Discusses the nature of time, suggests a hierarchical model of human temporal experience, and proposes a new definition of consciousness.

There is evidence from neuropsychological and psychophysical measurements that conscious sensory information is processed in discrete time segments. The segmentation process may be described as neuronal activity at a frequency of 40 Hz. Stimulus-induced neuronal activities of this frequency are found in the middle latency range of the auditory evoked potential . First, we have studied the effects of different general anesthetics on MLAEP and auditory evoked 40-Hz activity. Second, we investigated MLAEP and explicit and implicit memory for information presented (...) during cardiac anesthesia. In the awake patients peak latencies of the MLAEP were in the normal range. An auditory evoked 40-Hz activity was present 20–100 ms poststimulus. Under nonspecific anesthetics MLAEP and the 40-Hz activity were suppressed, and under receptor-specific agents MLAEP and the 40-Hz activity were partly preserved. None of the cardiac patients had conscious explicit recall of the intraoperative events, whereas some patients showed unconscious implicit memory for an intraoperative tape message. The implicit memory could be related to midlatency auditory evoked potentials. No implicit memory was detectable when MLAEP and the primary cortical processing of the auditory stimuli and 40-Hz activity were blocked. Implicit memory could be detected in more than 50% of the cases when MLAEP, a 30-Hz activity, and the primary cortical stimulus processing were preserved. In conclusion, our observations support the view that a high frequency oscillatory mechanisms, recorded as a grouped neuronal activity in the MLAEP, may be part of a basic neuronal program for conscious sensory information processing. (shrink)

Contemporary psychiatry is becoming more biologically oriented in the attempt to elicit a biological rationale of mental diseases. Although mental disorders comprise mostly functional abnormalities, there is a substantial overlap between neurology and psychiatry in addressing cognitive disturbances. In schizophrenia, the presence of cognitive impairment prior to the onset of psychosis and early after its manifestation suggests that some neurocognitive abnormalities precede the onset of psychosis and may represent a trait marker. These cognitive alterations may arise from functional disconnectivity, as (...) no significant brain damage has been found. In this review we aim to revise A.R. Luria’s systematic approach used in the neuropsychological evaluation of cognitive functions, which was primarily applied in patients with neurological disorders and in the cognitive evaluation in schizophrenia and other related disorders. As proposed by Luria, cognitive processes, associated with higher cortical functions, may represent functional systems that are not localized in narrow, circumscribed areas of the brain, but occur among groups of concertedly working brain structures, each of which makes its own particular contribution to the organization of the functional system. Current developments in neuroscience provide evidence of functional connectivity in the brain. Therefore, Luria’s approach may serve as a frame of reference for the analysis and interpretation of cognitive functions in general and their abnormalities in schizophrenia in particular. Having said that, modern technology, as well as experimental evidence, may help us to understand the brain better and lead us towards creating a new classification of cognitive functions. In schizophrenia research, multidisciplinary approaches must be utilized to address specific cognitive alterations. The relationships among the components of cognitive functions derived from the functional connectivity of the brain may provide an insight into cognitive machinery. (shrink)

Using placebos in day-to-day practice is an ethical problem. This paper summarises the available epidemiological evidence to support this difficult decision. Based on these data we propose to differentiate between placebo and “knowledge framing”. While the use of placebo should be confined to experimental settings in clinical trials, knowledge framing — which is only conceptually different from placebo — is a desired, expected and necessary component of any doctor-patient encounter. Examples from daily practice demonstrate both, the need to investigate the (...) effects of knowledge framing and its impact on ethical, medical, economical and legal decisions. (shrink)

Using placebos in day-to-day practice is an ethical problem. This paper summarises the available epidemiological evidence to support this difficult decision. Based on these data we propose to differentiate between placebo and “knowledge framing”. While the use of placebo should be confined to experimental settings in clinical trials, knowledge framing — which is only conceptually different from placebo — is a desired, expected and necessary component of any doctor-patient encounter. Examples from daily practice demonstrate both, the need to investigate the (...) effects of knowledge framing and its impact on ethical, medical, economical and legal decisions. (shrink)

States of being conscious (S) can be defined on the basis of temporal information processing. A high-frequency mechanism provides atemporal system states with periods of approximately 30 msec to implement the functional connection of distributed activities allowing the construction of primordial events; a low frequency mechanism characterized by automatic temporal integration sets up temporal windows with approximately 3 seconds duration. This integration mechanism can be used to define S. P-consciousness and A-consciousness as conceived of by Block can be mapped onto (...) these neuronal mechanisms. (shrink)

Although Grodzinsky's target article has merit, it neglects the importance of neural mechanisms underlying language functions. We present results from our clinical studies on different levels of temporal information processing in aphasic patients and briefly review the existing data on neurobiology of language to cast new light on the main thesis of the target article.