google Scholar
Marco-Pallares, J., Grau, C., and Ruffini, G. (2005). Combined ICA-LORETA analysis of mismatch negativity. Neuroimage 25, 471–477.10.1016/j.neuroimage.2004.11.028Search in Google Scholar PubMed
Mazurek, B., Szczepek, A.J., and Hebert, S. (2015). Stress and tinnitus. HNO 63, 258–265.10.1007/s00106-014-2973-7Search in Google Scholar PubMed
McEwen, B.S. (2007). Physiology and neurobiology of stress and adaptation: central role of the brain. Physiol. Rev. 87, 873–904.10.1152/physrev.00041.2006Search in Google Scholar PubMed
Mitchell, L.A., MacDonald, R.A., and Brodie, E.E. (2004). Temperature and the cold pressor test. J. Pain 5, 233–237.10.1016/j.jpain.2004.03.004Search in Google Scholar PubMed
Mobus, G.E. and Kalton, M.C. (2015). Principles of Systems Science (New York, USA: Springer).10.1007/978-1-4939-1920-8Search in Google Scholar
Molholm, S., Martinez, A., Ritter, W., Javitt, D.C., and Foxe, J.J. (2005). The neural circuitry of pre-attentive auditory change-detection: an fMRI study of pitch and duration mismatch negativity generators. Cereb. Cortex 15, 545–551.10.1093/cercor/bhh155Search in Google Scholar
Morey, J.N., Boggero, I.A., Scott, A.B., and Segerstrom, S.C. (2015). Current directions in stress and human immune function. Curr. Opin. Psychol. 5, 13–17.10.1016/j.copsyc.2015.03.007Search in Google Scholar
Novakova, B., Harris, P.R., Ponnusamy, A., and Reuber, M. (2013). The role of stress as a trigger for epileptic seizures: a narrative review of evidence from human and animal studies. Epilepsia 54, 1866–1876.10.1111/epi.12377Search in Google Scholar
NPR/Robert Wood Johnson Foundation/Harvard School (2014). The burden of stress in America. Available at: http://www.rwjf.org/content/dam/farm/reports/surveyspolls/2014/rwjf414295. Accessed 25 Apr 2016.Search in Google Scholar
Oken, B.S., Chamine, I., and Wakeland, W. (2015). A systems approach to stress, stressors and resilience in humans. Behav. Brain Res. 282, 144–154.10.1016/j.bbr.2014.12.047Search in Google Scholar
Pattyn, T., Van Den Eede, F., Vanneste, S., Cassiers, L., Veltman, D.J., Van De Heyning, P., and Sabbe, B.C. (2016). Tinnitus and anxiety disorders: a review. Hear. Res. 333, 255–65.10.1016/j.heares.2015.08.014Search in Google Scholar
Rentzsch, J., Penzhorn, A., Kernbichler, K., Plockl, D., Gomez-Carrillo de Castro, A., Gallinat, J., and Jockers-Scherubl, M.C. (2007). Differential impact of heavy cannabis use on sensory gating in schizophrenic patients and otherwise healthy controls. Exp. Neurol. 205, 241–249.10.1016/j.expneurol.2007.02.004Search in Google Scholar
Reul, J.M. and de Kloet, E.R. (1985). Two receptor systems for corticosterone in rat brain: microdistribution and differential occupation. Endocrinology 117, 2505–2511.10.1210/endo-117-6-2505Search in Google Scholar
Robert, L. and Labat-Robert, J. (2015). Stress in biology and medicine, role in aging. Pathol. Biol. (Paris) 63, 230–234.10.1016/j.patbio.2015.07.008Search in Google Scholar
Roth, M.K., Bingham, B., Shah, A., Joshi, A., Frazer, A., Strong, R., and Morilak, D.A. (2012). Effects of chronic plus acute prolonged stress on measures of coping style, anxiety, and evoked HPA-axis reactivity. Neuropharmacology 63, 1118–1126.10.1016/j.neuropharm.2012.07.034Search in Google Scholar
Sahley, T.L. and Nodar, R.H. (2001). A biochemical model of peripheral tinnitus. Hear. Res. 152, 43–54.10.1016/S0378-5955(00)00235-5Search in Google Scholar
Schroger, E. (1997). On the detection of auditory deviations: a pre-attentive activation model. Psychophysiology 34, 245–257.10.1111/j.1469-8986.1997.tb02395.xSearch in Google Scholar
Schwabe, L., Joels, M., Roozendaal, B., Wolf, O.T., and Oitzl, M.S. (2012). Stress effects on memory: an update and integration. Neurosci. Biobehav. Rev. 36, 1740–1749.10.1016/j.neubiorev.2011.07.002Search in Google Scholar
Sgoutas-Emch, S.A., Cacioppo, J.T., Uchino, B.N., Malarkey, W., Pearl, D., Kiecolt-Glaser, J.K., and Glaser, R. (1994). The effects of an acute psychological stressor on cardiovascular, endocrine, and cellular immune response: a prospective study of individuals high and low in heart rate reactivity. Psychophysiology 31, 264–271.10.1111/j.1469-8986.1994.tb02215.xSearch in Google Scholar
Simoens, V.L., Istok, E., Hyttinen, S., Hirvonen, A., Naatanen, R., and Tervaniemi, M. (2007). Psychosocial stress attenuates general sound processing and duration change detection. Psychophysiology 44, 30–38.10.1111/j.1469-8986.2006.00476.xSearch in Google Scholar
Smith, D.A., Boutros, N.N., and Schwarzkopf, S.B. (1994). Reliability of P50 auditory event-related potential indices of sensory gating. Psychophysiology 31, 495–502.10.1111/j.1469-8986.1994.tb01053.xSearch in Google Scholar
Starcke, K. and Brand, M. (2012). Decision making under stress: a selective review. Neurosci. Biobehav. Rev. 36, 1228–1248.10.1016/j.neubiorev.2012.02.003Search in Google Scholar
Stevens, K.E., Meltzer, J., and Rose, G.M. (1993). Disruption of sensory gating by the α2 selective noradrenergic antagonist yohimbine. Biol. Psychiatry 33, 130–132.10.1016/0006-3223(93)90313-3Search in Google Scholar
Streff, A., Kuehl, L.K., Michaux, G., and Anton, F. (2010). Differential physiological effects during tonic painful hand immersion tests using hot and ice water. Eur. J. Pain 14, 266–272.10.1016/j.ejpain.2009.05.011Search in Google Scholar PubMed
Trainor, L.J. and He, Ch. (2013). Auditory and musical development. P.R. Zelazo, eds. The Oxford Handbook of Developmental Psychology (New York, NY, USA: Oxford University Press), pp. 310–337.Search in Google Scholar
Velasco, M., Gomez, J., Blanco, M., and Rodriguez, I. (1997). The cold pressor test: pharmacological and therapeutic aspects. Am. J. Ther. 4, 34–38.10.1097/00045391-199701000-00008Search in Google Scholar PubMed
Wagenaar, O., Wieringa, M., and Verschuure, H. (2010). A cognitive model of tinnitus and hyperacusis; a clinical tool for patient information, appeasement and assessment. Int. Tinnitus J. 16, 66–72.Search in Google Scholar
Walia, L. and Ahuja, G.K. (2000). Effect of cold pressor test on visual reaction time and auditory reaction time. Indian J. Exp. Biol. 38, 831–833.Search in Google Scholar
White, P.M. and Yee, C.M. (1997). Effects of attentional and stressor manipulations on the P50 gating response. Psychophysiology 34, 703–711.10.1111/j.1469-8986.1997.tb02145.xSearch in Google Scholar PubMed
White, P.M., Kanazawa, A., and Yee, C.M. (2005). Gender and suppression of mid-latency ERP components during stress. Psychophysiology 42, 720–725.10.1111/j.1469-8986.2005.00365.xSearch in Google Scholar PubMed
Xiong, F. and Zhang, L. (2013). Role of the hypothalamic-pituitary-adrenal axis in developmental programming of health and disease. Front. Neuroendocrinol. 34, 27–46.10.1016/j.yfrne.2012.11.002Search in Google Scholar PubMed PubMed Central
Yee, C.M. and White, P.M. (2001). Experimental modification of P50 suppression. Psychophysiology 38, 531–539.10.1017/S0048577201981454Search in Google Scholar
©2017 Walter de Gruyter GmbH, Berlin/Boston