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PW4-2 Human medial frontal cortex and value judgment
S88 Methods: We trained rhesus macaques (Macaca mulatta) to make choices between alternatives that differed in reward (magnitude and probability) or differed in the costs required to obtain reward (delay, physical effort). We simultaneously recorded the activity of neurons from ACC, OFC, lateral prefrontal cortex (LPFC) and the striatum while subjects made choices based on these variables. In a second series of studies, we made selective lesions of either the ACC or OFC and assessed pre- and postoperative performance on both reward-based and social-based decisionmaking tasks. Results: Neurophysiological results revealed decision-making selectivity was most prevalent in ACC, where 84% of neurons encoded decision value for manipulations of either reward or physical cost, followed by OFC (56%) and LPFC (49%). Many ACC neurons (but few OFC or LPFC neurons) also encoded a reward prediction error signal. Selective lesions of either ACC or OFC caused severe, but separable, reward-based decision-making deficits. Notably, deficits on social decision-making tasks were most apparent following ACC damage. Conclusions: These results highlight the importance of the medial frontal cortex, in particular areas of ACC, in representing the value of different types of decisions, suggesting this region may serve as a common valuation system for both reward-based and social-based decisions. PW4-2 Human medial frontal cortex and value judgment R.J. Seitz1 1 Department of Neurology, Heinrich-Heine-University Dusseldorf, Dusseldorf, Germany Objective: Humans act in response to emotions which are observed in other people and judged as subjectively relevant. Such value judgments are of great interest for understanding how people control their actions and interact in social situations. Methods: Recent findings in neurophysiology and functional neuroimaging will be presented addressing the question which brain areas are engaged in the communication, e.g. expression and perception, of emotions. Results: When humans were required to appraise emotional face expressions, the medial frontal cortex became engaged along with activation of the left inferior frontal cortex. These changes occurred as early as 150 ms following the presentation. A closely adjacent region in the medial frontal and adjacent anterior cingulate cortex was activated by imagining the pain observed in someone else as one’s own experience. The activation of the medial frontal cortex was found to be modulated by gender, cross cultural stimulation and alexithymic disorders revealing the subjective character of empathy. When humans were confronted with emotional gestures of positive or negative valence, the left inferior frontal, middle temporal and medial frontal cortex became activated. In contrast to this pattern reflecting the perspective of the addressee, mental imagery of generating the same emblematic gestures involved only the inferior frontal and middle temporal cortex as did the perception of meaningless gestures. These findings agree with the notion that the human mirror-neuron circuitry mediates non-verbal communication. Conclusions: It is suggested that the medial frontal cortex comprises multiple differentiated representations subserving the egocentric default perspective which is a fundamental attribute of the important, though long neglected human valuation system. PW4-3 Role of the medial frontal cortex in communication R. Kawashima1 1 SAIRC, IDAC, Tohoku University, Japan The medial frontal cortex (MFC) is known to be a member of neural correlates involved in the theory of mind, or mentalization (Frith and Frith, 2003; Gallagher and Frith, 2003). In our previous investigations, we found this area is also activated during communicative speech production (Sassa et al., 2007) and explicit monitoring of general situational relationships (Wakusawa et al., 2009), which indicates the MFC plays a role in processing social signals. In addition, from the results of these studies, we identified anatomically and functionally distinct two areas in the MFC, one in the polar, another in the dorsal parts. The dorsal part was commonly activated in both studies. In the former study, this part was more activated during a communication task than during a description task. In the later study, the same part was more activated during situation tasks when compared with physical tasks. Together with the results of previous human and animal studies, our results suggest a role for the
Oral Presentations: Proposed Workshops dorsal part of the MFC in understanding the context of social interaction, which is essential for communication. On the other hand, in the former study, the activation of the polar part during the communication task was greater for familiar than for unfamiliar actors. This interaction of personal familiarity and the communication task may be explained by the increased load of processing the social interaction caused by the larger amount of biological information that must be integrated into the social context when a familiar person is involved. PW5. Neuronal oscillations in multi-scale brain networks PW5-1 The role of neuronal oscillations in local computation and long-range communication R.T. Canolty1 , K. Ganguly1 , R.T. Knight1 , J.M. Carmena1 1 Helen Wills Neuroscience Institute, University of California, Berkeley, USA Neuronal oscillations appear to influence both local cortical computation as well as long-range communication between brain regions. However, the role of oscillations in coordinating the large-scale brain networks that underlie perception, cognition, and action remains unclear. To address this issue, we investigated two related questions using data from both humans and macaques. First, what is the relationship between oscillatory dynamics and global functional operations such as language comprehension and attention? The subdural electrocorticogram (ECoG) was recorded while human neurosurgical patients performed an auditory linguistic target-detection task in order to identify spatiotemporal ECoG signatures associated with local cortical activation and network engagement. Second, how do changes in neuronal oscillations interact with the spiking activity of single neurons and cell assemblies? We examined multichannel spike and local field potential (LFP) data recorded from multiple areas in macaques engaged in a motor control task in order to determine the patterns of spiking activity associated with largescale patterns of LFP phase coupling. In general, our results support the method of (1) identifying functional network nodes via localized changes in high-frequency activity, (2) investigating the effective connectivity between nodes via low frequency phase coherence, and (3) inferring probable spike patterns based on predictions from field potential activity. This approach clarifies the spatial and temporal evolution of cortical activity associated with complex perception and action, and is consistent with the hypothesis that an oscillatory hierarchy coordinates the flow of information between distinct cortical regions during goal-directed behavior. PW5-2 Shifts in gamma phase-amplitude coupling frequency from theta to alpha over posterior cortex during visual tasks B. Voytek1 , R.T. Canolty1,2 , A. Shestyuk1 , N.E. Crone4 , J. Parvizi5 , R.T. Knight1,3 1 Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, USA, 2 Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California, USA, 3 Department of Psychology, University of California, Berkeley, Berkeley, California, USA, 4 Department of Neurology, The Johns Hopkins Hospital, Baltimore, Maryland, USA, 5 Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA The phase of ongoing theta (4 8 Hz) and alpha (8 12 Hz) electrophysiological oscillations is coupled to high gamma (80 150 Hz) power, which suggests that low frequency oscillations modulate local cortical activity. While this phase-amplitude coupling (PAC) has been demonstrated in a variety of tasks and cortical regions, it has not been shown within a single subject whether behavioral state affects the preferred coupling frequency that modulates gamma. Thus we investigated multiple-rhythm PAC in two subjects with implanted subdural electrocorticographic grids. We show that gamma power couples to the theta and alpha troughs and that, during visual tasks, alpha/gamma coupling preferentially increases in visual cortical regions. These results suggest that low-frequency phase to high-frequency power PAC is modulated by behavioral task and may reflect a mechanism for selection between communicating neuronal networks.
Oral Presentations: Proposed Workshops dorsal part of the MFC in understanding the context of social interaction, which is essential for communication. On the other hand, in the former study, the activation of the polar part during the communication task was greater for familiar than for unfamiliar actors. This interaction of personal familiarity and the communication task may be explained by the increased load of processing the social interaction caused by the larger amount of biological information that must be integrated into the social context when a familiar person is involved. PW5. Neuronal oscillations in multi-scale brain networks PW5-1 The role of neuronal oscillations in local computation and long-range communication R.T. Canolty1 , K. Ganguly1 , R.T. Knight1 , J.M. Carmena1 1 Helen Wills Neuroscience Institute, University of California, Berkeley, USA Neuronal oscillations appear to influence both local cortical computation as well as long-range communication between brain regions. However, the role of oscillations in coordinating the large-scale brain networks that underlie perception, cognition, and action remains unclear. To address this issue, we investigated two related questions using data from both humans and macaques. First, what is the relationship between oscillatory dynamics and global functional operations such as language comprehension and attention? The subdural electrocorticogram (ECoG) was recorded while human neurosurgical patients performed an auditory linguistic target-detection task in order to identify spatiotemporal ECoG signatures associated with local cortical activation and network engagement. Second, how do changes in neuronal oscillations interact with the spiking activity of single neurons and cell assemblies? We examined multichannel spike and local field potential (LFP) data recorded from multiple areas in macaques engaged in a motor control task in order to determine the patterns of spiking activity associated with largescale patterns of LFP phase coupling. In general, our results support the method of (1) identifying functional network nodes via localized changes in high-frequency activity, (2) investigating the effective connectivity between nodes via low frequency phase coherence, and (3) inferring probable spike patterns based on predictions from field potential activity. This approach clarifies the spatial and temporal evolution of cortical activity associated with complex perception and action, and is consistent with the hypothesis that an oscillatory hierarchy coordinates the flow of information between distinct cortical regions during goal-directed behavior. PW5-2 Shifts in gamma phase-amplitude coupling frequency from theta to alpha over posterior cortex during visual tasks B. Voytek1 , R.T. Canolty1,2 , A. Shestyuk1 , N.E. Crone4 , J. Parvizi5 , R.T. Knight1,3 1 Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California, USA, 2 Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California, USA, 3 Department of Psychology, University of California, Berkeley, Berkeley, California, USA, 4 Department of Neurology, The Johns Hopkins Hospital, Baltimore, Maryland, USA, 5 Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA The phase of ongoing theta (4 8 Hz) and alpha (8 12 Hz) electrophysiological oscillations is coupled to high gamma (80 150 Hz) power, which suggests that low frequency oscillations modulate local cortical activity. While this phase-amplitude coupling (PAC) has been demonstrated in a variety of tasks and cortical regions, it has not been shown within a single subject whether behavioral state affects the preferred coupling frequency that modulates gamma. Thus we investigated multiple-rhythm PAC in two subjects with implanted subdural electrocorticographic grids. We show that gamma power couples to the theta and alpha troughs and that, during visual tasks, alpha/gamma coupling preferentially increases in visual cortical regions. These results suggest that low-frequency phase to high-frequency power PAC is modulated by behavioral task and may reflect a mechanism for selection between communicating neuronal networks.