Prefrontal Cortex Responses to Conflicting Information

Prefrontal cortical unit activity and delayed alternation performance in monkeys.

Top-Down Control-Signal Dynamics in Anterior Cingulate and Prefrontal Cortex Neurons following Task Switching

Closing the Gate in the Limbic Striatum: Prefrontal Suppression of Hippocampal and Thalamic Inputs

Learning Substrates in the Primate Prefrontal Cortex and Striatum: Sustained Activity Related to Successful Actions

Searching for “the Top” in Top-Down Control

Activity in the Lateral Prefrontal Cortex Reflects Multiple Steps of Future Events in Action Plans

Background: In order to evaluate usefulness of a time-resolved spectroscopy (TRS) in screening test of cognitive dysfunction, we studied the effects of aging, cognitive dysfunction, brain atrophy on hemoglobin (Hb) concentrations and optical pathlengths (OPLs) in the prefrontal cortex (PFC) at rest, using TRS. Methods: Employing TRS, we measured Hb concentrations and OPLs at rest in the PFC, and evaluated the relationship between the TRS parameters and cognitive function assessed by Mini-Mental State Examination (MMSE). In addition, we evaluated the relationship between the TRS parameters and the brain atrophy assessed by MRI. Results: We found positive correlations between MMSE scores and oxygen saturation (SO2), oxy-Hb in the PFC, suggesting that the greater the degree of PFC activity, the higher the cognitive function. In addition, we found the negative correlation between the subject’s age and SO2 and oxy-Hb in the PFC, suggesting that the older the subject, the lower the PFC activity at rest. Moreover, the OPLs in the right PFC negatively correlated with degree of brain atrophy evaluated by MRI, indicating that the shorter the OPL, greater degree of brain atrophy. Conclusions: TRS allowed us to evaluate the relation between the cerebral blood oxygenation (CBO) in the PFC at rest and cognitive function.

Event Abstract Back to Event Localizing the origin of executive control over distributed processing to prefrontal cortex Human cognition and behavior are characterized by flexibility. A fixed pattern of sensory input can evoke innumerable actions, depending on which goals or strategies the brain has engaged. The consensus is that prefrontal cortex is essential to this computational flexibility, but the neural mechanisms responsible are not fully understood. To address this question, we trained a monkey to flexibly assign visual stimuli to different spatial categories according to a variable grouping criterion that altered how categories were defined across trials. We then used dual, depth adjustable 16 microelectrode arrays to simultaneously record neural activity in parietal (309 neurons) and prefrontal (427 neurons) cortex during task performance. In this task, we presented a line that divided the display area into two regions. Each region comprised a spatial category containing a set of positions having the same spatial relationship to the category boundary. For example, when the category boundary was vertical, it divided the display area into the categories 'left' and 'right'. When the boundary was horizontal, it re-parsed the same set of spatial positions into the spatial categories 'above' and 'below'. By changing the orientation of the category boundary we required the brain to remap one set of spatial positions to alternative spatial categories according to a variable rule, placing spatial cognition under executive control. This enabled us to isolate neural signals coding spatial position and spatial category, as well as examine how these signals were modulated as a function of the rule mapping positions to categories. The first question we wished to answer was whether some neurons coded spatial category independently of spatial position. We found that the activity of significantly more neurons in prefrontal cortex (27% of task-related neurons) than parietal cortex (11% of task-related neurons) coded the spatial category of the stimulus independently of its spatial position. This suggested that the neural representation of category was more fully abstracted from stimulus feature information in prefrontal than in parietal cortex. The second question we wished to answer was where neural activity coding category was first or most strongly modulated by the rule in effect, in order to localize the origin of executive control in the network. For that purpose we applied linear discriminant analysis to decode spatial position, spatial rule, and spatial category (defined by the interaction between rule and position) from successive 50 ms bins of neural population activity in prefrontal and parietal cortex. We found that both parietal and prefrontal neurons sustained representations of category that exhibited rule-dependence (and therefore reflected executive control), but that signals coding category in prefrontal cortex were more powerfully modulated by the rule at earlier times in the trial. This is consistent with prefrontal cortex being the origin of executive control over distributed spatial cognitive processing mediated by the parietal-prefrontal network. Conference: Computational and systems neuroscience 2009, Salt Lake City, UT, United States, 26 Feb - 3 Mar, 2009. Presentation Type: Poster and Short Oral Presentation Topic: Poster and Short Oral Presentations Citation: (2009). Localizing the origin of executive control over distributed processing to prefrontal cortex. Front. Syst. Neurosci. Conference Abstract: Computational and systems neuroscience 2009. doi: 10.3389/conf.neuro.06.2009.03.226 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 03 Feb 2009; Published Online: 03 Feb 2009. Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Google Google Scholar PubMed Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

If I do A, B will happen: Dissecting circuits detecting causal relations between actions and outcomes in marmoset prefrontal cortex

To examine functional interactions between prefrontal and medial temporal brain areas during face memory, blood flow was measured in patients with Alzheimer's disease and healthy controls using PET. We hypothesized that controls would show correlated activity between frontal and posterior brain areas, including the medial temporal cortex, whereas patients would not, although frontal activity per se might be spared or even increased compared with controls. We used a delayed match to sample paradigm with delays from 1 to 16 s. There was no change in recognition accuracy with increasing delay in controls, whereas patients showed impaired recognition over all delays that worsened as delay increased. Controls showed increased activity in the bilateral prefrontal and parietal cortex with increasing delay, whereas the patients had increased activity in the right prefrontal, anterior cingulate and left amygdala. Increased activity in the right prefrontal cortex was associated with better memory performance in both groups and activity in the left amygdala was correlated with better performance in the patients. Based on these task and behavioural effects, we examined functional connectivity of the right prefrontal cortex and left amygdala in both groups by determining those areas whose activity was correlated with activity in these regions. In controls, activity in the right prefrontal cortex was positively correlated with blood flow in the left prefrontal cortex, bilateral extrastriate and parietal areas and the right hippocampus. In patients, activity in the right prefrontal cortex was correlated mainly with other prefrontal regions. Areas where activity was correlated with the left amygdala in patients included the bilateral posterior parahippocampal gyri, a number of left prefrontal regions, anterior and posterior cingulate, thalamus, and insula. Controls had a relatively restricted set of regions where activity correlated with the left amygdala, mainly temporal and occipital areas. These results support the idea of a functional disconnection between the prefrontal cortex and the hippocampus in Alzheimer's disease and suggest that memory breakdown in early Alzheimer's disease is related to a reduction in the integrated activity within a distributed network that includes these two areas. The unexpected finding of increased involvement of the amygdala suggests that the patients may have processed the emotional content of the faces to a greater degree than did the controls. Furthermore, the positive association between amygdala activity and memory performance in the patients suggests a possible compensatory role for an emotion-related network of regions.

ObjectivesThis study examined prefrontal cortex (PFC) activation during dual-task seated stepping and walking performed by subacute stroke patients with hemiplegia and evaluated the relationship between PFC activation, frontal lobe functions, and dual-task interference.MethodsPatients with functional ambulation category (FAC) scores ≤ 2 comprised the seated stepping task group. Those with FAC scores > 2 comprised the walking task group. There were 11 patients in the seated stepping task group (mean age, 65.3±12.2 years; age range, 55-73.5 years; 7 male and 4 female patients; time since stroke onset, 45.7±9.9 days) and 11 patients in the walking task group (mean age, 65.6±15.2 years; age range, 49.5-74.5 years; 7 male and 4 female patients; time since stroke onset, 57.5±18.3 days). Both groups completed the Frontal Assessment Battery (FAB). The seated stepping task group performed the following three tasks: cognitive task (CT), normal seated stepping (NSS), and dual-task seated stepping (DTSS). The walking task group completed the following tasks: CT, normal walking (NW), and dual-task walking (DTW). The CT was a letter fluency task; this letter fluency task was simultaneously performed during seated stepping (DTSS) and walking (DTW). Changes in the oxygenated hemoglobin (O2Hb) concentration and deoxygenated hemoglobin concentration during the tasks were measured using near-infrared spectroscopy (Pocket NIRS HM; Dynasense Inc., Japan). The number of steps, walking speed, and percentage of correct responses to the CT were recorded.ResultsThe results showed that DTSS activated the PFC significantly more than performing a single task and that NSS was associated with a significantly higher difference in the hemoglobin concentration when compared to that associated with the CT, which was a single task. In the walking task group, PFC activation was significantly higher during DTW, NW, and CT (in that order), and O2Hb concentrations were significantly higher in the contralesional hemisphere than in the ipsilesional hemisphere during all tasks. Associations between PFC activation, FAB scores, and dual-task interference in the seated task group indicated significant positive correlations between FAB scores and cognitive performance with dual-task interference.ConclusionDTSS may be an effective means of activating the PFC of patients with difficulty walking.

The functional organization of human primary visual and auditory cortices is influenced by sensory experience and exhibits cross-modal plasticity in the absence of input from one modality. However, it remains debated whether the functional architecture of the prefrontal cortex, when engaged in social cognitive processes, is shaped by sensory experience. The present study investigated whether activity in the medial prefrontal cortex underlying self-reflective thinking of one's own traits is modality-specific and whether it undergoes cross-modal plasticity in the absence of visual input. We scanned 47 sighted participants and 21 congenitally blind individuals using functional magnetic resonance imaging during trait judgements of the self and a familiar other. Sighted participants showed medial prefrontal activation and enhanced functional connectivity between the medial prefrontal and visual cortices during self-judgements compared to other-judgements on visually but not aurally presented trait words, indicating that medial prefrontal activity underlying self-representation is visual modality-specific in sighted people. In contrast, blind individuals showed medial prefrontal activation and enhanced functional connectivity between the medial prefrontal and occipital cortices during self-judgements relative to other-judgements on aurally presented stimuli, suggesting that visual deprivation leads to functional reorganization of the medial prefrontal cortex so as to be tuned by auditory inputs during self-referential processing. The medial prefrontal activity predicted memory performances on trait words used for self-judgements in both subject groups, implicating a similar functional role of the medial prefrontal cortex in self-referential processing in sighted and blind individuals. Together, our findings indicate that self-representation in the medial prefrontal cortex is strongly shaped by sensory experience.

Synchronized Activity between the Ventral Hippocampus and the Medial Prefrontal Cortex during Anxiety

Brain tissue from 44 patients with Parkinson's disease (PD) and 36 age-matched controls was examined for choline acetyltransferase (ChAT) activity, and for densities of D1 and D2 dopamine receptors. Brain samples were examined for Alzheimer' disease (AD) type changes and for Lewy bodies (LBs), and for apolipoprotein E genotype. Patients were evaluated for the stage of cognitive impairment using Reisberg's global deterioration scale. ChAT activity in PD was reduced in all brain areas examined, being 51% of the control mean in the hippocampus (P<0.001), 57% in the prefrontal cortex (P< 0.001) and 64% in the temporal cortex (P<0.001). The number of LBs had a significant negative correlation with ChAT activity in both prefrontal (r=-0.33, P<0.05) and temporal cortex (r=-0.32, P<0.05). The reduction in ChAT activity in the prefrontal cortex had a significant negative correlation (r=-0.38, P=0.012) with the extent of cognitive impairment. When the CERAD class 'C' was excluded, cognitive impairment correlated significantly with both prefrontal ChAT activity (r=-0.52, P=0.0051) and the density of D1 dopamine receptors in the caudate nucleus (r=-0.40, P=0.037). The number of D1 and D2 dopamine receptors was reduced in both caudate nucleus and putamen in PD patients without neuroleptics as compared to controls. An increased D2 receptor number was found in the caudate nucleus and putamen in PD patients treated with neuroleptics. The present study showed that cognitive decline in PD is associated with reduced ChAT activity in the prefrontal cortex and the D1 dopamine receptor number in the caudate nucleus, even in the absence of AD-type pathology.

Possible Functions of Prefrontal Cortical Neurons in Duration Discrimination