PubMed Health⌕ Search

Biomedical subjects

Georg Northoff

Publications and source records attributed to Georg Northoff.

At least 19 recordsLinked to original sources
PubMed2006

First-Person Neuroscience: a new methodological approach for linking mental and neuronal states.

Though the brain and its neuronal states have been investigated extensively, the neural correlates of mental states remain to be determined. Since mental states are experienced in first-person perspective and neuronal states are observed in third-person perspective, a special method must be developed for linking both states and their respective perspectives. We suggest that such method is provided by First-Person Neuroscience. What is First-Person Neuroscience? We define First-Person Neuroscience as investigation of neuronal states under guidance of and on orientation to mental states. An empirical example of such methodological approach is demonstrated by an fMRI study on emotions. It is shown that third- and first-person analysis of data yield different results. First-person analysis reveals neural activity in cortical midline structures during subjective emotional experience. Based on these and other results neural processing in cortical midline structures is hypothesized to be crucially involved in generating mental states. Such direct linkage between first- and third-person approaches to analysis of neural data allows insight into the "point of view from within the brain", that is what we call the First-Brain Perspective. In conclusion, First-Person Neuroscience and First-Brain Perspective provide valuable methodological tools for revealing the neuronal correlate of mental states.

Journal Article↗
PubMed2006

Self-referential processing in our brain--a meta-analysis of imaging studies on the self.

The question of the self has intrigued philosophers and psychologists for a long time. More recently, distinct concepts of self have also been suggested in neuroscience. However, the exact relationship between these concepts and neural processing across different brain regions remains unclear. This article reviews neuroimaging studies comparing neural correlates during processing of stimuli related to the self with those of non-self-referential stimuli. All studies revealed activation in the medial regions of our brains' cortex during self-related stimuli. The activation in these so-called cortical midline structures (CMS) occurred across all functional domains (e.g., verbal, spatial, emotional, and facial). Cluster and factor analyses indicate functional specialization into ventral, dorsal, and posterior CMS remaining independent of domains. Taken together, our results suggest that self-referential processing is mediated by cortical midline structures. Since the CMS are densely and reciprocally connected to subcortical midline regions, we advocate an integrated cortical-subcortical midline system underlying human self. We conclude that self-referential processing in CMS constitutes the core of our self and is critical for elaborating experiential feelings of self, uniting several distinct concepts evident in current neuroscience.

Attention↗
PubMed2006

Affective judgment and beneficial decision making: ventromedial prefrontal activity correlates with performance in the Iowa Gambling Task.

Damasio proposes in his somatic marker theory that not only cognitive but also affective components are critical for decision making. Since affective judgment requires an interplay between affective and cognitive components, it might be considered a key process in decision making that has been linked to neural activity in ventromedial prefrontal cortex (VMPFC). Using functional magnetic resonance imaging (fMRI), we examined the relationship between VMPFC, emotionally (unexpected)- and cognitively (expected)-accentuated affective judgment, and beneficial decision making (Iowa Gambling Task; IGT) in healthy subjects. Neuronal activity in the VMPFC during unexpected affective judgment significantly correlated with both global and final performance in the IGT task. These findings suggest that the degree to which subjects recruit the VMPFC during affective judgment is related to beneficial performance in decision making in gambling.

Adult↗
PubMed2006

Attentional modulation of emotional stimulus processing: an fMRI study using emotional expectancy.

We used emotional expectancy to study attentional modulation in the processing of emotional stimuli. During functional magnetic resonance imaging (fMRI), volunteers saw emotional and neutral expectancy cues signaling the subsequent presentation of corresponding emotional or neutral pictorial stimuli. As a control, emotional and neutral pictures were presented without preceding expectancy cue, resulting in a 2 x 2 factorial design with the factors "expectancy" and "emotion." Statistical analysis revealed a significant positive interaction effect between these factors in the medial prefrontal cortex (MPFC, Brodmann area [BA] 9/10), amygdala, and dorsal midbrain. In all these regions, expectancy augmented the neural response to emotional but not to neutral pictures. Time course analysis of raw data suggests that this augmented activation was not preceded by baseline increases in MPFC and amygdala during the period of emotional expectancy. In a post-scanning session, the paradigm was presented for a second time to allow emotional intensity rating. Again, a significant interaction between expectancy and emotion was observed, with intensity ratings specifically enhanced in emotional photographs preceded by expectancy. There was a positive correlation between intensity ratings and blood oxygenation level-dependent (BOLD) signals in the left amygdala. We conclude that specific components of the emotion network show enhanced activation in response to emotional stimuli when these are preceded by expectancy. This enhancement effect is not present in neutral pictures and might parallel accentuated subjective feeling states.

Adult↗
PubMed2006

Neuroscience of decision making and informed consent: an investigation in neuroethics.

Progress in neuroscience will allow us to reveal the neuronal correlates of psychological processes involved in ethically relevant notions such as informed consent. Informed consent involves decision making, the psychological and neural processes of which have been investigated extensively in neuroscience. The neuroscience of decision making may be able to contribute to an ethics of informed consent by providing empirical and thus descriptive criteria. Since, however, descriptive criteria must be distinguished from normative criteria, the neuroscience of decision making cannot replace the ethics of informed consent. Instead, the neuroscience of decision making could complement the current ethics, resulting in what can be called neuroethics of informed consent. It is concluded that current progress in the neurosciences could complement and change the way in which we approach ethical problems in neuropsychiatry.

Bioethical Issues↗
PubMed2005

Effect of low-frequency transcranial magnetic stimulation on an affective go/no-go task in patients with major depression: role of stimulation site and depression severity.

Repetitive transcranial magnetic stimulation (rTMS) holds promise as a therapeutic tool in major depression. However, a means to assess the effects of a single rTMS session on mood to guide subsequent sessions would be desirable. The present study examined the effects of a single rTMS session on an affective go/no-go task known to measure emotional-cognitive deficits associated with major depression. Ten patients with an acute episode of unipolar major depression and eight partially or completely remitted (improved) patients underwent 1 Hz rTMS over the left and right dorsolateral prefrontal cortex prior to task performance. TMS over the mesial occipital cortex was used as a control. We observed significantly improved performance in depressed patients following right prefrontal rTMS. This beneficial effect declined with decreasing depression severity and tended to reverse in the improved group. Left prefrontal rTMS had no significant effect in the depressed group, but it resulted in impaired task performance in the improved group. Our findings indicate that the acute response of depressed patients to rTMS varies with the stimulation site and depression severity. Further studies are needed to determine whether the present paradigm could be used to predict antidepressant treatment success or to individualize stimulation parameters according to specific pathology.

Antidepressive Agents↗
PubMed2005

Volume and neuron number of the mediodorsal thalamic nucleus in schizophrenia: a replication study.

Previous neuropathological studies on the mediodorsal thalamic nucleus (MD) in schizophrenia have yielded conflicting results. While some studies suggested that patients with schizophrenia have a pronounced reduction of the volume and neuron number in the MD, more recent data have not found anatomical alterations in this thalamic nucleus. However, most studies have considerable methodological shortcomings. In the present study, we investigated the volume, neuron density and neuron number in the left and right MD in patients with schizophrenia (n=20) and normal control subjects without neuropsychiatric disorders (n=18). Patients with schizophrenia showed no significant difference in neuron density and total neuron number in the MD. Compared with the control group, patients with schizophrenia had a smaller MD volume in both hemispheres, a difference that approached significance in the left MD (-7.3%) when the whole brain volume was included as a covariate. No significant main group effect of diagnosis was found for the right MD volume. There were no significant correlations between MD volume, neuron density, total neuron number and the duration of illness or the age of the patients. Taken together, the present results suggest that schizophrenia is associated with a moderate volume reduction in the left mediodorsal thalamic nucleus, while the neuron density and the total neuron number are unchanged.

Adult↗
PubMed2005

Dissociable networks for the expectancy and perception of emotional stimuli in the human brain.

William James posited that comparable brain regions were implicated in the anticipation and perception of a stimulus; however, dissociable networks (at least in part) may also underlie these processes. Recent functional neuroimaging studies have addressed this issue by comparing brain systems associated with the expectancy and perception of visual, tactile, nociceptive, and reward stimuli. In the present fMRI study, we addressed this issue in the domain of pictorial emotional stimuli (IAPS). Our paradigm involved the experimental conditions emotional expectancy, neutral expectancy, emotional picture perception, and neutral picture perception. Specifically, the emotional expectancy cue was uncertain in that it did not provide additional information regarding the positive or negative valence of the subsequent picture. Neutral expectancy and neutral picture perception served as control conditions, allowing the identification of expectancy and perception effects specific for emotion processing. To avoid contamination of the perception conditions by the preceding expectancy periods, 50% of the pictorial stimuli were presented without preceding expectancy cues. We found that the emotional expectancy cue specifically produced activation in the supracallosal anterior cingulate, cingulate motor area, and parieto-occipital sulcus. These regions were not significantly activated by emotional picture perception which recruited a different neuronal network, including the amygdala, insula, medial and lateral prefrontal cortex, cerebellum, and occipitotemporal areas. This dissociation may reflect a distinction between anticipatory and perceptive components of emotional stimulus processing.

Adult↗
PubMed2005

Segregated neural representation of distinct emotion dimensions in the prefrontal cortex-an fMRI study.

Emotions are frequently characterized by distinct dimensions such as valence, intensity, and recognition. However, the exact neural representation of these dimensions in different prefrontal cortical regions remains unclear. One of the problems in revealing prefrontal cortical representation is that the very same regions are also involved in cognitive functions associated with emotion processing. We therefore conducted an fMRI study involving the viewing of emotional pictures (using the International Affective Picture System; IAPS) and controlled for associated cognitive processing like judgment and preceding attention. Functional activation was correlated with subjective post-scanning ratings of valence, intensity, and recognition. Valence significantly correlated with the functional response in ventromedial prefrontal cortex (VMPFC) and dorsolateral prefrontal cortex (DLPFC), intensity with activation in ventrolateral prefrontal cortex (VLPFC) and dorsomedial prefrontal cortex (DMPFC), and recognition with the functional response in perigenual anterior cingulate cortex (PACC). In conclusion, our results indicate segregated neural representation of the different emotion dimensions in different prefrontal cortical regions.

Adult↗
PubMed2005

Left prefrontal repetitive transcranial magnetic stimulation impairs performance in affective go/no-go task.

Functional neuroimaging studies have associated affective go/no-go function with lateral prefrontal activation, but they have not established a causal role and have not determined whether one hemisphere is predominantly engaged. In the present study, 11 normal volunteers underwent slow repetitive transcranial magnetic stimulation of the left and right dorsolateral prefrontal cortex, and the occipital cortex prior to performance of a picture-based affective go/no-go task. We found an interfering effect of left prefrontal repetitive transcranial magnetic stimulation compared with both right prefrontal and occipital repetitive transcranial magnetic stimulation. This impairment concerned positive and negative task stimuli to a similar extent, and tended to be greater in shift compared with nonshift blocks. Our findings demonstrate a functionally relevant lateralization of the prefrontal contribution to affective go/no-go tasks.

Adult↗
PubMed2005

Deficit in decision making in catatonic schizophrenia: an exploratory study.

Catatonic schizophrenia can be distinguished from paranoid schizophrenia by prominent behavioral and motor anomalies. As demonstrated in recent imaging studies, behavioral symptoms may be related to dysfunction in the ventral prefrontal cortex. However, the neuropsychological correlates of ventral prefrontal cortical dysfunction remain unclear. In an exploratory study, we investigated eight patients with catatonic schizophrenia and compared them with 19 patients with paranoid schizophrenia and 26 healthy subjects. The Iowa Gambling Task (IGT) and the Object Alternation Task (OAT) served as measures of ventral prefrontal cortical function. In addition, other prefrontal cortical tests such as a visual working memory task, a Go-NoGo task, and the Wisconsin Card Sorting Test, as well as attentional tasks, were included in the test battery. Catatonic patients showed significant deficits in the IGT characterized by an inability to shift from the initial preference for high-risk cards to a more advantageous strategy with low-risk cards. Moreover, catatonic patients showed significant deficits in the OAT. In conclusion, our preliminary results suggest a specific deficit in catatonic schizophrenia in those neuropsychological measures that are associated with ventral prefrontal cortical function.

Adult↗
PubMed2005

NMDA hypofunction in the posterior cingulate as a model for schizophrenia: an exploratory ketamine administration study in fMRI.

BACKGROUND: Based on animal data, NMDA receptor hypofunction has been suggested as a model for positive symptoms in schizophrenia. NMDA receptor hypofunction affects several corticolimbic brain regions, of which the posterior cingulate seems to be the most sensitive. However, empirical support for a crucial role of posterior cingulate NMDA hypofunction in the pathophysiology of positive symptoms is still missing in humans. We therefore conducted an fMRI study using the NMDA antagonist ketamine in healthy human subjects during episodic memory retrieval, which is supposed to activate the posterior cingulate. METHODS: We investigated 16 healthy subjects which were assigned to either placebo (n = 7; saline) or ketamine (n = 9; 0.6 mg/kg/h) group in a double-blind study design. All subjects received their infusion while performing an episodic memory retrieval task in the scanner. Immediately after the fMRI session, psychopathological effects of ketamine were measured using the Altered States of Consciousness Questionnaire. RESULTS: The placebo group showed BOLD signal increases in the posterior and anterior cingulate during retrieval. Signal increases were significantly lower in the ketamine group. Lower signal increases in the posterior cingulate correlated significantly with positive (i.e. psychosis-like) symptoms induced by ketamine. CONCLUSION: The present study for the first time demonstrates a relationship between NMDA receptors, posterior cingulate and positive (i.e. psychosis-like) symptoms in humans. Confirming findings from animal studies, it supports the hypothesis of a pathophysiological role of NMDA receptor hypofunction in the posterior cingulate in schizophrenia.

Adult↗
PubMed2005

How do we modulate our emotions? Parametric fMRI reveals cortical midline structures as regions specifically involved in the processing of emotional valences.

One of the major problems in affective neuroscience of healthy subjects as well as of patients with emotional dysfunctions is to disentangle emotional core functions and non-emotional processes. Emotional valence is considered an emotional key process. The present study employed a parametric functional magnetic resonance imaging (fMRI) study to address this question. Thirteen healthy volunteers were scanned during emotional stimulus processing (International Affective Picture System). The presented pictures covered the entire range of emotional valences. The fMRI data were consecutively subjected to a preliminary categorical (valence-independent) and a detailed parametric analysis, the latter using individual valence ratings as regressor. The parametric analysis revealed a linear valence-dependent modulation of the BOLD signal in the orbito- and dorsomedial prefrontal cortex (OMPFC, DMPFC), medial parietal cortex (MPC), and insula. In addition, we observed that emotional valence exerts its effects predominantly via modulation of signal decreases. We conclude that the psychological concept of emotional valence may be related to neural processing in cortical midline regions.

Adult↗
PubMed2004

Reciprocal modulation and attenuation in the prefrontal cortex: an fMRI study on emotional-cognitive interaction.

Everyday and clinical experience demonstrate strong interactions between emotions and cognitions. Nevertheless the neural correlates underlying emotional-cognitive interaction remain unclear. Using event-related fMRI, we investigated BOLD-signal increases and decreases in medial and lateral prefrontal cortical regions during emotional and non-emotional judgment of photographs taken from the International Affective Picture System (IAPS). Emotional and non-emotional judgment conditions were compared to each other as well as with baseline allowing for distinction between relative signal changes (comparison between conditions) and true signal changes (referring to baseline). We have found that: (1) both emotional and non-emotional judgment of IAPS pictures were characterized by signal increases in ventrally and dorsally located lateral prefrontal cortical areas and concurrent signal decreases in ventro- and dorsomedial prefrontal cortex; (2) direct comparison between emotional and non-emotional judgment showed relative signal increases in ventro- and dorsomedial prefrontal cortex, and in contrast, relative signal increases were detected in ventrally and dorsally located lateral prefrontal cortical areas when comparing non-emotional to emotional judgment; and (3) as shown in separate comparisons with baseline, these relative signal changes were due to smaller signal decreases in ventro- and dorsomedial prefrontal cortex and smaller signal increases in ventrally and dorsally located lateral prefrontal cortical areas during emotional judgment. Therefore, the emotional load of a cognitive task lead to both less deactivation of medial prefrontal regions and, at the same time, less activation of lateral prefrontal regions. Analogous patterns of reciprocal modulation and attenuation have previously been described for other cortical regions such as visual and auditory areas. Reciprocal modulation and attenuation in medial and lateral prefrontal cortex might constitute the neurophysiologic basis for emotional-cognitive interaction as observed in both healthy and psychiatric subjects.

Adult↗
PubMed2004

Cortical midline structures and the self.

For a long time philosophers and psychologists have been intrigued by the question of the self. More recently, this has become a topic of discussion in neuroscience. In this article, we suggest that the processing of self-referential stimuli in cortical midline structures (CMS) is a fundamental component in generating a model of the self. Drawing from neuroimaging studies, we distinguish between representation, monitoring, evaluation and integration of self-referential stimuli. All of these subfunctions are related to distinct regions within the CMS. This relationship between self-referential processing and CMS might provide novel insight into the neural correlates underlying the constitution of the self.

Awareness↗
PubMed2004

Orbitofrontal cortical dysfunction in akinetic catatonia: a functional magnetic resonance imaging study during negative emotional stimulation.

Catatonia is a psychomotor syndrome characterized by concurrent emotional, behavioral, and motor anomalies. Pathophysiological mechanisms of psychomotor disturbances may be related to abnormal emotional-motor processing in prefrontal cortical networks. We therefore investigated prefrontal cortical activation and connectivity patterns during emotional-motor stimulation using functional magnetic resonance imaging (FMRI). We investigated 10 akinetic catatonic patients in a postacute state and compared them with 10 noncatatonic postacute psychiatric controls (age-, sex-, diagnosis-, and medication-matched) and 10 healthy controls. Positive and negative pictures from the International Affective Picture System were used for emotional stimulation. FMRI measurements covered the whole frontal lobe, activation signals in various frontal cortical regions were obtained, and functional connectivity between the different prefrontal cortical regions was investigated using structural equation modeling. Catatonic patients showed alterations in the orbitofrontal cortical activation pattern and in functional connectivity to the premotor cortex in negative and positive emotions compared to psychiatric and healthy controls. Catatonic behavioral and affective symptoms correlated significantly with orbitofrontal activity, whereas catatonic motor symptoms were rather related to medial prefrontal activity. It is concluded that catatonic symptoms may be closely related to dysfunction in the orbitofrontal cortex and consequent alteration in the prefrontal cortical network during emotional processing. Because we investigated postacute patients, orbitofrontal cortical alterations may be interpreted as a trait marker predisposing for development of catatonic syndrome in schizophrenic or affective psychosis.

Acute Disease↗