Strait, Caleb E.; Blanchard, Tommy C.; Hayden, Benjamin Y.
Recent theories suggest that reward-based choice reflects competition between value signals in the ventromedial prefrontal cortex (vmPFC). We tested this idea by recording vmPFC neurons while macaques performed a gambling task with asynchronous offer presentation. We found that neuronal activity shows four patterns consistent with selection via mutual inhibition. (1) Correlated tuning for probability and reward size, suggesting that vmPFC carries an integrated value signal, (2) anti-correlated tuning curves for the two options, suggesting mutual inhibition, (3) neurons rapidly come to signal the value of the chosen offer, suggesting the circuit serves to produce a choice, (4) after regressing out the effects of option values, firing rates still could predict choice – a choice probability signal. In addition, neurons signaled gamble outcomes, suggesting that vmPFC contributes to both monitoring and choice processes. These data suggest a possible mechanism for reward-based choice and endorse the centrality of vmPFC in that process. PMID:24881835
Peters, Jamie; LaLumiere, Ryan T.; Kalivas, Peter W.
The rat prelimbic prefrontal cortex and nucleus accumbens core are critical for initiating cocaine seeking. In contrast, the neural circuitry responsible for inhibiting cocaine seeking during extinction is unknown. The present findings using inhibition of selected brain nuclei with GABA agonists show that the suppression of cocaine seeking produced by prior extinction training required activity in the rat infralimbic cortex. Conversely, the reinstatement of drug seeking by a cocaine injection in extinguished animals was suppressed by increasing neuronal activity in infralimbic cortex with the glutamate agonist AMPA. The cocaine seeking induced by inactivating infralimbic cortex resembled other forms of reinstated drug seeking by depending on activity in prelimbic cortex and the basolateral amygdala. A primary efferent projection from the infralimbic cortex is to the nucleus accumbens shell. Akin to infralimbic cortex, inhibition of the accumbens shell induced cocaine seeking in extinguished rats. However, bilateral inhibition of the shell also elicited increased locomotor activity. Nonetheless, unilateral inhibition of the accumbens shell did not increase motor activity, and simultaneous unilateral inactivation of the infralimbic cortex and shell induced cocaine seeking, suggesting that an interaction between these two structures is necessary for extinction training to inhibit cocaine seeking. The infralimbic cortex and accumbens shell appear to be recruited by extinction learning because inactivation of these structures prior to extinction training did not alter cocaine seeking. Together, these findings suggest that a neuronal network involving the infralimbic cortex and accumbens shell is recruited by extinction training to suppress cocaine seeking. PMID:18524910
Levy, Benjamin J.; Wagner, Anthony D.
Delineating the functional organization of the prefrontal cortex is central to advancing models of goal-directed cognition. Considerable evidence indicates that specific forms of cognitive control are associated with distinct subregions of the left ventrolateral prefrontal cortex (VLPFC), but less is known about functional specialization within the right VLPFC. We report a functional MRI meta-analysis of two prominent theories of right VLPFC function: stopping of motor responses and reflexive orienting to abrupt perceptual onsets. Along with a broader review of right VLPFC function, extant data indicate that stopping and reflexive orienting similarly recruit the inferior frontal junction (IFJ), suggesting that IFJ supports the detection of behaviorally relevant stimuli. By contrast, other right VLPFC subregions are consistently active during motor inhibition, but not reflexive reorienting tasks, with posterior-VLPFC being active during the updating of action plans and mid-VLPFC responding to decision uncertainty. These results highlight the rich functional heterogeneity that exists within right VLPFC. PMID:21486295
Zhou, Xin; Zhu, Dantong; King, Samson G; Lees, Cynthia J; Bennett, Allyson J; Salinas, Emilio; Stanford, Terrence R; Constantinidis, Christos
Executive functions including behavioral response inhibition mature after puberty, in tandem with structural changes in the prefrontal cortex. Little is known about how activity of prefrontal neurons relates to this profound cognitive development. To examine this, we tracked neuronal responses of the prefrontal cortex in monkeys as they transitioned from puberty into adulthood and compared activity at different developmental stages. Performance of the antisaccade task greatly improved in this period. Among neural mechanisms that could facilitate it, reduction of stimulus-driven activity, increased saccadic activity, or enhanced representation of the opposing goal location, only the latter was evident in adulthood. Greatly accentuated in adults, this neural correlate of vector inversion may be a prerequisite to the formation of a motor plan to look away from the stimulus. Our results suggest that the prefrontal mechanisms that underlie mature performance on the antisaccade task are more strongly associated with forming an alternative plan of action than with suppressing the neural impact of the prepotent stimulus.
Hardung, Stefanie; Epple, Robert; Jäckel, Zoe; Eriksson, David; Uran, Cem; Senn, Verena; Gibor, Lihi; Yizhar, Ofer; Diester, Ilka
The ability to plan and execute appropriately timed responses to external stimuli is based on a well-orchestrated balance between movement initiation and inhibition. In impulse control disorders involving the prefrontal cortex (PFC) , this balance is disturbed, emphasizing the critical role that PFC plays in appropriately timing actions [2-4]. Here, we employed optogenetic and electrophysiological techniques to systematically analyze the functional role of five key subareas of the rat medial PFC (mPFC) and orbitofrontal cortex (OFC) in action control [5-9]. Inactivation of mPFC subareas induced drastic changes in performance, namely an increase (prelimbic cortex, PL) or decrease (infralimbic cortex, IL) of premature responses. Additionally, electrophysiology revealed a significant decrease in neuronal activity of a PL subpopulation prior to premature responses. In contrast, inhibition of OFC subareas (mainly the ventral OFC, i.e., VO) significantly impaired the ability to respond rapidly after external cues. Consistent with these findings, mPFC activity during response preparation predicted trial outcomes and reaction times significantly better than OFC activity. These data support the concept of opposing roles of IL and PL in directing proactive behavior and argue for an involvement of OFC in predominantly reactive movement control. By attributing defined roles to rodent PFC sections, this study contributes to a deeper understanding of the functional heterogeneity of this brain area and thus may guide medically relevant studies of PFC-associated impulse control disorders in this animal model for neural disorders [10-12].
George, David N; Duffaud, Anaïs M; Pothuizen, Helen H J; Haddon, Josephine E; Killcross, Simon
The acquisition of a conditioned response to a stimulus when it is paired with a reinforcer is retarded if the stimulus has previously been repeatedly pre-exposed in the absence of the reinforcer. This effect, called latent inhibition, has previously been found to be insensitive to lesions of the medial prefrontal cortex (mPFC) in rats. Using an on-baseline conditioned emotional response procedure, which is especially sensitive to small variations in the absolute magnitude of latent inhibition, we found increased latent inhibition following excitotoxic lesions of the mPFC (Experiment 1) or the ventral mPFC alone (Experiment 2) as compared with sham-operated control rats. Lesions restricted to the dorsal mPFC, however, were without effect (Experiment 2). These results are consistent with those of experiments employing another type of interference procedure, extinction. Together, these findings suggest that when different contingencies between a stimulus and a reinforcer are established in separate learning phases, lesions to the ventral mPFC result in increased interference between first-learned and second-learned contingencies. As a consequence, retrieval of the second-learned contingency is impaired, and performance is dominated by the first-learned contingency. These findings are discussed in light of the use of latent inhibition to model cognitive deficits in schizophrenia.
Halladay, Lindsay R; Blair, Hugh T
The infralimbic subregion of the prefrontal cortex (IL) is broadly involved in behavioral flexibility, risk assessment, and outcome reinforcement. In aversive conditioning tasks, the IL has been implicated in fear extinction and in mediating transitions between Pavlovian and instrumental responses. Here we examine the role of the IL in mediating transitions between two competing Pavlovian fear responses, conditioned motor inhibition (CMI) and conditioned motor excitation (CME). Rats were trained to fear an auditory conditioned stimulus (CS) by pairing it with periorbital shock to one eyelid (the unconditioned stimulus [US]). Trained animals exhibited CMI responses (movement suppression) to the CS when they had not recently encountered the US (>24 hr), but, after recent encounters with the US (<5 min), the CS evoked CME responses (turning in circles away from anticipated shock). Animals then received bilateral infusions of muscimol or picrotoxin to inactivate or hyperactivate the IL, respectively. Neither drug reliably affected CMI responses, but there was a bidirectional effect on CME responses; inactivation of the IL attenuated CME responses, whereas hyperactivation potentiated CME responses. These results provide evidence that activation of the IL may promote behavioral strategies that involve mobilizing the body and suppress strategies that involve immobilizing the body. © 2016 Wiley Periodicals, Inc.
Karim, Ahmed A; Schneider, Markus; Lotze, Martin; Veit, Ralf; Sauseng, Paul; Braun, Christoph; Birbaumer, Niels
Recent neuroimaging studies have indicated a predominant role of the anterior prefrontal cortex (aPFC) in deception and moral cognition, yet the functional contribution of the aPFC to deceptive behavior remains unknown. We hypothesized that modulating the excitability of the aPFC by transcranial direct current stimulation (tDCS) could reveal its functional contribution in generating deceitful responses. Forty-four healthy volunteers participated in a thief role-play in which they were supposed to steal money and then to attend an interrogation with the Guilty Knowledge Test. During the interrogation, participants received cathodal, anodal, or sham tDCS. Remarkably, inhibition of the aPFC by cathodal tDCS did not lead to an impairment of deceptive behavior but rather to a significant improvement. This effect manifested in faster reaction times in telling lies, but not in telling the truth, a decrease in sympathetic skin-conductance response and feelings of guilt while deceiving the interrogator and a significantly higher lying quotient reflecting skillful lying. Increasing the excitability of the aPFC by anodal tDCS did not affect deceptive behavior, confirming the specificity of the stimulation polarity. These findings give causal support to recent correlative data obtained by functional magnetic resonance imaging studies indicating a pivotal role of the aPFC in deception.
Mika, Agnieszka; Mazur, Gabriel J; Hoffman, Ann N; Talboom, Joshua S; Bimonte-Nelson, Heather A; Sanabria, Federico; Conrad, Cheryl D
Chronic stress leads to neurochemical and structural alterations in the prefrontal cortex (PFC) that correspond to deficits in PFC-mediated behaviors. The present study examined the effects of chronic restraint stress on response inhibition (using a response-withholding task, the fixed-minimum interval schedule of reinforcement, or FMI), and working memory (using a radial arm water maze, RAWM). Adult male Sprague-Dawley rats were first trained on the RAWM and subsequently trained on FMI. After acquisition of FMI, rats were assigned to a restraint stress (6h/d/28d in wire mesh restrainers) or control condition. Immediately after chronic stress, rats were tested on FMI and subsequently on RAWM. FMI results suggest that chronic stress reduces response inhibition capacity and motivation to initiate the task on selective conditions when sucrose reward was not obtained on the preceding trial. RAWM results suggest that chronic stress produces transient deficits in working memory without altering previously consolidated reference memory. Behavioral measures from FMI failed to correlate with metrics from RAWM except for one in which changes in FMI timing imprecision negatively correlated with changes in RAWM working memory errors for the controls, a finding that was not observed following chronic stress. Fisher's r-to-z transformation revealed no significant differences between control and stress groups with correlation coefficients. These findings are the first to show that chronic stress impairs both response inhibition and working memory, two behaviors that have never been directly compared within the same animals after chronic stress, using FMI, an appetitive task, and RAWM, a nonappetitive task.
Nelson, A J D; Thur, K E; Marsden, C A; Cassaday, H J
Latent inhibition (LI) refers to the reduction in conditioning to a stimulus that has received repeated non-reinforced pre-exposure. Investigations into the neural substrates of LI have focused on the nucleus accumbens (NAc) and its inputs from the hippocampal formation and adjacent cortical areas. Previous work has suggested that lesions to the medial prefrontal cortex (mPFC), another major source of input to the NAc, do not disrupt LI. However, a failure to observe disrupted LI does not preclude the possibility that a particular brain region is involved in the expression of LI. Moreover, the mPFC is a heterogeneous structure and there has been no investigation of a possible role of different regions within the mPFC in regulating LI under conditions that prevent LI in controls. Here, we tested whether 6-hydroxydopamine (6-OHDA)-induced lesions of dopamine (DA) terminals within the prelimbic (PL) and infralimbic (IL) mPFC would lead to the emergence of LI under conditions that do produce LI in controls (weak pre-exposure). LI was measured in a thirst motivated conditioned emotional response procedure with 10 pre-exposures to a noise conditioned stimulus (CS) and two conditioning trials. Sham-operated and IL-lesioned animals did not show LI and conditioned to the pre-exposed CS at comparable levels to the non-pre-exposed controls. 6-OHDA lesions to the PL, however, produced potentiation of LI. These results provide the first demonstration that the PL mPFC is a component of the neural circuitry underpinning LI.
Nelson, A.J.D.; Thur, K.E.; Marsden, C.A.; Cassaday, H.J.
Latent inhibition (LI) refers to the reduction in conditioning to a stimulus that has received repeated non-reinforced pre-exposure. Investigations into the neural substrates of LI have focused on the nucleus accumbens (NAc) and its inputs from the hippocampal formation and adjacent cortical areas. Previous work has suggested that lesions to the medial prefrontal cortex (mPFC), another major source of input to the NAc, do not disrupt LI. However, a failure to observe disrupted LI does not preclude the possibility that a particular brain region is involved in the expression of LI. Moreover, the mPFC is a heterogeneous structure and there has been no investigation of a possible role of different regions within the mPFC in regulating LI under conditions that prevent LI in controls. Here, we tested whether 6-hydroxydopamine (6-OHDA)-induced lesions of dopamine (DA) terminals within the prelimbic (PL) and infralimbic (IL) mPFC would lead to the emergence of LI under conditions that do produce LI in controls (weak pre-exposure). LI was measured in a thirst motivated conditioned emotional response procedure with 10 pre-exposures to a noise conditioned stimulus (CS) and two conditioning trials. Sham-operated and IL-lesioned animals did not show LI and conditioned to the pre-exposed CS at comparable levels to the non-pre-exposed controls. 6-OHDA lesions to the PL, however, produced potentiation of LI. These results provide the first demonstration that the PL mPFC is a component of the neural circuitry underpinning LI. PMID:20619321
Sheline, Yvette I.; Black, Kevin J.; Lin, Daniel Y.; Pimmel, Joseph; Wang, Po; Haller, John W.; Csernansky, John G.; Gado, Mokhtar; Walkup, Ronald K.; Brunsden, Barry S.; Vannier, Michael W.
Prefrontal cortex volumetry by brain magnetic resonance (MR) is required to estimate changes postulated to occur in certain psychiatric and neurologic disorders. A semiautomated method with quantitative characterization of its performance is sought to reliably distinguish small prefrontal cortex volume changes within individuals and between groups. Stereological methods were tested by a blinded comparison of measurements applied to 3D MR scans obtained using an MPRAGE protocol. Fixed grid stereologic methods were used to estimate prefrontal cortex volumes on a graphic workstation, after the images are scaled from 16 to 8 bits using a histogram method. In addition images were resliced into coronal sections perpendicular to the bicommissural plane. Prefrontal cortex volumes were defined as all sections of the frontal lobe anterior to the anterior commissure. Ventricular volumes were excluded. Stereological measurement yielded high repeatability and precision, and was time efficient for the raters. The coefficient of error was
McEown, Kristopher; Takata, Yohko; Cherasse, Yoan; Nagata, Nanae; Aritake, Kosuke; Lazarus, Michael
Rapid eye movement (REM) sleep loss is associated with increased consumption of weight-promoting foods. The prefrontal cortex (PFC) is thought to mediate reward anticipation. However, the precise role of the PFC in mediating reward responses to highly palatable foods (HPF) after REM sleep deprivation is unclear. We selectively reduced REM sleep in mice over a 25-48 hr period and chemogenetically inhibited the medial PFC (mPFC) by using an altered glutamate-gated and ivermectin-gated chloride channel that facilitated neuronal inhibition through hyperpolarizing infected neurons. HPF consumption was measured while the mPFC was inactivated and REM sleep loss was induced. We found that REM sleep loss increased HPF consumption compared to control animals. However, mPFC inactivation reversed the effect of REM sleep loss on sucrose consumption without affecting fat consumption. Our findings provide, for the first time, a causal link between REM sleep, mPFC function and HPF consumption.
Byeon, Jung Seop
It has been suggested that the hippocampus and the prefrontal cortex (PFC) play key roles in representing contextual memory and utilizing contextual information for flexible response selection. During response selection, a correct response should be facilitated and an incorrect response should be inhibited flexibly in association with a cueing stimulus. However, it is poorly understood how the hippocampal and PFC networks behave during such flexible control of facilitation and inhibition of behavioral responses. To find neural correlates of context-cued flexible response selection, the current study employed an object-place paired-associate (OPPA) task in which object A is only rewarded in place 1 and object B is associated with reward in place 2 while recording single units simultaneously from the hippocampus and PFC. During the task, response inhibition in front of a contextually wrong object is required for successful performance and such inhibitory responses were observed before the rat learned the task. A significant proportion of neurons that fired differentially depending on the existence of inhibitory behavior in the PFC was observed during the pre-learning stage. By contrast, the proportion of such neurons in the hippocampus was significantly greater than chance during post-learning stage. The results suggest that the development of inhibitory behavior is a critical behavioral marker that foretells an upcoming acquisition of the task and the hippocampus and PFC are involved in learning contextual response selection by learning how to control the inhibition of behavior as learning progresses. PMID:24963284
Cheng, Zheng-Xiang; Lan, Dan-Mei; Wu, Pei-Ying; Zhu, Yan-Hua; Dong, Yi; Ma, Lan; Zheng, Ping
Dehydroepiandrosterone sulphate is one of the most important neurosteroids. In the present paper, we studied the effect of dehydroepiandrosterone sulphate on persistent sodium currents and its mechanism and functional consequence with whole-cell patch clamp recording method combined with a pharmacological approach in the rat medial prefrontal cortex slices. The results showed that dehydroepiandrosterone sulphate inhibited the amplitude of persistent sodium currents and the inhibitory effect was significant at 0.1 microM, reached maximum at 1 microM and decreased with the increase in the concentrations of above 1 microM. The effect of dehydroepiandrosterone sulphate on persistent sodium currents was canceled by the Gi protein inhibitor and the protein kinase C inhibitor, but not by the protein kinase A inhibitor. The effect of dehydroepiandrosterone sulphate on persistent sodium currents was also canceled by the sigma-1 receptor blockers and the sigma-1 receptor agonist could mimic the effect of dehydroepiandrosterone sulphate. Dehydroepiandrosterone sulphate had no significant influence on neuronal excitability but could significantly inhibit chemical inhibition of mitochondria-evoked increase in persistent sodium currents. These results suggest that dehydroepiandrosterone sulphate inhibits persistent sodium currents via the activation of sigma-1 receptors-Gi protein-protein kinase C-coupled signaling pathway, and the main functional consequence of this effect of DHEAS is presumably to protect neurons under ischemia.
Narayanan, Nandakumar S.; Laubach, Mark
SUMMARY Dorsomedial prefrontal cortex is critical for the temporal control of behavior. Dorsomedial prefrontal cortex might alter neuronal activity in areas such as motor cortex to inhibit temporally inappropriate responses. We tested this hypothesis by recording from neuronal ensembles in rodent dorsomedial prefrontal cortex during a delayed-response task. One-third of dorsomedial prefrontal neurons were significantly modulated during the delay period. The activity of many of these neurons was predictive of premature responding. We then reversibly inactivated dorsomedial prefrontal cortex while recording ensemble activity in motor cortex. Inactivation of dorsomedial prefrontal cortex reduced delay-related firing, but not response-related firing, in motor cortex. Finally, we made simultaneous recordings in dorsomedial prefrontal cortex and motor cortex and found strong delay-related temporal correlations between neurons in the two cortical areas. These data suggest that functional interactions between dorsomedial prefrontal cortex and motor cortex might serve as a top-down control signal that inhibits inappropriate responding. PMID:17145511
McEown, Kristopher; Takata, Yohko; Cherasse, Yoan; Nagata, Nanae; Aritake, Kosuke; Lazarus, Michael
Rapid eye movement (REM) sleep loss is associated with increased consumption of weight-promoting foods. The prefrontal cortex (PFC) is thought to mediate reward anticipation. However, the precise role of the PFC in mediating reward responses to highly palatable foods (HPF) after REM sleep deprivation is unclear. We selectively reduced REM sleep in mice over a 25–48 hr period and chemogenetically inhibited the medial PFC (mPFC) by using an altered glutamate-gated and ivermectin-gated chloride channel that facilitated neuronal inhibition through hyperpolarizing infected neurons. HPF consumption was measured while the mPFC was inactivated and REM sleep loss was induced. We found that REM sleep loss increased HPF consumption compared to control animals. However, mPFC inactivation reversed the effect of REM sleep loss on sucrose consumption without affecting fat consumption. Our findings provide, for the first time, a causal link between REM sleep, mPFC function and HPF consumption. DOI: http://dx.doi.org/10.7554/eLife.20269.001 PMID:27919319
Manson, Kirk F.; Schiller, Daniela
Abstract Decision-making studies have implicated the ventromedial prefrontal cortex (vmPFC) in tracking the value of rewards and punishments. At the same time, fear-learning studies have pointed to a role of the same area in updating previously learned cue–outcome associations. To disentangle these accounts, we used a reward reversal-learning paradigm in a functional magnetic resonance imaging study in 18 human participants. Participants first learned that one of two colored squares (color A) was associated with monetary reward, whereas the other (color B) was not, and then had to learn that these contingencies reversed. Consistent with value representation, activity of a dorsal region of vmPFC was positively correlated with reward magnitude. Conversely, a more ventral region of vmPFC responded more to color A than to color B after contingency reversal, compatible with a role of inhibiting the previously learned response that was no longer appropriate. Moreover, the response strength was correlated with subjects’ behavioral learning strength. Our findings provide direct evidence for the spatial dissociation of value representation and affective response inhibition in the vmPFC. PMID:26730406
Vidal, Julie; Mills, Travis; Pang, Elizabeth W.; Taylor, Margot J.
Inhibition is a core executive function reliant on the frontal lobes that shows protracted maturation through to adulthood. We investigated the spatiotemporal characteristics of response inhibition during a visual go/no-go task in 14 teenagers and 14 adults using magnetoencephalography (MEG) and a contrast between two no-go experimental conditions…
It has long been thought that the prefrontal cortex, as the seat of most higher brain functions, is functionally silent during most of infancy. This review highlights recent work concerned with the precise mapping (localization) of brain activation in human infants, providing evidence that prefrontal cortex exhibits functional activation much…
Radhu, Natasha; Garcia Dominguez, Luis; Farzan, Faranak; Richter, Margaret A.; Semeralul, Mawahib O.; Chen, Robert; Fitzgerald, Paul B.
Abnormal gamma-aminobutyric acid inhibitory neurotransmission is a key pathophysiological mechanism underlying schizophrenia. Transcranial magnetic stimulation can be combined with electroencephalography to index long-interval cortical inhibition, a measure of GABAergic receptor-mediated inhibitory neurotransmission from the frontal and motor cortex. In previous studies we have reported that schizophrenia is associated with inhibitory deficits in the dorsolateral prefrontal cortex compared to healthy subjects and patients with bipolar disorder. The main objective of the current study was to replicate and extend these initial findings by evaluating long-interval cortical inhibition from the dorsolateral prefrontal cortex in patients with schizophrenia compared to patients with obsessive-compulsive disorder. A total of 111 participants were assessed: 38 patients with schizophrenia (average age: 35.71 years, 25 males, 13 females), 27 patients with obsessive-compulsive disorder (average age: 36.15 years, 11 males, 16 females) and 46 healthy subjects (average age: 33.63 years, 23 females, 23 males). Long-interval cortical inhibition was measured from the dorsolateral prefrontal cortex and motor cortex through combined transcranial magnetic stimulation and electroencephalography. In the dorsolateral prefrontal cortex, long-interval cortical inhibition was significantly reduced in patients with schizophrenia compared to healthy subjects (P = 0.004) and not significantly different between patients with obsessive-compulsive disorder and healthy subjects (P = 0.5445). Long-interval cortical inhibition deficits in the dorsolateral prefrontal cortex were also significantly greater in patients with schizophrenia compared to patients with obsessive-compulsive disorder (P = 0.0465). There were no significant differences in long-interval cortical inhibition across all three groups in the motor cortex. These results demonstrate that long-interval cortical inhibition deficits in the
Grimm, Simone; Schubert, Florian; Jaedke, Maren; Gallinat, Jürgen; Bajbouj, Malek
Extraversion is considered one of the core traits of personality. Low extraversion has been associated with increased vulnerability to affective and anxiety disorders. Brain imaging studies have linked extraversion, approach behaviour and the production of positive emotional states to the dorsolateral prefrontal cortex (DLPFC) and glutamatergic neurotransmission. However, the relationship between extraversion and glutamate in the DLPFC has not been investigated so far. In order to address this issue, absolute glutamate concentrations in the DLPFC and the visual cortex as a control region were measured by 3-Tesla proton magnetic resonance spectroscopy (1H-MRS) in 29 subjects with high and low extraversion. We found increased glutamate levels in the DLPFC of introverts as compared with extraverts. The increased glutamate concentration was specific for the DLPFC and negatively associated with state anxiety. Although preliminary, results indicate altered top-down control of DLPFC due to reduced glutamate concentration as a function of extraversion. Glutamate measurement with 1H-MRS may facilitate the understanding of biological underpinnings of personality traits and psychiatric diseases associated with dysfunctions in approach behaviour and the production of positive emotional states.
Fitzgerald, Kate Dimond; Zbrozek, Christopher D.; Welsh, Robert C.; Britton, Jennifer C.; Liberzon, Israel; Taylor, Stephan F.
Background: Recent neuroimaging work suggests that inhibitory and error processing in healthy adults share overlapping, but functionally distinct neural circuitries within the posterior medial frontal cortex (pMFC); however, it remains unknown whether the pMFC is differentially engaged by response inhibition compared to error commission in the…
The representation of space and its function in the prefrontal cortex have been examined using a variety of behavioral tasks. Among them, since the delayed-response task requires the temporary maintenance of spatial information, this task has been used to examine the mechanisms of spatial representation. In addition, the concept of working memory to explain prefrontal functions has helped us to understand the nature and functions of space representation in the prefrontal cortex. The detailed analysis of delay-period activity observed in spatial working memory tasks has provided important information for understanding space representation in the prefrontal cortex. Directional delay-period activity has been shown to be a neural correlate of the mechanism for temporarily maintaining information and represent spatial information for the visual cue and the saccade. In addition, many task-related prefrontal neurons exhibit spatially selective activities. These neurons are also important components of spatial information processing. In fact, information flow from sensory-related neurons to motor-related neurons has been demonstrated, along with a change in spatial representation as the trial progresses. The dynamic functional interactions among neurons exhibiting different task-related activities and representing different aspects of information could play an essential role in information processing. In addition, information provided from other cortical or subcortical areas might also be necessary for the representation of space in the prefrontal cortex. To better understand the representation of space and its function in the prefrontal cortex, we need to understand the nature of functional interactions between the prefrontal cortex and other cortical and subcortical areas.
Oldrati, Viola; Patricelli, Jessica; Colombo, Barbara; Antonietti, Alessandro
The main characteristic of the cognitive reflection test (CRT) is that it requires people to overcome a cognitive conflict. Solving this conflict requires (1) inhibitory control of prepotent but incorrect responses and (2) mental set-shifting in order to reframe the problem and reach a meaningful solution. Based on the well-known involvement of the dorsolateral prefrontal cortex (DLPFC) in inhibitory control we hypothesised that transcranial direct current stimulation (tDCS) of the DLPFC would modulate its contribution to problem-solving performance. Thirty-nine participants undergoing anodal, cathodal, or sham tDCS were asked to solve the CRT and similar mathematical problems that were structured to induce an automatic, impulsive but incorrect response. To provide a multi-dimensional picture of the processes underlying responding we assessed impulsivity traits using self-report measures and recorded physiological indices using biofeedback equipment. The results indicated that participants were more likely to provide incorrect impulsive responses after cathodal stimulation, i.e. when inhibitory control associated to the DLPFC was reduced. Baseline values of blood volume pulses predicted solution recognition, highlighting the potential role of individual physiological differences in problem solving. In conclusion, this study provides evidence supporting the role of the DLPFC in modulation of processes involved in solving CRTs and similar problems, thanks to its association to the inhibitory control mechanisms involved in suppressing impulsive responses.
Rogasch, Nigel C; Daskalakis, Zafiris J; Fitzgerald, Paul B
Paired-pulse transcranial magnetic stimulation combined with electroencephalography (TMS-EEG) is a method for studying cortical inhibition from the dorsolateral prefrontal cortex (DLPFC). However, little is known about the mechanisms underlying TMS-evoked cortical potentials (TEPs) from this region, let alone inhibition of these components. The aim of this study was to assess cortical inhibition of distinct TEPs and oscillations in the DLPFC using TMS-EEG and to investigate the relationship of these mechanisms to working memory. 30 healthy volunteers received single and paired (interstimulus interval = 100 msec) TMS to the left DLPFC. Variations in long-interval cortical inhibition (LICI) of different TEP peaks (N40, P60, N100) and different TMS-evoked oscillations (alpha, lower beta, upper beta, gamma) were compared between individuals. Variation in N100 slope following single pulse TMS, another putative marker of inhibition, was also compared with LICI of each measure. Finally, these measures were correlated with performance of a working memory task. LICI resulted in significant suppression of all TEP peaks and TMS-evoked oscillations (all p < .05). There were no significant correlations between LICI of different TEP peaks or TMS-evoked oscillations with the exception of P60 and N100. Variation in N100 slope correlated with LICI of N40 and beta oscillations. In addition, LICI of P60 and N100 were differentially correlated with working memory performance. The results suggest that both the LICI paradigm and N100 following single pulse TMS reflect complementary methods for assessing GABAB-mediated cortical inhibition in the DLPFC. Furthermore, these measures demonstrate the importance of prefrontal GABAB-mediated inhibitory control for working memory performance.
Eslinger, Paul J.; Flaherty-Craig, Claire V.; Benton, Arthur L.
The neuropsychological bases of cognitive, social, and moral development are minimally understood, with a seemingly wide chasm between developmental theories and brain maturation models. As one approach to bridging ideas in these areas, we review 10 cases of early prefrontal cortex damage from the clinical literature, highlighting overall clinical…
Han, Xiao; Li, Nanxin; Xue, Xiaofang; Shao, Feng; Wang, Weiwen
Adolescence is a critical period for neurodevelopment. In the present study, we investigated the effects of peri-adolescent social isolation on latent inhibition (LI) and dopamine D2 receptor expression in the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) of young adult rats. Male Sprague-Dawley rats were randomly divided into adolescent isolation (ISO; isolated housing, 21-34 days of age) and social housing (SOC) groups. LI was tested at postnatal day 56. After behavioral testing, the number of dopamine D2 receptor-expressing cells was determined using immunohistochemistry. Adolescent social isolation impaired LI and increased the number of cells expressing the D2 receptor in the mPFC and NAc. The results suggest that adolescent social isolation produces profound effects on cognitive and dopaminergic function in adult rats, and could be used as an animal model of various neurodevelopmental disorders.
Egashira, Nobuaki; Iwasaki, Katsunori; Ishibashi, Ayumi; Hayakawa, Kazuhide; Okuno, Ryoko; Abe, Moe; Uchida, Naoki; Mishima, Kenichi; Takasaki, Kotaro; Nishimura, Ryoji; Oishi, Ryozo; Fujiwara, Michihiro
Behavioral and psychological symptoms of dementia (BPSD) are commonly seen in patients with Alzheimer's disease (AD) and other forms of senile dementia. BPSD have a serious impact on the quality of life of dementia patients, as well as their caregivers. However, an effective drug therapy for BPSD has not been established. Recently, the traditional Japanese medicine Yokukansan (YKS, Yi-gan san in Chinese) has been reported to improve BPSD in a randomized, single-blind, placebo-controlled study. Moreover, abnormalities of the serotonin (5-HT) system such as 5-HT2A receptors have been reported to be associated with BPSD of AD patients. In the present study, we investigated the effect of YKS on head-twitch response induced by 2,5-dimethoxy-4-iodoamphetamine (DOI, 5 mg/kg, i.p.) in mice, a behavioral response that is mediated, in part, by 5-HT2A receptors. Acute treatment with YKS (100 and 300 mg/kg, p.o.) had no effect on the DOI-induced head-twitch response, whilst 14 days repeated treatment with YKS (300 mg/kg, p.o.) significantly inhibited this response. Moreover, repeated treatment with YKS (300 mg/kg, p.o.) decreased expression of 5-HT2A receptors in the prefrontal cortex, which is part of the circuitry mediating the head-twitch response. These findings suggest that the inhibition of DOI-induced head-twitch response by YKS may be mediated, in part, by altered expression of 5-HT2A receptors in the prefrontal cortex, which suggests the involvement of the 5-HT system in psychopharmacological effects of YKS.
Humans can be instructed verbally to perform computationally complex cognitive tasks; their performance then improves relatively slowly over the course of practice. Many skills underlie these abilities; in this paper, we focus on the particular question of a uniform architecture for the instantiation of habitual performance and the storage, recall, and execution of simple rules. Our account builds on models of gated working memory, and involves a bilinear architecture for representing conditional input-output maps and for matching rules to the state of the input and working memory. We demonstrate the performance of our model on two paradigmatic tasks used to investigate prefrontal and basal ganglia function. PMID:18946523
Teffer, Kate; Semendeferi, Katerina
The prefrontal cortex is critical to many cognitive abilities that are considered particularly human, and forms a large part of a neural system crucial for normal socio-emotional and executive functioning in humans and other primates. In this chapter, we survey the literature regarding prefrontal development and pathology in humans as well as comparative studies of the region in humans and closely related primate species. The prefrontal cortex matures later in development than more caudal regions, and some of its neuronal subpopulations exhibit more complex dendritic arborizations. Comparative work suggests that the human prefrontal cortex differs from that of closely related primate species less in relative size than it does in organization. Specific reorganizational events in neural circuitry may have taken place either as a consequence of adjusting to increases in size or as adaptive responses to specific selection pressures. Living in complex environments has been recognized as a considerable factor in the evolution of primate cognition. Normal frontal lobe development and function are also compromised in several neurological and psychiatric disorders. A phylogenetically recent reorganization of frontal cortical circuitry may have been critical to the emergence of human-specific executive and social-emotional functions, and developmental pathology in these same systems underlies many psychiatric and neurological disorders, including autism and schizophrenia.
Psychopathy is a personality disorder characterized by remorseless and impulsive antisocial behavior. Given the significant societal costs of the recidivistic criminal activity associated with the disorder, there is a pressing need for more effective treatment strategies, and hence, a better understanding of the psychobiological mechanisms underlying the disorder. The prefrontal cortex (PFC) is likely to play an important role in psychopathy. In particular, the ventromedial and anterior cingulate sectors of PFC are theorized to mediate a number of social and affective decision-making functions that appear to be disrupted in psychopathy. This article provides a critical summary of human neuroimaging data implicating prefrontal dysfunction in psychopathy. A growing body of evidence associates psychopathy with structural and functional abnormalities in ventromedial PFC and anterior cingulate cortex. Although this burgeoning field still faces a number of methodological challenges and outstanding questions that will need to be resolved by future studies, the research to date has established a link between psychopathy and PFC. PMID:22752782
Sacchi, Silvia; Novellis, Vito De; Paolone, Giovanna; Nuzzo, Tommaso; Iannotta, Monica; Belardo, Carmela; Squillace, Marta; Bolognesi, Paolo; Rosini, Elena; Motta, Zoraide; Frassineti, Martina; Bertolino, Alessandro; Pollegioni, Loredano; Morari, Michele; Maione, Sabatino; Errico, Francesco; Usiello, Alessandro
D-aspartate levels in the brain are regulated by the catabolic enzyme D-aspartate oxidase (DDO). D-aspartate activates NMDA receptors, and influences brain connectivity and behaviors relevant to schizophrenia in animal models. In addition, recent evidence reported a significant reduction of D-aspartate levels in the post-mortem brain of schizophrenia-affected patients, associated to higher DDO activity. In the present work, microdialysis experiments in freely moving mice revealed that exogenously administered D-aspartate efficiently cross the blood brain barrier and stimulates L-glutamate efflux in the prefrontal cortex (PFC). Consistently, D-aspartate was able to evoke L-glutamate release in a preparation of cortical synaptosomes through presynaptic stimulation of NMDA, mGlu5 and AMPA/kainate receptors. In support of a potential therapeutic relevance of D-aspartate metabolism in schizophrenia, in vitro enzymatic assays revealed that the second-generation antipsychotic olanzapine, differently to clozapine, chlorpromazine, haloperidol, bupropion, fluoxetine and amitriptyline, inhibits the human DDO activity. In line with in vitro evidence, chronic systemic administration of olanzapine induces a significant extracellular release of D-aspartate and L-glutamate in the PFC of freely moving mice, which is suppressed in Ddo knockout animals. These results suggest that the second-generation antipsychotic olanzapine, through the inhibition of DDO activity, increases L-glutamate release in the PFC of treated mice. PMID:28393897
Abelaira, Helena M; Réus, Gislaine Z; Ignácio, Zuleide M; Dos Santos, Maria Augusta B; de Moura, Airam B; Matos, Danyela; Demo, Júlia P; da Silva, Júlia B I; Danielski, Lucineia G; Petronilho, Fabricia; Carvalho, André F; Quevedo, João
Studies indicated that mammalian target of rapamycin (mTOR), oxidative stress, and inflammation are involved in the pathophysiology of major depressive disorder (MDD). Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has been identified as a novel MDD therapy; however, the antidepressant mechanism is not fully understood. In addition, the effects of ketamine after mTOR inhibition have not been fully investigated. In the present study, we examined the behavioral and biochemical effects of ketamine in the prefrontal cortex (PFC), hippocampus, amygdala, and nucleus accumbens after inhibition of mTOR signaling in the PFC. Male adult Wistar rats received pharmacological mTOR inhibitor, rapamycin (0.2 nmol) or vehicle into the PFC and then a single dose of ketamine (15 mg/kg, i.p.). Immobility was assessed in forced swimming tests, and then oxidative stress parameters and inflammatory markers were evaluated in the brain and periphery. mTOR activation in the PFC was essential to ketamine's antidepressant-like effects. Ketamine increased lipid damage in the PFC, hippocampus, and amygdala. Protein carbonyl was elevated in the PFC, amygdala, and NAc after ketamine administration. Ketamine also increased nitrite/nitrate in the PFC, hippocampus, amygdala, and NAc. Myeloperoxidase activity increased in the hippocampus and NAc after ketamine administration. The activities of superoxide dismutase and catalase were reduced after ketamine administration in all brain areas studied. Inhibition of mTOR signaling pathways by rapamycin in the PFC was required to protect against oxidative stress by reducing damage and increasing antioxidant enzymes. Finally, the TNF-α level was increased in serum by ketamine; however, the rapamycin plus treatment group was not able to block this increase. Activation of mTOR in the PFC is involved in the antidepressant-like effects of ketamine; however, the inhibition of this pathway was able to protect certain brain areas against
Cognitive flexibility depends on the integrity of the prefrontal cortex (PFC). We showed previously that impaired decision making in pain results from amygdala-driven inhibition of medial PFC neurons, but the underlying mechanisms remain to be determined. Using whole cell patch clamp in rat brain slices and a cognitive behavioral task, we tested the hypothesis that group I metabotropic glutamate receptors (mGluRs) activate feed-forward inhibition to decrease excitability and output function of PFC pyramidal cells, thus impairing decision making. Polysynaptic inhibitory postsynaptic currents (IPSCs) and monosynaptic excitatory postsynaptic currents (EPSCs) were evoked in layer V pyramidal cells by stimulating presumed amygdala afferents. An mGluR1/5 agonist [(S)-3,5-dihydroxyphenylglycine, DHPG] increased synaptic inhibition more strongly than excitatory transmission. The facilitatory effects were blocked by an mGluR1 [(S)-(+)-α-amino-4-carboxy-2-methylbenzeneacetic acid, LY367385], but not mGluR5, antagonist, 3-[(2-methyl-1,3-thiazol-4-yl)ethynyl]pyridine. IPSCs were blocked by bicuculline and decreased by 2,3-dioxo-6-nitro-1,2,3,4-tetrahydrobenzo[f]quinoxaline-7-sulfonamide disodium salt (NBQX). Facilitation of synaptic inhibition by DHPG was glutamate driven because it was blocked by NBQX. DHPG increased frequency but not amplitude of spontaneous IPSCs; consistent with action potential-dependent synaptic inhibition, tetrodotoxin (TTX) prevented the facilitatory effects. DHPG decreased synaptically evoked spikes (E-S coupling) and depolarization-induced spiking [frequency-current (f-I) relationship]. This effect was indirect, resulting from glutamate-driven synaptic inhibition, because it persisted when a G protein blocker was included in the pipette but was blocked by GABAA receptor antagonists and NBQX. In contrast, DHPG increased E-S coupling and f-I relationships in mPFC interneurons through a presynaptic action, further supporting the concept of feed
Guida, Natascia; Laudati, Giusy; Mascolo, Luigi; Cuomo, Ornella; Anzilotti, Serenella; Sirabella, Rossana; Santopaolo, Marianna; Galgani, Mario; Montuori, Paolo; Di Renzo, Gianfranco; Canzoniero, Lorella M T; Formisano, Luigi
Ethylmercury thiosalicylate (thimerosal) is an organic mercury-based compound commonly used as an antimicrobial preservative that has been found to be neurotoxic. In contrast, histone deacetylases (HDACs) inhibition has been found to be neuroprotective against several environmental contaminants, such as polychlorinated biphenyls, di-2-ethylhexyl phthalate, and methylmercury. The aim of this study was to investigate the effect of HDAC inhibition on thimerosal-induced neurotoxicity in neuroblastoma cells and cortical neurons. Interestingly, we found that thimerosal, at 0.5 μM in SH-SY5Y cells and at 1 μM in neurons, caused cell death by activation of apoptosis, which was prevented by the HDAC class IIA inhibitor MC1568 but not the class I inhibitor MS275. Furthermore, thimerosal specifically increased HDAC4 protein expression but not that of HDACs 5, 6, 7, and 9. Western blot analysis revealed that MC1568 prevented thimerosal-induced HDAC4 increase. In addition, both HDAC4 knocking-down and MC1568 inhibited thimerosal-induced cell death in SH-SY5Y cells and cortical neurons. Importantly, intramuscular injection of 12 μg/kg thimerosal on postnatal days 7, 9, 11, and 15 increased HDAC4 levels in the prefrontal cortex (PFC), which decreased histone H4 acetylation in infant male rats, in parallel increased motor activity changes. In addition, coadministration of 40 mg/kg MC1568 (intraperitoneal injection) moderated the HDAC4 increase which reduced histone H4 deacetylation and caspase-3 cleavage in the PFC. Finally, open-field testing showed that thimerosal-induced motor activity changes are reduced by MC1568. These findings indicate that HDAC4 regulates thimerosal-induced cell death in neurons and that treatment with MC1568 prevents thimerosal-induced activation of caspase-3 in the rat PFC.
Bicks, Lucy K.; Koike, Hiroyuki; Akbarian, Schahram; Morishita, Hirofumi
Social cognition is a complex process that requires the integration of a wide variety of behaviors, including salience, reward-seeking, motivation, knowledge of self and others, and flexibly adjusting behavior in social groups. Not surprisingly, social cognition represents a sensitive domain commonly disrupted in the pathology of a variety of psychiatric disorders including Autism Spectrum Disorder (ASD) and Schizophrenia (SCZ). Here, we discuss convergent research from animal models to human disease that implicates the prefrontal cortex (PFC) as a key regulator in social cognition, suggesting that disruptions in prefrontal microcircuitry play an essential role in the pathophysiology of psychiatric disorders with shared social deficits. We take a translational perspective of social cognition, and review three key behaviors that are essential to normal social processing in rodents and humans, including social motivation, social recognition, and dominance hierarchy. A shared prefrontal circuitry may underlie these behaviors. Social cognition deficits in animal models of neurodevelopmental disorders like ASD and SCZ have been linked to an altered balance of excitation and inhibition (E/I ratio) within the cortex generally, and PFC specifically. A clear picture of the mechanisms by which altered E/I ratio in the PFC might lead to disruptions of social cognition across a variety of behaviors is not well understood. Future studies should explore how disrupted developmental trajectory of prefrontal microcircuitry could lead to altered E/I balance and subsequent deficits in the social domain. PMID:26635701
Covington, Herbert E.; Lobo, Mary Kay; Maze, Ian; Vialou, Vincent; Hyman, James M; Zaman, Samir; LaPlant, Quincey; Mouzon, Ezekiel; Ghose, Subroto; Tamminga, Carol A.; Neve, Rachael L.; Deisseroth, Karl; Nestler, Eric J.
Brain stimulation and imaging studies in humans have highlighted a key role for the prefrontal cortex in clinical depression, however, it remains unknown whether excitation or inhibition of prefrontal cortical neuronal activity is associated with antidepressant responses. Here, we examined cellular indicators of functional activity, including the immediate early genes (IEG), zif268 (egr1), c-fos and arc, in the prefrontal cortex of clinically depressed humans obtained postmortem. We also examined these genes in the ventral portion of the medial prefrontal cortex (mPFC) of mice after chronic social defeat stress, a mouse model of depression. In addition, we used viral vectors to overexpress channel rhodopsin 2 (a light-activated cation channel) in mouse mPFC in order to optogenetically drive “burst” patterns of cortical firing in-vivo and examine the behavioral consequences. Prefrontal cortical tissue derived from clinically depressed humans displayed significant reductions in IEG expression, consistent with a deficit in neuronal activity within this brain region. Mice subjected to chronic social defeat stress exhibited similar reductions in levels of IEG expression in mPFC. Interestingly, some of these changes were not observed in defeated mice that escape the deleterious consequences of the stress, i.e., resilient animals. In those mice that expressed a strong depressive-like phenotype, i.e., susceptible animals, optogenetic stimulation of mPFC exerted potent antidepressant-like effects, without affecting general locomotor activity, anxiety-like behaviors, or social memory. These results indicate that the activity of the mPFC is a key determinant of depression-like behavior, as well as antidepressant responses. PMID:21123555
Faccidomo, Sara; Reid, Grant T; Agoglia, Abigail E; Ademola, Sherifat A; Hodge, Clyde W
Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is a multifunctional enzyme that is required for synaptic plasticity and has been proposed to be a primary molecular component of the etiology of alcohol addiction. Chronic alcohol intake upregulates CaMKIIα protein expression in reward-related brain regions including the amygdala and nucleus accumbens, and CaMKIIα activity in the amygdala is required for the positive reinforcing effects of alcohol, suggesting this system promotes consumption in the early stages of alcohol addiction. Alternatively, the medial prefrontal cortex (mPFC) is known to inhibit limbic activity via CaMKII-dependent excitatory projections and may, therefore, enable top-down regulation of motivation. Here we sought to remove that regulatory control by site-specifically inhibiting CaMKII activity in the mPFC, and measured effects on the positive reinforcing effects of sweetened alcohol in C57BL/6J mice. Infusion of the CAMKII inhibitor KN-93 (0-10.0 μg) in the mPFC primarily increased alcohol+sucrose reinforced response rate in a dose- and time-dependent manner. KN-93 infusion reduced response rate in behavior-matched sucrose-only controls. Importantly, potentiation of operant responding for sweetened alcohol occurred immediately after infusion, at a time during which effects on sucrose responding were not observed, and persisted through the session. These results suggest that endogenous CaMKII activity in the mPFC exerts inhibitory control over the positive reinforcing effects of alcohol. Downregulation of CaMKII signaling in the mPFC might contribute to escalated alcohol use.
Haddon, J. E.; Killcross, A. S.
There is much debate as to the extent and nature of functional specialization within the different subregions of the prefrontal cortex. The current study was undertaken to investigate the effect of damage to medial prefrontal cortex subregions in the rat. Rats were trained on two biconditional discrimination tasks, one auditory and one visual, in…
Patients with the damage to the orbital region of the prefrontal cortex and monkeys with lesions in this area show impairment in emotional and motivational behavior. They also have difficulty in the extinction of learned behavior and in the reversal learning. This brain area is concerned with not only the value estimation of reward and aversive stimuli but also the expectation of these stimuli. The lateral prefrontal cortex plays an important role in the integration of emotion/motivation and cognition. The medial prefrontal cortex is concerned with action selection based on the previous reward history. The ventrolateral prefrontal cortex that comprises the anterior parts of the orbital and inferior medial prefrontal cortex plays an important role in emotion-based decision-making.
Leal-Campanario, Rocío; Fairén, Alfonso; Delgado-García, José M.; Gruart, Agnès
We have studied the role of rostral medial prefrontal cortex (mPFC) on reflexively evoked blinks and on classically conditioned eyelid responses in alert-behaving rabbits. The rostral mPFC was identified by its afferent projections from the medial half of the thalamic mediodorsal nuclear complex. Classical conditioning consisted of a delay paradigm using a 370-ms tone as the conditioned stimulus (CS) and a 100-ms air puff directed at the left cornea as the unconditioned stimulus (US). The CS coterminated with the US. Electrical train stimulation of the contralateral rostral mPFC produced a significant inhibition of air-puff-evoked blinks. The same train stimulation of the rostral mPFC presented during the CS–US interval for 10 successive conditioning sessions significantly reduced the generation of conditioned responses (CRs) as compared with values reached by control animals. Interestingly, the percentage of CRs almost reached control values when train stimulation of the rostral mPFC was removed from the fifth conditioning session on. The electrical stimulation of the rostral mPFC in well conditioned animals produced a significant decrease in the percentage of CRs. Moreover, the stimulation of the rostral mPFC was also able to modify the kinematics (latency, amplitude, and velocity) of evoked CRs. These results suggest that the rostral mPFC is a potent inhibitor of reflexively evoked and classically conditioned eyeblinks but that activation prevents only the expression of CRs, not their latent acquisition. Functional and behavioral implications of this inhibitory role of the rostral mPFC are discussed. PMID:17592148
Yen, Yi-Chun; Gassen, Nils C; Zellner, Andreas; Rein, Theo; Landgraf, Rainer; Wotjak, Carsten T; Anderzhanova, Elmira
Psychostimulants show therapeutic efficacy in the treatment of attention-deficit hyperactivity disorder (ADHD). It is generally assumed that they ameliorate ADHD symptoms via interfering with monoaminergic signaling. We combined behavioral pharmacology, neurochemistry and molecular analyses to identify mechanisms underlying the paradoxical calming effect of amphetamine in low trait anxiety behavior (LAB) mice, a novel multigenetic animal model of ADHD. Amphetamine (1 mg/kg) and methylphenidate (10 mg/kg) elicited similar dopamine and norepinephrine release in the medial prefrontal cortex (mPFC) and in the striatum of LAB mice. In contrast, amphetamine decreased, while methylphenidate increased locomotor activity. This argues against changes in dopamine and/or norepinephrine release as mediators of amphetamine paradoxical effects. Instead, the calming activity of amphetamine corresponded to the inhibition of glycogen synthase kinase 3β (GSK3β) activity, specifically in the mPFC. Accordingly, not only systemic administration of the GSK3β inhibitor TDZD-8 (20 mg/kg), but also local microinjections of TDZD-8 and amphetamine into the mPFC, but not into the striatum, decreased locomotor activity in LAB mice. Amphetamine effects seem to depend on NMDA receptor signaling, since pre- or co-treatment with MK-801 (0.3 mg/kg) abolished the effects of amphetamine (1 mg/kg) on the locomotion and on the phosphorylation of GSK3β at the level of the mPFC. Taken together, the paradoxical calming effect of amphetamine in hyperactive LAB mice concurs with a decreased GSK3β activity in the mPFC. This effect appears to be independent of dopamine or norepinephrine release, but contingent on NMDA receptor signaling.
Xu, Xinyu; Tian, Yu; Wang, Guolin; Tian, Xin
Working memory (WM) refers to the temporary storage and manipulation of information necessary for performance of complex cognitive tasks. There is a growing interest in whether and how propofol anesthesia inhibits WM function. The aim of this study is to investigate the possible inhibition mechanism of propofol anesthesia from the view of single neuron and neuronal ensemble activities. Adult SD rats were randomly divided into two groups: propofol group (0.9 mg kg(-1)min(-1), 2h via a tail vein catheter) and control group. All the rats were tested for working memory performances in a Y-maze-rewarded alternation task (a task of delayed non-matched-to-sample) at 24, 48, 72 h after propofol anesthesia, and the behavior results of WM tasks were recorded at the same time. Spatio-temporal trains of action potentials were obtained from the original signals. Single neuron activity was characterized by peri-event time histograms analysis and neuron ensemble activities were characterized by Granger causality to describe the interactions within the neuron ensemble. The results show that: comparing with the control group, the percentage of neurons excited and related to WM was significantly decreased (p<0.01 in 24h, p<0.05 in 48 h); the interactions within neuron ensemble were significantly weakened (p<0.01 in 24h, p<0.05 in 48 h), whereas no significant difference in 72 h (p>0.05), which were consistent with the behavior results. These findings could lead to improved understanding of the mechanism of anesthesia inhibition on WM functions from the view of single neuron activity and neuron ensemble interactions.
Higaki, Nobuaki; Goto, Takaharu; Ichikawa, Tetsuo
The prefrontal cortex (PFC) plays a role in complex cognitive behavioural planning, decision-making, and social behaviours. However, the effects of sensory integration during motor tasks on PFC activation have not been studied to date. Therefore, we investigated the effect of peripheral sensory information and external information on PFC activation using functional near-infrared spectroscopy (fNIRS). Cerebral blood flow (CBF) was increased around bilateral Brodmann areas 46 and 10 during visual and auditory information integration during an occlusal force (biting) task. After local anesthesia, CBF values were significantly decreased, but occlusal force was similar. In conclusion, the effects of peripheral sensory information from the periodontal ligament and external information have minimal impacts on occlusal force maintenance but are important for PFC activation. PMID:27833164
Voytek, Bradley; Davis, Matar; Yago, Elena; Barceló, Francisco; Vogel, Edward K; Knight, Robert T
Memory and attention deficits are common after prefrontal cortex (PFC) damage, yet people generally recover some function over time. Recovery is thought to be dependent upon undamaged brain regions, but the temporal dynamics underlying cognitive recovery are poorly understood. Here, we provide evidence that the intact PFC compensates for damage in the lesioned PFC on a trial-by-trial basis dependent on cognitive load. The extent of this rapid functional compensation is indexed by transient increases in electrophysiological measures of attention and memory in the intact PFC, detectable within a second after stimulus presentation and only when the lesioned hemisphere is challenged. These observations provide evidence supporting a dynamic and flexible model of compensatory neural plasticity.
Bondarenko, E; Hodgson, D M; Nalivaiko, E
The prefrontal cortex is one of the key areas of the central mechanism of cardiovascular and respiratory control. Disinhibition of the prelimbic medial prefrontal cortex elicits tachypnoeic responses in anesthetized rats (Hassan et al., J. Physiol. 591: 6069-6088, 2013). The current study examines the effects of inhibition of the prelimbic prefrontal cortex during presentation of stressors of various lengths and intensities in conscious unrestrained rats. 8 Wistar rats were implanted with bilateral guide cannulas targeting the prelimbic prefrontal cortex and received microinjections of either saline of GABAA agonist muscimol prior to recording sessions. Inhibition of the prelimbic prefrontal cortex significantly attenuated respiratory responses to a novel environment stress, 30s light stimulus and restraint stress. It did not affect respiratory responses to 500 ms acoustic stimuli of varying intensities (40-90 dB). We conclude that the prelimbic prefrontal cortex contributes to generation of tachypnoeic responses to prolonged stressors, but does not contribute to respiratory arousal in response to brief stressors.
Cytotoxic lesion of the medial prefrontal cortex abolishes the partial reinforcement extinction effect, attenuates prepulse inhibition of the acoustic startle reflex and induces transient hyperlocomotion, while sparing spontaneous object recognition memory in the rat.
Yee, B K
The partial reinforcement extinction effect refers to the increase in resistance to extinction of an operant response acquired under partial reinforcement relative to that acquired under continuous reinforcement. Prepulse inhibition of the acoustic startle response refers to the reduction in startle reactivity towards an intense acoustic pulse stimulus when it is shortly preceded by a weak prepulse stimulus. These two behavioural phenomena appear to be related to different forms of attentional processes. While the prepulse inhibition effect reflects an inherent early attentional gating mechanism, the partial reinforcement extinction effect is believed to involve the development of acquired inattention, i.e. the latter requires the animals to learn about what to and what not to attend. Impairments in prepulse inhibition and the partial reinforcement extinction effect have been independently linked to the neuropsychology of attentional dysfunctions seen in schizophrenia. The proposed neural substrates underlying these behaviourial phenomena also appear to overlap considerably: both focus on the nucleus accumbens and emphasize the functional importance of its limbic afferents, including that originating from the medial prefrontal cortex, on accumbal output/activity. The present study demonstrated that cytotoxic medial prefrontal cortex lesions which typically damaged the prelimbic, the infralimbic and the dorsal anterior cingulate areas could lead to the abolition of the partial reinforcement extinction effect and the attenuation of prepulse inhibition. The lesions also resulted in a transient elevation of spontaneous locomotor activity. In contrast, the same lesions spared performance in a spontaneous object recognition memory test, in which the lesioned animals displayed normal preference for a novel object when the novel object was presented in conjunction with a familiar object seen 10 min earlier within an open field arena. The present results lend support to the
Moghaddam, Bita; Homayoun, Houman
The ‘executive’ regions of the prefrontal cortex (PFC) such as the dorsolateral PFC (dlPFC) and its rodent equivalent medial PFC (mPFC) are thought to respond in concert with the ‘limbic’ regions of the PFC such as the orbitofrontal (OFC) cortex to orchestrate behavior that is consistent with context and expected outcome. Both groups of regions have been implicated in behavioral abnormalities associated with addiction and psychiatric disorders, in particular, schizophrenia and mood disorders. Theories about the pathophysiology of these disorders, however, incorporate abnormalities in discrete PFC regions independently of each other or assume they are one and the same and, thus, bunch them under umbrella of ‘PFC dysfunction.’ Emerging data from animal studies suggest that mPFC and OFC neurons display opposing patterns of plasticity during associative learning and in response to repeated exposure to psychostimulants. These data corroborate clinical studies reporting different patterns of activation in OFC versus dlPFC in individuals with schizophrenia or addictive disorders. These suggest that concomitant but divergent engagement of discrete PFC regions is critical for learning stimulus-outcome associations, and the execution of goal-directed behavior that is based on these associations. An atypical interplay between these regions may lead to abnormally high or low salience assigned to stimuli, resulting in symptoms that are fundamental to many psychiatric and addictive disorders, including attentional deficits, improper affective response to stimuli, and inflexible or impulsive behavior. PMID:17912252
Riga, Danai; Matos, Mariana R.; Glas, Annet; Smit, August B.; Spijker, Sabine; Van den Oever, Michel C.
The medial prefrontal cortex (mPFC) is critically involved in numerous cognitive functions, including attention, inhibitory control, habit formation, working memory and long-term memory. Moreover, through its dense interconnectivity with subcortical regions (e.g., thalamus, striatum, amygdala and hippocampus), the mPFC is thought to exert top-down executive control over the processing of aversive and appetitive stimuli. Because the mPFC has been implicated in the processing of a wide range of cognitive and emotional stimuli, it is thought to function as a central hub in the brain circuitry mediating symptoms of psychiatric disorders. New optogenetics technology enables anatomical and functional dissection of mPFC circuitry with unprecedented spatial and temporal resolution. This provides important novel insights in the contribution of specific neuronal subpopulations and their connectivity to mPFC function in health and disease states. In this review, we present the current knowledge obtained with optogenetic methods concerning mPFC function and dysfunction and integrate this with findings from traditional intervention approaches used to investigate the mPFC circuitry in animal models of cognitive processing and psychiatric disorders. PMID:25538574
Weber, Bernd; Rangel, Antonio; Wibral, Matthias; Falk, Armin
Behavioral economists have proposed that money illusion, which is a deviation from rationality in which individuals engage in nominal evaluation, can explain a wide range of important economic and social phenomena. This proposition stands in sharp contrast to the standard economic assumption of rationality that requires individuals to judge the value of money only on the basis of the bundle of goods that it can buy—its real value—and not on the basis of the actual amount of currency—its nominal value. We used fMRI to investigate whether the brain's reward circuitry exhibits money illusion. Subjects received prizes in 2 different experimental conditions that were identical in real economic terms, but differed in nominal terms. Thus, in the absence of money illusion there should be no differences in activation in reward-related brain areas. In contrast, we found that areas of the ventromedial prefrontal cortex (vmPFC), which have been previously associated with the processing of anticipatory and experienced rewards, and the valuation of goods, exhibited money illusion. We also found that the amount of money illusion exhibited by the vmPFC was correlated with the amount of money illusion exhibited in the evaluation of economic transactions. PMID:19307555
Loh, Marco; Pasupathy, Anitha; Miller, Earl K; Deco, Gustavo
The prefrontal cortex is believed to be important for cognitive control, working memory, and learning. It is known to play an important role in the learning and execution of conditional visuomotor associations, a cognitive task in which stimuli have to be associated with actions by trial-and-error learning. In our modeling study, we sought to integrate several hypotheses on the function of the prefrontal cortex using a computational model, and compare the results to experimental data. We constructed a module of prefrontal cortex neurons exposed to two different inputs, which we envision to originate from the inferotemporal cortex and the basal ganglia. We found that working memory properties do not describe the dominant dynamics in the prefrontal cortex, but the activation seems to be transient, probably progressing along a pathway from sensory to motor areas. During the presentation of the cue, the dynamics of the prefrontal cortex is bistable, yielding a distinct activation for correct and error trails. We find that a linear change in network parameters relates to the changes in neural activity in consecutive correct trials during learning, which is important evidence for the underlying learning mechanisms.
Funahashi, Shintaro; Andreau, Jorge Mario
Executive function is a product of the coordinated operation of multiple neural systems and an essential prerequisite for a variety of cognitive functions. The prefrontal cortex is known to be a key structure for the performance of executive functions. To accomplish the coordinated operations of multiple neural systems, the prefrontal cortex must monitor the activities in other cortical and subcortical structures and control and supervise their operations by sending command signals, which is called top-down signaling. Although neurophysiological and neuroimaging studies have provided evidence that the prefrontal cortex sends top-down signals to the posterior cortices to control information processing, the neural correlate of these top-down signals is not yet known. Through use of the paired association task, it has been demonstrated that top-down signals are used to retrieve specific information stored in long-term memory. Therefore, we used a paired association task to examine the neural correlates of top-down signals in the prefrontal cortex. The preliminary results indicate that 32% of visual neurons exhibit pair-selectivity, which is similar to the characteristics of pair-coding activities in temporal neurons. The latency of visual responses in prefrontal neurons was longer than bottom-up signals but faster than top-down signals in inferior temporal neurons. These results suggest that pair-selective visual responses may be top-down signals that the prefrontal cortex provides to the temporal cortex, although further studies are needed to elucidate the neural correlates of top-down signals and their characteristics to understand the neural mechanism of executive control by the prefrontal cortex.
Peters, Gregory J.; David, Christopher N.; Marcus, Madison D.; Smith, David M.
The prefrontal cortex (PFC) is known to be critically involved in strategy switching, attentional set shifting, and inhibition of prepotent responses. A central feature of this kind of behavioral flexibility is the ability to resolve conflicting response tendencies, suggesting a general role of the PFC in resolving interference. If so, the PFC…
Castillo-Gómez, Esther; Pérez-Rando, Marta; Vidueira, Sandra; Nacher, Juan
The structure and function of the medial prefrontal cortex (mPFC) is affected in several neuropsychiatric disorders, including schizophrenia and major depression. Recent studies suggest that imbalances between excitatory and inhibitory activity (E/I) may be responsible for this cortical dysfunction and therefore, may underlie the core symptoms of these diseases. This E/I imbalance seems to be correlated with alterations in the plasticity of interneurons but there is still scarce information on the mechanisms that may link these phenomena. The polysialylated form of the neural cell adhesion molecule (PSA-NCAM) is a good candidate, because it modulates the neuronal plasticity of interneurons and its expression is altered in schizophrenia and major depression. To address this question, we have developed an in vitro model using mPFC organotypic cultures of transgenic mice displaying fluorescent spiny interneurons. After enzymatic depletion of PSA, the spine density of interneurons, the number of synaptic puncta surrounding pyramidal neuron somata and the E/I ratio were strongly affected. These results point to the polysialylation of NCAM as an important factor in the maintenance of E/I balance and the structural plasticity of interneurons. This may be particularly relevant for better understanding the etiology of schizophrenia and major depression. PMID:27445697
Hashimoto, Ryuichiro; Sakai, Kuniyoshi L
Using functional magnetic resonance imaging (fMRI), we examined cortical activation under syntactic decision tasks and a short-term memory task for sentences, focusing on essential properties of syntactic processing. By comparing activation in these tasks with a short-term memory task for word lists, we found that two regions in the left prefrontal cortex showed selective activation for syntactic processing: the dorsal prefrontal cortex (DPFC) and the inferior frontal gyrus (IFG). Moreover, the left DPFC showed more prominent activation under the short-term memory task for sentences than that for word lists, which cannot be explained by general cognitive factors such as task difficulty and verbal short-term memory. These results support the proposal of specialized systems for sentence comprehension in the left prefrontal cortex.
McGarry, Laura M.
Interactions between the prefrontal cortex (PFC) and basolateral amygdala (BLA) regulate emotional behaviors. However, a circuit-level understanding of functional connections between these brain regions remains incomplete. The BLA sends prominent glutamatergic projections to the PFC, but the overall influence of these inputs is predominantly inhibitory. Here we combine targeted recordings and optogenetics to examine the synaptic underpinnings of this inhibition in the mouse infralimbic PFC. We find that BLA inputs preferentially target layer 2 corticoamygdala over neighboring corticostriatal neurons. However, these inputs make even stronger connections onto neighboring parvalbumin and somatostatin expressing interneurons. Inhibitory connections from these two populations of interneurons are also much stronger onto corticoamygdala neurons. Consequently, BLA inputs are able to drive robust feedforward inhibition via two parallel interneuron pathways. Moreover, the contributions of these interneurons shift during repetitive activity, due to differences in short-term synaptic dynamics. Thus, parvalbumin interneurons are activated at the start of stimulus trains, whereas somatostatin interneuron activation builds during these trains. Together, these results reveal how the BLA impacts the PFC through a complex interplay of direct excitation and feedforward inhibition. They also highlight the roles of targeted connections onto multiple projection neurons and interneurons in this cortical circuit. Our findings provide a mechanistic understanding for how the BLA can influence the PFC circuit, with important implications for how this circuit participates in the regulation of emotion. SIGNIFICANCE STATEMENT The prefrontal cortex (PFC) and basolateral amygdala (BLA) interact to control emotional behaviors. Here we show that BLA inputs elicit direct excitation and feedforward inhibition of layer 2 projection neurons in infralimbic PFC. BLA inputs are much stronger at
McGarrity, Stephanie; Mason, Rob; Fone, Kevin C.
Attentional deficits are core symptoms of schizophrenia, contributing strongly to disability. Prefrontal dysfunction has emerged as a candidate mechanism, with clinical evidence for prefrontal hypoactivation and disinhibition (reduced GABAergic inhibition), possibly reflecting different patient subpopulations. Here, we tested in rats whether imbalanced prefrontal neural activity impairs attention. To induce prefrontal hypoactivation or disinhibition, we microinfused the GABA-A receptor agonist muscimol (C4H6N2O2; 62.5, 125, 250 ng/side) or antagonist picrotoxin (C30H34O13; 75, 150, 300 ng/side), respectively, into the medial prefrontal cortex. Using the five-choice serial reaction time (5CSRT) test, we showed that both muscimol and picrotoxin impaired attention (reduced accuracy, increased omissions). Muscimol also impaired response control (increased premature responses). In addition, muscimol dose dependently reduced open-field locomotor activity, whereas 300 ng of picrotoxin caused locomotor hyperactivity; sensorimotor gating (startle prepulse inhibition) was unaffected. Therefore, infusion effects on the 5CSRT test can be dissociated from sensorimotor effects. Combining microinfusions with in vivo electrophysiology, we showed that muscimol inhibited prefrontal firing, whereas picrotoxin increased firing, mainly within bursts. Muscimol reduced and picrotoxin enhanced bursting and both drugs changed the temporal pattern of bursting. Picrotoxin also markedly enhanced prefrontal LFP power. Therefore, prefrontal hypoactivation and disinhibition both cause attentional deficits. Considering the electrophysiological findings, this suggests that attention requires appropriately tuned prefrontal activity. Apart from attentional deficits, prefrontal disinhibition caused additional neurobehavioral changes that may be relevant to schizophrenia pathophysiology, including enhanced prefrontal bursting and locomotor hyperactivity, which have been linked to psychosis
Bauer, David J; Peterson, Todd C; Swain, Rodney A
Anatomical tracing studies in primates have revealed neural tracts from the cerebellar dentate nuclei to prefrontal cortex, implicating a cerebellar role in nonmotor processes. Experiments in rats examining the functional role of this cerebellothalamocortical pathway have demonstrated the development of visuospatial and motivational deficits following lesions of the dentate nuclei, in the absence of motor impairment. These behavioral deficits possibly occur due to structural modifications of the cerebral cortex secondary to loss of cerebellar input. The current study characterized morphological alterations in prefrontal cortex important for visuospatial and motivational processes following bilateral cerebellar dentate nuclei lesions. Rats received either bilateral electrolytic cerebellar dentate nuclei lesions or sham surgery followed by a 30-day recovery. Randomly selected Golgi-impregnated neurons in prefrontal cortex were examined for analysis. Measures of branch length and spine density revealed no differences between lesioned and sham rats in either apical or basilar arbors; however, the proportion of immature to mature spines significantly decreased in lesioned rats as compared to sham controls, with reductions of 33% in the basilar arbor and 28% in the apical arbor. Although expected pruning of branches and spines did not occur, the results are consistent with the hypothesis that cerebellar lesions influence prefrontal morphology and support the possibility that functional deficits following cerebellar dentate nuclei lesions are related to prefrontal morphological alteration.
Kang, S; Paul, K; Hankosky, E R; Cox, C L; Gulley, J M
Amphetamine (AMPH) exposure leads to changes in behavior and dopamine receptor function in the prefrontal cortex (PFC). Since dopamine plays an important role in regulating GABAergic transmission in the PFC, we investigated if AMPH exposure induces long-lasting changes in dopamine's ability to modulate inhibitory transmission in the PFC as well as whether the effects of AMPH differed depending on the age of exposure. Male Sprague-Dawley rats were given saline or 3 mg/kg AMPH (i.p.) repeatedly during adolescence or adulthood and following a withdrawal period of up to 5 weeks (Experiment 1) or up to 14 weeks (Experiment 2), they were sacrificed for in vitro whole-cell recordings in layer V/VI of the medial PFC. We found that in brain slices from either adolescent- or adult-exposed rats, there was an attenuation of dopamine-induced increases in inhibitory synaptic currents in pyramidal cells. These effects did not depend on age of exposure, were mediated at least partially by a reduced sensitivity of D1 receptors in AMPH-treated rats, and were associated with an enhanced behavioral response to the drug in a separate group of rats given an AMPH challenge following the longest withdrawal period. Together, these data reveal a prolonged effect of AMPH exposure on medial PFC function that persisted for up to 14 weeks in adolescent-exposed animals. These long-lasting neurophysiological changes may be a contributing mechanism to the behavioral consequences that have been observed in those with a history of amphetamine abuse.
Yoshitake, Shimako; Ijiri, Soichiro; Kehr, Jan; Yoshitake, Takashi
The neuropeptide galanin is co-localized with histamine in subpopulations of neurons in the tuberomammillary nucleus suggesting its involvement in modulating histaminergic neurotransmission. The purpose of the present study was to investigate, by use of microdialysis, the effects of local intraparenchymal (combined infusion and microdialysis probe), and intracerebroventricular (i.c.v.) infusions of galanin on extracellular levels of histamine in its major projecting areas, ventromedial hypothalamic nucleus ventrolateral part (VMHVL), CA3 area of ventral hippocampus (vHipp) and medial prefrontal cortex (mPFC) in separate groups (n=5 rats/each) of freely moving rats. Galanin (0.5nmol and 1.5nmol) dose-dependently decreased the basal histamine levels in the VMHVL to 77.1% (i.c.v.) at 40min and to 82.1% (intra-VMHVL infusion) already at 20min, of the control group (32.6±3.5fmol/10μl), whereas only 1.5nmol i.c.v. galanin and not the local infusions deceased the histamine levels in the vHipp (8.4±0.6fmol/10μl) to 82.8% and in mPFC (9.8±0.9fmol/10μl) to 87.5%. It is concluded that central administration of galanin decreased the basal extracellular histamine levels in major histamine projecting areas, however, these effects were less prominent than those observed for 5-HT (Kehr et al., 2002 ) and ACh (Yoshitake et al., 2011 ) in the ventral hippocampus following i.c.v. and/or local galanin infusions.
Asinof, Samuel K; Paine, Tracie A
Attention deficits are a core cognitive symptom of schizophrenia; the neuropathology underlying these deficits is not known. Attention is regulated, at least in part, by the prefrontal cortex (PFC), a brain area in which pathology of γ-aminobutyric acid (GABA) neurons has been consistently observed in post-mortem analysis of the brains of people with schizophrenia. Specifically, expression of the 67-kD isoform of the GABA synthesis enzyme glutamic acid decarboxylase (GAD67) is reduced in parvalbumin-containing fast-spiking GABA interneurons. Thus it is hypothesized that reduced cortical GABA synthesis and release may contribute to the attention deficits in schizophrenia. Here the effect of reducing cortical GABA synthesis with l-allylglycine (LAG) on attention was tested using three different versions of the 5-choice serial reaction time task (5CSRTT). Because 5CSRTT performance can be affected by locomotor activity, we also measured this behavior in an open field. Finally, the expression of Fos protein was used as an indirect measure of reduced GABA synthesis. Intra-cortical LAG (10 μg/0.5 μl/side) infusions increased Fos expression and resulted in hyperactivity in the open field. Intra-cortical LAG infusions did not affect attention in any version of the 5CSRTT. These results suggest that a general decrease in GABA synthesis is not sufficient to cause attention deficits. It remains to be tested whether a selective decrease in GABA synthesis in parvalbumin-containing GABA neurons could cause attention deficits. Decreased cortical GABA synthesis did increase locomotor activity; this may reflect the positive symptoms of schizophrenia.
Badre, David; Wagner, Anthony D.
Cognitive control mechanisms permit memory to be accessed strategically, and so aid in bringing knowledge to mind that is relevant to current goals and actions. In this review, we consider the contribution of left ventrolateral prefrontal cortex (VLPFC) to the cognitive control of memory. Reviewed evidence supports a two-process model of mnemonic…
Cruse, Damian; Wilding, Edward L.
Although the prefrontal cortex (PFC) plays roles in episodic memory judgments, the specific processes it supports are not understood fully. Event-related potential (ERP) studies of episodic retrieval have revealed an electrophysiological modulation--the right-frontal ERP old/new effect--which is thought to reflect activity in PFC. The functional…
Peters, Jamie; Kalivas, Peter W.; Quirk, Gregory J.
Extinction is a form of inhibitory learning that suppresses a previously conditioned response. Both fear and drug seeking are conditioned responses that can lead to maladaptive behavior when expressed inappropriately, manifesting as anxiety disorders and addiction, respectively. Recent evidence indicates that the medial prefrontal cortex (mPFC) is…
Dumontheil, Iroise; Burgess, Paul W.; Blakemore, Sarah-Jayne
Information on the development and functions of rostral prefrontal cortex (PFC), or Brodmann area 10, has been gathered from different fields, from anatomical development to functional neuroimaging in adults, and put forward in relation to three particular cognitive and behavioural disorders. Rostral PFC is larger and has a lower cell density in…
Jeye, Brittany M; Karanian, Jessica M; Slotnick, Scott D
False memories commonly activate the anterior/dorsolateral prefrontal cortex (A/DLPFC) and the hippocampus. These regions are assumed to work in concert during false memories, which would predict a positive correlation between the magnitudes of activity in these regions across participants. However, the A/DLPFC may also inhibit the hippocampus, which would predict a negative correlation between the magnitudes of activity in these regions. In the present functional magnetic resonance imaging (fMRI) study, during encoding, participants viewed abstract shapes in the left or right visual field. During retrieval, participants classified each old shape as previously in the "left" or "right" visual field followed by an "unsure"-"sure"-"very sure" confidence rating. The contrast of left-hits and left-misses produced two activations in the hippocampus and three activations in the left A/DLPFC. For each participant, activity associated with false memories (right-"left"-"very sure" responses) from the two hippocampal regions was plotted as a function of activity in each A/DLPFC region. Across participants, for one region in the left anterior prefrontal cortex, there was a negative correlation between the magnitudes of activity in this region and the hippocampus. This suggests that the anterior prefrontal cortex might inhibit the hippocampus during false memories and that participants engage either the anterior prefrontal cortex or the hippocampus during false memories.
Jeye, Brittany M.; Karanian, Jessica M.; Slotnick, Scott D.
False memories commonly activate the anterior/dorsolateral prefrontal cortex (A/DLPFC) and the hippocampus. These regions are assumed to work in concert during false memories, which would predict a positive correlation between the magnitudes of activity in these regions across participants. However, the A/DLPFC may also inhibit the hippocampus, which would predict a negative correlation between the magnitudes of activity in these regions. In the present functional magnetic resonance imaging (fMRI) study, during encoding, participants viewed abstract shapes in the left or right visual field. During retrieval, participants classified each old shape as previously in the “left” or “right” visual field followed by an “unsure”–“sure”–“very sure” confidence rating. The contrast of left-hits and left-misses produced two activations in the hippocampus and three activations in the left A/DLPFC. For each participant, activity associated with false memories (right–“left”–“very sure” responses) from the two hippocampal regions was plotted as a function of activity in each A/DLPFC region. Across participants, for one region in the left anterior prefrontal cortex, there was a negative correlation between the magnitudes of activity in this region and the hippocampus. This suggests that the anterior prefrontal cortex might inhibit the hippocampus during false memories and that participants engage either the anterior prefrontal cortex or the hippocampus during false memories. PMID:28124986
The prefrontal cortex (PFC)—the most evolved brain region—subserves our highest-order cognitive abilities. However, it is also the brain region that is most sensitive to the detrimental effects of stress exposure. Even quite mild acute uncontrollable stress can cause a rapid and dramatic loss of prefrontal cognitive abilities, and more prolonged stress exposure causes architectural changes in prefrontal dendrites. Recent research has begun to reveal the intracellular signalling pathways that mediate the effects of stress on the PFC. This research has provided clues as to why genetic or environmental insults that disinhibit stress signalling pathways can lead to symptoms of profound prefrontal cortical dysfunction in mental illness. PMID:19455173
Maier, Steven F.; Amat, Jose; Baratta, Michael V.; Paul, Evan; Watkins, Linda R.
The degree of control that an organism has over a stressor potently modulates the impact of the stressor, with uncontrollable stressors producing a constellation of outcomes that do not occur if the stressor is behaviorally controllable. It has generally been assumed that this occurs because uncontrollability actively potentiates the effects of stressors. Here it will be suggested that in addition, or instead, the presence of control actively inhibits the impact of stressors. At least in part this occurs because (i) the presence of control is detected by regions of the ventral medial prefrontal cortex (mPFCv); and (ii) detection of control activates mPFCv output to stress-responsive brain stem and limbic structures that actively inhibit stress-induced activation of these structures, Furthermore, an initial experience with control over stress alters the mPFCv response to subsequent stressors so that mPFCv output is activated even if the subsequent stressor is uncontrollable, thereby making the organism resilient. The general implications of these results for understanding resilience in the face of adversity are discussed. PMID:17290798
Moriguchi, Yusuke; Hiraki, Kazuo
Executive function (EF) refers to the higher-order cognitive control process for the attainment of a specific goal. There are several subcomponents of EF, such as inhibition, cognitive shifting, and working memory. Extensive neuroimaging research in adults has revealed that the lateral prefrontal cortex plays an important role in EF. Developmental studies have reported behavioral evidence showing that EF changes significantly during preschool years. However, the neural mechanism of EF in young children is still unclear. This article reviews recent near-infrared spectroscopy (NIRS) research that examined the relationship between the development of EF and the lateral prefrontal cortex. Specifically, this review focuses on inhibitory control, cognitive shifting, and working memory in young children. Research has consistently shown significant prefrontal activation during tasks in typically developed children, but this activation may be abnormal in children with developmental disorders. Finally, methodological issues and future directions are discussed. PMID:24381551
Arvanov, V L; Liang, X; Russo, A; Wang, R Y
Both the phenethylamine hallucinogen (-)-1-2, 5-dimethoxy-4-bromophenyl-2-aminopropane (DOB), a selective serotonin 5-HT2A,2C receptor agonist, and the indoleamine hallucinogen D-lysergic acid diethylamide (LSD, which binds to 5-HT1A, 1B, 1D, 1E, 1F, 2A, 2C, 5, 6, 7, dopamine D1 and D2, and alpha1 and alpha2 adrenergic receptors), but not their non-hallucinogenic congeners, inhibited N-methyl-D-aspartate (NMDA)-induced inward current and NMDA receptor-mediated synaptic responses evoked by electrical stimulation of the forceps minor in pyramidal cells of the prefrontal cortical slices. The inhibitory effect of hallucinogens was mimicked by 5-HT in the presence of selective 5-HT1A and 5-HT3 receptor antagonists. The inhibitory action of DOB, LSD and 5-HT on the NMDA transmission was blocked by the 5-HT2A receptor antagonists R-(+)-alpha-(2, 3-dimethoxyphenil)-1-[4-fluorophenylethyl]-4-piperidineme thanol (M100907) and ketanserin. However, at low concentrations, when both LSD and DOB by themselves only partially depressed the NMDA response, they blocked the inhibitory effect of 5-HT, suggesting a partial agonist action. Whereas N-(4-aminobutyl)-5-chloro-2-naphthalenesulphonamide (W-7, a calmodulin antagonist) and N-[2-[[[3-(4'-chlorophenyl)- 2-propenyl]methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4'-methoxy-b enzenesulphonamide phosphate (KN-93, a Ca2+/CaM-KII inhibitor), but not the negative control 2-[N-4'methoxybenzenesulphonyl]amino-N-(4'-chlorophenyl)-2-propeny l-N -methylbenzylamine phosphate (KN-92), blocked the inhibitory action of LSD and DOB, the selective protein kinase C inhibitor chelerythrine was without any effect. We conclude that phenethylamine and indoleamine hallucinogens may exert their hallucinogenic effect by interacting with 5-HT2A receptors via a Ca2+/CaM-KII-dependent signal transduction pathway as partial agonists and modulating the NMDA receptors-mediated sensory, perceptual, affective and cognitive processes.
Al-Hakim, Ramsey; Fallon, James; Nain, Delphine; Melonakos, John; Tannenbaum, Allen
Structural, functional, and clinical studies in schizophrenia have, for several decades, consistently implicated dysfunction of the prefrontal cortex in the etiology of the disease. Functional and structural imaging studies, combined with clinical, psychometric, and genetic analyses in schizophrenia have confirmed the key roles played by the prefrontal cortex and closely linked "prefrontal system" structures such as the striatum, amygdala, mediodorsal thalamus, substantia nigra-ventral tegmental area, and anterior cingulate cortices. The nodal structure of the prefrontal system circuit is the dorsal lateral prefrontal cortex (DLPFC), or Brodmann area 46, which also appears to be the most commonly studied and cited brain area with respect to schizophrenia. 1, 2, 3, 4 In 1986, Weinberger et. al. tied cerebral blood flow in the DLPFC to schizophrenia.1 In 2001, Perlstein et. al. demonstrated that DLPFC activation is essential for working memory tasks commonly deficient in schizophrenia. 2 More recently, groups have linked morphological changes due to gene deletion and increased DLPFC glutamate concentration to schizophrenia. 3, 4 Despite the experimental and clinical focus on the DLPFC in structural and functional imaging, the variability of the location of this area, differences in opinion on exactly what constitutes DLPFC, and inherent difficulties in segmenting this highly convoluted cortical region have contributed to a lack of widely used standards for manual or semi-automated segmentation programs. Given these implications, we developed a semi-automatic tool to segment the DLPFC from brain MRI scans in a reproducible way to conduct further morphological and statistical studies. The segmenter is based on expert neuroanatomist rules (Fallon-Kindermann rules), inspired by cytoarchitectonic data and reconstructions presented by Rajkowska and Goldman-Rakic. 5 It is semi-automated to provide essential user interactivity. We present our results and provide details on
Fujii, Naotaka; Hihara, Sayaka; Nagasaka, Yasuo; Iriki, Atsushi
One of the cardinal mental faculties of humans and other primates is social brain function, the collective name assigned to the distributed system of social cognitive processes that orchestrate our sophisticated adaptive social behavior. These must include processes for recognizing current social context and maintaining an internal representation of the current social state as a reference for decision-making. But how and where the brain processes such social-state information is unknown. To home in on the neural substrates of social-state representation, the activity of 196 prefrontal (PFC) neurons was recorded from two monkeys simultaneously during a food-grab task under varying social conditions. Of PFC neurons, 39% showed activity modulation during movement-free periods and seemed to be representing current social state. The direction of modulation was opposite between the dominant and submissive monkeys: During social engagement, PFC activity increased in the dominant monkey and was suppressed in the submissive monkey. The modulation was consistently observed in additional PFC neurons (27/72) in additional pairings with two other monkeys. Notably, PFC activity in one formerly submissive monkey switched to dominant modulation mode when he was paired with a new monkey of lower social status. These findings suggest that PFC, as part of a larger social brain network, maintains a multistate classification of social context for use as a behavioral reference for social decision-making.
Coelho, Carl; Lê, Karen; Mozeiko, Jennifer; Krueger, Frank; Grafman, Jordan
Individuals with damage to the prefrontal cortex, and the dorsolateral prefrontal cortex (DLPFC) in particular, often demonstrate difficulties with the formulation of complex language not attributable to aphasia. The present study employed a discourse analysis procedure to characterize the language of individuals with left (L) or right (R) DLPFC lesions. All participants were 30-35 years post-onset of injury and presented with persistent discourse impairments. The discourse performance of the R DLPFC group was not significantly different from either the L DLPFC group or the non-injured comparison group. Individuals from the L DLPFC group demonstrated specific difficulties with narrative coherence and inclusion of critical story components. Both measures were significantly different from the comparison group. The discourse ability of the DLPFC groups was significantly correlated with measures of working memory. Findings support the use of discourse analysis for examining language impairments in individuals with PFC lesions.
Rocha, Angelica; Kalivas, Peter W
Although the involvement of the medial prefrontal cortex projection to the nucleus accumbens in the reinstatement of cocaine seeking has been well studied, it is not known if this projection plays a similar role in the reinstatement of cue- and methamphetamine-induced drug seeking in animals extinguished from methamphetamine self-administration. Accordingly, following extinction from long-access methamphetamine self-administration, rats were bilaterally microinjected with either a combination of the GABA agonists baclofen/muscimol or vehicle (artificial cerebrospinal fluid) into the infralimbic or prelimbic subcompartments of the medial prefrontal cortex or into the shell or core subcompartments of the nucleus accumbens. Similar to cocaine seeking, inactivation of either the prelimbic cortex or accumbens core eliminated cue- and methamphetamine-induced reinstatement, and inactivation of neither the infralimbic cortex nor shell subcompartments inhibited methamphetamine-induced drug seeking. However, in contrast to previous reports with cocaine, cue-induced reinstatement of methamphetamine seeking was inhibited by inactivation of the infralimbic cortex. In conclusion, although a primary role in reinstated drug seeking by the prelimbic and the accumbens core is similar between cocaine and methamphetamine, the recruitment of the infralimbic cortex by conditioned cues differs between these two psychostimulant drugs.
Laurent, Vincent; Westbrook, R. Frederick
We studied the roles of the basolateral amygdala (BLA) and the medial prefrontal cortex (mPFC) in learning and relearning to inhibit context conditioned fear (freezing) in extinction. In Experiment 1, pre-extinction BLA infusion of the NMDA receptor (NMDAr) antagonist, ifenprodil, impaired the development and retention of inhibition but…
Asp, Erik; Ramchandran, Kanchna; Tranel, Daniel
Objective The psychological processes of doubting and skepticism have recently become topics of neuroscientific investigation. In this context, we developed the False Tagging Theory, a neurobiological model of the belief and doubt process, which proposes that the prefrontal cortex is critical for normative doubt regarding properly comprehended cognitive representations. Here, we put our theory to an empirical test, hypothesizing that patients with prefrontal cortex damage would have a doubt deficit that would manifest as higher authoritarianism and religious fundamentalism. Method Ten patients with bilateral damage to the ventromedial prefrontal cortex (vmPFC), ten patients with damage to areas outside the vmPFC, and sixteen medical comparison patients, who experienced life-threatening (but non-neurological) medical events, completed a series of scales measuring authoritarianism, religious fundamentalism, and specific religious beliefs. Results VMPFC patients reported significantly higher authoritarianism and religious fundamentalism than the other groups. The degrees of authoritarianism and religious fundamentalism in the vmPFC group were significantly higher than normative values, as well; by contrast, the comparison groups did not differ from normative values. Moreover, vmPFC patients reported increased specific religious beliefs after brain injury. Conclusions The findings support the False Tagging Theory, and suggest that the vmPFC is critical for psychological doubt and resistance to authoritarian persuasion. PMID:22612576
Rae, Charlotte L; Hughes, Laura E; Anderson, Michael C; Rowe, James B
Communication between the prefrontal cortex and subcortical nuclei underpins the control and inhibition of behavior. However, the interactions in such pathways remain controversial. Using a stop-signal response inhibition task and functional imaging with analysis of effective connectivity, we show that the lateral prefrontal cortex influences the strength of communication between regions in the frontostriatal motor system. We compared 20 generative models that represented alternative interactions between the inferior frontal gyrus, presupplementary motor area (preSMA), subthalamic nucleus (STN), and primary motor cortex during response inhibition. Bayesian model selection revealed that during successful response inhibition, the inferior frontal gyrus modulates an excitatory influence of the preSMA on the STN, thereby amplifying the downstream polysynaptic inhibition from the STN to the motor cortex. Critically, the strength of the interaction between preSMA and STN, and the degree of modulation by the inferior frontal gyrus, predicted individual differences in participants' stopping performance (stop-signal reaction time). We then used diffusion-weighted imaging with tractography to assess white matter structure in the pathways connecting these three regions. The mean diffusivity in tracts between preSMA and the STN, and between the inferior frontal gyrus and STN, also predicted individual differences in stopping efficiency. Finally, we found that white matter structure in the tract between preSMA and STN correlated with effective connectivity of the same pathway, providing important cross-modal validation of the effective connectivity measures. Together, the results demonstrate the network dynamics and modulatory role of the prefrontal cortex that underpin individual differences in inhibitory control.
The role of prefrontal dopamine D1 receptors in prefrontal cortex (PFC) functions, including working memory, is widely investigated. However, human (healthy volunteers and schizophrenia patients) positron emission tomography (PET) studies about the relationship between prefrontal D1 receptors and PFC functions are somewhat inconsistent. We argued that several factors including an inverted U-shaped relationship between prefrontal D1 receptors and PFC functions might be responsible for these inconsistencies. In contrast to D1 receptors, relatively less attention has been paid to the role of D2 receptors in PFC functions. Several animal and human pharmacological studies have reported that the systemic administration of D2 receptor agonist/antagonist modulates PFC functions, although those studies do not tell us which region(s) is responsible for the effect. Furthermore, while prefrontal D1 receptors are primarily involved in working memory, other PFC functions such as set-shifting seem to be differentially modulated by dopamine. PET studies of extrastriatal D2 receptors including ours suggested that orchestration of prefrontal dopamine transmission and hippocampal dopamine transmission might be necessary for a broad range of normal PFC functions. In order to understand the complex effects of dopamine signaling on PFC functions, measuring a single index related to basic dopamine tone is not sufficient. For a better understanding of the meanings of PET indices related to neurotransmitters, comprehensive information (presynaptic, postsynaptic, and beyond receptor signaling) will be required. Still, an interdisciplinary approach combining molecular imaging techniques with cognitive neuroscience and clinical psychiatry will provide new perspectives for understanding the neurobiology of neuropsychiatric disorders and their innovative drug developments.
Shalini, Suku-Maran; Herr, Deron R; Ong, Wei-Yi
Pain and anxiety have a complex relationship and pain is known to share neurobiological pathways and neurotransmitters with anxiety. Top-down modulatory pathways of pain have been shown to originate from cortical and subcortical regions, including the dorsolateral prefrontal cortex. In this study, a novel docosahexaenoic acid (DHA)-containing nutraceutical, Souvenaid, was administered to mice with infraorbital nerve ligation-induced neuropathic pain and behavioral responses recorded. Infraorbital nerve ligation resulted in increased face wash strokes of the face upon von Frey hair stimulation, indicating increased nociception. Part of this response involves general pain sensitization that is dependent on the CNS, since increased nociception was also found in the paws during the hot plate test. Mice receiving oral gavage of Souvenaid, a nutraceutical containing DHA; choline; and other cell membrane components, showed significantly reduced pain sensitization. The mechanism of Souvenaid's activity involves supraspinal antinociception, originating in the prefrontal cortex, since inhibition of the DHA-metabolizing enzyme 15-lipoxygenase (Alox15) in the prefrontal cortex attenuated the antinociceptive effect of Souvenaid. Alox15 inhibition also modulated anxiety behavior associated with pain after infraorbital nerve ligation. The effects of Souvenaid components and Alox15 on reducing central sensitization of pain may be due to strengthening of a known supraspinal antinociceptive pathway from the prefrontal cortex to the periaqueductal gray. Together, results indicate the importance of the prefrontal cortex and DHA/Alox15 in central antinociceptive pathways and suggest that Souvenaid may be a novel therapeutic for neuropathic pain.
de Lange, Floris P; Toni, Ivan; Roelofs, Karin
Conversion paralysis (CP) is a frequent and impairing psychiatric disorder, affecting voluntary motor function. Yet, we have previously shown that the motor system of CP patients with a unilateral conversion paresis is recruited to a similar degree during imagined movements of the affected and unaffected limb. In contrast, imagery of movements with the affected limb results in larger prefrontal activation. It remains unclear how this hand-specific increased prefrontal activity relates to the reduced responsiveness of motor and somatosensory areas, a consistent and important feature of CP patients. In the current study, we investigated changes in the inter-regional coupling between prefrontal cortex (PFC) and sensorimotor regions when CP patients imagined movements involving either the affected or the unaffected hand. We found that there were distinct connectivity patterns for different parts of the PFC. While ventromedial PFC was not functionally connected to the motor system, we observed strong functional coupling between the dorsolateral PFC and various sensorimotor areas. Furthermore, this coupling was modulated by whether patients imagined movements of their affected or unaffected hand. Together, these results suggest that the reduced motor responsitivity observed in CP may be linked to altered dorsolateral prefrontal-motor connectivity.
Himichi, Toshiyuki; Fujita, Hiroyo; Nomura, Michio
The lateral prefrontal cortex (lPFC) plays a critical role in inhibiting self-perspective information, which is necessary for theory of mind (ToM) processing. Additionally, previous research has indicated that negative emotions interfere with lPFC activation during executive tasks. In this study, we hypothesized that negative emotions would inhibit lPFC activation during a ToM task. While female participants performed the director task following the observation of emotionally laden movies (neutral/negative/positive), their prefrontal hemodynamic activity was measured using near-infrared spectroscopy. After viewing the neutral movie, bilateral lPFC activity was significantly enhanced during ToM process compared to the control condition. In contrast, after viewing the negative movie, left lPFC activity during ToM process was significantly impaired. These results were interpreted to support the idea that negative emotions interfere with inhibition of self-perspective information through inactivation of the lPFC.
Grabenhorst, Fabian; Rolls, Edmund T
Rapid advances have recently been made in understanding how value-based decision-making processes are implemented in the brain. We integrate neuroeconomic and computational approaches with evidence on the neural correlates of value and experienced pleasure to describe how systems for valuation and decision-making are organized in the prefrontal cortex of humans and other primates. We show that the orbitofrontal and ventromedial prefrontal (VMPFC) cortices compute expected value, reward outcome and experienced pleasure for different stimuli on a common value scale. Attractor networks in VMPFC area 10 then implement categorical decision processes that transform value signals into a choice between the values, thereby guiding action. This synthesis of findings across fields provides a unifying perspective for the study of decision-making processes in the brain.
SUMMARY Normal brain functioning relies critically on the ability to control appropriate behavioral responses to fearful stimuli. Overgeneralized fear is the major symptom of anxiety disorders including posttraumatic stress disorder. This review describes recent data demonstrating that the medial prefrontal cortex (mPFC) plays a critical role in the refining of cues that drive the acquisition of fear response. Recent studies on molecular mechanisms that underlie the role of mPFC in fear discrimination learning are discussed. These studies suggest that prefrontal N-methyl-D-aspartate receptors expressed in excitatory neurons govern fear discrimination learning via a mechanism involving cAMP response element-binding protein–dependent engagement of acetyltransferase. PMID:26244030
Perry, Jennifer L.; Joseph, Jane E.; Jiang, Yang; Zimmerman, Rick S.; Kelly, Thomas H.; Darna, Mahesh; Huettl, Peter; Dwoskin, Linda P.; Bardo, Michael T.
Vulnerability to drug abuse is related to both reward seeking and impulsivity, two constructs thought to have a biological basis in the prefrontal cortex (PFC). This review addresses similarities and differences in neuroanatomy, neurochemistry and behavior associated with PFC function in rodents and primates. Emphasis is placed on monoamine and amino acid neurotransmitter systems located in anatomically distinct subregions: medial prefrontal cortex (mPFC); lateral prefrontal cortex (lPFC); anterior cingulate cortex (ACC); and orbitofrontal cortex (OFC). While there are complex interconnections and overlapping functions among these regions, each is thought to be involved in various functions related to health-related risk behaviors and drug abuse vulnerability. Among the various functions implicated, evidence suggests that mPFC is involved in reward processing, attention and drug reinstatement; lPFC is involved in decision-making, behavioral inhibition and attentional gating; ACC is involved in attention, emotional processing and self-monitoring; and OFC is involved in behavioral inhibition, signaling of expected outcomes and reward/punishment sensitivity. Individual differences factors (e.g., age and sex) influence functioning of these regions, which, in turn, impacts drug abuse vulnerability. Implications for the development of drug abuse prevention and treatment strategies aimed at engaging PFC inhibitory processes that may reduce risk-related behaviors are discussed, including the design of effective public service announcements, cognitive exercises, physical activity, direct current stimulation, feedback control training and pharmacotherapies. A major challenge in drug abuse prevention and treatment rests with improving intervention strategies aimed at strengthening PFC inhibitory systems among at-risk individuals. PMID:20837060
Perry, Jennifer L; Joseph, Jane E; Jiang, Yang; Zimmerman, Rick S; Kelly, Thomas H; Darna, Mahesh; Huettl, Peter; Dwoskin, Linda P; Bardo, Michael T
Vulnerability to drug abuse is related to both reward seeking and impulsivity, two constructs thought to have a biological basis in the prefrontal cortex (PFC). This review addresses similarities and differences in neuroanatomy, neurochemistry and behavior associated with PFC function in rodents and humans. Emphasis is placed on monoamine and amino acid neurotransmitter systems located in anatomically distinct subregions: medial prefrontal cortex (mPFC); lateral prefrontal cortex (lPFC); anterior cingulate cortex (ACC); and orbitofrontal cortex (OFC). While there are complex interconnections and overlapping functions among these regions, each is thought to be involved in various functions related to health-related risk behaviors and drug abuse vulnerability. Among the various functions implicated, evidence suggests that mPFC is involved in reward processing, attention and drug reinstatement; lPFC is involved in decision-making, behavioral inhibition and attentional gating; ACC is involved in attention, emotional processing and self-monitoring; and OFC is involved in behavioral inhibition, signaling of expected outcomes and reward/punishment sensitivity. Individual differences (e.g., age and sex) influence functioning of these regions, which, in turn, impacts drug abuse vulnerability. Implications for the development of drug abuse prevention and treatment strategies aimed at engaging PFC inhibitory processes that may reduce risk-related behaviors are discussed, including the design of effective public service announcements, cognitive exercises, physical activity, direct current stimulation, feedback control training and pharmacotherapies. A major challenge in drug abuse prevention and treatment rests with improving intervention strategies aimed at strengthening PFC inhibitory systems among at-risk individuals.
Aggleton, John P.; Wright, Nicholas F.; Rosene, Douglas L.; Saunders, Richard C.
The projections from the amygdala and hippocampus (including subiculum and presubiculum) to prefrontal cortex were compared using anterograde tracers injected into macaque monkeys (Macaca fascicularis, Macaca mulatta). Almost all prefrontal areas were found to receive some amygdala inputs. These connections, which predominantly arose from the intermediate and magnocellular basal nucleus, were particularly dense in parts of the medial and orbital prefrontal cortex. Contralateral inputs were not, however, observed. The hippocampal projections to prefrontal areas were far more restricted, being confined to the ipsilateral medial and orbital prefrontal cortex (within areas 11, 13, 14, 24a, 32, and 25). These hippocampal projections principally arose from the subiculum, with the fornix providing the sole route. Thus, while the lateral prefrontal cortex essentially receives only amygdala inputs, the orbital prefrontal cortex receives both amygdala and hippocampal inputs, though these typically target different areas. Only in medial prefrontal cortex do direct inputs from both structures terminate in common sites. But, even when convergence occurs within an area, the projections predominantly terminate in different lamina (hippocampal inputs to layer III and amygdala inputs to layers I, II, and VI). The resulting segregation of prefrontal inputs could enable the parallel processing of different information types in prefrontal cortex. PMID:25715284
Environmental Enrichment Prevent the Juvenile Hypoxia-Induced Developmental Loss of Parvalbumin-Immunoreactive Cells in the Prefrontal Cortex and Neurobehavioral Alterations Through Inhibition of NADPH Oxidase-2-Derived Oxidative Stress.
Zhang, Mingqiang; Wu, Jing; Huo, Lan; Luo, Liang; Song, Xi; Fan, Fei; Lu, Yiming; Liang, Dong
We compared the expression of phenotype of parvalbumin (PV)-immunoreactive cells in the prefrontal cortex (PFC) of juvenile rats reared in enriched environment (EE) after daily intermittent hypoxia (IH) exposure to those reared in standard environment (SE) and investigated the involvement of NADPH oxidase-2 (NOX2)-derived oxidative stress in the IH-induced neurodevelopmental and neurobehavioral consequences in a juvenile rat model of obstructive sleep apnea. Postnatal day 21 (P21) rats were exposed to IH or room air 8 h daily for 14 consecutive days. After the daily exposure, the rats were raised in SE or EE. In the PFC of P34 rats, we determined the impact (i) of IH exposures on NOX2-derived oxidative stress and PV immunoreactivity, (ii) of pharmacological NOX2 inhibition on IH-induced oxidative stress and PV immunoreactivity, and (iii) of EE on the IH-induced oxidative stress and PV immunoreactivity. Behavioral testing of psychiatric anxiety was carried out consecutively in the open-field test and elevated plus maze at P35 and P36. The results showed IH exposures increased NOX2 expression in the PFC of P34 rats, which was accompanied with elevation of NOX activity and indirect markers of oxidative stress (4-HNE). IH exposures increased 4-HNE immunoreactivity in cortical PV cells, which was accompanied with reduction of PV immunoreactivity. Treatment of IH rats with the antioxidant/NOX inhibitor apocynin prevented the PV cells loss in the PFC and reversed the IH-induced psychiatric anxiety. EE attenuated the NOX2-derived oxidative stress and reversed the PV-immunoreactivity reduction in the PFC induced by IH. Our data suggest that EE might prevent the juvenile hypoxia-induced developmental loss of PV cells in the PFC and attenuate the neurobehavioral alterations through inhibition of NOX2-derived oxidative stress.
Pleger, Burkhard; Ruff, Christian C.; Blankenburg, Felix; Bestmann, Sven; Wiech, Katja; Stephan, Klaas E.; Capilla, Almudena; Friston, Karl J.; Dolan, Raymond J.
The neural processes underlying tactile decisions in the human brain remain elusive. We addressed this question in a functional magnetic resonance imaging study using a somatosensory discrimination task, requiring participants to compare the frequency of two successive tactile stimuli. Tactile stimuli per se engaged somatosensory, parietal, and frontal cortical regions. Using a statistical model that accounted for the relative difference in frequencies (i.e., Weber fraction) and discrimination accuracy (i.e., correct or incorrect), we show that trial-by-trial relative frequency difference is represented linearly by activity changes in the left dorsolateral prefrontal cortex (DLPFC), the dorsal anterior cingulate cortex, and bilateral anterior insular cortices. However, a circumscribed region within the left DLPFC showed a different response pattern expressed as activity changes that were monotonically related to relative stimulation difference only for correct but not for incorrect trials. Our findings suggest that activity in the left DLPFC encodes stimulus representations that underlie veridical tactile decisions in humans. PMID:17135421
Sirohi, Sunil; Walker, Brendan M
Opioid receptors can display spontaneous agonist-independent G-protein signaling (basal signaling/constitutive activity). While constitutive κ-opioid receptor (KOR) activity has been documented in vitro, it remains unknown if KORs are constitutively active in native systems. Using [(35) S] guanosine 5'-O-[gamma-thio] triphosphate coupling assay that measures receptor functional state, we identified the presence of medial prefrontal cortex KOR constitutive activity in young rats that declined with age. Furthermore, basal signaling showed an age-related decline and was insensitive to neutral opioid antagonist challenge. Collectively, the present data are first to demonstrate age-dependent alterations in the medial prefrontal cortex KOR constitutive activity in rats and changes in the constitutive activity of KORs can differentially impact KOR ligand efficacy. These data provide novel insights into the functional properties of the KOR system and warrant further consideration of KOR constitutive activity in normal and pathophysiological behavior. Opioid receptors exhibit agonist-independent constitutive activity; however, kappa-opioid receptor (KOR) constitutive activity has not been demonstrated in native systems. Our results confirm KOR constitutive activity in the medial prefrontal cortex (mPFC) that declines with age. With the ability to presynaptically inhibit multiple neurotransmitter systems in the mPFC, maturational or patho-logical alterations in constitutive activity could disrupt corticofugal glutamatergic pyramidal projection neurons mediating executive function. Regulation of KOR constitutive activity could serve as a therapeutic target to treat compromised executive function.
Giustino, Thomas F.; Maren, Stephen
Once acquired, a fearful memory can persist for a lifetime. Although learned fear can be extinguished, extinction memories are fragile. The resilience of fear memories to extinction may contribute to the maintenance of disorders of fear and anxiety, including post-traumatic stress disorder (PTSD). As such, considerable effort has been placed on understanding the neural circuitry underlying the acquisition, expression, and extinction of emotional memories in rodent models as well as in humans. A triad of brain regions, including the prefrontal cortex, hippocampus, and amygdala, form an essential brain circuit involved in fear conditioning and extinction. Within this circuit, the prefrontal cortex is thought to exert top-down control over subcortical structures to regulate appropriate behavioral responses. Importantly, a division of labor has been proposed in which the prelimbic (PL) and infralimbic (IL) subdivisions of the medial prefrontal cortex (mPFC) regulate the expression and suppression of fear in rodents, respectively. Here, we critically review the anatomical and physiological evidence that has led to this proposed dichotomy of function within mPFC. We propose that under some conditions, the PL and IL act in concert, exhibiting similar patterns of neural activity in response to aversive conditioned stimuli and during the expression or inhibition of conditioned fear. This may stem from common synaptic inputs, parallel downstream outputs, or cortico-cortical interactions. Despite this functional covariation, these mPFC subdivisions may still be coding for largely opposing behavioral outcomes, with PL biased towards fear expression and IL towards suppression. PMID:26617500
Nguyen, Michael D; Lee, Scott T; Ross, Ashley E; Ryals, Matthew; Choudhry, Vishesh I; Venton, B Jill
Adenosine is a neuroprotective agent that inhibits neuronal activity and modulates neurotransmission. Previous research has shown adenosine gradually accumulates during pathologies such as stroke and regulates neurotransmission on the minute-to-hour time scale. Our lab developed a method using carbon-fiber microelectrodes to directly measure adenosine changes on a sub-second time scale with fast-scan cyclic voltammetry (FSCV). Recently, adenosine release lasting a couple of seconds has been found in murine spinal cord slices. In this study, we characterized spontaneous, transient adenosine release in vivo, in the caudate-putamen and prefrontal cortex of anesthetized rats. The average concentration of adenosine release was 0.17±0.01 µM in the caudate and 0.19±0.01 µM in the prefrontal cortex, although the range was large, from 0.04 to 3.2 µM. The average duration of spontaneous adenosine release was 2.9±0.1 seconds and 2.8±0.1 seconds in the caudate and prefrontal cortex, respectively. The concentration and number of transients detected do not change over a four hour period, suggesting spontaneous events are not caused by electrode implantation. The frequency of adenosine transients was higher in the prefrontal cortex than the caudate-putamen and was modulated by A1 receptors. The A1 antagonist DPCPX (8-cyclopentyl-1,3-dipropylxanthine, 6 mg/kg i.p.) increased the frequency of spontaneous adenosine release, while the A1 agonist CPA (N(6)-cyclopentyladenosine, 1 mg/kg i.p.) decreased the frequency. These findings are a paradigm shift for understanding the time course of adenosine signaling, demonstrating that there is a rapid mode of adenosine signaling that could cause transient, local neuromodulation.
Simone, Luciano; Bimbi, Marco; Rodà, Francesca; Fogassi, Leonardo; Rozzi, Stefano
Prefrontal cortex is crucial for exploiting contextual information for the planning and guidance of behavioral responses. Among contextual cues, those provided by others’ behavior are particularly important, in primates, for selecting appropriate reactions and suppressing the inappropriate ones. These latter functions deeply rely on the ability to understand others’ actions. However, it is largely unknown whether prefrontal neurons are activated by action observation. To address this issue, we recorded the activity of ventrolateral prefrontal (VLPF) neurons of macaque monkeys during the observation of videos depicting biological movements performed by a monkey or a human agent, and object motion. Our results show that a population of VLPF neurons respond to the observation of biological movements, in particular those representing goal directed actions. Many of these neurons also show a preference for the agent performing the action. The neural response is present also when part of the observed movement is obscured, suggesting that these VLPF neurons code a high order representation of the observed action rather than a simple visual description of it. PMID:28290511
Ramos, Brian P.; Arnsten, Amy F.T.
Norepinephrine (NE) has widespread projections throughout brain, and thus is ideally positioned to orchestrate neural functions based on arousal state. For example, NE can increase “signal/noise” ratio in the processing of sensory stimuli, and can enhance long-term memory consolidation in the amygdala and hippocampus through actions at α-1 and β adrenoceptors. Over the last 20 years, NE has also been shown to play a powerful role in regulating the working memory and attention functions of the prefrontal cortex (PFC). Moderate levels of NE released under control conditions strengthen prefrontal cortical functions via actions at post-synaptic α-2A adrenoceptors with high affinity for NE, while high levels of NE release during stress impair PFC cortical functions via α-1 and possibly β-1 receptors with lower affinity for NE. Thus, levels of NE determine whether prefrontal cortical or posterior cortical systems control our behavior and thought. Understanding these receptor mechanisms has led to new, intelligent treatments for neuropsychiatric disorders associated with PFC dysfunction. PMID:17303246
Garrison, Jane R; Fernandez-Egea, Emilio; Zaman, Rashid; Agius, Mark; Simons, Jon S
Reality monitoring impairment is often reported in schizophrenia but the neural basis of this deficit is poorly understood. Difficulties with reality monitoring could be attributable to the same pattern of neural dysfunction as other cognitive deficits that characterize schizophrenia, or might instead represent a separable and dissociable impairment. This question was addressed through direct comparison of behavioral performance and neural activity associated with reality monitoring and working memory in patients with schizophrenia and matched healthy controls. Participants performed a word-pair reality monitoring task and a Sternberg working memory task while undergoing fMRI scanning. Distinct behavioral deficits were observed in the patients during performance of each task, which were associated with separable task- and region-specific dysfunction in the medial anterior prefrontal cortex for reality monitoring and dorsolateral prefrontal cortex for working memory. The results suggest that reality monitoring impairment is a distinct neurocognitive deficit in schizophrenia. The findings are consistent with the presence of a range of dissociable cognitive deficits in schizophrenia which may be associated with variable functional and structural dysconnectivity in underlying processing networks.
Shiner, T; Symmonds, M; Guitart-Masip, M; Fleming, S M; Friston, K J; Dolan, R J
Dopamine is implicated in multiple functions, including motor execution, action learning for hedonically salient outcomes, maintenance, and switching of behavioral response set. Here, we used a novel within-subject psychopharmacological and combined functional neuroimaging paradigm, investigating the interaction between hedonic salience, dopamine, and response set shifting, distinct from effects on action learning or motor execution. We asked whether behavioral performance in response set shifting depends on the hedonic salience of reversal cues, by presenting these as null (neutral) or salient (monetary loss) outcomes. We observed marked effects of reversal cue salience on set-switching, with more efficient reversals following salient loss outcomes. L-Dopa degraded this discrimination, leading to inappropriate perseveration. Generic activation in thalamus, insula, and striatum preceded response set switches, with an opposite pattern in ventromedial prefrontal cortex (vmPFC). However, the behavioral effect of hedonic salience was reflected in differential vmPFC deactivation following salient relative to null reversal cues. l-Dopa reversed this pattern in vmPFC, suggesting that its behavioral effects are due to disruption of the stability and switching of firing patterns in prefrontal cortex. Our findings provide a potential neurobiological explanation for paradoxical phenomena, including maintenance of behavioral set despite negative outcomes, seen in impulse control disorders in Parkinson's disease.
Morici, Juan Facundo; Bekinschtein, Pedro; Weisstaub, Noelia V
The study of the neurobiology of recognition memory, defined by the integration of the different components of experiences that support recollection of past experiences have been a challenge for memory researches for many years. In the last twenty years, with the development of the spontaneous novel object recognition task and all its variants this has started to change. The features of recognition memory include a particular object or person ("what"), the context in which the experience took place, which can be the arena itself or the location within a particular arena ("where") and the particular time at which the event occurred ("when"). This definition instead of the historical anthropocentric one allows the study of this type of episodic memory in animal models. Some forms of recognition memory that require integration of different features recruit the medial prefrontal cortex. Focusing on findings from spontaneous recognition memory tasks performed by rodents, this review concentrates on the description of previous works that have examined the role that the medial prefrontal cortex has on the different steps of recognition memory. We conclude that this structure, independently of the task used, is required at different memory stages when the task cannot be solved by a single item strategy.
Chan, Annie W.-Y.; Downing, Paul E.
Much of the work on face-selective neural activity has focused on posterior, ventral areas of the human and non-human primate brain. However, electrophysiological and fMRI studies have identified face responses in the prefrontal cortex. Here we used fMRI to characterize these responses in the human prefrontal cortex compared with face selectivity in posterior ventral region. We examined a region at the junction of the right inferior frontal sulcus and the precentral sulcus (right inferior frontal junction or rIFJ) that responds more to faces than to several other object categories. We find that the rIFJ and the right fusiform face area (rFFA) are broadly similar in their responses to whole faces, headless bodies, tools, and scenes. Strikingly, however, while the rFFA preferentially responds to the whole face, the rIFJ response to faces appears to be driven primarily by the eyes. This dissociation provides clues to the functional role of the rIFJ face response. We speculate on this role with reference to emotion perception, gaze perception, and to behavioral relevance more generally. PMID:21687796
Lin, Wen-Jing; Horner, Aidan J.; Burgess, Neil
The medial prefrontal cortex (mPFC) has been consistently implicated in autobiographical memory recall and decision making. Its function in decision making tasks is believed to relate to value representation, but its function in autobiographical memory recall is not yet clear. We hypothesised that the mPFC represents the subjective value of elements during autobiographical memory retrieval. Using functional magnetic resonance imaging during an autobiographical memory recall task, we found that the blood oxygen level dependent (BOLD) signal in ventromedial prefrontal cortex (vmPFC) was parametrically modulated by the affective values of items in participants’ memories when they were recalling and evaluating these items. An unrelated modulation by the participant’s familiarity with the items was also observed. During retrieval of the event, the BOLD signal in the same region was modulated by the personal significance and emotional intensity of the memory, which was correlated with the values of the items within them. These results support the idea that vmPFC processes self-relevant information, and suggest that it is involved in representing the personal emotional values of the elements comprising autobiographical memories. PMID:27338616
Capitao, Liliana; Sampaio, Adriana; Fernandez, Montse; Sousa, Nuno; Pinheiro, Ana; Goncalves, Oscar F.
Individuals with Williams syndrome display indiscriminate approach towards strangers. Neuroimaging studies conducted so far have linked this social profile to structural and/or functional abnormalities in WS amygdala and prefrontal cortex. In this study, the neuropsychological hypotheses of amygdala and prefrontal cortex involvement in WS…
Ariza, Jeanelle; Rogers, Haille; Hashemi, Ezzat; Noctor, Stephen C; Martínez-Cerdeño, Verónica
An interneuron alteration has been proposed as a source for the modified balance of excitation / inhibition in the cerebral cortex in autism. We previously demonstrated a decreased number of parvalbumin (PV)-expressing interneurons in prefrontal cortex in autism. PV-expressing interneurons include chandelier (Ch) and basket (Bsk) cells. We asked whether the decreased PV+ interneurons affected both Ch cells and Bsk cells in autism. The lack of single markers to specifically label Ch cells or Bsk cells presented an obstacle for addressing this question. We devised a method to discern between PV-Ch and PV-Bsk cells based on the differential expression of Vicia villosa lectin (VVA). VVA binds to N-acetylgalactosamine, that is present in the perineuronal net surrounding some cell types where it plays a role in intercellular communication. N-acetylgalactosamine is present in the perineuronal net surrounding Bsk but not Ch cells. We found that the number of Ch cells is consistently decreased in the prefrontal cortex of autistic (n = 10) when compared with control (n = 10) cases, while the number of Bsk cells is not as severely affected. This finding expand our understanding of GABAergic system functioning in the human cerebral cortex in autism, which will impact translational research directed towards providing better treatment paradigms for individuals with autism.
Müri, R M; Rivaud, S; Gaymard, B; Ploner, C J; Vermersch, A I; Hess, C W; Pierrot-Deseilligny, C
Single pulse transcranial magnet stimulation (TMS) was applied in five subjects during a saccadic gap task, i.e. with a temporal gap of 200 ms between the extinguishing of the central fixation point and the appearance of the lateral target. In all subjects, a significant increase of contralateral express saccades was found when TMS was applied over the dorsolateral prefrontal cortex (DPFC) at the end of the gap of 200 ms. Earlier stimulation over the DPFC during the gap had no significant effect. Furthermore, stimulation over the posterior parietal cortex with the same time intervals, and stimulation during a no gap task had no significant influence on express saccades. These results suggest that TMS is capable of interfering specifically with the functioning of the DPFC, probably by inhibition of this region. Possibly such stimulation of the DPFC reduces the inhibition by this region onto the superior colliculus, which results in a facilitation of express saccades.
Hunt, Laurence T; Behrens, Timothy EJ; Hosokawa, Takayuki; Wallis, Jonathan D; Kennerley, Steven W
Activity in prefrontal cortex (PFC) has been richly described using economic models of choice. Yet such descriptions fail to capture the dynamics of decision formation. Describing dynamic neural processes has proven challenging due to the problem of indexing the internal state of PFC and its trial-by-trial variation. Using primate neurophysiology and human magnetoencephalography, we here recover a single-trial index of PFC internal states from multiple simultaneously recorded PFC subregions. This index can explain the origins of neural representations of economic variables in PFC. It describes the relationship between neural dynamics and behaviour in both human and monkey PFC, directly bridging between human neuroimaging data and underlying neuronal activity. Moreover, it reveals a functionally dissociable interaction between orbitofrontal cortex, anterior cingulate cortex and dorsolateral PFC in guiding cost-benefit decisions. We cast our observations in terms of a recurrent neural network model of choice, providing formal links to mechanistic dynamical accounts of decision-making. DOI: http://dx.doi.org/10.7554/eLife.11945.001 PMID:26653139
Simmons, Alan; Stein, Murray B; Matthews, Scott C; Feinstein, Justin S; Paulus, Martin P
Affective appraisal often involves processing complex and ambiguous stimuli, such as the mood of a group people. However, affective neuroimaging research often uses individual faces as stimuli when exploring the neural circuitry involved in social appraisal. Results from studies using single face paradigms may not generalize to settings where multiple faces are simultaneously processed. The goal of the current study was to use a novel task that presents groups of affective faces to probe the medial prefrontal cortex (PFC), a region that is critically involved in appraisal of ambiguous affective stimuli, in healthy volunteers. In the current study, 27 subjects performed the Wall of Faces (WOF) task in which multiple matrices of faces were briefly presented during functional MRI. Subjects were asked to decide whether there were more angry or happy faces (emotional decision) or whether there were more male or female faces (gender decision). In each condition, the array contained either an equal (ambiguous trials) or an unequal (unambiguous trials) distribution of one affect or gender. Ambiguous trials relative to unambiguous trials activated regions implicated in conflict monitoring and cognitive control, including the dorsal anterior cingulate cortex (ACC), dorsolateral PFC, and posterior parietal cortex. When comparing ambiguous affective decisions with ambiguous gender decisions, the ventromedial PFC (including the ventral ACC) was significantly more active. This supports the dissociation of the ACC into dorsal cognitive and ventral affective divisions, and suggests that the ventromedial PFC may play a critical role in appraising affective tone in a complex display of multiple human faces.
Smith, Craig; Goswami, Nandu; Robinson, Ryan; von der Wiesche, Melanie; Schneider, Stefan
Artificial gravity has been proposed as a method to counteract the physiological deconditioning of long-duration spaceflight; however, the effects of hypergravity on the central nervous system has had little study. The study aims to investigate whether there is a relationship between prefrontal cortex brain activity and prefrontal cortex oxygenation during exposure to hypergravity. Twelve healthy participants were selected to undergo hypergravity exposure aboard a short-arm human centrifuge. Participants were exposed to hypergravity in the +Gz axis, starting from 0.6 +Gz for women, and 0.8 +Gz for men, and gradually increasing by 0.1 +Gz until the participant showed signs of syncope. Brain cortical activity was measured using electroencephalography (EEG) and localized to the prefrontal cortex using standard low-resolution brain electromagnetic tomography (LORETA). Prefrontal cortex oxygenation was measured using near-infrared spectroscopy (NIRS). A significant increase in prefrontal cortex activity (P < 0.05) was observed during hypergravity exposure compared with baseline. Prefrontal cortex oxygenation was significantly decreased during hypergravity exposure, with a decrease in oxyhemoglobin levels (P < 0.05) compared with baseline and an increase in deoxyhemoglobin levels (P < 0.05) with increasing +Gz level. No significant correlation was found between prefrontal cortex activity and oxy-/deoxyhemoglobin. It is concluded that the increase in prefrontal cortex activity observed during hypergravity was most likely not the result of increased +Gz values resulting in a decreased oxygenation produced through hypergravity exposure. No significant relationship between prefrontal cortex activity and oxygenation measured by NIRS concludes that brain activity during exposure to hypergravity may be difficult to measure using NIRS. Instead, the increase in prefrontal cortex activity might be attributable to psychological stress, which could pose a problem for the use of a
Knoch, Daria; Fehr, Ernst
Imagine you are overweight and you spot your favorite pastry in the storefront of a bakery. How do you manage to resist this temptation? Or to give other examples, how do you manage to restrain yourself from overspending or succumbing to sexual temptations? The present article summarizes two recent studies stressing the fundamental importance of inhibition in the process of decision making. Based on the results of these studies, we dare to claim that the capacity to resist temptation depends on the activity level of the right prefrontal cortex (PFC).
Nakayama, Sachiko; Suda, Akimitsu; Nakanishi, Atsushi; Motoi, Yumiko; Hattori, Nobutaka
Behavioral and psychological symptoms of dementia (BPSD) occur in up to 80% of AD patients and represent one of the largest factors contributing to caregiver burden. To analyze the effect of galantamine on BPSD and caregiver burden, we treated a total of 50 patients with mild AD for 12 weeks and evaluated them using the Neuropsychiatric Inventory (NPI) and Japanese version of the Zarit Caregiver Burden Interview (ZBI). We also performed regional cerebral blood flow single photon emission computed tomography (rCBF SPECT) at baseline using three-dimensional sterotatic surface projections. Total NPI and ZBI scores did not significantly change after 12-week galantamine treatment. To identify the characteristics of patients who showed improvement after galantamine treatment, we divided patients into two groups, those with and those without sub-items on the NPI. Patients with aggression showed improvement in ZBI scores (p < 0.05). A comparison of rCBF SPECT between these two groups indicated that patients with aggression exhibited increased rCBF in the right prefrontal cortex compared with those without aggression. In a patient with aggression, 20-month treatment with galantamine inhibited increases in the rCBF area in the right prefrontal lobe. These results suggest that galantamine response may be related to aggression and dysfunction of the prefrontal cortex.
Arnsten, Amy F.T.
Attention deficit/hyperactivity disorder (ADHD) is characterized by symptoms of inattention, impulsivity, and locomotor hyperactivity. Recent advances in neurobiology, imaging, and genetics have led to a greater understanding of the etiology and treatment of ADHD. Studies have found that ADHD is associated with weaker function and structure of prefrontal cortex (PFC) circuits, especially in the right hemisphere. The prefrontal association cortex plays a crucial role in regulating attention, behavior, and emotion, with the right hemisphere specialized for behavioral inhibition. The PFC is highly dependent on the correct neurochemical environment for proper function: noradrenergic stimulation of postsynaptic alpha-2A adrenoceptors and dopaminergic stimulation of D1 receptors is necessary for optimal prefrontal function. ADHD is associated with genetic changes that weaken catecholamine signaling and, in some patients, with slowed PFC maturation. Effective pharmacologic treatments for ADHD all enhance catecholamine signaling in the PFC and strengthen its regulation of attention and behavior. Recent animal studies show that therapeutic doses of stimulant medications preferentially increase norepinephrine and, to a lesser extent, dopamine, in the PFC. These doses reduce locomotor activity and improve PFC regulation of attention and behavior through enhanced catecholamine stimulation of alpha-2A and D1 receptors. These findings in animals are consistent with improved PFC function in normal human subjects and, more prominently, in patients with ADHD. Thus, a highly cohesive story is emerging regarding the etiology and treatment of ADHD. PMID:20596295
Petrie, Kimberly A; Schmidt, Dennis; Bubser, Michael; Fadel, Jim; Carraway, Robert E; Deutch, Ariel Y
Converging data suggest a dysfunction of prefrontal cortical GABAergic interneurons in schizophrenia. Morphological and physiological studies indicate that cortical GABA cells are modulated by a variety of afferents. The peptide transmitter neurotensin may be one such modulator of interneurons. In the rat prefrontal cortex (PFC), neurotensin is exclusively localized to dopamine axons and has been suggested to be decreased in schizophrenia. However, the effects of neurotensin on cortical interneurons are poorly understood. We used in vivo microdialysis in freely moving rats to assess whether neurotensin regulates PFC GABAergic interneurons. Intra-PFC administration of neurotensin concentration-dependently increased extracellular GABA levels; this effect was impulse dependent, being blocked by treatment with tetrodotoxin. The ability of neurotensin to increase GABA levels in the PFC was also blocked by pretreatment with 2-[1-(7-chloro-4-quinolinyl)-5-(2,6-dimethoxyphenyl)pyrazole-3-yl)carbonylamino]tricyclo(184.108.40.206 [EC] .3.7)decan-2-carboxylic acid (SR48692), a high-affinity neurotensin receptor 1 (NTR1) antagonist. This finding is consistent with our observation that NTR1 was localized to GABAergic interneurons in the PFC, particularly parvalbumin-containing interneurons. Because neurotensin is exclusively localized to dopamine axons in the PFC, we also determined whether neurotensin plays a role in the ability of dopamine agonists to increase extracellular GABA levels. We found that D2 agonist-elicited increases in PFC GABA levels were blocked by pretreatment with SR48692, consistent with data indicating that D2 autoreceptor agonists increase neurotensin release from dopamine-neurotensin axons in the PFC. These findings suggest that neurotensin plays an important role in regulating prefrontal cortical interneurons and that it may be useful to consider neurotensin agonists as an adjunct in the treatment of schizophrenia.
Politzer-Ahles, Stephen; Gwilliams, Laura
The present study investigated the neural correlates of the realisation of scalar inferences, i.e., the interpretation of some as meaning some but not all. We used magnetoencephalography, which has high temporal resolution, to measure neural activity while participants heard stories that included the scalar inference trigger some in contexts that either provide strong cues for a scalar inference or provide weaker cues. The middle portion of the lateral prefrontal cortex (Brodmann area 46) showed an increased response to some in contexts with fewer cues to the inference, suggesting that this condition elicited greater effort. While the results are not predicted by traditional all-or-nothing accounts of scalar inferencing that assume the process is always automatic or always effortful, they are consistent with more recent gradient accounts which predict that the speed and effort of scalar inferences is strongly modulated by numerous contextual factors. PMID:26247054
Schuck, Nicolas W.; Gaschler, Robert; Wenke, Dorit; Heinzle, Jakob; Frensch, Peter A.; Haynes, John-Dylan; Reverberi, Carlo
Summary Many daily behaviors require us to actively focus on the current task and ignore all other distractions. Yet, ignoring everything else might hinder the ability to discover new ways to achieve the same goal. Here, we studied the neural mechanisms that support the spontaneous change to better strategies while an established strategy is executed. Multivariate neuroimaging analysis showed that before the spontaneous change to an alternative strategy, medial prefrontal cortex (MPFC) encoded information that was irrelevant for the current strategy but necessary for the later strategy. Importantly, this neural effect was related to future behavioral changes: information encoding in MPFC was changed only in participants who eventually switched their strategy and started before the actual strategy change. This allowed us to predict spontaneous strategy shifts ahead of time. These findings suggest that MPFC might internally simulate alternative strategies and sheds new light on the organization of PFC. PMID:25819613
Kurczek, Jake; Duff, Melissa C
Discourse cohesion and coherence give communication its continuity providing the grammatical and lexical links that hold an utterance or text together and give it meaning. Researchers often link cohesion and coherence deficits to the frontal lobes by drawing attention to frontal lobe dysfunction in populations where discourse cohesion and coherence deficits are reported and through attribution of these deficits to underlying cognitive impairments putatively associated with the frontal lobes. We examined the distinct contribution of a region of the frontal lobes, the ventromedial prefrontal cortex (vmPFC), to discourse cohesion and coherence across a range of discourse tasks. We found that bilateral vmPFC damage does not impair cohesion and coherence in spoken discourse. This study provides insights into the contribution of the major anatomical subdivisions of the frontal lobes to language use and furthers our understanding of the neural and cognitive underpinnings of discourse cohesion and coherence.
Saez, A; Rigotti, M; Ostojic, S; Fusi, S; Salzman, C D
Neurons in prefrontal cortex (PFC) encode rules, goals, and other abstract information thought to underlie cognitive, emotional, and behavioral flexibility. Here we show that the amygdala, a brain area traditionally thought to mediate emotions, also encodes abstract information that could underlie this flexibility. Monkeys performed a task in which stimulus-reinforcement contingencies varied between two sets of associations, each defining a context. Reinforcement prediction required identifying a stimulus and knowing the current context. Behavioral evidence indicated that monkeys utilized this information to perform inference and adjust their behavior. Neural representations in both amygdala and PFC reflected the linked sets of associations implicitly defining each context, a process requiring a level of abstraction characteristic of cognitive operations. Surprisingly, when errors were made, the context signal weakened substantially in the amygdala. These data emphasize the importance of maintaining abstract cognitive information in the amygdala to support flexible behavior.
Szczepanski, Sara M.; Knight, Robert T.
SUMMARY The prefrontal cortex (PFC), a cortical region that was once thought to be functionally insignificant, is now known to play an essential role in the organization and control of goal-directed thought and behavior. Neuroimaging, neurophysiological, and modeling techniques have lead to tremendous advances in our understanding of PFC functions over the last few decades. It should be noted, however, that neurological, neuropathological, and neuropsychological studies have contributed some of the most essential, historical, and often prescient, conclusions regarding the functions of this region. Importantly, examination of patients with brain damage allows one to draw conclusions about whether a brain area is necessary for a particular function. Here, we provide a broad overview of PFC functions based upon behavioral and neural changes resulting from damage to PFC in both human patients and non-human primates. PMID:25175878
Young, Liane; Bechara, Antoine; Tranel, Daniel; Damasio, Hanna; Hauser, Marc; Damasio, Antonio
Summary Moral judgments, whether delivered in ordinary experience or in the courtroom, depend on our ability to infer intentions. We forgive unintentional or accidental harms and condemn failed attempts to harm. Prior work demonstrates that patients with damage to the ventromedial prefrontal cortex (VMPC) deliver abnormal judgments in response to moral dilemmas, and that these patients are especially impaired in triggering emotional responses to inferred or abstract events (e.g., intentions), as opposed to real or actual outcomes. We therefore predicted that VMPC patients would deliver abnormal moral judgments of harmful intentions in the absence of harmful outcomes, as in failed attempts to harm. This prediction was confirmed in the current study: VMPC patients judged attempted harms including attempted murder as more morally permissible relative to controls. These results highlight the critical role of the VMPC in processing harmful intent for moral judgment. PMID:20346759
Ciaramelli, Elisa; Sperotto, Rebecca G.; Mattioli, Flavia
Disgust for contaminating objects (core disgust), immoral behaviors (moral disgust) and unsavory others (interpersonal disgust), have been assumed to be closely related. It is not clear, however, whether different forms of disgust are mediated by overlapping or specific neural substrates. We report that 10 patients with damage to the ventromedial prefrontal cortex (vmPFC) avoided behaviors that normally elicit interpersonal disgust (e.g. using the scarf of a busker) less frequently than healthy and brain-damaged controls, whereas they avoided core and moral disgust elicitors at normal rates. These results indicate that different forms of disgust are dissociated neurally. We propose that the vmPFC is causally (and selectively) involved in mediating interpersonal disgust, shaping patterns of social avoidance and approach. PMID:22842816
Background A detailed behavioral profile associated with focal congenital malformation of the ventromedial prefrontal cortex (vmPFC) has not been reported previously. Here we describe a 14 year-old boy, B.W., with neurological and psychiatric sequelae stemming from focal cortical malformation of the left vmPFC. Case Presentation B.W.'s behavior has been characterized through extensive review Patience of clinical and personal records along with behavioral and neuropsychological testing. A central feature of the behavioral profile is severe antisocial behavior. He is aggressive, manipulative, and callous; features consistent with psychopathy. Other problems include: egocentricity, impulsivity, hyperactivity, lack of empathy, lack of respect for authority, impaired moral judgment, an inability to plan ahead, and poor frustration tolerance. Conclusions The vmPFC has a profound contribution to the development of human prosocial behavior. B.W. demonstrates how a congenital lesion to this cortical region severely disrupts this process. PMID:22136635
Nishitani, Shota; Kuwamoto, Saori; Takahira, Asuka; Miyamura, Tsunetake; Shinohara, Kazuyuki
Mothers are attracted by infant cues of a variety of different modalities. To clarify the possible neural mechanisms underlying maternal attraction to infant odor cues, we used near-infrared spectroscopy to examine prefrontal cortex (PFC) activity during odor detection tasks in which 19 mothers and 19 nulliparous females (nonmothers) were presented with infant or adult male odors. They were instructed to make a judgment about whether they smelled an odor during each task. We estimated the PFC activity by measuring the relative oxyhemoglobin (oxyHb) concentrations. The results showed that while detecting the infant odors, bilateral PFC activities were increased in mothers but not in nonmothers. In contrast, adult male odors activated the PFC similarly in mothers and nonmothers. These findings suggest that maternal activation of the PFC in response to infant odors explains a part of the neural mechanisms for maternal attraction to infant odors.
Donoso, Maël; Collins, Anne G E; Koechlin, Etienne
The prefrontal cortex (PFC) subserves reasoning in the service of adaptive behavior. Little is known, however, about the architecture of reasoning processes in the PFC. Using computational modeling and neuroimaging, we show here that the human PFC has two concurrent inferential tracks: (i) one from ventromedial to dorsomedial PFC regions that makes probabilistic inferences about the reliability of the ongoing behavioral strategy and arbitrates between adjusting this strategy versus exploring new ones from long-term memory, and (ii) another from polar to lateral PFC regions that makes probabilistic inferences about the reliability of two or three alternative strategies and arbitrates between exploring new strategies versus exploiting these alternative ones. The two tracks interact and, along with the striatum, realize hypothesis testing for accepting versus rejecting newly created strategies.
Stollstorff, Melanie; Vartanian, Oshin; Goel, Vinod
Right lateral prefrontal cortex (rlPFC) has previously been implicated in logical reasoning under conditions of conflict. A functional magnetic resonance imaging (fMRI) study was conducted to explore its role in conflict more precisely. Specifically, we distinguished between belief-logic conflict and belief-content conflict, and examined the role of rlPFC under each condition. The results demonstrated that a specific region of rlPFC is consistently activated under both types of conflict. Moreover, the results of a parametric analysis demonstrated that the same region was modulated by the level of conflict contained in reasoning arguments. This supports the idea that this specific region is engaged to resolve conflict, including during deductive reasoning. This article is part of a Special Issue entitled "The Cognitive Neuroscience of Thought".
Ciaramelli, Elisa; Neri, Francesco; Marini, Luca; Braghittoni, Davide
We tested (1) whether the PQRST method, involving Preview (P), Question (Q), Read (R), State (S), and Test (T) phases, is effective in enhancing long-term memory in patients with mild memory problems due to prefrontal cortex lesions, and (2) whether patients also benefit from a more self-initiated version of the PQRST. Seven patients with prefrontal lesions encoded new texts under three different conditions: the Standard condition, requiring to read texts repeatedly, the PQRST-Other condition, in which the experimenter formulated questions about the text (Q phase), and the PQRST-Self condition, in which patients formulated the relevant questions on their own. Compared to the Standard condition, both the PQRST-Other and the PQRST-Self condition resulted in higher immediate and delayed recall rates, as well as a higher ability to answer questions about the texts. Importantly, the two PQRST conditions did not differ in efficacy. These results confirm that the PQRST method is effective in improving learning of new material in brain-injured populations with mild memory problems. Moreover, they indicate that the PQRST proves effective even under conditions with higher demands on patients’ autonomy and self-initiation, which encourages its application to real-life situations. PMID:26321932
Rodrigo, Achala H; Di Domenico, Stefano I; Graves, Bryanna; Lam, Jaeger; Ayaz, Hasan; Bagby, R Michael; Ruocco, Anthony C
Inhibitory control is subserved in part by discrete regions of the prefrontal cortex whose functionality may be altered according to specific trait-based phenotypes. Using a unified model of normal range personality traits, we examined activation within lateral and medial aspects of the prefrontal cortex during a manual go/no-go task. Evoked hemodynamic oxygenation within the prefrontal cortex was measured in 106 adults using a 16-channel continuous-wave functional near-infrared spectroscopy system. Within lateral regions of the prefrontal cortex, greater activation was associated with higher trait levels of extraversion, agreeableness and conscientiousness, and lower neuroticism. Higher agreeableness was also related to more activation in the medial prefrontal cortex during inhibitory control. These results suggest that personality traits reflecting greater emotional stability, extraversion, agreeableness and conscientiousness may be associated with more efficient recruitment of control processes subserved by lateral regions of the prefrontal cortex. These findings highlight key links between trait-based phenotypes and neural activation patterns in the prefrontal cortex underlying inhibitory control.
Tsutsui-Kimura, Iku; Yoshida, Takayuki; Izumi, Takeshi; Yoshioka, Mitsuhiro
Background: Deficits in impulse control are often observed in psychiatric disorders in which abnormalities of the prefrontal cortex are observed, including attention-deficit/hyperactivity disorder and bipolar disorder. We recently found that milnacipran, a serotonin/noradrenaline reuptake inhibitor, could suppress impulsive action in normal rats. However, whether milnacipran could suppress elevated impulsive action in rats with lesions of the ventromedial prefrontal cortex, which is functionally comparable with the human prefrontal cortex, remains unknown. Methods: Selective lesions of the ventromedial prefrontal cortex were made using quinolinic acid in rats previously trained on a 3-choice serial reaction time task. Sham rats received phosphate buffered saline. Following a period of recovery, milnacipran (0 or 10mg/kg/d × 14 days) was orally administered 60 minutes prior to testing on the 3-choice task. After 7 days of drug cessation, Western blotting, immunohistochemistry, electrophysiological analysis, and morphological analysis were conducted. Results: Lesions of the ventromedial prefrontal cortex induced impulsive deficits, and repeated milnacipran ameliorated the impulsive deficit both during the dosing period and after the cessation of the drug. Repeated milnacipran remediated the protein levels of mature brain-derived neurotrophic factor and postsynaptic density-95, dendritic spine density, and excitatory currents in the few surviving neurons in the ventromedial prefrontal cortex of ventromedial prefrontal cortex-lesioned rats. Conclusions: The findings of this study suggest that milnacipran treatment could be a novel strategy for the treatment of psychiatric disorders that are associated with a lack of impulse control. PMID:25522418
Rodrigo, Achala H.; Di Domenico, Stefano I.; Graves, Bryanna; Lam, Jaeger; Ayaz, Hasan; Bagby, R. Michael
Inhibitory control is subserved in part by discrete regions of the prefrontal cortex whose functionality may be altered according to specific trait-based phenotypes. Using a unified model of normal range personality traits, we examined activation within lateral and medial aspects of the prefrontal cortex during a manual go/no-go task. Evoked hemodynamic oxygenation within the prefrontal cortex was measured in 106 adults using a 16-channel continuous-wave functional near-infrared spectroscopy system. Within lateral regions of the prefrontal cortex, greater activation was associated with higher trait levels of extraversion, agreeableness and conscientiousness, and lower neuroticism. Higher agreeableness was also related to more activation in the medial prefrontal cortex during inhibitory control. These results suggest that personality traits reflecting greater emotional stability, extraversion, agreeableness and conscientiousness may be associated with more efficient recruitment of control processes subserved by lateral regions of the prefrontal cortex. These findings highlight key links between trait-based phenotypes and neural activation patterns in the prefrontal cortex underlying inhibitory control. PMID:26163672
Manzardo, Ann M.; Gunewardena, Sumedha; Wang, Kun; Butler, Merlin G.
Background Alcohol abuse is associated with cellular and biochemical disturbances that impact upon protein and nucleic acid synthesis, brain development, function and behavioral responses. To further characterize the genetic influences in alcoholism and the effects of alcohol consumption on gene expression, we used a highly sensitive exon microarray to examine mRNA expression in human frontal cortex of alcoholics and control males. Methods Messenger RNA was isolated from the dorsolateral prefrontal cortex (dlPFC, Brodmann area 9) of 7 adult Alcoholic (6 males, 1 female, mean age 48 years) and 7 matched controls. Affymetrix Human Exon 1.0 ST Array was performed according to standard procedures and the results analyzed at the gene level. Microarray findings were validated using qRT-PCR, and the ontology of disturbed genes characterized using Ingenuity Pathway Analysis (IPA). Results Decreased mRNA expression was observed for genes involved in cellular adhesion (e.g., CTNNA3, ITGA2), transport (e.g., TF, ABCA8), nervous system development (e.g., LRP2, UGT8, GLDN) and signaling (e.g., RASGRP, LGR5) with influence over lipid and myelin synthesis (e.g., ASPA, ENPP2, KLK6). IPA identified disturbances in network functions associated with neurological disease, and development including cellular assembly and organization impacting on psychological disorders. Conclusions Our data in alcoholism support a reduction in expression of dlPFC mRNA for genes involved with neuronal growth, differentiation and signaling that targets white matter of the brain. PMID:24890784
Flores-Martínez, Ernesto; Peña-Ortega, Fernando
Alterations in prefrontal cortex (PFC) function and abnormalities in its interactions with other brain areas (i.e., the hippocampus) have been related to Alzheimer Disease (AD). Considering that these malfunctions correlate with the increase in the brain's amyloid beta (Aβ) peptide production, here we looked for a causal relationship between these pathognomonic signs of AD. Thus, we tested whether or not Aβ affects the activity of the PFC network and the activation of this cortex by hippocampal input stimulation in vitro. We found that Aβ application to brain slices inhibits PFC spontaneous network activity as well as PFC activation, both at the population and at the single-cell level, when the hippocampal input is stimulated. Our data suggest that Aβ can contribute to AD by disrupting PFC activity and its long-range interactions throughout the brain.
Alterations in prefrontal cortex (PFC) function and abnormalities in its interactions with other brain areas (i.e., the hippocampus) have been related to Alzheimer Disease (AD). Considering that these malfunctions correlate with the increase in the brain's amyloid beta (Aβ) peptide production, here we looked for a causal relationship between these pathognomonic signs of AD. Thus, we tested whether or not Aβ affects the activity of the PFC network and the activation of this cortex by hippocampal input stimulation in vitro. We found that Aβ application to brain slices inhibits PFC spontaneous network activity as well as PFC activation, both at the population and at the single-cell level, when the hippocampal input is stimulated. Our data suggest that Aβ can contribute to AD by disrupting PFC activity and its long-range interactions throughout the brain. PMID:28127312
Haj-Dahmane, S; Andrade, R
The mammalian prefrontal cortex receives a dense cholinergic innervation from subcortical regions. We previously have shown that cholinergic stimulation of layer V pyramidal neurons of the rat prefrontal cortex results in a depolarization and the appearance of a slow afterdepolarization (sADP). In the current report we examine the mechanism underlying the sADP with the use of sharp microelectrode and whole cell recording techniques in in vitro brain slices. The ability of acetylcholine (ACh) and carbachol to induce the appearance of an sADP in pyramidal cells of layer V of prefrontal cortex is antagonized in a surmountable manner by atropine and is mimicked by application of muscarine or oxotremorine. These results indicate that ACh acts on muscarinic receptors to induce the sADP. In many cell types afterpotentials are triggered by calcium influx into the cell. Therefore we examined the possibility that calcium influx might be the trigger for the generation of the sADP. Consistent with this possibility, buffering intracellular calcium reduced or abolished the sADP but had little effect on the direct muscarinic receptor-induced depolarization also seen in these cells. These results, coupled to the previous observation that calcium channel blockers inhibit the sADP, indicated that the sADP results from a rise in intracellular calcium secondary to calcium influx into the cell. The ionic basis for the current underlying the sADP (IsADP) was examined with the use of ion substitution experiments. The amplitude of IsADP was found to be reduced in a graded fashion by replacement of extracellular sodium with N-methyl-D-glucamine (NMDG). In contrast no clear evidence for the involvement of potassium or chloride channels in the generation of the sADP or IsADP could be found. This result indicated that IsADP is carried by sodium ions flowing into the cell. However, the dependence of IsADP on extracellular sodium was less pronounced than expected for a pure sodium current. We
Conson, Massimiliano; Errico, Domenico; Mazzarella, Elisabetta; Giordano, Marianna; Grossi, Dario; Trojano, Luigi
Recent neurofunctional studies suggested that lateral prefrontal cortex is a domain-general cognitive control area modulating computation of social information. Neuropsychological evidence reported dissociations between cognitive and affective components of social cognition. Here, we tested whether performance on social cognitive and affective tasks can be modulated by transcranial direct current stimulation (tDCS) over dorsolateral prefrontal cortex (DLPFC). To this aim, we compared the effects of tDCS on explicit recognition of emotional facial expressions (affective task), and on one cognitive task assessing the ability to adopt another person’s visual perspective. In a randomized, cross-over design, male and female healthy participants performed the two experimental tasks after bi-hemispheric tDCS (sham, left anodal/right cathodal, and right anodal/left cathodal) applied over DLPFC. Results showed that only in male participants explicit recognition of fearful facial expressions was significantly faster after anodal right/cathodal left stimulation with respect to anodal left/cathodal right and sham stimulations. In the visual perspective taking task, instead, anodal right/cathodal left stimulation negatively affected both male and female participants’ tendency to adopt another’s point of view. These findings demonstrated that concurrent facilitation of right and inhibition of left lateral prefrontal cortex can speed-up males’ responses to threatening faces whereas it interferes with the ability to adopt another’s viewpoint independently from gender. Thus, stimulation of cognitive control areas can lead to different effects on social cognitive skills depending on the affective vs. cognitive nature of the task, and on the gender-related differences in neural organization of emotion processing. PMID:25951227
Conson, Massimiliano; Errico, Domenico; Mazzarella, Elisabetta; Giordano, Marianna; Grossi, Dario; Trojano, Luigi
Recent neurofunctional studies suggested that lateral prefrontal cortex is a domain-general cognitive control area modulating computation of social information. Neuropsychological evidence reported dissociations between cognitive and affective components of social cognition. Here, we tested whether performance on social cognitive and affective tasks can be modulated by transcranial direct current stimulation (tDCS) over dorsolateral prefrontal cortex (DLPFC). To this aim, we compared the effects of tDCS on explicit recognition of emotional facial expressions (affective task), and on one cognitive task assessing the ability to adopt another person's visual perspective. In a randomized, cross-over design, male and female healthy participants performed the two experimental tasks after bi-hemispheric tDCS (sham, left anodal/right cathodal, and right anodal/left cathodal) applied over DLPFC. Results showed that only in male participants explicit recognition of fearful facial expressions was significantly faster after anodal right/cathodal left stimulation with respect to anodal left/cathodal right and sham stimulations. In the visual perspective taking task, instead, anodal right/cathodal left stimulation negatively affected both male and female participants' tendency to adopt another's point of view. These findings demonstrated that concurrent facilitation of right and inhibition of left lateral prefrontal cortex can speed-up males' responses to threatening faces whereas it interferes with the ability to adopt another's viewpoint independently from gender. Thus, stimulation of cognitive control areas can lead to different effects on social cognitive skills depending on the affective vs. cognitive nature of the task, and on the gender-related differences in neural organization of emotion processing.
Matsui, Joy T.; Vaidya, Jatin G.; Wassermann, Demian; Kim, Regina Eunyoung; Magnotta, Vincent A.; Johnson, Hans J.; Paulsen, Jane S.
Huntington disease (HD) is most widely known for its selective degeneration of striatal neurons but there is also growing evidence for white matter (WM) deterioration. The primary objective of this research was to conduct a large-scale analysis using multisite diffusion-weighted imaging (DWI) tractography data to quantify diffusivity properties along major prefrontal cortex WM tracts in prodromal HD. Fifteen international sites participating in the PREDICT-HD study collected imaging and neuropsychological data on gene-positive HD participants without a clinical diagnosis (i.e. prodromal) and gene-negative control participants. The anatomical prefrontal WM tracts of the corpus callosum (PFCC), anterior thalamic radiations (ATR), inferior fronto-occipital fasciculi (IFO), and uncinate fasciculi (UNC) were identified using streamline tractography of DWI. Within each of these tracts, tensor scalars for fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity coefficients were calculated. We divided prodromal HD subjects into three CAG-age product (CAP) groups having Low, Medium, or High probabilities of onset indexed by genetic exposure. We observed significant differences in WM properties for each of the four anatomical tracts for the High CAP group in comparison to controls. Additionally, the Medium CAP group presented differences in the ATR and IFO in comparison to controls. Furthermore, WM alterations in the PFCC, ATR, and IFO showed robust associations with neuropsychological measures of executive functioning. These results suggest long-range tracts essential for cross-region information transfer show early vulnerability in HD and may explain cognitive problems often present in the prodromal stage. PMID:26179962
Matsui, Joy T; Vaidya, Jatin G; Wassermann, Demian; Kim, Regina Eunyoung; Magnotta, Vincent A; Johnson, Hans J; Paulsen, Jane S
Huntington disease (HD) is most widely known for its selective degeneration of striatal neurons but there is also growing evidence for white matter (WM) deterioration. The primary objective of this research was to conduct a large-scale analysis using multisite diffusion-weighted imaging (DWI) tractography data to quantify diffusivity properties along major prefrontal cortex WM tracts in prodromal HD. Fifteen international sites participating in the PREDICT-HD study collected imaging and neuropsychological data on gene-positive HD participants without a clinical diagnosis (i.e., prodromal) and gene-negative control participants. The anatomical prefrontal WM tracts of the corpus callosum (PFCC), anterior thalamic radiations (ATRs), inferior fronto-occipital fasciculi (IFO), and uncinate fasciculi (UNC) were identified using streamline tractography of DWI. Within each of these tracts, tensor scalars for fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity coefficients were calculated. We divided prodromal HD subjects into three CAG-age product (CAP) groups having Low, Medium, or High probabilities of onset indexed by genetic exposure. We observed significant differences in WM properties for each of the four anatomical tracts for the High CAP group in comparison to controls. Additionally, the Medium CAP group presented differences in the ATR and IFO in comparison to controls. Furthermore, WM alterations in the PFCC, ATR, and IFO showed robust associations with neuropsychological measures of executive functioning. These results suggest long-range tracts essential for cross-region information transfer show early vulnerability in HD and may explain cognitive problems often present in the prodromal stage. Hum Brain Mapp 36:3717-3732, 2015. © 2015 Wiley Periodicals, Inc.
Foy, Hannah J.; Runham, Patrick; Chapman, Peter
Road traffic accidents consistently show a significant over-representation for young, novice and particularly male drivers. This research examines the prefrontal cortex activation of young drivers and the changes in activation associated with manipulations of mental workload and inhibitory control. It also considers the explanation that a lack of prefrontal cortex maturation is a contributing factor to the higher accident risk in this young driver population. The prefrontal cortex is associated with a number of factors including mental workload and inhibitory control, both of which are also related to road traffic accidents. This experiment used functional near infrared spectroscopy to measure prefrontal cortex activity during five simulated driving tasks: one following task and four overtaking tasks at varying traffic densities which aimed to dissociate workload and inhibitory control. Age, experience and gender were controlled for throughout the experiment. The results showed that younger drivers had reduced prefrontal cortex activity compared to older drivers. When both mental workload and inhibitory control increased prefrontal cortex activity also increased, however when inhibitory control alone increased there were no changes in activity. Along with an increase in activity during overtaking manoeuvres, these results suggest that prefrontal cortex activation is more indicative of workload in the current task. There were no differences in the number of overtakes completed by younger and older drivers but males overtook significantly more than females. We conclude that prefrontal cortex activity is associated with the mental workload required for overtaking. We additionally suggest that the reduced activation in younger drivers may be related to a lack of prefrontal maturation which could contribute to the increased crash risk seen in this population. PMID:27227990
Foy, Hannah J; Runham, Patrick; Chapman, Peter
Road traffic accidents consistently show a significant over-representation for young, novice and particularly male drivers. This research examines the prefrontal cortex activation of young drivers and the changes in activation associated with manipulations of mental workload and inhibitory control. It also considers the explanation that a lack of prefrontal cortex maturation is a contributing factor to the higher accident risk in this young driver population. The prefrontal cortex is associated with a number of factors including mental workload and inhibitory control, both of which are also related to road traffic accidents. This experiment used functional near infrared spectroscopy to measure prefrontal cortex activity during five simulated driving tasks: one following task and four overtaking tasks at varying traffic densities which aimed to dissociate workload and inhibitory control. Age, experience and gender were controlled for throughout the experiment. The results showed that younger drivers had reduced prefrontal cortex activity compared to older drivers. When both mental workload and inhibitory control increased prefrontal cortex activity also increased, however when inhibitory control alone increased there were no changes in activity. Along with an increase in activity during overtaking manoeuvres, these results suggest that prefrontal cortex activation is more indicative of workload in the current task. There were no differences in the number of overtakes completed by younger and older drivers but males overtook significantly more than females. We conclude that prefrontal cortex activity is associated with the mental workload required for overtaking. We additionally suggest that the reduced activation in younger drivers may be related to a lack of prefrontal maturation which could contribute to the increased crash risk seen in this population.
Liu, Zheng; Wang, Yao; Cai, Li; Li, Yizhi; Chen, Bo; Dong, Yan
Sleep profoundly affects the emotional and motivational state. In humans and animals, loss of sleep often results in enhanced motivation for reward, which has direct implications for health risks as well as potential benefits. Current study aims at understanding the mechanisms underlying sleep deprivation (SDe)-induced enhancement of reward seeking. We found that after acute SDe, mice had an increase in sucrose seeking and consumption but not food intake, suggesting a selective enhancement of motivation for reward. In the nucleus accumbens (NAc), a key brain region regulating emotional and motivational responses, we observed a decrease in the ratio of the overall excitatory over inhibitory synaptic inputs onto NAc principle neurons after SDe. The shift was partly mediated by reduced glutamatergic transmission of presynaptic origin. Further analysis revealed that there was selective reduction of the glutamate release probability at the medial prefrontal cortex (mPFC)-to-NAc synapses, but not those from the hippocampus, thalamus, or the basal lateral amygdala. To reverse this SDe-induced synaptic alteration, we expressed the stabilized step function opsin (SSFO) in the mPFC; optogenetic stimulation of SSFO at mPFC-to-NAc projection terminals persistently enhanced the action potential-dependent glutamate release. Intra-NAc optogenetic stimulation of SSFO selectively at mPFC-to-NAc terminals restored normal sucrose seeking in mice after SDe without affecting food intake. These results highlight the mPFC-to-NAc projection as a key circuit-based target for sleep to regulate reward-motivated behaviors. SIGNIFICANCE STATEMENT Sleep loss, a costly challenge of modern society, has profound physiological and psychological consequences, including altered reward processing of the brain. The current study aims at understanding the mechanisms underlying sleep deprivation-induced enhancement of reward seeking. We identify that the medial prefrontal cortex (m
Hoss, Andrew G.; Labadorf, Adam; Beach, Thomas G.; Latourelle, Jeanne C.; Myers, Richard H.
Objective: The goal of this study was to compare the microRNA (miRNA) profile of Parkinson's disease (PD) frontal cortex with normal control brain, allowing for the identification of PD specific signatures as well as study the disease-related phenotypes of onset age and dementia. Methods: Small RNA sequence analysis was performed from prefrontal cortex for 29 PD samples and 33 control samples. After sample QC, normalization and batch correction, linear regression was employed to identify miRNAs altered in PD, and a PD classifier was developed using weighted voting class prediction. The relationship of miRNA levels to onset age and PD with dementia (PDD) was also characterized in case-only analyses. Results: One twenty five miRNAs were differentially expressed in PD at a genome-wide level of significance (FDR q < 0.05). A set of 29 miRNAs classified PD from non-diseased brain (93.9% specificity, 96.6% sensitivity). The majority of differentially expressed miRNAs (105/125) showed an ordinal relationship from control, to PD without dementia (PDN), to PDD. Among PD brains, 36 miRNAs classified PDD from PDN (sensitivity = 81.2%, specificity = 88.9%). Among differentially expressed miRNAs, miR-10b-5p had a positive association with onset age (q = 4.7e-2). Conclusions: Based on cortical miRNA levels, PD brains were accurately classified from non-diseased brains. Additionally, the PDD miRNA profile exhibited a more severe pattern of alteration among those differentially expressed in PD. To evaluate the clinical utility of miRNAs as potential clinical biomarkers, further characterization and testing of brain-related miRNA alterations in peripheral biofluids is warranted. PMID:26973511
Diamond, Adele; Prevor, Meredith B.; Druin, Donald P.; Callender, Glenda
Hypothesized that elevated ratio of phenylalanine to tyrosine in blood of children with phenylketonuria uniquely affects cognitive functions dependent on prefrontal cortex because of the special sensitivity of prefrontally projecting dopamine neurons to small decreases in tyrosine. Found that children whose phenylalanine levels were three to five…
Cisler, Josh M.; Elton, Amanda; Kennedy, Ashley P.; Young, Jonathan; Smitherman, Sonet; James, George Andrew; Kilts, Clinton D.
Interoception is theorized to be an important process mediating substance use disorders, and the insular cortex is recognized as a core neural region supporting interoception. The purpose of this study was to compare the integration of the insular cortex into prefrontal-related resting-state networks between individuals with cocaine dependence and healthy controls. 41 participants with cocaine dependence and 19 control participants underwent a resting-state 3T fMRI scan. Individuals with cocaine dependence demonstrated altered functional connectivity of the insular cortex, predominantly the right insular cortex, with all eight prefrontal-related resting-state networks identified through Independent Component Analysis (ICA). A conjunction analysis demonstrated that the right insular cortex was the neural region with the highest number of common group differences across the networks. There was no evidence that insular cortex connectivity commonly differed between groups for non-prefrontal-related networks. Further, seed-based functional connectivity analyses extended the network analyses and indicated that cocaine dependence was associated with greater connectivity of the right insula with the dorsomedial PFC, inferior frontal gyrus, and bilateral dlPFC. These data support the hypothesis that cocaine dependence is related to altered functional interactions of the insular cortex with prefrontal networks. The results suggest possible neural mechanisms by which the insular cortex and interoceptive information influence cognitive control and decision-making processes presumably mediated by prefrontal networks in the cocaine dependence process. PMID:23684980
Hoban, A E; Stilling, R M; Ryan, F J; Shanahan, F; Dinan, T G; Claesson, M J; Clarke, G; Cryan, J F
The prefrontal cortex (PFC) is a key region implicated in a range of neuropsychiatric disorders such as depression, schizophrenia and autism. In parallel, the role of the gut microbiota in contributing to these disorders is emerging. Germ-free (GF) animals, microbiota-deficient throughout life, have been instrumental in elucidating the role of the microbiota in many aspects of physiology, especially the role of the microbiota in anxiety-related behaviours, impaired social cognition and stress responsivity. Here we aim to further elucidate the mechanisms of the microbial influence by investigating changes in the homeostatic regulation of neuronal transcription of GF mice within the PFC using a genome-wide transcriptome profiling approach. Our results reveal a marked, concerted upregulation of genes linked to myelination and myelin plasticity. This coincided with upregulation of neural activity-induced pathways, potentially driving myelin plasticity. Subsequent investigation at the ultrastructural level demonstrated the presence of hypermyelinated axons within the PFC of GF mice. Notably, these changes in myelin and activity-related gene expression could be reversed by colonization with a conventional microbiota following weaning. In summary, we believe we demonstrate for the first time that the microbiome is necessary for appropriate and dynamic regulation of myelin-related genes with clear implications for cortical myelination at an ultrastructural level. The microbiota is therefore a potential therapeutic target for psychiatric disorders involving dynamic myelination in the PFC.
Pandey, Ghanshyam N; Rizavi, Hooriyah S; Ren, Xinguo; Fareed, Jawed; Hoppensteadt, Debra A; Roberts, Rosalinda C; Conley, Robert R; Dwivedi, Yogesh
Teenage suicide is a major public health concern, but its neurobiology is not well understood. Proinflammatory cytokines play an important role in stress and in the pathophysiology of depression-two major risk factors for suicide. Cytokines are increased in the serum of patients with depression and suicidal behavior; however, it is not clear if similar abnormality in cytokines occurs in brains of suicide victims. We therefore measured the gene and protein expression levels of proinflammatory cytokines interleukin (IL)-1β, IL-6, and tissue necrosis factor (TNF)-α in the prefrontal cortex (PFC) of 24 teenage suicide victims and 24 matched normal control subjects. Our results show that the mRNA and protein expression levels of IL-1β, IL-6, and TNF-α were significantly increased in Brodmann area 10 (BA-10) of suicide victims compared with normal control subjects. These results suggest an important role for IL-1β, IL-6, and TNF-α in the pathophysiology of suicidal behavior and that proinflammatory cytokines may be an appropriate target for developing therapeutic agents.
Molenberghs, Pascal; Morrison, Samantha
Group membership is an important aspect of our everyday behavior. Recently, we showed that existing relevant in-group labels increased activation in the medial prefrontal cortex (MPFC) compared with out-group labels, suggesting a role of the MPFC in social categorization. However, the question still remains whether this increase in MPFC activation for in-group representation is solely related with previous experience with the in-group. To test this, we randomly assigned participants to a red or blue team and in a subsequent functional magnetic resonance imaging experiment they categorized red and blue team words as belonging to either the in-group or the out-group. Results showed that even under these minimal conditions increased activation was found in the MPFC when participants indicated that they belonged to a group, as compared with when they did not. This effect was found to be associated with the level of group identification. These results confirm the role of MPFC in social categorization.
Cole, Michael W; Ito, Takuya; Braver, Todd S
Our ability to effectively adapt to novel circumstances--as measured by general fluid intelligence--has recently been tied to the global connectivity of lateral prefrontal cortex (LPFC). Global connectivity is a broad measure that summarizes both within-network connectivity and across-network connectivity. We used additional graph theoretical measures to better characterize the nature of LPFC connectivity and its relationship with fluid intelligence. We specifically hypothesized that LPFC is a connector hub with an across-network connectivity that contributes to fluid intelligence independent of within-network connectivity. We verified that LPFC was in the top 10% of brain regions in terms of across-network connectivity, suggesting it is a strong connector hub. Importantly, we found that the LPFC across-network connectivity predicted individuals' fluid intelligence and this correlation remained statistically significant when controlling for global connectivity (which includes within-network connectivity). This supports the conclusion that across-network connectivity independently contributes to the relationship between LPFC connectivity and intelligence. These results suggest that LPFC contributes to fluid intelligence by being a connector hub with a truly global multisystem connectivity throughout the brain.
Wang, Yin; Hamilton, Antonia F de C
The neural and cognitive mechanisms by which primed constructs can impact on social behavior are poorly understood. In the present study, we used functional magnetic resonance imaging (fMRI) to explore how scrambled sentence priming can impact on mimicry behavior. Sentences involving pro/antisocial events from a first/third-person point of view were presented in short blocks, followed by a reaction-time assessment of mimicry. Behavioral results showed that both prosociality and viewpoint impact on mimicry, and fMRI analysis showed this effect is implemented by anterior medial prefrontal cortex (amPFC). We suggest that social primes may subtly modulate processing in amPFC in a manner linked to the later behavior, and that this same region also implements the top-down control of mimicry responses. This priming may be linked to processing of self-schemas in amPFC. Our findings demonstrate how social priming can be studied with fMRI, and have important implications for our understanding of the underlying mechanisms of prime-to-behavior effects as well as for current theories in social psychology.
Bratman, Gregory N.; Hamilton, J. Paul; Hahn, Kevin S.; Daily, Gretchen C.; Gross, James J.
Urbanization has many benefits, but it also is associated with increased levels of mental illness, including depression. It has been suggested that decreased nature experience may help to explain the link between urbanization and mental illness. This suggestion is supported by a growing body of correlational and experimental evidence, which raises a further question: what mechanism(s) link decreased nature experience to the development of mental illness? One such mechanism might be the impact of nature exposure on rumination, a maladaptive pattern of self-referential thought that is associated with heightened risk for depression and other mental illnesses. We show in healthy participants that a brief nature experience, a 90-min walk in a natural setting, decreases both self-reported rumination and neural activity in the subgenual prefrontal cortex (sgPFC), whereas a 90-min walk in an urban setting has no such effects on self-reported rumination or neural activity. In other studies, the sgPFC has been associated with a self-focused behavioral withdrawal linked to rumination in both depressed and healthy individuals. This study reveals a pathway by which nature experience may improve mental well-being and suggests that accessible natural areas within urban contexts may be a critical resource for mental health in our rapidly urbanizing world. PMID:26124129
McEwen, Bruce S; Nasca, Carla; Gray, Jason D
The hippocampus provided the gateway into much of what we have learned about stress and brain structural and functional plasticity, and this initial focus has expanded to other interconnected brain regions, such as the amygdala and prefrontal cortex. Starting with the discovery of adrenal steroid, and later, estrogen receptors in the hippocampal formation, and subsequent discovery of dendritic and spine synapse remodeling and neurogenesis in the dentate gyrus, mechanistic studies have revealed both genomic and rapid non-genomic actions of circulating steroid hormones in the brain. Many of these actions occur epigenetically and result in ever-changing patterns of gene expression, in which there are important sex differences that need further exploration. Moreover, glucocorticoid and estrogen actions occur synergistically with an increasing number of cellular mediators that help determine the qualitative nature of the response. The hippocampus has also been a gateway to understanding lasting epigenetic effects of early-life experiences. These findings in animal models have resulted in translation to the human brain and have helped change thinking about the nature of brain malfunction in psychiatric disorders and during aging, as well as the mechanisms of the effects of early-life adversity on the brain and the body. PMID:26076834
Barbey, Aron K; Patterson, Richard
Causal reasoning is a ubiquitous feature of human cognition. We continuously seek to understand, at least implicitly and often explicitly, the causal scenarios in which we live, so that we may anticipate what will come next, plan a potential response and envision its outcome, decide among possible courses of action in light of their probable outcomes, make midstream adjustments in our goal-related activities as our situation changes, and so on. A considerable body of research shows that the lateral prefrontal cortex (PFC) is crucial for causal reasoning, but also that there are significant differences in the manner in which ventrolateral PFC, dorsolateral PFC, and anterolateral PFC support causal reasoning. We propose, on the basis of research on the evolution, architecture, and functional organization of the lateral PFC, a general framework for understanding its roles in the many and varied sorts of causal reasoning carried out by human beings. Specifically, the ventrolateral PFC supports the generation of basic causal explanations and inferences; dorsolateral PFC supports the evaluation of these scenarios in light of some given normative standard (e.g., of plausibility or correctness in light of real or imagined causal interventions); and anterolateral PFC supports explanation and inference at an even higher level of complexity, coordinating the processes of generation and evaluation with further cognitive processes, and especially with computations of hedonic value and emotional implications of possible behavioral scenarios - considerations that are often critical both for understanding situations causally and for deciding about our own courses of action.
Nee, Derek Evan; D'Esposito, Mark
Higher-level cognition depends on the lateral prefrontal cortex (LPFC), but its functional organization has remained elusive. An influential proposal is that the LPFC is organized hierarchically whereby progressively rostral areas of the LPFC process/represent increasingly abstract information facilitating efficient and flexible cognition. However, support for this theory has been limited. Here, human fMRI data revealed rostral/caudal gradients of abstraction in the LPFC. Dynamic causal modeling revealed asymmetrical LPFC interactions indicative of hierarchical processing. Contrary to dominant assumptions, the relative strength of efferent versus afferent connections positioned mid LPFC as the apex of the hierarchy. Furthermore, cognitive demands induced connectivity modulations towards mid LPFC consistent with a role in integrating information for control operations. Moreover, the strengths of these dynamics were related to trait-measured higher-level cognitive ability. Collectively, these results suggest that the LPFC is hierarchically organized with the mid LPFC positioned to synthesize abstract and concrete information to control behavior. DOI: http://dx.doi.org/10.7554/eLife.12112.001 PMID:26999822
Alexander, William H.; Brown, Joshua W.
A recent computational neural model of medial prefrontal cortex (mPFC), namely the predicted response-outcome (PRO) model (Alexander and Brown, 2011), suggests that mPFC learns to predict the outcomes of actions. The model accounted for a wide range of data on the mPFC. Nevertheless, numerous recent findings suggest that mPFC may signal predictions and prediction errors even when the predicted outcomes are not contingent on prior actions. Here we show that the existing PRO model can learn to predict outcomes in a general sense, and not only when the outcomes are contingent on actions. A series of simulations show how this generalized PRO model can account for an even broader range of findings in the mPFC, including human ERP, fMRI, and macaque single-unit data. The results suggest that the mPFC learns to predict salient events in general and provides a theoretical framework that links mPFC function to model-based reinforcement learning, Bayesian learning, and theories of cognitive control. PMID:25071539
Guise, Kevin G; Shapiro, Matthew L
The prefrontal cortex (PFC) is crucial for accurate memory performance when prior knowledge interferes with new learning, but the mechanisms that minimize proactive interference are unknown. To investigate these, we assessed the influence of medial PFC (mPFC) activity on spatial learning and hippocampal coding in a plus maze task that requires both structures. mPFC inactivation did not impair spatial learning or retrieval per se, but impaired the ability to follow changing spatial rules. mPFC and CA1 ensembles recorded simultaneously predicted goal choices and tracked changing rules; inactivating mPFC attenuated CA1 prospective coding. mPFC activity modified CA1 codes during learning, which in turn predicted how quickly rats adapted to subsequent rule changes. The results suggest that task rules signaled by the mPFC become incorporated into hippocampal representations and support prospective coding. By this mechanism, mPFC activity prevents interference by "teaching" the hippocampus to retrieve distinct representations of similar circumstances.
Barbey, Aron K.; Patterson, Richard
Causal reasoning is a ubiquitous feature of human cognition. We continuously seek to understand, at least implicitly and often explicitly, the causal scenarios in which we live, so that we may anticipate what will come next, plan a potential response and envision its outcome, decide among possible courses of action in light of their probable outcomes, make midstream adjustments in our goal-related activities as our situation changes, and so on. A considerable body of research shows that the lateral prefrontal cortex (PFC) is crucial for causal reasoning, but also that there are significant differences in the manner in which ventrolateral PFC, dorsolateral PFC, and anterolateral PFC support causal reasoning. We propose, on the basis of research on the evolution, architecture, and functional organization of the lateral PFC, a general framework for understanding its roles in the many and varied sorts of causal reasoning carried out by human beings. Specifically, the ventrolateral PFC supports the generation of basic causal explanations and inferences; dorsolateral PFC supports the evaluation of these scenarios in light of some given normative standard (e.g., of plausibility or correctness in light of real or imagined causal interventions); and anterolateral PFC supports explanation and inference at an even higher level of complexity, coordinating the processes of generation and evaluation with further cognitive processes, and especially with computations of hedonic value and emotional implications of possible behavioral scenarios – considerations that are often critical both for understanding situations causally and for deciding about our own courses of action. PMID:21845182
Puig, M. Victoria; Gulledge, Allan T.
Higher-order executive tasks such as learning, working memory, and behavioral flexibility depend on the prefrontal cortex (PFC), the brain region most elaborated in primates. The prominent innervation by serotonin neurons and the dense expression of serotonergic receptors in the PFC suggest that serotonin is a major modulator of its function. The most abundant serotonin receptors in the PFC, 5-HT1A, 5-HT2A and 5-HT3A receptors, are selectively expressed in distinct populations of pyramidal neurons and inhibitory interneurons, and play a critical role in modulating cortical activity and neural oscillations (brain waves). Serotonergic signaling is altered in many psychiatric disorders such as schizophrenia and depression, where parallel changes in receptor expression and brain waves have been observed. Furthermore, many psychiatric drug treatments target serotonergic receptors in the PFC. Thus, understanding the role of serotonergic neurotransmission in PFC function is of major clinical importance. Here we review recent findings concerning the powerful influences of serotonin on single neurons, neural networks, and cortical circuits in the PFC of the rat, where the effects of serotonin have been most thoroughly studied. PMID:22076606
Laroche, S; Davis, S; Jay, T M
The involvement of the hippocampus and the prefrontal cortex in cognitive processes and particularly in learning and memory has been known for a long time. However, the specific role of the projection which connects these two structures has remained elusive. The existence of a direct monosynaptic pathway from the ventral CA1 region of the hippocampus and subiculum to specific areas of the prefrontal cortex provides a useful model for conceptualizing the functional operations of hippocampal-prefrontal cortex communication in learning and memory. It is known now that hippocampal to prefrontal cortex synapses are modifiable synapses and can express different forms of plasticity, including long-term potentiation, long-term depression, and depotentiation. Here we review these findings and focus on recent studies that start to relate synaptic plasticity in the hippocampo-prefrontal cortex pathway to two specific aspects of learning and memory, i.e., the consolidation of information and working memory. The available evidence suggests that functional interactions between the hippocampus and prefrontal cortex in cognition and memory are more complex than previously anticipated, with the possibility for bidirectional regulation of synaptic strength as a function of the specific demands of tasks.
Moriya, M; Aoki, C; Sakatani, K
Physical exercise enhances prefrontal cortex activity and improves working memory performance in healthy older adults, but it is not clear whether this remains the case in post-stroke patients. Therefore, the aim of this study was to examine the acute effect of physical exercise on prefrontal cortex activity in post-stroke patients using near-infrared spectroscopy (NIRS). We studied 11 post-stroke patients. The patients performed Sternberg-type working memory tasks before and after moderate intensity aerobic exercise (40 % of maximal oxygen uptake) with a cycling ergometer for 15 min. We measured the NIRS response at the prefrontal cortex during the working memory task. We evaluated behavioral performance (response time and accuracy) of the working memory task. It was found that physical exercise improved behavioral performance of the working memory task compared with the control condition (p < 0.01). In addition, NIRS analysis indicated that physical exercise enhanced prefrontal cortex activation, particularly in the right prefrontal cortex (p < 0.05), during the working memory task compared with the control condition. These findings suggest that the moderate-intensity aerobic exercise enhances prefrontal cortex activity and improves working memory performance in post-stroke patients.
Insel, Nathan; Pilkiw, Maryna; Nobrega, José N; Hutchison, William D; Takehara-Nishiuchi, Kaori; Hamani, Clement
Deep brain stimulation (DBS) of the subgenual cingulate gyrus (SCG) has been used to treat patients with treatment-resistant depression. As in humans, DBS applied to the ventromedial prefrontal cortex of rats induces antidepressant-like responses. Physiological interactions between structures that play a role in depression and antidepressant treatment are still unknown. The present study examined the effect of DBS on inter-region communication by measuring the coherence of local field potentials in the rat infralimbic cortex (IL; homologue of the SCG) and one of its major afferents, the ventral hippocampus (VH). Rats received daily IL DBS treatment (100 μA, 90 μs, 130 Hz; 8h/day). Recordings were conducted in unrestrained, behaving animals on the day before treatment, after 1 and 10 days of treatment, and 10 days stimulation offset. VH-IL coherence in the 2-4 Hz range was reduced in DBS-treated animals compared with shams after 10 days, but not after only 1 day of treatment. No effect of DBS was observed in the 6-10 Hz (theta) range, where coherence was generally high and could be further evoked with a loud auditory stimulus. Finally, coherence was not affected by fluoxetine (10mg/kg), suggesting that the effects of DBS were not likely mediated by increased serotonin levels. While these data support the hypothesis that DBS disrupts communication between regions important for expectation-based control of emotion, they also suggest that lasting physiological effects require many days of treatment and, furthermore, may be specific to lower-frequency patterns, the nature and scope of which await further investigation.
Sakamoto, Kazuhiro; Katori, Yuichi; Saito, Naohiro; Yoshida, Shun; Aihara, Kazuyuki; Mushiake, Hajime
Flexible behaviors are organized by complex neural networks in the prefrontal cortex. Recent studies have suggested that such networks exhibit multiple dynamical states, and can switch rapidly from one state to another. In many complex systems such as the brain, the early-warning signals that may predict whether a critical threshold for state transitions is approaching are extremely difficult to detect. We hypothesized that increases in firing irregularity are a crucial measure for predicting state transitions in the underlying neuronal circuits of the prefrontal cortex. We used both experimental and theoretical approaches to test this hypothesis. Experimentally, we analyzed activities of neurons in the prefrontal cortex while monkeys performed a maze task that required them to perform actions to reach a goal. We observed increased firing irregularity before the activity changed to encode goal-to-action information. Theoretically, we constructed theoretical generic neural networks and demonstrated that changes in neuronal gain on functional connectivity resulted in a loss of stability and an altered state of the networks, accompanied by increased firing irregularity. These results suggest that assessing the temporal pattern of neuronal fluctuations provides important clues regarding the state stability of the prefrontal network. We also introduce a novel scheme that the prefrontal cortex functions in a metastable state near the critical point of bifurcation. According to this scheme, firing irregularity in the prefrontal cortex indicates that the system is about to change its state and the flow of information in a flexible manner, which is essential for executive functions. This metastable and/or critical dynamical state of the prefrontal cortex may account for distractibility and loss of flexibility in the prefrontal cortex in major mental illnesses such as schizophrenia. PMID:24349020
Romanski, L M; Bates, J F; Goldman-Rakic, P S
Recent anatomical and electrophysiological studies have expanded our knowledge of the auditory cortical system in primates and have described its organization as a series of concentric circles with a central or primary auditory core, surrounded by a lateral and medial belt of secondary auditory cortex with a tertiary parabelt cortex just lateral to this belt. Because recent studies have shown that rostral and caudal belt and parabelt cortices have distinct patterns of connections and acoustic responsivity, we hypothesized that these divergent auditory regions might have distinct targets in the frontal lobe. We, therefore, placed discrete injections of wheat germ agglutinin-horseradish peroxidase or fluorescent retrograde tracers into the prefrontal cortex of macaque monkeys and analyzed the anterograde and retrograde labeling in the aforementioned auditory areas. Injections that included rostral and orbital prefrontal areas (10, 46 rostral, 12) labeled the rostral belt and parabelt most heavily, whereas injections including the caudal principal sulcus (area 46), periarcuate cortex (area 8a), and ventrolateral prefrontal cortex (area12vl) labeled the caudal belt and parabelt. Projections originating in the parabelt cortex were denser than those arising from the lateral or medial belt cortices in most cases. In addition, the anterior third of the superior temporal gyrus and the dorsal bank of the superior temporal sulcus were also labeled after prefrontal injections, confirming previous studies. The present topographical results suggest that acoustic information diverges into separate streams that target distinct rostral and caudal domains of the prefrontal cortex, which may serve different acoustic functions.
Ardid, Salva; Vinck, Martin; Kaping, Daniel; Marquez, Susanna; Everling, Stefan; Womelsdorf, Thilo
Microcircuits are composed of multiple cell classes that likely serve unique circuit operations. But how cell classes map onto circuit functions is largely unknown, particularly for primate prefrontal cortex during actual goal-directed behavior. One difficulty in this quest is to reliably distinguish cell classes in extracellular recordings of action potentials. Here we surmount this issue and report that spike shape and neural firing variability provide reliable markers to segregate seven functional classes of prefrontal cells in macaques engaged in an attention task. We delineate an unbiased clustering protocol that identifies four broad spiking (BS) putative pyramidal cell classes and three narrow spiking (NS) putative inhibitory cell classes dissociated by how sparse, bursty, or regular they fire. We speculate that these functional classes map onto canonical circuit functions. First, two BS classes show sparse, bursty firing, and phase synchronize their spiking to 3-7 Hz (theta) and 12-20 Hz (beta) frequency bands of the local field potential (LFP). These properties make cells flexibly responsive to network activation at varying frequencies. Second, one NS and two BS cell classes show regular firing and higher rate with only marginal synchronization preference. These properties are akin to setting tonically the excitation and inhibition balance. Finally, two NS classes fired irregularly and synchronized to either theta or beta LFP fluctuations, tuning them potentially to frequency-specific subnetworks. These results suggest that a limited set of functional cell classes emerges in macaque prefrontal cortex (PFC) during attentional engagement to not only represent information, but to subserve basic circuit operations.
Dux, Paul E; Tombu, Michael N; Harrison, Stephenie; Rogers, Baxter P; Tong, Frank; Marois, René
Our ability to multitask is severely limited: task performance deteriorates when we attempt to undertake two or more tasks simultaneously. Remarkably, extensive training can greatly reduce such multitasking costs. While it is not known how training alters the brain to solve the multitasking problem, it likely involves the prefrontal cortex given this brain region's purported role in limiting multitasking performance. Here, we show that the reduction of multitasking interference with training is not achieved by diverting the flow of information processing away from the prefrontal cortex or by segregating prefrontal cells into independent task-specific neuronal ensembles, but rather by increasing the speed of information processing in this brain region, thereby allowing multiple tasks to be processed in rapid succession. These results not only reveal how training leads to efficient multitasking, they also provide a mechanistic account of multitasking limitations, namely the poor speed of information processing in human prefrontal cortex.
Vijayakumar, Nandita; Whittle, Sarah; Yücel, Murat; Dennison, Meg; Simmons, Julian; Allen, Nicholas B
Adolescence is a crucial period for the development of adaptive emotion regulation strategies. Despite the fact that structural maturation of the prefrontal cortex during adolescence is often assumed to underlie the maturation of emotion regulation strategies, no longitudinal studies have directly assessed this relationship. This study examined whether use of cognitive reappraisal strategies during late adolescence was predicted by (i) absolute prefrontal cortical thickness during early adolescence and (ii) structural maturation of the prefrontal cortex between early and mid-adolescence. Ninety-two adolescents underwent baseline and follow-up magnetic resonance imaging scans when they were aged approximately 12 and 16 years, respectively. FreeSurfer software was used to obtain cortical thickness estimates for three prefrontal regions [anterior cingulate cortex; dorsolateral prefrontal cortex (dlPFC); ventrolateral prefrontal cortex (vlPFC)]. The Emotion Regulation Questionnaire was completed when adolescents were aged approximately 19 years. Results showed that greater cortical thinning of the left dlPFC and left vlPFC during adolescence was significantly associated with greater use of cognitive reappraisal in females, though no such relationship was evident in males. Furthermore, baseline left dlPFC thickness predicted cognitive reappraisal at trend level. These findings suggest that cortical maturation may play a role in the development of adaptive emotion regulation strategies during adolescence.
López-Ramos, Juan Carlos; Guerra-Narbona, Rafael; Delgado-García, José M.
Decision-making and other cognitive processes are assumed to take place in the prefrontal cortex. In particular, the medial prefrontal cortex (mPFC) is identified in rodents by its dense connectivity with the mediodorsal (MD) thalamus, and because of its inputs from other sites, such as hippocampus and amygdala (Amyg). The aim of this study was to find a putative relationship between the behavior of mice during the performance of decision-making tasks that involve penalties as a consequence of induced actions, and the strength of field postsynaptic potentials (fPSPs) evoked in the prefrontal cortex from its thalamic, hippocampal, and amygdalar afferents. Mice were chronically implanted with stimulating electrodes in the MD thalamus, the hippocampal CA1 area, or the basolateral amygdala (BLA), and with recording electrodes in the prelimbic/infralimbic area of the prefrontal cortex. Additional stimulating electrodes aimed at evoking negative reinforcements were implanted on the trigeminal nerve. FPSPs evoked at the mPFC from the three selected projecting areas during the food/shock decision-making task decreased in amplitude with shock intensity and animals’ avoidance of the reward. FPSPs collected during the operant task also decreased in amplitude (but that evoked by amygdalar stimulation) when lever presses were associated with a trigeminal shock. Results showed a general decrease in the strength of these potentials when animals inhibited their natural or learned appetitive behaviors, suggesting an inhibition of the prefrontal cortex in these conflicting situations. PMID:25688195
Cho, Catherine; Smith, David V.; Delgado, Mauricio R.
Expressing one's preference via choice can be rewarding, particularly when decisions are voluntarily made as opposed to being forced. An open question is whether engaging in choices involving rewards recruits distinct neural systems as a function of sensitivity to reward. Reward sensitivity is a trait partly influenced by the mesolimbic dopamine system, which can impact an individual's neural and behavioral response to reward cues. Here, we investigated how reward sensitivity contributes to neural activity associated with free and forced choices. Participants underwent a simple decision-making task, which presented free- or forced-choice trials in the scanner. Each trial presented two cues (i.e., points or information) that led to monetary reward at the end of the task. In free-choice trials, participants were offered the opportunity to choose between different reward cues (e.g., points vs. information), whereas forced-choice trials forced individuals to choose within a given reward cue (e.g., information vs. information, or points vs. points). We found enhanced ventrolateral prefrontal cortex (VLPFC) activation during free choice compared to forced choice in individuals with high reward sensitivity scores. Next, using the VLPFC as a seed, we conducted a PPI analysis to identify brain regions that enhance connectivity with the VLPFC during free choice. Our PPI analyses on free vs. forced choice revealed increased VLPFC connectivity with the posterior cingulate and precentral gyrus in reward sensitive individuals. These findings suggest reward sensitivity may recruit attentional control processes during free choice potentially supporting goal-directed behavior and action selection. PMID:27917106
Schiller, Daniela; Kanen, Jonathan W.; LeDoux, Joseph E.; Monfils, Marie-H.; Phelps, Elizabeth A.
Controlling learned defensive responses through extinction does not alter the threat memory itself, but rather regulates its expression via inhibitory influence of the prefrontal cortex (PFC) over amygdala. Individual differences in amygdala–PFC circuitry function have been linked to trait anxiety and posttraumatic stress disorder. This finding suggests that exposure-based techniques may actually be least effective in those who suffer from anxiety disorders. A theoretical advantage of techniques influencing reconsolidation of threat memories is that the threat representation is altered, potentially diminishing reliance on this PFC circuitry, resulting in a more persistent reduction of defensive reactions. We hypothesized that timing extinction to coincide with threat memory reconsolidation would prevent the return of defensive reactions and diminish PFC involvement. Two conditioned stimuli (CS) were paired with shock and the third was not. A day later, one stimulus (reminded CS+) but not the other (nonreminded CS+) was presented 10 min before extinction to reactivate the threat memory, followed by extinction training for all CSs. The recovery of the threat memory was tested 24 h later. Extinction of the nonreminded CS+ (i.e., standard extinction) engaged the PFC, as previously shown, but extinction of the reminded CS+ (i.e., extinction during reconsolidation) did not. Moreover, only the nonreminded CS+ memory recovered on day 3. These results suggest that extinction during reconsolidation prevents the return of defensive reactions and diminishes PFC involvement. Reducing the necessity of the PFC–amygdala circuitry to control defensive reactions may help overcome a primary obstacle in the long-term efficacy of current treatments for anxiety disorders. PMID:24277809
Working memory (WM) is one of key concepts to understand functions of the prefrontal cortex. Delay-period activity is an important neural correlate to understand the role of WM in prefrontal functions. The importance of delay-period activity is that this activity can encode not only visuospatial information but also a variety of information including non-spatial visual features, auditory and tactile stimuli, task rules, expected reward, and numerical quantity. This activity also participates in a variety of information processing including sensory-to-motor information transformation. These mnemonic features of delay-period activity enable to perform various important operations that the prefrontal cortex participates in, such as executive controls, and therefore, support the notion that WM is an important function to understand prefrontal functions. On the other hand, although experiments using manual versions of the delayed-response task had revealed many important findings, an oculomotor version of this task enabled us to use multiple cue positions, exclude postural orientation during the delay period, and further prove the importance of mnemonic functions of the prefrontal cortex. In addition, monkeys with unilateral lesions exhibited specific impairment only in the performance of memory-guided saccades directed toward visual cues in the visual field contralateral to the lesioned hemisphere. This result indicates that memories for visuospatial coordinates in each hemifield are processed primarily in the contralateral prefrontal cortex. This result further strengthened the idea of mnemonic functions of the prefrontal cortex. Thus, the mnemonic functions of the prefrontal cortex and delay-period activity may not need to be reconsidered, but should be emphasized. PMID:25698942
Working memory (WM) is one of key concepts to understand functions of the prefrontal cortex. Delay-period activity is an important neural correlate to understand the role of WM in prefrontal functions. The importance of delay-period activity is that this activity can encode not only visuospatial information but also a variety of information including non-spatial visual features, auditory and tactile stimuli, task rules, expected reward, and numerical quantity. This activity also participates in a variety of information processing including sensory-to-motor information transformation. These mnemonic features of delay-period activity enable to perform various important operations that the prefrontal cortex participates in, such as executive controls, and therefore, support the notion that WM is an important function to understand prefrontal functions. On the other hand, although experiments using manual versions of the delayed-response task had revealed many important findings, an oculomotor version of this task enabled us to use multiple cue positions, exclude postural orientation during the delay period, and further prove the importance of mnemonic functions of the prefrontal cortex. In addition, monkeys with unilateral lesions exhibited specific impairment only in the performance of memory-guided saccades directed toward visual cues in the visual field contralateral to the lesioned hemisphere. This result indicates that memories for visuospatial coordinates in each hemifield are processed primarily in the contralateral prefrontal cortex. This result further strengthened the idea of mnemonic functions of the prefrontal cortex. Thus, the mnemonic functions of the prefrontal cortex and delay-period activity may not need to be reconsidered, but should be emphasized.
Clark, L.; Bechara, A.; Damasio, H.; Aitken, M. R. F.; Sahakian, B. J.; Robbins, T. W.
The ventromedial prefrontal cortex (vmPFC) and insular cortex are implicated in distributed neural circuitry that supports emotional decision-making. Previous studies of patients with vmPFC lesions have focused primarily on decision-making under uncertainty, when outcome probabilities are ambiguous (e.g. the Iowa Gambling Task). It remains unclear…
Quirk, Gregory J; Likhtik, Ekaterina; Pelletier, Joe Guillaume; Paré, Denis
In extinction of auditory fear conditioning, rats learn that a tone no longer predicts the occurrence of a footshock. Recent lesion and unit recording studies suggest that the medial prefrontal cortex (mPFC) plays an essential role in the inhibition of conditioned fear following extinction. mPFC has robust projections to the amygdala, a structure that is known to mediate the acquisition and expression of conditioned fear. Fear conditioning potentiates the tone responses of neurons in the basolateral amygdala (BLA), which excite neurons in the central nucleus (Ce) of the amygdala. In turn, the Ce projects to the brainstem and hypothalamic areas that mediate fear responses. The present study was undertaken to test the hypothesis that the mPFC inhibits conditioned fear via feedforward inhibition of Ce output neurons. Recording extracellularly from physiologically identified brainstem-projecting Ce neurons, we tested the effect of mPFC prestimulation on Ce responsiveness to synaptic input. In support of our hypothesis, mPFC prestimulation dramatically reduced the responsiveness of Ce output neurons to inputs from the insular cortex and BLA. Thus, our findings support the idea that mPFC gates impulse transmission from the BLA to Ce, perhaps through GABAergic intercalated cells, thereby gating the expression of conditioned fear.
Fernández, R.; Sabater, R.; Sáez, J. A.; Montes, R.; Alba, F.; Ferrer, J. M.
1 Intracortical microinjections of neurotensin (NT) selectively decreased intracranial self-stimulation (ICSS) of the medial prefrontal cortex in the rat. 2 To elucidate whether this effect is mediated by NT receptors or by the formation of NT-dopamine complexes, we investigated the effects on ICSS of intracortical microinjections of neurotensin (1-11), an NT fragment that forms extracellular complexes with dopamine but does not bind to NT receptors. 3 We also studied the effects of the peripheral administration of SR 48692, a selective antagonist of NT receptors, on the inhibition of ICSS produced by the intracortical administration of NT. 4 Unilateral microinjections of neurotensin (1-11) at doses of 10, 20 and 40 nmol into the medial prefrontal cortex did not change the basal ICSS rate of this area. 5 The intraperitoneal administration of SR 48692 at doses of 0.08 and 0.16 mg kg-1 30 min before microinjection of 10 nmol of NT into the medial prefrontal cortex, antagonized the inhibition of ICSS produced by the neuropeptide. 6 These results demonstrate that the inhibitory effect of NT on ICSS is mediated by NT receptors. PMID:8886412
Low, Kathy A.; Leaver, Echo E.; Kramer, Arthur F.; Fabiani, Monica; Gratton, Gabriele
Dual-task performance requires flexible attention allocation to two or more streams of information. Dorsolateral prefrontal cortex (DLPFC) is considered important for executive function and recent modeling work proposes that attention control may arise from selective activation and inhibition of different processing units within this region. Here we used a tone discrimination task and a visual letter memory task to examine whether this type of competition could be measurable using a neuroimaging technique, the event-related optical signal, with high spatial and temporal resolution. Left and right DLPFC structures were differentially affected by task priority and load, with the left middle frontal gyrus (MFG) being preferentially recruited by the visual memory task, whereas the two tasks competed for recruitment, in a spatially segregated manner, in right MFG. The data provide support for a competition view of dual-task processing. PMID:19572909
Lee, Inah; Shin, Ji Yun
The exact roles of the medial prefrontal cortex (mPFC) in conditional choice behavior are unknown and a visual contextual response selection task was used for examining the issue. Inactivation of the mPFC severely disrupted performance in the task. mPFC inactivations, however, did not disrupt the capability of perceptual discrimination for visual stimuli. Normal response selection was also observed when nonvisual cues were used as conditional stimuli. The results strongly suggest that the mPFC is not necessarily involved in the inhibition of response or flexible response selection in general, but is rather critical when response selection is required conditionally using visual context in the background. PMID:22595688
Maier, Steven F.; Watkins, Linda R.
The degree of behavioral control that an organism has over an aversive event is well known to modulate the behavioral and neurochemical consequences of exposure to the event. Here we review recent research that suggests that the experience of control over a potent stressor alters how the organism responds to future aversive events as well as to the stressor being controlled. More specifically, subjects that have experienced control show blunted behavioral and neurochemical responses to subsequent stressors occurring days to months later. Indeed, these subjects respond as if a later uncontrollable stressor is actually controllable. Further, we review research indicating that the stress-resistance induced by control depends on control-induced activation of ventral medial prefrontal cortical (vmPFC) inhibitory control over brainstem and limbic structures. Furthermore, there appears to be plasticity in these circuits such that the experience of control alters the vmPFC in such a way that later uncontrollable stressors now activate the vmPFC circuitry, leading to inhibition of stress-responsive limbic and brainstem structures, i.e., stressor resistance. This controllability-induced proactive stressor resistance generalizes across very different stressors and may be involved in determining individual difference in reactions to traumatic events. PMID:20727864
Background Brain glucose sensing may contribute to energy homeostasis control. The prefrontal cortex (PFC) participates in the hedonic component of feeding control. As high-fat diets may disrupt energy homeostasis, we evaluated in male Wistar rats whether intake of high-fat fish-oil diet modified cortical glucose extracellular levels and the feeding induced by intracerebroventricular glucose or PFC glucoprivation. Methods Glucose levels in PFC microdialysates were measured before and after a 30-min meal. Food intake was measured in animals receiving intracerebroventricular glucose followed, 30-min. later, by 2-deoxy-D-glucose injected into the PFC. Results The fish-oil group showed normal body weight and serum insulin while fat pads weight and glucose levels were increased. Baseline PFC glucose and 30-min. carbohydrates intake were similar between the groups. Feeding-induced PFC glucose levels increased earlier and more pronouncedly in fish-oil than in control rats. Intracerebroventricular glucose inhibited feeding consistently in the control but not in the fish-oil group. Local PFC glucoprivation with 2-DG attenuated glucose-induced hypophagia. Conclusions The present experiments have shown that, following food intake, more glucose reached the prefrontal cortex of the rats fed the high-fat fish-oil diet than of the rats fed the control diet. However, when administered directly into the lateral cerebral ventricle, glucose was able to consistently inhibit feeding only in the control rats. The findings indicate that, an impairment of glucose transport into the brain does not contribute to the disturbances induced by the high-fat fish-oil feeding. PMID:24369745
Zhang, Zhili; Li, Ting; Zheng, Yi; Luo, Qingming; Song, Ranran; Gong, Hui
Developmental dyslexia, a kind of prevalent psychological disease, represents that dyslexic children have unexpected difficulties in phonological processing and recognition test of Chinese characters. Some functional imaging technologies, such as fMRI and PET, have been used to study the brain activities of the children with dyslexia whose first language is English. In this paper, a portable, 16-channel, continuous-wave (CW) NIRS instrument was used to monitor the concentration changes of each hemoglobin species when Chinese children did the task of phonological processing and recognition test. The NIRS recorded the hemodynamic changes in the left prefrontal cortex of the children. 20 dyslexia-reading children (10~12 years old) and 20 normal-reading children took part in the phonological processing of Chinese characters including the phonological awareness section and the phonological decoding section. During the phonological awareness section, the changed concentration of deoxy-hemoglobin in dyslexia-reading children were significantly higher (p<0.05) than normal-reading children in the left ventrolateral prefrontal cortex (VLPFC). While in the phonological decoding section, both normal and dyslexic reading children had more activity in the left VLPFC, but only normal-reading children had activity in the left middorsal prefrontal cortex. In conclusion, both dyslexic and normal-reading children have activity in the left prefrontal cortex, but the degree and the areas of the prefrontal cortex activity are different between them when they did phonological processing.
Windmann, Sabine; Wehrmann, Michaela; Calabrese, Pasquale; Güntürkün, Onur
The primary source of top-down attentional control in object perception is the prefrontal cortex. This region is involved in the maintenance of goal-related information as well as in attentional selection and set shifting. Recent approaches have emphasized the role of top-down processes during elementary visual processes as exemplified in bistable vision where perception oscillates automatically between two mutually exclusive states. The prefrontal cortex might influence this process either by maintaining the dominant pattern while protecting it against the competing representation, or by facilitating perceptual switches between the two competing representations. To address this issue, we investigated reported perceptual reversals in patients with circumscribed lesions of the prefrontal cortex and healthy control participants in three experimental conditions: hold (maintaining the dominant view), speed (inducing as many perceptual switches as possible), and neutral (no intervention). Results indicated that although the patients showed normal switching rates in the neutral condition and were able to control perceptual switches in the hold condition as much as control subjects were, they were less able to facilitate reversals specifically in the speed condition. These results suggest that the prefrontal cortex is necessary to bias the selection of visual representations in accord with current goals, but is less essential for maintaining selected information active that is continuously available in the environment. As for attentional selection, the present results suggest that the prefrontal cortex initiates perceptual reversals by withdrawing top-down support from the dominant representation without (or prior to) boosting the suppressed view.
Meneses, S; Galicia, O; Brailowsky, S
It has been proposed that functions associated with the prefrontal cortex could change as a consequence of aging. Previous experiments in young rats have demonstrated that anatomical lesions or chronic GABA infusions into this area produce deficits in spatial delayed alternation tasks. The present study examines the effect of chronic (7 days) GABA or saline infusion into the prefrontal cortex on the performance of delayed alternation task in old rats (24 months). The results suggested that aged rats needed more sessions to acquire the delayed alternation task. GABA infusions into the prefrontal cortex produced deficits in spatial alternation tasks similar to those previously observed in young rats. Performance rapidly recovered after the infusion period. Histological analysis showed similar lesion size in both groups. The results suggest that aged prefrontal cortex and/or related areas participating in the acquisition of the delayed alternation task are more sensitive to aging processes. Furthermore, the prefrontal cortex is important for the retention of a previously learned spatial delayed alternation task. The structures involved in functional recovery from these deficits appear to be fully functional in aged rats.
Goel, Vinod; Lam, Elaine; Smith, Kathleen W; Goel, Amit; Raymont, Vanessa; Krueger, Frank; Grafman, Jordan
While it is widely accepted that lesions to orbital prefrontal cortex lead to emotion related disruptions and poor decision-making, there is very little patient data on this issue involving actual logical reasoning tasks. We tested patients with circumscribed, focal lesions largely confined to polar/orbital prefrontal cortex (BA 10 & 11) (N=17) on logical reasoning tasks involving neutral and emotional content, and compared their performance to that of an age and education-matched normal control group (N=22) and a posterior lesion control group (N=24). Our results revealed a significant group by content interaction driven by a selective impairment in the polar/orbital prefrontal cortex group compared to healthy normal controls and to the parietal patient group, in the emotional content reasoning trials. Subsequent analyses of congruent and incongruent reasoning trials indicated that this impairment was driven by the poor performance of patients with polar/orbital lesions in the incongruent trials. We conclude that the polar/orbital prefrontal cortex plays a critical role in filtering emotionally charged content from the material before it is passed on to the reasoning system in lateral/dorsal regions of prefrontal cortex. Where unfiltered content is passed to the reasoning engine, either as a result of pathology (as in the case of our patients) or as a result of individual differences, reasoning performance suffers.
Zhou, Hou-Cheng; Sun, Yan-Yan; Cai, Wei; He, Xiao-Ting; Yi, Feng; Li, Bao-Ming; Zhang, Xue-Han
The prefrontal cortex (PFC) plays a critical role in cognitive functions, including working memory, attention regulation, behavioral inhibition, as well as memory storage. The functions of PFC are very sensitive to norepinephrine (NE), and even low levels of endogenously released NE exert a dramatic influence on the functioning of the PFC.…
Bugatus, Lior; Weiner, Kevin S; Grill-Spector, Kalanit
A central question in neuroscience is how cognitive tasks affect category representations across the human brain. Regions in lateral occipito-temporal cortex (LOTC), ventral temporal cortex (VTC), and ventro-lateral prefrontal cortex (VLFPC) constitute the extended "what" pathway, which is considered instrumental for visual category processing. However, it is unknown (1) whether distributed responses across LOTC, VTC, and VLPC explicitly represent category, task, or some combination of both, and (2) in what way representations across these subdivisions of the extended 'what' pathway may differ. To fill these gaps in knowledge, we scanned 12 participants using fMRI to test the effect of category and task on distributed responses across LOTC, VTC, and VLPFC. Results reveal that task and category modulate responses in both high-level visual regions, as well as prefrontal cortex. However, we found fundamentally different types of representations across the brain. Distributed responses in high-level visual regions are more strongly driven by category than task, and exhibit task-independent category representations. In contrast, distributed responses in prefrontal cortex are more strongly driven by task than category, and contain task-dependent category representations. Together, these findings of differential representations across the brain support a new idea that LOTC and VTC maintain stable and separable category representations allowing efficient processing of visual information, while prefrontal cortex contains flexible representations in which separable category information may emerge only when relevant to the task.
Hutcherson, Cendri A; Montaser-Kouhsari, Leila; Woodward, James; Rangel, Antonio
Moral judgment often requires making difficult tradeoffs (e.g., is it appropriate to torture to save the lives of innocents at risk?). Previous research suggests that both emotional appraisals and more deliberative utilitarian appraisals influence such judgments and that these appraisals often conflict. However, it is unclear how these different types of appraisals are represented in the brain, or how they are integrated into an overall moral judgment. We addressed these questions using an fMRI paradigm in which human subjects provide separate emotional and utilitarian appraisals for different potential actions, and then make difficult moral judgments constructed from combinations of these actions. We found that anterior cingulate, insula, and superior temporal gyrus correlated with emotional appraisals, whereas temporoparietal junction and dorsomedial prefrontal cortex correlated with utilitarian appraisals. Overall moral value judgments were represented in an anterior portion of the ventromedial prefrontal cortex. Critically, the pattern of responses and functional interactions between these three sets of regions are consistent with a model in which emotional and utilitarian appraisals are computed independently and in parallel, and passed to the ventromedial prefrontal cortex where they are integrated into an overall moral value judgment. Significance statement: Popular accounts of moral judgment often describe it as a battle for control between two systems, one intuitive and emotional, the other rational and utilitarian, engaged in winner-take-all inhibitory competition. Using a novel fMRI paradigm, we identified distinct neural signatures of emotional and utilitarian appraisals and used them to test different models of how they compete for the control of moral behavior. Importantly, we find little support for competitive inhibition accounts. Instead, moral judgments resembled the architecture of simple economic choices: distinct regions represented emotional
Stepień, I; Stepień, L; Toeplitz, Z
In 20 dogs the manipulatory go left go right differentiation to acoustic directional cues was elaborated. All dogs received total prefrontal, or dorsolateral (total or partial) or medial (total or partial) cortical ablations. All total ablations markedly affected performance of the task, whereas the partial removals produced moderate or no impairment. Thus, both the dorsolateral and medial prefrontal cortex are involved in this type of differentiation.
Sudorgina, P V; Saulskaya, N B
In Sprague-Dawley rats by means of in vivo microdialysis, we have shown that presentation to rats-during conditioned fear expression of a sound conditioned stimulus previously paired with footshock (CS+) produces an increase in extracellular levels of citrulline (an NO co-product) in the medial prefrontal cortex. Presentation to the same rats of a different sound stimulus (not associated with footshock) (CS-) causes a very small increase in extracellular citrulline level. CS+ induced citrulline increase is prevented by infusions into the medial prefrontal cortex of Nomega-propyl-L-arginine (1 mM), a neuronal NO synthase inhibitor and it is not observed in control rats (same procedure, no footshock). These data indicate for the first time that sound signals of danger, but not safety signals activate nitrergic system of the medial prefrontal cortex.
Cattaneo, Zaira; Mattavelli, Giulia; Platania, Elisa; Papagno, Costanza
Stereotypes associated with gender, race, ethnicity and religion are powerful forces in human social interactions. Previous neuroimaging and neuropsychological studies point to a role of the prefrontal cortex in controlling stereotypical responses. Here we used transcranial magnetic stimulation (TMS) in combination with an Implicit Association Test (IAT) to highlight the possible causal role of the left dorsolateral prefrontal cortex (DLPFC) and the right anterior dorsomedial prefrontal cortex (aDMPFC) in controlling gender-stereotypical responses. Young male and female participants were tested. Our results showed that applying TMS over the left DLPFC and the right aDMPFC increased the gender-stereotypical bias in male participants compared to when TMS was applied to a control site (vertex). This suggests that both the left DLPFC and the right aDMPFC play a direct role in stereotyping. Females did not show a significant gender bias on the IAT; correspondingly their responses were unaffected by TMS.
Xi, Chunhua; Zhu, Youling; Niu, Chaoshi; Zhu, Chunyan; Lee, Tatia M C; Tian, Yanghua; Wang, Kai
Recent works have suggested an association between the ventromedial prefrontal cortex (VMPC) and social cognition or decision making. The aim of this study is to investigate the theory of mind and decision making in patients with VMPC lesions and in those with dorsolateral prefrontal cortex (DLPC) lesions. Patients with VMPC lesions (n=16) and those with DLPC lesions (n=14) were compared with healthy controls (HC) on faux pas recognition and 2 decision-making tasks. Consistent with previous data, patients with VMPC lesions performed worse on the theory of mind and decision making. Patients with DLPC lesions showed impairments of the theory of mind but performed at control levels on the 2 decision-making tasks. The results supported the view that a separation of function of 2 distinct subregions of the prefrontal cortex is important to the theory of mind and decision making.
Jeon, Hyeon-Ae; Friederici, Angela D
The lateral prefrontal cortex is known to be organized by cognitive hierarchies following a posterior-to-anterior gradient. Here we test whether this model applies across different cognitive domains by varying levels of cognitive hierarchy in first language, second language and non-language domains. These domains vary in their degree of automaticity with first language being the most automatic. For second language/non-language a clear gradient pattern of activation depending on the level of hierarchy is observed in the prefrontal cortex with the highest level of hierarchy recruiting its most anterior region, whereas for first language the highest level of hierarchy recruits its most posterior region. Moreover, second language/non-language and first language differ in the structural connectivity of their underlying networks. The current data strongly suggest that functional segregation of the prefrontal cortex is determined by cognitive hierarchy and the degree of automaticity.
Ito, Ayahito; Abe, Nobuhito; Fujii, Toshikatsu; Hayashi, Akiko; Ueno, Aya; Mugikura, Shunji; Takahashi, Shoki; Mori, Etsuro
Recent neuroimaging evidence suggests that the dorsolateral prefrontal cortex is associated with creating deceptive responses. However, the neural basis of the preparatory processes that create deception has yet to be explored. Previous neuroimaging studies have demonstrated that the preparation for a certain task activates brain areas relevant to the execution of that task, leading to the question of whether dorsolateral prefrontal activity is observed during the preparation for deception. In the present study, we used functional magnetic resonance imaging (fMRI) to determine whether dorsolateral prefrontal activity, which increases during the execution of deception compared with the execution of truth-telling, also increases during the preparation for deception compared with the preparation for truth-telling. Our data show that the execution of deception was associated with increased activity in several brain regions, including the left dorsolateral prefrontal cortex, compared with truth-telling, confirming the contribution of this region to the production of deceptive responses. The results also reveal that the preparations for both deception and truth-telling were associated with increased activity in certain brain regions, including the left dorsolateral prefrontal cortex. These findings suggest that the preparations for truth-telling and deception make similar demands on the brain and that the dorsolateral prefrontal activity identified in the preparation phase is associated with general preparatory processes, regardless of whether one is telling a lie or the truth.
Doll, Anselm; Hölzel, Britta K; Mulej Bratec, Satja; Boucard, Christine C; Xie, Xiyao; Wohlschläger, Afra M; Sorg, Christian
Mindfulness practice is beneficial for emotion regulation; however, the neural mechanisms underlying this effect are poorly understood. The current study focuses on effects of attention-to-breath (ATB) as a basic mindfulness practice on aversive emotions at behavioral and brain levels. A key finding across different emotion regulation strategies is the modulation of amygdala and prefrontal activity. It is unclear how ATB relevant brain areas in the prefrontal cortex integrate with amygdala activation during emotional stimulation. We proposed that, during emotional stimulation, ATB down-regulates activation in the amygdala and increases its integration with prefrontal regions. To address this hypothesis, 26 healthy controls were trained in mindfulness-based attention-to-breath meditation for two weeks and then stimulated with aversive pictures during both attention-to-breath and passive viewing while undergoing fMRI. Data were controlled for breathing frequency. Results indicate that (1) ATB was effective in regulating aversive emotions. (2) Left dorso-medial prefrontal cortex was associated with ATB in general. (3) A fronto-parietal network was additionally recruited during emotional stimulation. (4) ATB down regulated amygdala activation and increased amygdala-prefrontal integration, with such increased integration being associated with mindfulness ability. Results suggest amygdala-dorsal prefrontal cortex integration as a potential neural pathway of emotion regulation by mindfulness practice.
Hussey, Erika K.; Ward, Nathan; Christianson, Kiel; Kramer, Arthur F.
Recent research demonstrates that performance on executive-control measures can be enhanced through brain stimulation of lateral prefrontal regions. Separate psycholinguistic work emphasizes the importance of left lateral prefrontal cortex executive-control resources during sentence processing, especially when readers must override early, incorrect interpretations when faced with temporary ambiguity. Using transcranial direct current stimulation, we tested whether stimulation of left lateral prefrontal cortex had discriminate effects on language and memory conditions that rely on executive-control (versus cases with minimal executive-control demands, even in the face of task difficulty). Participants were randomly assigned to receive Anodal, Cathodal, or Sham stimulation of left lateral prefrontal cortex while they (1) processed ambiguous and unambiguous sentences in a word-by-word self-paced reading task and (2) performed an n-back memory task that, on some trials, contained interference lure items reputed to require executive-control. Across both tasks, we parametrically manipulated executive-control demands and task difficulty. Our results revealed that the Anodal group outperformed the remaining groups on (1) the sentence processing conditions requiring executive-control, and (2) only the most complex n-back conditions, regardless of executive-control demands. Together, these findings add to the mounting evidence for the selective causal role of left lateral prefrontal cortex for executive-control tasks in the language domain. Moreover, we provide the first evidence suggesting that brain stimulation is a promising method to mitigate processing demands encountered during online sentence processing. PMID:26528814
Brennan, Avis R.; Dolinsky, Beth; Vu, Mai-Anh T.; Stanley, Marion; Yeckel, Mark F.; Arnsten, Amy F.T.
Planning and directing thought and behavior require the working memory (WM) functions of prefrontal cortex. WM is compromised by stress, which activates phosphatidylinositol (PI)-mediated IP3-PKC intracellular signaling. PKC overactivation impairs WM operations and in vitro studies indicate that IP3 receptor (IP3R)-evoked calcium release results in SK channel-dependent hyperpolarization of prefrontal neurons. However, the effects of IP3R signaling on prefrontal function have not been investigated. The present findings demonstrate that blockade of IP3R or SK channels in the prefrontal cortex enhances WM performance in rats, suggesting that both arms of the PI cascade influence prefrontal cognitive function. PMID:18285467
McGAUGHY, J.; ROSS, R. S.; EICHENBAUM, H.
Both norepinephrine and acetylcholine have been shown to be critically involved in mediating attention but there remains debate about whether they serve similar or unique functions. Much of what is known about the role of these neurochemicals in cognition is based on manipulations done at the level of the cell body but these findings are difficult to reconcile with data regarding the unique contribution of cortical subregions, e.g. the dorsolateral prefrontal cortex, to attention. In the current study, we directly compared the effects of noradrenergic and cholinergic deafferentation of the rat medial prefrontal cortex, the homologue of primate dorsolateral prefrontal cortex, using an intradimensional/extradimensional attentional set shifting task, a task previously shown to be able to dissociate the function of the primate dorsolateral prefrontal cortex from orbitofrontal cortex. We found that noradrenergic, but not cholinergic, deafferentation produces specific impairments in the ability to shift attentional set. We also clarified the nature of the attentional deficits by assessing the ability of rats to disregard irrelevant stimuli. Noradrenergic lesions did not alter the ability of rats to ignore irrelevant stimuli, suggesting that the attentional deficit results from an overly focused attentional state that retards learning that a new stimulus dimension predicts reward. PMID:18355972
Huang, Wen-Chin; Chen, Youjun; Page, Damon T.
Multiple autism risk genes converge on the regulation of mTOR signalling, which is a key effector of neuronal growth and connectivity. We show that mTOR signalling is dysregulated during early postnatal development in the cerebral cortex of germ-line heterozygous Pten mutant mice (Pten+/−), which model macrocephaly/autism syndrome. The basolateral amygdala (BLA) receives input from subcortical-projecting neurons in the medial prefrontal cortex (mPFC). Analysis of mPFC to BLA axonal projections reveals that Pten+/− mice exhibit increased axonal branching and connectivity, which is accompanied by increased activity in the BLA in response to social stimuli and social behavioural deficits. The latter two phenotypes can be suppressed by pharmacological inhibition of S6K1 during early postnatal life or by reducing the activity of mPFC–BLA circuitry in adulthood. These findings identify a mechanism of altered connectivity that has potential relevance to the pathophysiology of macrocephaly/autism syndrome and autism spectrum disorders featuring dysregulated mTOR signalling. PMID:27845329
Luchicchi, Antonio; Mnie-Filali, Ouissame; Terra, Huub; Bruinsma, Bastiaan; de Kloet, Sybren F.; Obermayer, Joshua; Heistek, Tim S.; de Haan, Roel; de Kock, Christiaan P. J.; Deisseroth, Karl; Pattij, Tommy; Mansvelder, Huibert D.
Attending the sensory environment for cue detection is a cognitive operation that occurs on a time scale of seconds. The dorsal and ventral medial prefrontal cortex (mPFC) contribute to separate aspects of attentional processing. Pyramidal neurons in different parts of the mPFC are active during cognitive behavior, yet whether this activity is causally underlying attentional processing is not known. We aimed to determine the precise temporal requirements for activation of the mPFC subregions during the seconds prior to cue detection. To test this, we used optogenetic silencing of dorsal or ventral mPFC pyramidal neurons at defined time windows during a sustained attentional state. We find that the requirement of ventral mPFC pyramidal neuron activity is strictly time-locked to stimulus detection. Inhibiting the ventral mPFC 2 s before or during cue presentation reduces response accuracy and hampers behavioral inhibition. The requirement for dorsal mPFC activity on the other hand is temporally more loosely related to a preparatory attentional state, and short lapses in pyramidal neuron activity in dorsal mPFC do not affect performance. This only occurs when the dorsal mPFC is inhibited during the entire preparatory period. Together, our results reveal that a dissociable temporal recruitment of ventral and dorsal mPFC is required during attentional processing. PMID:27630545
Kirk, Ulrich; Gu, Xiaosi; Harvey, Ann H; Fonagy, Peter; Montague, P Read
Neuroimaging research has demonstrated that ventromedial prefrontal cortex (vmPFC) encodes value signals that can be modulated by top-down cognitive input such as semantic knowledge, price incentives, and monetary favors suggesting that such biases may have an identified biological basis. It has been hypothesized that mindfulness training (MT) provides one path for gaining control over such top-down influences; yet, there have been no direct tests of this hypothesis. Here, we probe the behavioral and neural effects of MT on value signals in vmPFC in a randomized longitudinal design of 8 weeks of MT on an initially naïve subject cohort. The impact of this within-subject training was assessed using two paradigms: one that employed primary rewards (fruit juice) in a simple conditioning task and another that used a well-validated art-viewing paradigm to test bias of monetary favors on preference. We show that MT behaviorally censors the top-down bias of monetary favors through a measurable influence on value signals in vmPFC. MT also modulates value signals in vmPFC to primary reward delivery. Using a separate cohort of subjects we show that 8 weeks of active control training (ACT) generates the same behavioral impact also through an effect on signals in the vmPFC. Importantly, functional connectivity analyses show that value signals in vmPFC are coupled with bilateral posterior insula in the MT groups in both paradigms, but not in the ACT groups. These results suggest that MT integrates interoceptive input from insular cortex in the context of value computations of both primary and secondary rewards.
Chan, Annie W.-Y.
Recent neuroimaging studies in both human and non-human primates have identified face selective activation in the ventral lateral prefrontal cortex (VLPFC) even in the absence of working memory (WM) demands. Further, research has suggested that this face-selective response is largely driven by the presence of the eyes. However, the nature and origin of visual category responses in the VLPFC remain unclear. In a broader sense, how do these findings relate to our current understandings of lateral prefrontal cortex? What do these findings tell us about the underlying function and organization principles of the VLPFC? What is the future direction for investigating visual representations in this cortex? This review focuses on the function, topography, and circuitry of the VLPFC to enhance our understanding of the evolution and development of this cortex. PMID:23847558
Glausier, Jill R.; Maddox, Marcelia; Hemmings, Hugh C.; Nairn, Angus C.; Greengard, Paul; Muly, E. Chris
The actions of dopamine D1 family receptors (D1R) depend upon a signal transduction cascade that modulates the phosphorylation state of important effector proteins, such as glutamate receptors and ion channels. This is accomplished both through activation of protein kinase A (PKA) and the inhibition of protein phosphatase-1 (PP1). Inhibition of PP1 occurs through PKA-mediated phosphorylation of DARPP-32 or the related protein inhibitor-1 (I-1), and the availability of DARPP-32 is essential to the functional outcome of D1R activation in the basal ganglia. While D1R activation is critical for prefrontal cortex (PFC) function, especially working memory, the functional role played by DARPP-32 or I-1 is less clear. In order to examine this more thoroughly, we have utilized immunoelectron microscopy to quantitatively determine the localization of DARPP-32 and I-1 in the neuropil of the rhesus monkey PFC. Both were distributed widely in the different components of the neuropil, but were enriched in dendritic shafts. I-1 label was more frequently identified in axon terminals than was DARPP-32, and DARPP-32 label was more frequently identified in glia than was I-1. We also quantified the extent to which these proteins were found in dendritic spines. DARPP-32 and I-1 were present in small subpopulations of dendritic spines, (4.4 and 7.7% and respectively), which were substantially smaller than observed for D1R in our previous studies (20%). Double-label experiments did not find evidence for colocalization of D1R and DARPP-32 or I-1 in spines or terminals. Thus, at the least, not all prefrontal spines which contain D1R also contain I-1 or DARPP-32, suggesting important differences in D1R signaling in the PFC compared to the striatum. PMID:20156529
Schmitz, Felipe; Pierozan, Paula; Rodrigues, André F; Biasibetti, Helena; Coelho, Daniella M; Mussulini, Ben Hur; Pereira, Mery S L; Parisi, Mariana M; Barbé-Tuana, Florencia; de Oliveira, Diogo L; Vargas, Carmen R; Wyse, Angela T S
The understanding of the consequences of chronic treatment with methylphenidate is very important since this psychostimulant is extensively prescribed to preschool age children, and little is known about the mechanisms underlying the persistent changes in behavior and neuronal function related with the use of methylphenidate. In this study, we initially investigate the effect of early chronic treatment with methylphenidate on amino acids profile in cerebrospinal fluid and prefrontal cortex of juvenile rats, as well as on glutamatergic homeostasis, Na(+),K(+)-ATPase function, and balance redox in prefrontal cortex of rats. Wistar rats at early age received intraperitoneal injections of methylphenidate (2.0 mg/kg) or an equivalent volume of 0.9% saline solution (controls), once a day, from the 15th to the 45th day of age. Twenty-four hours after the last injection, the animals were decapitated and the cerebrospinal fluid and prefrontal cortex were obtained. Results showed that methylphenidate altered amino acid profile in cerebrospinal fluid, increasing the levels of glutamate. Glutamate uptake was decreased by methylphenidate administration, but GLAST and GLT-1 were not altered by this treatment. In addition, the astrocyte marker GFAP was not altered by MPH. The activity and immunocontent of catalytic subunits (α1, α2, and α3) of Na(+),K(+)-ATPase were decreased in prefrontal cortex of rats subjected to methylphenidate treatment, as well as changes in α1 and α2 gene expression of catalytic α subunits of Na(+),K(+)-ATPase were also observed. CAT activity was increased and SOD/CAT ratio and sulfhydryl content were decreased in rat prefrontal cortex. Taken together, our results suggest that chronic treatment with methylphenidate at early age induces excitotoxicity, at least in part, due to inhibition of glutamate uptake probably caused by disturbances in the Na(+),K(+)-ATPase function and/or in protein damage observed in the prefrontal cortex.
Pascual-Leone, A; Catalá, M D; Pascual-Leone Pascual, A
We studied the effects of rapid-rate transcranial magnetic stimulation (rTMS) of different scalp positions on mood. Ten normal volunteers rated themselves before and after rTMS on five analog scales labeled "Tristeza" (Sadness), "Ansiedad" (Anxiety), "Alegria" (Happiness), "Cansancio" (Tiredness), and "Dolor/Malestar" (Pain/Discomfort). rTMS was applied to the right lateral prefrontal, left prefrontal, or midline frontal cortex in trains of 5 seconds' duration at 10 Hz and 110% of the subject's motor threshold intensity. Each stimulation position received 10 trains separated by a 25-second pause. No clinically apparent mood changes were evoked by rTMS to any of the scalp positions in any subject. However, left prefrontal rTMS resulted in a significant increase in the Sadness ratings (Tristeza) and a significant decrease in the Happiness ratings ("Alegria") as compared with right prefrontal and midfrontal cortex stimulation. These results show differential effects of rTMS of left and right prefrontal cortex stimulation on mood and illustrate the lateralized control of mood in normal volunteers.
García-Pacios, Javier; Garcés, Pilar; Del Río, David; Maestú, Fernando
Unpleasant emotional distraction can impair the retention of non-emotional information in working memory (WM). Research links the prefrontal cortex with the successful control of such biologically relevant distractors, although the temporal changes in this brain mechanism remain unexplored. We use magnetoencephalography to investigate the temporal dynamics of the cognitive control of both unpleasant and pleasant distraction, in the millisecond (ms) scale. Behavioral results demonstrate that pleasant events do not affect WM maintenance more than neutral ones. Neuroimaging results show that prefrontal cortices are recruited for the rapid detection of emotional distraction, at early latencies of the processing (70-130 ms). Later in the processing (360-450 ms), the dorsolateral, the medial and the orbital sections of the prefrontal cortex mediate the effective control of emotional distraction. In accordance with the behavioral performance, pleasant distractors do not require higher prefrontal activity than neutral ones. These findings extend our knowledge about the brain mechanisms of coping with emotional distraction in WM. In particular, they show for the first time that overriding the attentional capture triggered by emotional distractors, while maintaining task-relevant elements in mind, is based on the early detection of such linked-to-survival information and on its later cognitive control by the prefrontal cortex. PMID:26067780
Warren, Brandon L.; Mendoza, Michael P.; Cruz, Fabio C.; Leao, Rodrigo M.; Caprioli, Daniele; Rubio, F. Javier; Whitaker, Leslie R.; McPherson, Kylie B.; Bossert, Jennifer M.; Shaham, Yavin
In operant learning, initial reward-associated memories are thought to be distinct from subsequent extinction-associated memories. Memories formed during operant learning are thought to be stored in “neuronal ensembles.” Thus, we hypothesize that different neuronal ensembles encode reward- and extinction-associated memories. Here, we examined prefrontal cortex neuronal ensembles involved in the recall of reward and extinction memories of food self-administration. We first trained rats to lever press for palatable food pellets for 7 d (1 h/d) and then exposed them to 0, 2, or 7 daily extinction sessions in which lever presses were not reinforced. Twenty-four hours after the last training or extinction session, we exposed the rats to either a short 15 min extinction test session or left them in their homecage (a control condition). We found maximal Fos (a neuronal activity marker) immunoreactivity in the ventral medial prefrontal cortex of rats that previously received 2 extinction sessions, suggesting that neuronal ensembles in this area encode extinction memories. We then used the Daun02 inactivation procedure to selectively disrupt ventral medial prefrontal cortex neuronal ensembles that were activated during the 15 min extinction session following 0 (no extinction) or 2 prior extinction sessions to determine the effects of inactivating the putative food reward and extinction ensembles, respectively, on subsequent nonreinforced food seeking 2 d later. Inactivation of the food reward ensembles decreased food seeking, whereas inactivation of the extinction ensembles increased food seeking. Our results indicate that distinct neuronal ensembles encoding operant reward and extinction memories intermingle within the same cortical area. SIGNIFICANCE STATEMENT A current popular hypothesis is that neuronal ensembles in different prefrontal cortex areas control reward-associated versus extinction-associated memories: the dorsal medial prefrontal cortex (mPFC) promotes
Ray, Rebecca; Zald, David H.
Ray, R. and D. Zald. Anatomical insights into the interaction of emotion and cognition in the prefrontal cortex. NEUROSCI BIOBEHAV REV 36(X) XXX-XXX, 2011. -Psychological research increasingly indicates that emotional processes interact with other aspects of cognition. Studies have demonstrated both the ability of emotional stimuli to influence a broad range of cognitive operations, and the ability of humans to use top-down cognitive control mechanisms to regulate emotional responses. Portions of the prefrontal cortex appear to play a significant role in these interactions. However, the manner in which these interactions are implemented remains only partially elucidated. In the present review we describe the anatomical connections between ventral and dorsal prefrontal areas as well as their connections with limbic regions. Only a subset of prefrontal areas are likely to directly influence amygdalar processing, and as such models of prefrontal control of emotions and models of emotional regulation should be constrained to plausible pathways of influence. We also focus on how the specific pattern of feedforward and feedback connections between these regions may dictate the nature of information flow between ventral and dorsal prefrontal areas and the amygdala. These patterns of connections are inconsistent with several commonly expressed assumptions about the nature of communications between emotion and cognition. PMID:21889953
Akbarian, S.; Huntsman, M. M.; Kim, J. J.; Tafazzoli, A.; Potkin, S. G.; Bunney, W. E. Jr; Jones, E. G.; Bloom, F. E. (Principal Investigator)
The prefrontal cortex of schizophrenics is hypoactive and displays changes related to inhibitory, GABAergic neurons, and GABAergic synapses. These changes include decreased levels of glutamic acid decarboxylase (GAD), the enzyme for GABA synthesis, upregulation of muscimol binding, and downregulation of benzodiazepine binding to GABAA receptors. Studies in the visual cortex of nonhuman primates have demonstrated that gene expression for GAD and for several GABAA receptor subunit polypeptides is under control of neuronal activity, raising the possibility that similar mechanisms in the hypoactive prefrontal cortex of schizophrenics may explain the abnormalities in GAD and in GABAA receptor regulation. In the present study, which is the first of its type on human cerebral cortex, levels of mRNAs for six GABAA receptor subunits (alpha 1, alpha 2, alpha 5, beta 1, beta 2, gamma 2) and their laminar expression patterns were analyzed in the prefrontal cortex of schizophrenics and matched controls, using in situ hybridization histochemistry and densitometry. Three types of laminar expression pattern were observed: mRNAs for the alpha 1, beta 2, and gamma 2 subunits, which are the predominant receptor subunits expressed in the mature cortex, were expressed at comparatively high levels by cells of all six cortical layers, but most intensely by cells in lower layer III and layer IV. mRNAs for the alpha 2, alpha 5, and beta 1 subunits were expressed at lower levels; alpha 2 and beta 1 were expressed predominantly by cells in layers II, III, and IV; alpha 5 was expressed predominantly in layers IV, V, and VI. There were no significant changes in overall mRNA levels for any of the receptor subunits in the prefrontal cortex of schizophrenics, and the laminar expression pattern of all six receptor subunit mRNAs did not differ between schizophrenics and controls. Because gene expression for GABAA receptor subunits is not consistently altered in the prefrontal cortex of
Salzman, C. Daniel; Fusi, Stefano
Neuroscientists have often described cognition and emotion as separable processes implemented by different regions of the brain, such as the amygdala for emotion and the prefrontal cortex for cognition. In this framework, functional interactions between the amygdala and prefrontal cortex mediate emotional influences on cognitive processes such as decision-making, as well as the cognitive regulation of emotion. However, neurons in these structures often have entangled representations, whereby single neurons encode multiple cognitive and emotional variables. Here we review studies using anatomical, lesion, and neurophysiological approaches to investigate the representation and utilization of cognitive and emotional parameters. We propose that these mental state parameters are inextricably linked and represented in dynamic neural networks composed of interconnected prefrontal and limbic brain structures. Future theoretical and experimental work is required to understand how these mental state representations form and how shifts between mental states occur, a critical feature of adaptive cognitive and emotional behavior. PMID:20331363
Farahmandfar, Maryam; Bakhtazad, Atefeh; Akbarabadi, Ardeshir; Zarrindast, Mohammad-Reza
Dopaminergic modulations of glutamate receptors are essential for the prefrontal cortical (PFC) behavioral and cognitive functions. In order to understand the effect of dopamine/glutamate interactions on learning and memory, we investigated the effects of intra medial prefrontal cortex (mPFC) injections of dopaminergic agents on ketamine-induced amnesia by using a one-trial passive avoidance task in mice. Pre-training administration of ketamine (5, 10 and 15mg/kg, i.p.) dose-dependently decreased the memory acquisition of a one-trial passive avoidance task. Pre-training intra-mPFC administration of SKF 38393, D1 receptor agonist and quinpirol D2 receptor agonist, alone did not affect memory acquisition. However, amnesia induced by pre-training ketamine (15mg/kg) significantly decreased by pretreatment of SKF 38393 (2 and 4µg/mouse) and quinpirol (0.3, 1 and 3µg/mouse). Pre-training administration of SCH 23390, D1 receptor antagonist (0.75 and 1μg/mouse, intra-mPFC), and sulpiride D2 receptor antagonist (3μg/mouse, intra-mPFC) impaired memory acquisition. In addition, co-pretreatment of different doses of SCH 23390 and sulpiride with lower dose of ketamine (5mg/kg), which did not induce amnesia by itself, caused inhibition of memory formation. It may be concluded that dopaminergic system of medial prefrontal cortex is involved in the ketamine-induced impairment of memory acquisition.
Frattali, Carol; Hanna, Rebecca; McGinty, Anita Shukla; Gerber, Lynn; Wesley, Robert; Grafman, Jordan; Coelho, Carl
The function of suppression of context-inappropriate meanings during lexical ambiguity resolution was examined in 25 adults with prefrontal cortex damage (PFCD) localized to the left (N = 8), right (N = 6), or bilaterally (N = 11); and 21 matched Controls. Results revealed unexpected inverse patterns of suppression between PFCD and Control groups,…
Geday, Jacob; Gjedde, Albert
Attention deactivates the inferior medial prefrontal cortex (IMPC), but it is uncertain if emotions can attenuate this deactivation. To test the extent to which common emotions interfere with attention, we measured changes of a blood flow index of brain activity in key areas of the IMPC with positron emission tomography (PET) of labeled water…
Yamamuro, Kazuhiko; Kimoto, Sohei; Iida, Junzo; Kishimoto, Naoko; Nakanishi, Yoko; Tanaka, Shohei; Ota, Toyosaku; Makinodan, Manabu; Kishimoto, Toshifumi
Patients with methamphetamine abuse/dependence often exhibit high levels of impulsivity, which may be associated with the structural abnormalities and functional hypoactivities observed in the frontal cortex of these subjects. Although near-infrared spectroscopy (NIRS) is a simple and non-invasive method for characterizing the clinical features of various psychiatric illnesses, few studies have used NIRS to directly investigate the association between prefrontal cortical activity and inhibitory control in patients with methamphetamine-induced psychosis (MAP). Using a 24-channel NIRS system, we compared hemodynamic responses during the Stroop color-word task in 14 patients with MAP and 21 healthy controls matched for age, sex and premorbid IQ. In addition, we used the Barrett Impulsivity Scale-11 (BIS-11) to assess impulsivity between subject groups. The MAP group exhibited significantly less activation in the anterior and frontopolar prefrontal cortex accompanied by lower Stroop color-word task performance, compared with controls. Moreover, BIS-11 scores were significantly higher in the MAP group, and were negatively correlated with the hemodynamic responses in prefrontal cortex. Our data suggest that reduced hemodynamic responses in the prefrontal cortex might reflect higher levels of impulsivity in patients with MAP, providing new insights into disrupted inhibitory control observed in MAP. PMID:27050450
Hylin, Michael J.; Orsi, Sara A.; Moore, Anthony N.; Dash, Pramod K.
The perineuronal net (PNN) surrounds neurons in the central nervous system and is thought to regulate developmental plasticity. A few studies have shown an involvement of the PNN in hippocampal plasticity and memory storage in adult animals. In addition to the hippocampus, plasticity in the medial prefrontal cortex (mPFC) has been demonstrated to…
Beeman, Christopher L.; Bauer, Philip S.; Pierson, Jamie L.; Quinn, Jennifer J.
Previous work has shown that damage to the dorsal hippocampus (DH) occurring at recent, but not remote, timepoints following acquisition produces a deficit in trace conditioned fear memory expression. The opposite pattern has been observed with lesions to the medial prefrontal cortex (mPFC). The present studies address: (1) whether these lesion…
Yoon, Taejib; Okada, Jeffrey; Jung, Min W.; Kim, Jeansok J.
Both the medial prefrontal cortex (mPFC) and hippocampus are implicated in working memory tasks in rodents. Specifically, it has been hypothesized that the mPFC is primarily engaged in the temporary storage and processing of information lasting from a subsecond to several seconds, while the hippocampal function becomes more critical as the working…
Matsuzaka, Yoshiya; Akiyama, Tetsuya; Tanji, Jun; Mushiake, Hajime
The functional roles of the primate posterior medial prefrontal cortex have remained largely unknown. Here, we show that this region participates in the regulation of actions in the presence of multiple response tactics. Monkeys performed a forelimb task in which a visual cue required prompt decision of reaching to a left or a right target. The location of the cue was either ipsilateral (concordant) or contralateral (discordant) to the target. As a result of extensive training, the reaction times for the concordant and discordant trials were indistinguishable, indicating that the monkeys developed tactics to overcome the cue-response conflict. Prefrontal neurons exhibited prominent activity when the concordant and discordant trials were randomly presented, requiring rapid selection of a response tactic (reach toward or away from the cue). The following findings indicate that these neurons are involved in the selection of tactics, rather than the selection of action or monitoring of response conflict: (i) The response period activity of neurons in this region disappeared when the monkeys performed the task under the behavioral condition that required a single tactic alone, whereas the action varied across trials. (ii) The neuronal activity was found in the dorsomedial prefrontal cortex but not in the anterior cingulate cortex that has been implicated for the response conflict monitoring. These results suggest that the medial prefrontal cortex participates in the selection of a response tactic that determines an appropriate action. Furthermore, the observation of dynamic, task-dependent neuronal activity necessitates reconsideration of the conventional concept of cortical motor representation. PMID:22371582
Gilbert, Sam J.; Burgess, Paul W.
In this article, we discuss the role of rostral prefrontal cortex (approximating Brodmann Area 10) in two domains relevant to education: executive function (particularly prospective memory, our ability to realize delayed intentions) and social cognition (particularly our ability to reflect on our own mental states and the mental states of others).…
Baran, Sarah E.; Armstrong, Charles E.; Niren, Danielle C.; Conrad, Cheryl D.
Electrolytic lesions of the medial prefrontal cortex (PFCX) were examined using fear conditioning to assess the recall of fear extinction and performance in the Y-maze, open field, and object location/recognition in male and female Sprague-Dawley rats. Rats were conditioned to seven tone/footshocks, followed by extinction after 1-h and 24-h…
Lee, Inah; Shin, Ji Yun
The exact roles of the medial prefrontal cortex (mPFC) in conditional choice behavior are unknown and a visual contextual response selection task was used for examining the issue. Inactivation of the mPFC severely disrupted performance in the task. mPFC inactivations, however, did not disrupt the capability of perceptual discrimination for visual…
Blouin, Ashley M.; Han, Sungho; Pearce, Anne M.; Cheng, KaiLun; Lee, JongAh J.; Johnson, Alexander W.; Wang, Chuansong; During, Matthew J.; Holland, Peter C.; Shaham, Yavin; Baraban, Jay M.; Reti, Irving M.
Narp knockout (KO) mice demonstrate an impaired extinction of morphine conditioned place preference (CPP). Because the medial prefrontal cortex (mPFC) has been implicated in extinction learning, we tested whether Narp cells in this region play a role in the extinction of morphine CPP. We found that intracranial injections of adenoassociated virus…
Poletti, Michele; Bonuccelli, Ubaldo
A recent paper (Zald & Andreotti, 2010) reviewed neuropsychological tasks that assess the function of the orbital and ventromedial portions of the prefrontal cortex (OMPFC). Neuropathological studies have shown that the function of the OMPFC should be preserved in the early stages of Parkinson's disease (PD) but becomes affected in the advanced…
Samson, Dana; Connolly, Catherine; Humphreys, Glyn W.
The contribution of the left inferior prefrontal cortex in semantic processing has been widely investigated in the last decade. Converging evidence from functional imaging studies shows that this region is involved in the "executive" or "controlled" aspects of semantic processing. In this study, we report a single case study of a patient, PW, with…
Garrett, Amy S.; Reiss, Allan L.; Howe, Meghan E.; Kelley, Ryan G.; Singh, Manpreet K.; Adleman, Nancy E.; Karchemskiy, Asya; Chang, Kiki D.
Objective: Previous functional magnetic resonance imaging (fMRI) studies in pediatric bipolar disorder (BD) have reported greater amygdala and less dorsolateral prefrontal cortex (DLPFC) activation to facial expressions compared to healthy controls. The current study investigates whether these differences are associated with the early or late…
Garcia, Rene; Farinelli, Melissa; Deschaux, Olivier; Hugues, Sandrine; Thevenet, Aurelie
It has been shown that long-term potentiation (LTP) develops in the connection between the mediodorsal thalamus (MD) and the medial prefrontal cortex (mPFC) and between the hippocampus (HPC) and the mPFC following fear extinction, and correlates with extinction retention. However, recent lesion studies have shown that combined lesions of the MD…
Simons, Jon S; Gilbert, Sam J; Owen, Adrian M; Fletcher, Paul C; Burgess, Paul W
A key feature of human recollection is the ability to remember details of the context in which events were experienced, as well as details of the events themselves. Previous studies have implicated a number of regions of prefrontal cortex in contextual recollection, but the role of anterior prefrontal cortex has so far resisted detailed characterization. We used event-related functional MRI (fMRI) to contrast recollection of two forms of contextual information: 1) decisions one had previously made about stimuli (task memory) and 2) which of two temporally distinct lists those stimuli had been presented in (list memory). In addition, a retrieval cue manipulation permitted evaluation of the stage of the retrieval process in which the activated regions might be involved. The results indicated that anterior prefrontal cortex responded significantly more during recollection of task than list context details. Furthermore, activation profiles for lateral and medial aspects of anterior prefrontal cortex suggested differing roles in recollection. Lateral regions seem to be more involved in the early retrieval specification stages of recollection, with medial regions contributing to later stages (e.g., monitoring and verification).
Tronel, Sophie; Feenstra, Matthijs G. P.; Sara, Susan J.
These experiments investigated the role of the noradrenergic system in the late stage of memory consolidation and in particular its action at beta receptors in the prelimbic region (PL) of the prefrontal cortex in the hours after training. Rats were trained in a rapidly acquired, appetitively motivated foraging task based on olfactory…
Fogelson, Noa; Shah, Mona; Scabini, Donatella; Knight, Robert T.
We investigated the role of prefrontal cortex (PFC) in local contextual processing using a combined event-related potentials and lesion approach. Local context was defined as the occurrence of a short predictive series of visual stimuli occurring before delivery of a target event. Targets were preceded by either randomized sequences of standards…
Zhao, Zhongyao; Wang, Xin C.; Chance, Britton
A data bank on prefrontal imaging under stressful conditions including deceit, has been gathered over several years on National and International populations using a contact imager pad consisting of 16 detectors and 4 sources, validating the concept of imaging prefrontal responses to stress, not only following the response of the PFC to imaging stress but especially of precognitive activations. We designed a new portable and non-invasive optical detecting system for remote sensing of deceit at 1~2m distance. The signals of pre- and post-cognitive function in deceit can be detected with very high sensitivity for blood volume and blood oxygenation detection at depths sufficient for PFC imaging and sensitivities of sub-micromolar oxy-hemoglobin and blood concentration detection. Thus, remote imaging of the process of decision making seems possible and examples will be presented using both contact and flying spot remote sensing.
Konstantoudaki, X; Chalkiadaki, K; Tivodar, S; Karagogeos, D; Sidiropoulou, K
Interneurons are inhibitory neurons, which protect neural tissue from excessive excitation. They are interconnected with glutamatergic pyramidal neurons in the cerebral cortex and regulate their function. Particularly in the prefrontal cortex (PFC), interneurons have been strongly implicated in regulating pathological states which display deficits in the PFC. The aim of this study is to investigate the adaptations in the adult glutamatergic system, when defects in interneuron development do not allow adequate numbers of interneurons to reach the cerebral cortex. To this end, we used a mouse model that displays ~50% fewer cortical interneurons due to the Rac1 protein loss from Nkx2.1/Cre expressing cells (Rac1 conditional knockout (cKO) mice), to examine how the developmental loss of interneurons may affect basal synaptic transmission, synaptic plasticity and neuronal morphology in the adult PFC. Despite the decrease in the number of interneurons, basal synaptic transmission, as examined by recording field excitatory postsynaptic potentials (fEPSPs) from layer II networks, is not altered in the PFC of Rac1 cKO mice. However, there is decreased paired-pulse ratio (PPR) and decreased long-term potentiation (LTP), in response to tetanic stimulation, in the layer II PFC synapses of Rac1 cKO mice. Furthermore, expression of N-methyl-d-aspartate (NMDA) subunits is decreased and dendritic morphology is altered, changes that could underlie the decrease in LTP in the Rac1 cKO mice. Finally, we find that treating Rac1 cKO mice with diazepam in early postnatal life can reverse changes in dendritic morphology observed in non-treated Rac1 cKO mice. Therefore, our data show that disruption in GABAergic inhibition alters glutamatergic function in the adult PFC, an effect that could be reversed by enhancement of GABAergic function during an early postnatal period.
Garcia-Molina, A; Ensenat, A
Introduccion. Actualmente, cuando reflexionamos sobre cual es la estructura mas relevante del encefalo humano invariablemente pensamos en las regiones anteriores de la corteza cerebral, concretamente en la corteza prefrontal. Si bien este ha sido el dogma predominante a lo largo de mas de 150 años, investigadores de reconocido prestigio han cuestionado abiertamente tal supuesto. Desarrollo. A caballo entre los siglos XIX y XX, diversos investigadores consideraron que las regiones corticales posteriores son la sede neuroanatomica de las mas altas facultades intelectuales. Entre todos ellos destaco, por la elaboracion de sus propuestas e impacto en la comunidad cientifica, el neuroanatomista aleman Paul Emil Flechsig (1847-1929). Wilder Graves Penfield (1891-1976) fue otro detractor del dogma que considera la corteza prefrontal el sustrato anatomico de los procesos mentales mas complejos y sublimes del ser humano. A mediados del siglo XX, Penfield mantuvo la hipotesis de la existencia de lo que denomino el sistema de integracion centrencefalico, responsable del nivel mas elevado de integracion del sistema nervioso central. Conclusiones. Las concepciones corticocentricas otorgan el preciado cetro de 'estructura mas importante del encefalo' a la corteza prefrontal. Sin embargo, no han faltado propuestas alternativas que, con mayor o menor exito, han intentado arrebatarselo en favor de otras estructuras encefalicas.
Toepper, Max; Markowitsch, Hans J; Gebhardt, Helge; Beblo, Thomas; Bauer, Eva; Woermann, Friedrich G; Driessen, Martin; Sammer, Gebhard
Healthy aging is accompanied by a decline in spatial working memory that is related to functional cerebral changes within the spatial working memory network. In the last decade, important findings were presented concerning the location (e.g., prefrontal), kind (e.g., 'underactivation,' 'overactivation'), and meaning (e.g., functional deficits, compensation) of these changes. Less is known about how functional connections between specific brain regions are affected by age and how these changes are related to behavioral performance. To address these issues, we used functional magnetic resonance imaging to examine retrieval-related brain activation and functional connectivity in 18 younger individuals and 18 older individuals. We assessed working memory with a modified version of the Corsi Block-Tapping test, which requires the storage and reproduction of spatial target sequences. Analyses of group differences in brain activation and functional connectivity included comparisons between younger individuals, older individuals, older high-performers, and older low-performers. In addition, we conducted a functional connectivity analysis by using a seed region approach. In comparison to younger individuals, older individuals showed lower right-hemispheric dorsolateral prefrontal activation and lower functional connectivity between the right dorsolateral prefrontal cortex and the bilateral orbitofrontal cortex. Older high-performers showed higher right dorsolateral and anterior prefrontal cortex activation than older low-performers, as well as higher functional connectivity between these brain regions. The present results suggest age-related reductions of prefrontal activation during spatial working memory retrieval. Moreover, task-related functional connectivity appears to be lower in older adults. Performance accuracy in older adults is associated with right dorsolateral and anterior prefrontal cortex activation, and with the functional connection between these regions.
Kurauchi, Yuki; Hisatsune, Akinori; Seki, Takahiro; Katsuki, Hiroshi
Cerebrovascular endothelial cell dysfunction resulting in imbalance of cerebral blood flow contributes to the onset of psychiatric disorders such as depression, schizophrenia and bipolar disorder. Although decrease in Na(+), K(+)-ATPase activity has been reported in the patients with schizophrenia and bipolar disorder, the contribution of Na(+), K(+)-ATPase to endothelial cell dysfunction remains poorly understood. Here, by using rat neonatal prefrontal cortex slice cultures, we demonstrated that pharmacological inhibition of Na(+), K(+)-ATPase by ouabain induced endothelial cell injury. Treatment with ouabain significantly decreased immunoreactive area of rat endothelial cell antigen-1 (RECA-1), a marker of endothelial cells, in a time-dependent manner. Ouabain also decreased Bcl-2/Bax ratio and phosphorylation level of glycogen synthase kinase 3β (GSK3β) (Ser9), which were prevented by lithium carbonate. On the other hand, ouabain-induced endothelial cell injury was exacerbated by concomitant treatment with LY294002, an inhibitor of phosphoinositide 3- (PI3-) kinase. We also found that xestospongin C, an inhibitor of inositol triphosphate (IP3) receptor, but not SEA0400, an inhibitor of Na(+), Ca(2+) exchanger (NCX), protected endothelial cells from cytotoxicity of ouabain. These results suggest that cerebrovascular endothelial cell degeneration induced by Na(+), K(+)-ATPase inhibition resulting in Ca(2+) release from endoplasmic reticulum (ER) and activation of GSK3β signaling underlies pathogenesis of these psychiatric disorders.
Jurik, Angela; Auffenberg, Eva; Klein, Sabine; Deussing, Jan M; Schmid, Roland M; Wotjak, Carsten T; Thoeringer, Christoph K
Visceral pain represents a major clinical challenge in the management of many gastrointestinal disorders, eg, pancreatitis. However, cerebral neurobiological mechanisms underlying visceral nociception are poorly understood. As a representative model of visceral nociception, we applied cerulein hyperstimulation in C57BL6 mice to induce acute pancreatitis and performed a behavioral test battery and c-Fos staining of brains. We observed a specific pain phenotype and a significant increase in c-Fos immunoreactivity in the paraventricular nucleus of the thalamus (PVT), the periaqueductal gray, and the medial prefrontal cortex (mPFC). Using neuronal tracing, we observed projections of the PVT to cortical layers of the mPFC with contacts to inhibitory GABAergic neurons. These inhibitory neurons showed more activation after cerulein treatment suggesting thalamocortical "feedforward inhibition" in visceral nociception. The activity of neurons in pancreatitis-related pain centers was pharmacogenetically modulated by designer receptors exclusively activated by designer drugs, selectively and cell type specifically expressed in target neurons using adeno-associated virus-mediated gene transfer. Pharmacogenetic inhibition of PVT but not periaqueductal gray neurons attenuated visceral pain and induced an activation of the descending inhibitory pain pathway. Activation of glutamatergic principle neurons in the mPFC, but not inhibitory neurons, also reversed visceral nociception. These data reveal novel insights into central pain processing that underlies visceral nociception and may trigger the development of novel, potent centrally acting analgesic drugs.
Li, Ai-Ling; Yang, Xiaofei; Chiao, Jung-Chih; Peng, Yuan Bo
Nociceptive signals produced by noxious stimuli at the periphery reach the brain through ascending pathways. These signals are processed by various brain areas and lead to activity changes in those areas. The medial prefrontal cortex (mPFC) is involved in higher cognitive functions and emotional processing. It receives projections from brain areas involved in nociception. In this study, we investigated how nociceptive input from the periphery changes the local field potential (LFP) activity in the mPFC. Three different types of noxious stimuli were applied to the hind paw contralateral to the LFP recording site. They were transcutaneous electrical stimulations, mechanical stimuli and a chemical stimulus (formalin injection). High intensity transcutaneous stimulations (10V to 50V) and noxious mechanical stimulus (pinch) significantly reduced the LFP power during the stimulating period (p<0.05), but not the low intensity subcutaneous stimulations (0.1V to 5V) and other innocuous mechanical stimuli (brush and pressure). More frequency bands were inhibited with increased intensity of transcutaneous electrical stimulation, and almost all frequency bands were inhibited by stimulations at or higher than 30v. Pinch significantly reduced the power for beta band and formalin injection significantly reduced the power of alpha and beta band. Our data demonstrated the noxious stimuli-induced reduction of LFP power in the mPFC, which indicates the active processing of nociceptive information by the mPFC.
Goldberg, Melissa C.; Spinelli, Simona; Joel, Suresh; Pekar, James J.; Denckla, Martha B.; Mostofsky, Stewart H.
Evidence exists for deficits in error monitoring in autism. These deficits may be particularly important because they may contribute to excessive perseveration and repetitive behavior in autism. We examined the neural correlates of error monitoring using fMRI in 8–12-year-old children with high-functioning autism (HFA, n=11) and typically developing children (TD, n=15) during performance of a Go/No-Go task by comparing the neural correlates of commission errors versus correct response inhibition trials. Compared to TD children, children with HFA showed increased BOLD fMRI signal in the anterior medial prefrontal cortex (amPFC) and the left superior temporal gyrus (STempG) during commission error (versus correct inhibition) trials. A follow-up region-of-interest analysis also showed increased BOLD signal in the right insula in HFA compared to TD controls. Our findings of increased amPFC and STempG activity in HFA, together with the increased activity in the insula, suggest a greater attention towards the internally-driven emotional state associated with making an error in children with HFA. Since error monitoring occurs across different cognitive tasks throughout daily life, an increased emotional reaction to errors may have important consequences for early learning processes. PMID:21151713
Porrino, L J; Lyons, D
One approach to pursuing questions about the neural substrates that support substance abuse-related behaviors involves the use of animal models. Carefully controlled animal experiments can be conducted without the confounds commonly found in studies of human addicts, such as polydrug abuse, variable drug history and premorbid psychiatric conditions. The present paper considers the orbitofrontal and related limbic prefrontal cortex in the context of such models of substance abuse. First, the importance of recognizing the heterogeneous structural and functional nature of orbitofrontal cortex in both rodents and primates is addressed, and the results of studies involving the prefrontal cortex in substance abuse-related behaviors are considered in light of this diversity. Second, data from metabolic mapping studies are described that indicate that the pattern of functional activity within medial and orbitofrontal cortex shifts as the duration of exposure to drugs such as cocaine is extended. These functional differences, in turn, may reflect progressive phases of the addictive process. In order to understand the neurobiological consequences of long-term drug use, it will be important to establish the differing roles played by distinct anatomical territories within orbital and medial prefrontal cortex during the course of chronic substance abuse.
Pleil, Kristen E; Lowery-Gionta, Emily G; Crowley, Nicole A; Li, Chia; Marcinkiewcz, Catherine A; Rose, Jamie H; McCall, Nora M; Maldonado-Devincci, Antoniette M; Morrow, A Leslie; Jones, Sara R; Kash, Thomas L
Chronic alcohol consumption and withdrawal leads to anxiety, escalated alcohol drinking behavior, and alcohol dependence. Alterations in the function of key structures within the cortico-limbic neural circuit have been implicated in underlying the negative behavioral consequences of chronic alcohol exposure in both humans and rodents. Here, we used chronic intermittent ethanol vapor exposure (CIE) in male C57BL/6J mice to evaluate the effects of chronic alcohol exposure and withdrawal on anxiety-like behavior and basal synaptic function and neuronal excitability in prefrontal cortical and extended amygdala brain regions. Forty-eight hours after four cycles of CIE, mice were either assayed in the marble burying test (MBT) or their brains were harvested and whole-cell electrophysiological recordings were performed in the prelimbic and infralimbic medial prefrontal cortex (PLC and ILC), the lateral and medial central nucleus of the amygdala (lCeA and mCeA), and the dorsal and ventral bed nucleus of the stria terminalis (dBNST and vBNST). Ethanol-exposed mice displayed increased anxiety in the MBT compared to air-exposed controls, and alterations in neuronal function were observed in all brain structures examined, including several distinct differences between subregions within each structure. Chronic ethanol exposure induced hyperexcitability of the ILC, as well as a shift toward excitation in synaptic drive and hyperexcitability of vBNST neurons; in contrast, there was a net inhibition of the CeA. This study reveals extensive effects of chronic ethanol exposure on the basal function of cortico-limbic brain regions, suggests that there may be complex interactions between these regions in the regulation of ethanol-dependent alterations in anxiety state, and highlights the need for future examination of projection-specific effects of ethanol in cortico-limbic circuitry.
Pleil, Kristen E.; Lowery-Gionta, Emily G.; Crowley, Nicole A.; Li, Chia; Marcinkiewcz, Catherine A.; Rose, Jamie H.; McCall, Nora M.; Maldonado-Devincci, Antoniette M.; Morrow, A. Leslie; Jones, Sara R.; Kash, Thomas L.
Chronic alcohol consumption and withdrawal leads to anxiety, escalated alcohol drinking behavior, and alcohol dependence. Alterations in the function of key structures within the cortico-limbic neural circuit have been implicated in underlying the negative behavioral consequences of chronic alcohol exposure in both humans and rodents. Here, we used chronic intermittent ethanol vapor exposure (CIE) in male C57BL/6J mice to evaluate the effects of chronic alcohol exposure and withdrawal on anxiety-like behavior and basal synaptic function and neuronal excitability in prefrontal cortical and extended amygdala brain regions. Forty-eight hours after four cycles of CIE, mice were either assayed in the marble burying test (MBT) or their brains were harvested and whole-cell electrophysiological recordings were performed in the prelimbic and infralimbic medial prefrontal cortex (PLC and ILC), the lateral and medial central nucleus of the amygdala (lCeA and mCeA), and the dorsal and ventral bed nucleus of the stria terminalis (dBNST and vBNST). Ethanol-exposed mice displayed increased anxiety in the MBT compared to air-exposed controls, and alterations in neuronal function were observed in all brain structures examined, including several distinct differences between subregions within each structure. Chronic ethanol exposure induced hyperexcitability of the ILC, as well as a shift toward excitation in synaptic drive and hyperexcitability of vBNST neurons; in contrast, there was a net inhibition of the CeA. This study reveals extensive effects of chronic ethanol exposure on the basal function of cortico-limbic brain regions, suggests that there may be complex interactions between these regions in the regulation of ethanol-dependent alterations in anxiety state, and highlights the need for future examination of projection-specific effects of ethanol in cortico-limbic circuitry. PMID:26188147
Moore, Tara L; Schettler, Stephen P; Killiany, Ronald J; Rosene, Douglas L; Moss, Mark B
The prefrontal cortex has been identified as essential for executive function, as well as for aspects of rule learning and recognition memory. As part of our studies to assess prefrontal cortical function in the monkey, we evaluated the effects of damage to the dorsal prefrontal cortex (DPFC) on the Category Set Shifting Task (CSST), a test of abstraction and set-shifting, and on the Delayed Nonmatching to Sample (DNMS) task, a benchmark test of rule learning and recognition memory. The DPFC lesions in this study included dorsolateral and dorsomedial aspects of the PFC. In a previous report, we published evidence of an impairment on the CSST as a consequence of DPFC lesions (Moore, Schettler, Killiany, Rosene, & Moss, 2009). Here we report that monkeys with lesions of the DPFC were also markedly impaired relative to controls on both the acquisition (rule learning) and performance (recognition memory) conditions of trial-unique DNMS. The presence and extent of the deficits that we observed were of some surprise and support the possibility that the dorsal prefrontal cortex plays a more direct role in learning and recognition memory than had been previously thought.
Moore, Tara L; Schettler, Stephen P.; Killiany, Ronald J.; Rosene, Douglas L.; Moss, Mark B.
The prefrontal cortex has been identified as essential for executive function, as well as for aspects of rule learning and recognition memory. As part of our studies to assess prefrontal cortical function in the monkey, we evaluated the effects of damage to the dorsal prefrontal cortex (DPFC) on the Category Set Shifting Task (CSST), a test of abstraction and set-shifting, and on the Delayed Non Matching-to-Sample (DNMS) task, a benchmark test of rule learning and recognition memory. The DPFC lesions in this study included dorsolateral and dorsomedial aspects of the PFC. In a previous report, we published evidence of an impairment on the CSST as a consequence of DPFC lesions (Moore et al, 2009). Here we report that monkeys with lesions of the DPFC were also markedly impaired relative to controls on both the acquisition (rule learning) and performance (recognition memory) conditions of trial-unique DNMS. The presence and extent of the deficits that we observed were of some surprise and support the possibility that the dorsal prefrontal cortex plays a more direct role in learning and recognition memory than had been previously thought. PMID:23088539
Crego, Alberto; Rodriguez-Holguín, Socorro; Parada, María; Mota, Nayara; Corral, Montserrat; Cadaveira, Fernando
Working memory (WM) is a major cognitive function that is altered by chronic alcohol consumption. This impairment has been linked to alterations in the hippocampus and prefrontal cortex (PFC). Animal and human studies have shown that the adolescent brain is more sensitive to the neurotoxic effects of alcohol than the adult brain, particularly those structures that mature late on in development, such as the hippocampus and prefrontal brain. The aim of the present study was to assess visual working memory and its neural correlates in young university students who partake in intermittent consumption of large amounts of alcohol (binge drinkers). A sample of 42 binge drinkers and 53 corresponding control subjects performed an identical pairs continuous performance task (IP-CPT) in a combined event-related potential (ERP) and exact low-resolution brain electromagnetic tomography (eLORETA) study. The results revealed that, despite adequate performance, binge drinkers showed a smaller late positive component (LPC) associated with hypoactivation of the right anterior prefrontal cortex (aPFC) for matching stimuli, in comparison with control subjects. These findings may reveal binge drinking-related functional alteration in recognition working memory processes and suggest that impaired prefrontal cortex function may occur at an early age in binge drinkers.
Rossato, Janine I; Köhler, Cristiano A; Radiske, Andressa; Bevilaqua, Lia R M; Cammarota, Martín
Active memories can incorporate new information through reconsolidation. However, the notion that memory retrieval is necessary for reconsolidation has been recently challenged. Non-reinforced retrieval induces hippocampus and medial prefrontal cortex (mPFC)-dependent reconsolidation of spatial memory in the Morris water maze (MWM). We found that the effect of protein synthesis inhibition on this process is abolished when retrieval of the learned spatial preference is hindered through mPFC inactivation but not when it is blocked by deactivation of dorsal CA1. Our results do not fully agree with the hypothesis that retrieval is unneeded for reconsolidation. Instead, they support the idea that a hierarchic interaction between the hippocampus and the mPFC controls spatial memory in the MWM, and indicate that this cortex is sufficient to retrieve the information essential to reconsolidate the spatial memory trace, even when the hippocampus is inactivated.
Ozyurt, Jale; Lorenzen, Anna; Gebhardt, Ursel; Warmuth-Metz, Monika; Müller, Hermann L; Thiel, Christiane M
Albeit histologically low grade (WHO I(o)) brain tumors, craniopharyngiomas and/or their surgical removal frequently affect the hypothalamus, amongst other brain regions at risk. Due to rich hypothalamic connections with prefrontal and limbic regions, hypothalamic injury may adversely affect neural substrates of emotion processing and higher cognitive control, including memory and executive functions. The current study is the first to investigate the consequences of hypothalamic involvement on neural substrates of emotional and cognitive functioning. Ten patients with childhood craniopharyngioma and known hypothalamic involvement and fifteen age- and intelligence matched control subjects (median age: 17.8 and 17.3 yrs.) were studied with functional magnetic resonance imaging and an emotional face recognition task. During encoding, participants were asked to classify neutral and emotional faces. In a subsequent recognition phase, participants had to recognize these old faces within a set of new faces. Behavioral performance was comparable between patients and controls. Neural activity revealed, however, differential recruitment of fronto-limbic brain regions during recognition. Patients exhibited an abnormal pattern of task-induced activation and deactivation in the anterior and posterior rostral medial prefrontal cortex and a higher functional coupling between anterior rostral medial prefrontal cortex and the thalamus. Additionally, we found a higher reactivity in the patients' amygdala to emotional relative to neutral faces when compared to healthy controls. Our data provide first evidence that hypothalamic damage impacts neural correlates of memory retrieval in medial prefrontal cortex, indicating a less efficient use of an area involved in executive control processes. We propose that the deactivation failure in the patients' anterior rostral medial prefrontal cortex is related to an increased coupling with the thalamus and reflects a reduced efficiency to
Felix-Ortiz, A C; Burgos-Robles, A; Bhagat, N D; Leppla, C A; Tye, K M
The basolateral amygdala (BLA) and the medial prefrontal cortex (mPFC) modulate anxiety and social behaviors. It remains to be elucidated, however, whether direct projections from the BLA to the mPFC play a functional role in these behaviors. We used optogenetic approaches in behaving mice to either activate or inhibit BLA inputs to the mPFC during behavioral assays that assess anxiety-like behavior and social interaction. Channelrhodopsin-2 (ChR2)-mediated activation of BLA inputs to the mPFC produced anxiogenic effects in the elevated plus maze and open field test, whereas halorhodopsin (NpHR)-mediated inhibition produced anxiolytic effects. Furthermore, activation of the BLA-mPFC pathway reduced social interaction in the resident-intruder test, whereas inhibition facilitated social interaction. These results establish a causal relationship between activity in the BLA-mPFC pathway and the bidirectional modulation of anxiety-related and social behaviors.
Baxter, Mark G.; Browning, Philip G. F.; Mitchell, Anna S.
Surgical disconnection of the frontal cortex and inferotemporal cortex severely impairs many aspects of visual learning and memory, including learning of new object-in-place scene memory problems, a monkey model of episodic memory. As part of a study of specialization within prefrontal cortex in visual learning and memory, we tested monkeys with…
Otis, James M; Namboodiri, Vijay M K; Matan, Ana M; Voets, Elisa S; Mohorn, Emily P; Kosyk, Oksana; McHenry, Jenna A; Robinson, J Elliott; Resendez, Shanna L; Rossi, Mark A; Stuber, Garret D
The prefrontal cortex is a critical neuroanatomical hub for controlling motivated behaviours across mammalian species. In addition to intra-cortical connectivity, prefrontal projection neurons innervate subcortical structures that contribute to reward-seeking behaviours, such as the ventral striatum and midline thalamus. While connectivity among these structures contributes to appetitive behaviours, how projection-specific prefrontal neurons encode reward-relevant information to guide reward seeking is unknown. Here we use in vivo two-photon calcium imaging to monitor the activity of dorsomedial prefrontal neurons in mice during an appetitive Pavlovian conditioning task. At the population level, these neurons display diverse activity patterns during the presentation of reward-predictive cues. However, recordings from prefrontal neurons with resolved projection targets reveal that individual corticostriatal neurons show response tuning to reward-predictive cues, such that excitatory cue responses are amplified across learning. By contrast, corticothalamic neurons gradually develop new, primarily inhibitory responses to reward-predictive cues across learning. Furthermore, bidirectional optogenetic manipulation of these neurons reveals that stimulation of corticostriatal neurons promotes conditioned reward-seeking behaviour after learning, while activity in corticothalamic neurons suppresses both the acquisition and expression of conditioned reward seeking. These data show how prefrontal circuitry can dynamically control reward-seeking behaviour through the opposing activities of projection-specific cell populations.
Schubert, D; Martens, G J M; Kolk, S M
The prefrontal cortex (PFC), seat of the highest-order cognitive functions, constitutes a conglomerate of highly specialized brain areas and has been implicated to have a role in the onset and installation of various neurodevelopmental disorders. The development of a properly functioning PFC is directed by transcription factors, guidance cues and other regulatory molecules and requires the intricate and temporal orchestration of a number of developmental processes. Disturbance or failure of any of these processes causing neurodevelopmental abnormalities within the PFC may contribute to several of the cognitive deficits seen in patients with neurodevelopmental disorders. In this review, we elaborate on the specific processes underlying prefrontal development, such as induction and patterning of the prefrontal area, proliferation, migration and axonal guidance of medial prefrontal progenitors, and their eventual efferent and afferent connections. We furthermore integrate for the first time the available knowledge from genome-wide studies that have revealed genes linked to neurodevelopmental disorders with experimental molecular evidence in rodents. The integrated data suggest that the pathogenic variants in the neurodevelopmental disorder-associated genes induce prefrontal cytoarchitectonical impairments. This enhances our understanding of the molecular mechanisms of prefrontal (mis)development underlying the four major neurodevelopmental disorders in humans, that is, intellectual disability, autism spectrum disorders, attention deficit hyperactivity disorder and schizophrenia, and may thus provide clues for the development of novel therapies.
Le Pira, Francesco; Giuffrida, Salvatore; Maci, Tiziana; Reggio, Ester; Zappalà, Giuseppe; Perciavalle, Vincenzo
The aim of this study is to verify, after recovery, the presence of specific patterns of cognitive dysfunctions in Transient Global Amnesia (TGA). Fourteen patients with the diagnosis of TGA were submitted to a battery of neuropsychological tests and compared to a matched control group. We found significant qualitative and quantitative differences between TGA patients and controls in the California Verbal Learning Test (CLVT) and Rey-Osterrieth Complex Figure Test. Our data support the presence of selective cognitive dysfunctions after the clinical recovery. Moreover, for Verbal Fluency, Digit Span Backward, and Number of Clusters in the CVLT short-term memory test, the relation resulted as positively related with the temporal interval from the TGA episode. Reduction of categorical learning, attention, and qualitative alterations of spatial strategy seem to postulate a planning defect due to a prefrontal impairment.
Saleem, Kadharbatcha S; Miller, Brad; Price, Joseph L
Neuroanatomical studies have long indicated that corticocortical connections are organized in networks that relate distinct sets of areas. Such networks have been emphasized by development of functional imaging methods for correlating activity across the cortex. Previously, two networks were recognized in the orbitomedial prefrontal cortex, the "orbital" and "medial" networks (OPFC and MPFC, respectively). In this study, three additional networks are proposed for the lateral prefrontal cortex: 1) a ventrolateral network (VLPFC) in and ventral to the principal sulcus; 2) a dorsal network (DPFC) in and dorsal to the principal sulcus and in the frontal pole; 3) a caudolateral network (CLPFC) in and rostral to the arcuate sulcus and the caudal principal sulcus. The connections of the first two networks are described here. Areas in each network are connected primarily with other areas in the same network, with overlaps around the principal sulcus. The VLPFC and DPFC are also connected with the OPFC and MPFC, respectively. Outside the prefrontal cortex, the VLPFC connects with specific areas related to somatic/visceral sensation and vision, in the frontoparietal operculum, insula, ventral bank/fundus of the superior temporal sulcus, inferior temporal gyrus, and inferior parietal cortex. In contrast, the DPFC connects with the rostral superior temporal gyrus, dorsal bank of the superior temporal sulcus, parahippocampal cortex, and posterior cingulate and retrosplenial cortex. Area 45a, in caudal VLPFC, is unique, having connections with all the networks. Its extrinsic connections resemble those of the DPFC. In addition, it has connections with both auditory belt/parabelt areas, and visual related areas.
Cordova, Chris A; Jackson, Danielle; Langdon, Kristopher D; Hewlett, Krista A; Corbett, Dale
Small (lacunar) infarcts frequently arise in frontal and midline thalamic regions in the absence of major stroke. Damage to these areas often leads to impairment of executive function likely as a result of interrupting connections of the prefrontal cortex. Thus, patients experience frontal-like symptoms such as impaired ability to shift ongoing behavior and attention. In contrast, executive dysfunction has not been demonstrated in rodent models of stroke, thereby limiting the development of potential therapies for human executive dysfunction. Male Sprague-Dawley rats (n=40) underwent either sham surgery or bilateral endothelin-1 injections in the mediodorsal nucleus of the thalamus or in the medial prefrontal cortex. Executive function was assessed using a rodent attention set shifting test that requires animals to shift attention to stimuli in different stimulus dimensions. Medial prefrontal cortex ischemia impaired attention shift performance between different stimulus dimensions while sparing stimulus discrimination and attention shifts within a stimulus dimension, indicating a selective attention set-shift deficit. Rats with mediodorsal thalamic lacunar damage did not exhibit a cognitive impairment relative to sham controls. The selective attention set shift impairment observed in this study is consistent with clinical data demonstrating selective executive disorders following stroke within specific sub-regions of frontal cortex. These data contribute to the development and validation of a preclinical animal model of executive dysfunction, that can be employed to identify potential therapies for ameliorating cognitive deficits following stroke.
Ueno, Hiroshi; Suemitsu, Shunsuke; Matsumoto, Yosuke; Okamoto, Motoi
Early loss of one sensory system can cause improved function of other sensory systems. However, both the time course and neuronal mechanism of cross-modal plasticity remain elusive. Recent study using functional MRI in humans suggests a role of the prefrontal cortex (PFC) in cross-modal plasticity. Since this phenomenon is assumed to be associated with altered GABAergic inhibition in the PFC, we have tested the hypothesis that early postnatal sensory deprivation causes the changes of inhibitory neuronal circuit in different regions of the PFC of the mice. We determined the effects of sensory deprivation from birth to postnatal day 28 (P28) or P58 on the density of parvalbumin (PV), calbindin (CB), and calretinin (CR) neurons in the prelimbic, infralimbic, and dorsal anterior cingulate cortices. The density of PV and CB neurons was significantly increased in layer 5/6 (L5/6). Moreover, the density of CR neurons was higher in L2/3 in sensory deprived mice compared to intact mice. These changes were more prominent at P56 than at P28. These results suggest that long-term sensory deprivation causes the changes of intracortical inhibitory networks in the PFC and the changes of inhibitory networks in the PFC may contribute to cross-modal plasticity. PMID:26161272
Cuesta, Santiago; Severin, Maria J; Batuecas, Jorgelina; Rosso, Silvana B; Pacchioni, Alejandra M
Behavioral sensitization is a progressive and enduring enhancement of the motor stimulant effects elicited by repeated administration of drugs of abuse. It can be divided into two distinct temporal and anatomical domains, termed initiation and expression, which are characterized by specific molecular and neurochemical changes. This study examines the role of the Wnt canonical pathway mediating the induction of cocaine sensitization. We found that β-catenin levels in the prefrontal cortex (PFC), amygdala (Amyg) and dorsal striatum (CPu) are decreased in animals that show sensitization. Accordingly, GSK3β activity levels are increased in the same areas. Moreover, β-catenin levels in nuclear fraction, mRNA expression of Axin2 and Wnt7b are decreased in the PFC of sensitized animals. Then, in order to demonstrate that changes in the PFC are crucial for initiation of sensitization, we either rescue β-catenin levels with a systemic treatment of a GSK3β inhibitor (Lithium Chloride) or inhibit Wnt/β-catenin pathway with an intracerebral infusion of Sulindac before each cocaine injection. As expected, rescuing β-catenin levels in the PFC as well as CPu and Amyg blocks cocaine-induced sensitization, while decreasing β-catenin levels exclusively in the PFC exacerbates it. Therefore, our results demonstrate a new role for the Wnt/β-catenin pathway as a required neuroadaptation in inducing behavioral sensitization.
Ferrari, Chiara; Vecchi, Tomaso; Todorov, Alexander; Cattaneo, Zaira
In our everyday social interactions we often need to deal with others' unpredictable behaviors. Integrating unexpected information in a consistent representation of another agent is a cognitively demanding process. Several neuroimaging studies point to the medial prefrontal cortex (mPFC) as a critical structure in mediating social evaluations. Our aim here was to shed light on the possible causal role of the mPFC in the dynamic process of forming and updating social impressions about others. We addressed this issue by suppressing activity in the mPFC by means of 1 Hz offline transcranial magnetic stimulation (TMS) prior to a task requiring participants to evaluate other agents' trustworthiness after reading about their social behavior. In two different experiments, we found that inhibiting activity in the mPFC increased perceived trustworthiness when inconsistent information about one agent's behavior was provided. In turn, when only negative or positive behaviors of a person were described, TMS over the mPFC did not affect judgments. Our results indicate that the mPFC is causally involved in mediating social impressions updating-at least in cases in which judgment is uncertain due to conflicting information to be processed.
McClatchy, Daniel B.; Savas, Jeffrey N.; Martínez-Bartolomé, Salvador; Park, Sung Kyu; Maher, Pamela; Powell, Susan B.; Yates, John R.
Prepulse inhibition (PPI) is an example of sensorimotor gating and deficits in PPI have been demonstrated in schizophrenia patients. Phencyclidine (PCP) suppression of PPI in animals has been studied to elucidate the pathological elements of schizophrenia. However, the molecular mechanisms underlying PCP treatment or PPI in the brain are still poorly understood. In this study, quantitative phosphoproteomic analysis was performed on the prefrontal cortex from rats that were subjected to PPI after being systemically injected with PCP or saline. PCP down-regulated phosphorylation events were significantly enriched in proteins associated with long-term potentiation (LTP). Importantly, this dataset identifies functionally novel phosphorylation sites on known LTP-associated signaling molecules. In addition, mutagenesis of a significantly altered phosphorylation site on xCT (SLC7A11), the light chain of system xc-, the cystine/glutamate antiporter, suggests that PCP also regulates the activity of this protein. Finally, new insights were also derived on PPI signaling independent of PCP treatment. This is the first quantitative phosphorylation proteomic analysis providing new molecular insights into sensorimotor gating. PMID:25869802
McClatchy, D B; Savas, J N; Martínez-Bartolomé, S; Park, S K; Maher, P; Powell, S B; Yates, J R
Prepulse inhibition (PPI) is an example of sensorimotor gating and deficits in PPI have been demonstrated in schizophrenia patients. Phencyclidine (PCP) suppression of PPI in animals has been studied to elucidate the pathological elements of schizophrenia. However, the molecular mechanisms underlying PCP treatment or PPI in the brain are still poorly understood. In this study, quantitative phosphoproteomic analysis was performed on the prefrontal cortex from rats that were subjected to PPI after being systemically injected with PCP or saline. PCP downregulated phosphorylation events were significantly enriched in proteins associated with long-term potentiation (LTP). Importantly, this data set identifies functionally novel phosphorylation sites on known LTP-associated signaling molecules. In addition, mutagenesis of a significantly altered phosphorylation site on xCT (SLC7A11), the light chain of system xc-, the cystine/glutamate antiporter, suggests that PCP also regulates the activity of this protein. Finally, new insights were also derived on PPI signaling independent of PCP treatment. This is the first quantitative phosphorylation proteomic analysis providing new molecular insights into sensorimotor gating.
Ueno, Hiroshi; Suemitsu, Shunsuke; Matsumoto, Yosuke; Okamoto, Motoi
Early loss of one sensory system can cause improved function of other sensory systems. However, both the time course and neuronal mechanism of cross-modal plasticity remain elusive. Recent study using functional MRI in humans suggests a role of the prefrontal cortex (PFC) in cross-modal plasticity. Since this phenomenon is assumed to be associated with altered GABAergic inhibition in the PFC, we have tested the hypothesis that early postnatal sensory deprivation causes the changes of inhibitory neuronal circuit in different regions of the PFC of the mice. We determined the effects of sensory deprivation from birth to postnatal day 28 (P28) or P58 on the density of parvalbumin (PV), calbindin (CB), and calretinin (CR) neurons in the prelimbic, infralimbic, and dorsal anterior cingulate cortices. The density of PV and CB neurons was significantly increased in layer 5/6 (L5/6). Moreover, the density of CR neurons was higher in L2/3 in sensory deprived mice compared to intact mice. These changes were more prominent at P56 than at P28. These results suggest that long-term sensory deprivation causes the changes of intracortical inhibitory networks in the PFC and the changes of inhibitory networks in the PFC may contribute to cross-modal plasticity.
Guirado, Ramon; Umemori, Juzoh; Sipilä, Pia; Castrén, Eero
Inputs to sensory cortices are known to compete for target innervation through an activity-dependent mechanism during critical periods. To investigate whether this principle also applies to association cortices such as the medial prefrontal cortex (mPFC), we produced a bilateral lesion during early development to the ventral hippocampus (vHC), an input to the mPFC, and analyzed the intensity of the projection from another input, the basolateral amgydala (BLA). We found that axons from the BLA had a higher density of “en passant” boutons in the mPFC of lesioned animals. Furthermore, the density of neurons labeled with retrograde tracers was increased, and neurons projecting from the BLA to the mPFC showed increased expression of FosB. Since neonatal ventral hippocampal lesion has been used as an animal model of schizophrenia, we investigated its effects on behavior and found a negative correlation between the density of retrogradely labeled neurons in the BLA and the reduction of the startle response in the prepulse inhibition test. Our results not only indicate that the inputs from the BLA and the vHC compete for target innervation in the mPFC during postnatal development but also that subsequent abnormal rewiring might underlie the pathophysiology of neuropsychiatric disorders such as schizophrenia. PMID:26637448
Tapocik, Jenica D.; Juergens, Nathan; Pitcairn, Caleb; Borich, Abbey; Schank, Jesse R.; Sun, Hui; Schuebel, Kornel; Zhou, Zhifeng; Yuan, Qiaoping; Vendruscolo, Leandro F.; Goldman, David; Heilig, Markus
Recent studies have suggested an association between alcoholism and DNA methylation, a mechanism that can mediate long-lasting changes in gene transcription. Here, we examined the contribution of DNA methylation to the long-term behavioral and molecular changes induced by a history of alcohol dependence. In search of mechanisms underlying persistent rather than acute dependence-induced neuroadaptations, we studied the role of DNA methylation regulating medial prefrontal cortex (mPFC) gene expression and alcohol-related behaviors in rats 3 weeks into abstinence following alcohol dependence. Postdependent rats showed escalated alcohol intake, which was associated with increased DNA methylation as well as decreased expression of genes encoding synaptic proteins involved in neurotransmitter release in the mPFC. Infusion of the DNA methyltransferase inhibitor RG108 prevented both escalation of alcohol consumption and dependence-induced downregulation of 4 of the 7 transcripts modified in postdependent rats. Specifically, RG108 treatment directly reversed both downregulation of synaptotagmin 2 (Syt2) gene expression and hypermethylation on CpG#5 of its first exon. Lentiviral inhibition of Syt2 expression in the mPFC increased aversion-resistant alcohol drinking, supporting a mechanistic role of Syt2 in compulsive-like behavior. Our findings identified a functional role of DNA methylation in alcohol dependence-like behavioral phenotypes and a candidate gene network that may mediate its effects. Together, these data provide novel evidence for DNA methyltransferases as potential therapeutic targets in alcoholism. PMID:25878287
Gonzalez-Burgos, Guillermo; Miyamae, Takeaki; Pafundo, Diego E; Yoshino, Hiroki; Rotaru, Diana C; Hoftman, Gil; Datta, Dibyadeep; Zhang, Yun; Hammond, Mahjub; Sampson, Allan R; Fish, Kenneth N; Ermentrout, G Bard; Lewis, David A
Development of inhibition onto pyramidal cells may be crucial for the emergence of cortical network activity, including gamma oscillations. In primate dorsolateral prefrontal cortex (DLPFC), inhibitory synaptogenesis starts in utero and inhibitory synapse density reaches adult levels before birth. However, in DLPFC, the expression levels of γ-aminobutyric acid (GABA) synapse-related gene products changes markedly during development until young adult age, suggesting a highly protracted maturation of GABA synapse function. Therefore, we examined the development of GABA synapses by recording GABAAR-mediated inhibitory postsynaptic currents (GABAAR-IPSCs) from pyramidal cells in the DLPFC of neonatal, prepubertal, peripubertal, and adult macaque monkeys. We found that the decay of GABAAR-IPSCs, possibly including those from parvalbumin-positive GABA neurons, shortened by prepubertal age, while their amplitude increased until the peripubertal period. Interestingly, both GABAAR-mediated quantal response size, estimated by miniature GABAAR-IPSCs, and the density of GABAAR synaptic appositions, measured with immunofluorescence microscopy, were stable with age. Simulations in a computational model network with constant GABA synapse density showed that the developmental changes in GABAAR-IPSC properties had a significant impact on oscillatory activity and predicted that, whereas DLPFC circuits can generate gamma frequency oscillations by prepubertal age, mature levels of gamma band power are attained at late stages of development.
Murano, Tomoyuki; Koshimizu, Hisatsugu; Hagihara, Hideo; Miyakawa, Tsuyoshi
Alcoholism, which is defined as the recurring harmful use of alcohol despite its negative consequences, has a lifetime prevalence of 17.8%. Previous studies have shown that chronic alcohol consumption disrupts various brain functions and behaviours. However, the precise mechanisms that underlie alcoholism are currently unclear. Recently, we discovered “pseudo-immature” brain cell states of the dentate gyrus and prefrontal cortex (PFC) in mouse models of psychotic disorders and epileptic seizure. Similar pseudo-immaturity has been observed in patients with psychotic disorders, such as schizophrenia and bipolar disorder. Patients with alcoholism occasionally exhibit similar psychological symptoms, implying shared molecular and cellular mechanisms between these diseases. Here, we performed a meta-analysis to compare microarray data from the hippocampi/PFCs of the patients with alcoholism to data from these regions in developing human brains and mouse developmental data for specific cell types. We identified immature-like gene expression patterns in post-mortem hippocampi/PFCs of alcoholic patients and the dominant contributions of fast-spiking (FS) neurons to their pseudo-immaturity. These results suggested that FS neuron dysfunction and the subsequent imbalance between excitation and inhibition can be associated with pseudo-immaturity in alcoholism. These immaturities in the hippocampi/PFCs and the underlying mechanisms may explain the psychotic symptom generation and pathophysiology of alcoholism. PMID:28295046
Petrie, Kimberly A; Bubser, Michael; Casey, Cheryl D; Davis, M Duff; Roth, Bryan L; Deutch, Ariel Y
Dopaminergic axons innervating the prefrontal cortex (PFC) target both pyramidal cells and GABAergic interneurons. Many of these dopamine (DA) axons in the rat coexpress the peptide neurotransmitter neurotensin. Previous electrophysiological data have suggested that neurotensin activates GABAergic interneurons in the PFC. Activation of D2-like DA receptors increases extracellular GABA levels in the PFC, as opposed to the striatum, where D2 receptor activation inhibits GABAergic neurons. Because activation of presynaptic D2 release-modulating autoreceptors in the PFC suppresses DA release but increases release of the cotransmitter neurotensin, D2 agonists may enhance the activity of GABAergic interneurons via release of neurotensin. In order to determine if neurotensin can activate GABAergic interneurons, we treated rats with the peptide neurotensin agonist, PD149163, and examined Fos expression in PFC neurons. Systemic administration of PD149163 increased overall Fos expression in the PFC, but not in the dorsal striatum. PD149163 induced Fos in PFC interneurons, as defined by the presence of calcium-binding proteins, and in pyramidal cells. Pretreatment with the high-affinity neurotensin antagonist, SR48692, blocked neurotensin agonist-induced Fos expression. These data suggest that neurotensin activates interneurons in the PFC of the rat.
Barbier, Estelle; Tapocik, Jenica D; Juergens, Nathan; Pitcairn, Caleb; Borich, Abbey; Schank, Jesse R; Sun, Hui; Schuebel, Kornel; Zhou, Zhifeng; Yuan, Qiaoping; Vendruscolo, Leandro F; Goldman, David; Heilig, Markus
Recent studies have suggested an association between alcoholism and DNA methylation, a mechanism that can mediate long-lasting changes in gene transcription. Here, we examined the contribution of DNA methylation to the long-term behavioral and molecular changes induced by a history of alcohol dependence. In search of mechanisms underlying persistent rather than acute dependence-induced neuroadaptations, we studied the role of DNA methylation regulating medial prefrontal cortex (mPFC) gene expression and alcohol-related behaviors in rats 3 weeks into abstinence following alcohol dependence. Postdependent rats showed escalated alcohol intake, which was associated with increased DNA methylation as well as decreased expression of genes encoding synaptic proteins involved in neurotransmitter release in the mPFC. Infusion of the DNA methyltransferase inhibitor RG108 prevented both escalation of alcohol consumption and dependence-induced downregulation of 4 of the 7 transcripts modified in postdependent rats. Specifically, RG108 treatment directly reversed both downregulation of synaptotagmin 2 (Syt2) gene expression and hypermethylation on CpG#5 of its first exon. Lentiviral inhibition of Syt2 expression in the mPFC increased aversion-resistant alcohol drinking, supporting a mechanistic role of Syt2 in compulsive-like behavior. Our findings identified a functional role of DNA methylation in alcohol dependence-like behavioral phenotypes and a candidate gene network that may mediate its effects. Together, these data provide novel evidence for DNA methyltransferases as potential therapeutic targets in alcoholism.
Bembich, Stefano; Clarici, Andrea; Vecchiet, Cristina; Baldassi, Giulio; Cont, Gabriele; Demarini, Sergio
Prefrontal cortex plays an important role in decision making (DM), supporting choices in the ordinary uncertainty of everyday life. To assess DM in an unpredictable situation, a playing card task, such as the Iowa Gambling Task (IGT), has been proposed. This task is supposed to specifically test emotion-based learning, linked to the integrity of the ventromedial prefrontal cortex (VMPFC). However, the dorsolateral prefrontal cortex (DLPFC) has demonstrated a role in IGT performance too. Our aim was to study, by multichannel near-infrared spectroscopy, the contribution of DLPFC to the IGT execution over time. We tested the hypothesis that low and high risk choices would differentially activate DLPFC, as IGT execution progressed. We enrolled 11 healthy adults. To identify DLPFC activation associated with IGT choices, we compared regional differences in oxy-hemoglobin variation, from baseline to the event. The time course of task execution was divided in four periods, each one consisting of 25 choices, and DLPFC activation was distinctly analyzed for low and high risk choices in each period. We found different time courses in DLPFC activation, associated with low or high risk choices. During the first period, a significant DLPFC activation emerged with low risk choices, whereas, during the second period, we found a cortical activation with high risk choices. Then, DLPFC activation decreased to non-significant levels during the third and fourth period. This study shows that DLPFC involvement in IGT execution is differentiated over time and according to choice risk level. DLPFC is activated only in the first half of the task, earlier by low risk and later by high risk choices. We speculate that DLPFC may sustain initial and more cognitive functions, such as attention shifting and response inhibition. The lack of DLPFC activation, as the task progresses, may be due to VMPFC activation, not detectable by fNIRS, which takes over the IGT execution in its second half. PMID
Achterberg, E J Marijke; van Kerkhof, Linda W M; Damsteegt, Ruth; Trezza, Viviana; Vanderschuren, Louk J M J
Positive social interactions during the juvenile and adolescent phases of life, in the form of social play behavior, are important for social and cognitive development. However, the neural mechanisms of social play behavior remain incompletely understood. We have previously shown that methylphenidate and atomoxetine, drugs widely used for the treatment of attention-deficit hyperactivity disorder (ADHD), suppress social play in rats through a noradrenergic mechanism of action. Here, we aimed to identify the neural substrates of the play-suppressant effects of these drugs. Methylphenidate is thought to exert its effects on cognition and emotion through limbic corticostriatal systems. Therefore, methylphenidate was infused into prefrontal and orbitofrontal cortical regions as well as into several subcortical limbic areas implicated in social play. Infusion of methylphenidate into the anterior cingulate cortex, infralimbic cortex, basolateral amygdala, and habenula inhibited social play, but not social exploratory behavior or locomotor activity. Consistent with a noradrenergic mechanism of action of methylphenidate, infusion of the noradrenaline reuptake inhibitor atomoxetine into these same regions also reduced social play. Methylphenidate administration into the prelimbic, medial/ventral orbitofrontal, and ventrolateral orbitofrontal cortex, mediodorsal thalamus, or nucleus accumbens shell was ineffective. Our data show that the inhibitory effects of methylphenidate and atomoxetine on social play are mediated through a distributed network of prefrontal and limbic subcortical regions implicated in cognitive control and emotional processes. These findings increase our understanding of the neural underpinnings of this developmentally important social behavior, as well as the mechanism of action of two widely used treatments for ADHD.
McCarthy, Deirdre M; Bhide, Pradeep G
Cocaine abuse during pregnancy produces harmful effects not only on the mother but also on the unborn child. The neurotransmitters dopamine and serotonin are known as the principal targets of the action of cocaine in the fetal and postnatal brain. However, recent evidence suggests that cocaine can impair cerebral cortical GABA neuron development and function. We sought to analyze the effects of prenatal cocaine exposure on the number and distribution of GABA and projection neurons (inhibitory interneurons and excitatory output neurons, respectively) in the mouse cerebral cortex. We found that the prenatal cocaine exposure decreased GABA neuron numbers and GABA-to-projection neuron ratio in the medial prefrontal cortex of 60-day-old mice. The neighboring prefrontal cortex did not show significant changes in either of these measures. However, there was a significant increase in projection neuron numbers in the prefrontal cortex but not in the medial prefrontal cortex. Thus, the effects of cocaine on GABA and projection neurons appear to be cortical region specific. The population of parvalbumin-immunoreactive GABA neurons was decreased in the medial prefrontal cortex following the prenatal cocaine exposure. The cocaine exposure also delayed the developmental decline in the volume of the medial prefrontal cortex. Thus, prenatal cocaine exposure produced persisting and region-specific effects on cortical cytoarchitecture and impaired the physiological balance between excitatory and inhibitory neurotransmission. These structural changes may underlie the electrophysiological and behavioral effects of prenatal cocaine exposure observed in animal models and human subjects.
Goel, Vinod; Dolan, Raymond J
While inductive and deductive reasoning are considered distinct logical and psychological processes, little is known about their respective neural basis. To address this issue we scanned 16 subjects with fMRI, using an event-related design, while they engaged in inductive and deductive reasoning tasks. Both types of reasoning were characterized by activation of left lateral prefrontal and bilateral dorsal frontal, parietal, and occipital cortices. Neural responses unique to each type of reasoning determined from the Reasoning Type (deduction and induction) by Task (reasoning and baseline) interaction indicated greater involvement of left inferior frontal gyrus (BA 44) in deduction than induction, while left dorsolateral (BA 8/9) prefrontal gyrus showed greater activity during induction than deduction. This pattern suggests a dissociation within prefrontal cortex for deductive and inductive reasoning.
Rhodes, Sarah E V; Murray, Elisabeth A
We assessed the involvement of the orbital prefrontal cortex (PFo), the prelimbic region of the medial prefrontal cortex (PL), and the amygdala in goal-directed behavior. Rhesus monkeys were trained on a task in which two different instrumental responses were linked to two different outcomes. One response, called "tap," required the monkeys to repeatedly touch a colored square on a video monitor to produce one kind of food reward. The other response, called "hold," required persistent contact of an identical stimulus, and it produced a different kind of food reward. After training, we assessed the effects of sensory-specific reinforcer devaluation as a way to probe each monkey's use of goal-directed behavior. In this procedure, monkeys were allowed to consume one of the two foods to satiety and were then tested for tap/hold preference under extinction. Unoperated control monkeys showed a reduction in the response associated with obtaining the devalued food, called the "devaluation effect," a hallmark of goal-directed behavior. Monkeys with bilateral lesions of PFo or the amygdala exhibited significantly reduced devaluation effects. Results from monkeys with PL lesions were equivocal. We conclude that both PFo and the amygdala play a significant role in goal-directed behavior in monkeys. Notably, the findings for PFo challenge the idea that orbital and medial prefrontal regions are exclusively dedicated to object- and action-based processes, respectively.
Malkin, S L; Kim, K Kh; Tikhonov, D B; Zaitsev, A V
Quantum analysis of postsynaptic currents is important for fundamental and applied studies of synaptic transmission. In the present work, we investigated the possibility of using the characteristics of spontaneous excitatory postsynaptic currents (EPSCs) for estimation of quantum parameters of excitatory synaptic transmission in different types of neurons from rat prefrontal cortex slices. By blocking spontaneous spiking activity in slices by tetrodotoxin, we showed that spontaneous and miniature EPSCs in prefrontal cortex neurons did not differ by their properties. Thereby, both spontaneous and miniature responses can be used for estimation of quantum parameters of excitatory synaptic transmission in this preparation. We also revealed that excitatory spontaneous responses of pyramidal cells were 2 times lower by amplitude, had twice lower the coefficient of variation and exhibited much slower kinetics than responses of the fast-spiking and regular-spiking interneurons. Possible mechanisms of these differences are considered.
Martins-de-Souza, Daniel; Gattaz, Wagner F; Schmitt, Andrea; Rewerts, Christiane; Maccarrone, Giuseppina; Dias-Neto, Emmanuel; Turck, Christoph W
Schizophrenia is a complex disease, likely to be caused by a combination of serial alterations in a number of genes and environmental factors. The dorsolateral prefrontal cortex (Brodmann's Area 46) is involved in schizophrenia and executes high-level functions such as working memory, differentiation of conflicting thoughts, determination of right and wrong concepts and attitudes, correct social behavior and personality expression. Global proteomic analysis of post-mortem dorsolateral prefrontal cortex samples from schizophrenia patients and non-schizophrenic individuals was performed using stable isotope labeling and shotgun proteomics. The analysis resulted in the identification of 1,261 proteins, 84 of which showed statistically significant differential expression, reinforcing previous data supporting the involvement of the immune system, calcium homeostasis, cytoskeleton assembly, and energy metabolism in schizophrenia. In addition a number of new potential markers were found that may contribute to the understanding of the pathogenesis of this complex disease.
Fenton, Georgina E; Halliday, David M; Mason, Rob; Bredy, Timothy W; Stevenson, Carl W
Sex differences in learned fear expression and extinction involve the medial prefrontal cortex (mPFC). We recently demonstrated that enhanced learned fear expression during auditory fear extinction and its recall is linked to persistent theta activation in the prelimbic (PL) but not infralimbic (IL) cortex of female rats. Emerging evidence indicates that gamma oscillations in mPFC are also implicated in the expression and extinction of learned fear. Therefore we re-examined our in vivo electrophysiology data and found that females showed persistent PL gamma activation during extinction and a failure of IL gamma activation during extinction recall. Altered prefrontal gamma oscillations thus accompany sex differences in learned fear expression and its extinction. These findings are relevant for understanding the neural basis of post-traumatic stress disorder, which is more prevalent in women and involves impaired extinction and mPFC dysfunction.
Weilbächer, Regina A.; Gluth, Sebastian
Episodic memory and value-based decision making are two central and intensively studied research domains in cognitive neuroscience, but we are just beginning to understand how they interact to enable memory-based decisions. The two brain regions that have been associated with episodic memory and value-based decision making are the hippocampus and the ventromedial prefrontal cortex, respectively. In this review article, we first give an overview of these brain–behavior associations and then focus on the mechanisms of potential interactions between the hippocampus and ventromedial prefrontal cortex that have been proposed and tested in recent neuroimaging studies. Based on those possible interactions, we discuss several directions for future research on the neural and cognitive foundations of memory-based decision making. PMID:28036071
Golebiowska, Joanna; Rygula, Rafal
Neuroimaging studies in humans have recently shown that the prefrontal cortex (PFC) and orbitofrontal cortex (OFC) mediate bias in the judgment of forthcoming events. In the present study, we sought to determine whether cognitive judgment bias (CJB) is also dependent on these prefrontal regions in non-human animals. For this, we trained a cohort of rats in the ambiguous-cue interpretation (ACI) paradigm, subjected them to excitotoxic lesions in the medial PFC (mPFC) and OFC, and tested the effects of neuronal loss within these regions on CJB. Comparison of the lesions’ behavioral effects in the ACI paradigm revealed that neuronal loss within the OFC but not within the mPFC influences the interpretation of ambiguous cues by animals. Our findings demonstrate the specific involvement of the OFC in CJB in rats. PMID:28377703
Khadka, Sabin; Chityala, Srujan R.; Tian, Fenghua; Liu, Hanli
Stroop test is commonly used as a behavior-testing tool for psychological examinations that are related to attention and cognitive control of the human brain. Studies have shown activations in Broadmann area 10 (BA10) of prefrontal cortex (PFC) during attention and cognitive process. The use of diffuse optical tomography (DOT) for human brain mapping is becoming more prevalent. In this study we expect to find neural correlates between the performed cognitive tasks and hemodynamic signals detected by a DOT system. Our initial observation showed activation of oxy-hemoglobin concentration in BA 10, which is consistent with some results seen by positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Our study demonstrates the possibility of combining DOT with Stroop test to quantitatively investigate cognitive functions of the human brain at the prefrontal cortex.
Eippert, Falk; Wiens, Stefan; Birbaumer, Niels; Lotze, Martin; Wildgruber, Dirk
different phenomenal experiences of affect, depending on the depth of cortical processing. They are in line with a model in which the left ventrolateral prefrontal cortex is a relay station that integrates information about subcortically triggered somatic responses and information resulting from in-depth cortical stimulus processing. Tentatively, we suggest that the observed decoupling of somatic responses and experienced affect, and the reduction of negative phenomenal experience, can be explained by a left ventrolateral prefrontal cortex-mediated inhibition of affect-related somatosensory activity. PMID:19767414
Tsujii, Takeo; Komatsu, Kazutoshi; Sakatani, Kaoru
We examined the acute effect of physical exercise on prefrontal cortex activity in older adults using functional near-infrared spectroscopy (NIRS). Fourteen older adults visited our laboratory twice: once for exercise and once for the control condition. On each visit, subjects performed working memory tasks before and after moderate intensity exercise with a cycling ergo-meter. We measured the NIRS response at the prefrontal cortex during the working memory task. We found that physical exercise improved behavioral performance of the working memory task compared with the control condition. Moreover, NIRS analysis showed that physical exercise enhanced the prefrontal cortex activity, especially in the left hemisphere, during the working memory task. These findings suggest that the moderate intensity exercise enhanced the prefrontal cortex activity associated with working memory performance in older adults.
Asp, Erik; Manzel, Kenneth; Koestner, Bryan; Denburg, Natalie L.; Tranel, Daniel
The False Tagging Theory (FTT) is a neuroanatomical model of belief and doubt processes that proposes a single, unique function for the prefrontal cortex. Here, we review evidence pertaining to the FTT, the implications of the FTT regarding fractionation of the prefrontal cortex, and the potential benefits of the FTT for new neuroanatomical conceptualizations of executive functions. The FTT provides a parsimonious account that may help overcome theoretical problems with prefrontal cortex mediated executive control such as the homunculus critique. Control in the FTT is examined via the “heuristics and biases” psychological framework for human judgment. The evidence indicates that prefrontal cortex mediated doubting is at the core of executive functioning and may explain some biases of intuitive judgments. PMID:23745103
Watson, Thomas C; Becker, Nadine; Apps, Richard; Jones, Matthew W
Although recent neuroanatomical evidence has demonstrated closed-loop connectivity between prefrontal cortex and the cerebellum, the physiology of cerebello-cerebral circuits and the extent to which cerebellar output modulates neuronal activity in neocortex during behavior remain relatively unexplored. We show that electrical stimulation of the contralateral cerebellar fastigial nucleus (FN) in awake, behaving rats evokes distinct local field potential (LFP) responses (onset latency ~13 ms) in the prelimbic (PrL) subdivision of the medial prefrontal cortex. Trains of FN stimulation evoke heterogeneous patterns of response in putative pyramidal cells in frontal and prefrontal regions in both urethane-anesthetized and awake, behaving rats. However, the majority of cells showed decreased firing rates during stimulation and subsequent rebound increases; more than 90% of cells showed significant changes in response. Simultaneous recording of on-going LFP activity from FN and PrL while rats were at rest or actively exploring an open field arena revealed significant network coherence restricted to the theta frequency range (5-10 Hz). Granger causality analysis indicated that this coherence was significantly directed from cerebellum to PrL during active locomotion. Our results demonstrate the presence of a cerebello-prefrontal pathway in rat and reveal behaviorally dependent coordinated network activity between the two structures, which could facilitate transfer of sensorimotor information into ongoing neocortical processing during goal directed behaviors.
Kostopoulos, Penelope; Petrides, Michael
There is evidence from the visual, verbal, and tactile memory domains that the midventrolateral prefrontal cortex plays a critical role in the top–down modulation of activity within posterior cortical areas for the selective retrieval of specific aspects of a memorized experience, a functional process often referred to as active controlled retrieval. In the present functional neuroimaging study, we explore the neural bases of active retrieval for auditory nonverbal information, about which almost nothing is known. Human participants were scanned with functional magnetic resonance imaging (fMRI) in a task in which they were presented with short melodies from different locations in a simulated virtual acoustic environment within the scanner and were then instructed to retrieve selectively either the particular melody presented or its location. There were significant activity increases specifically within the midventrolateral prefrontal region during the selective retrieval of nonverbal auditory information. During the selective retrieval of information from auditory memory, the right midventrolateral prefrontal region increased its interaction with the auditory temporal region and the inferior parietal lobule in the right hemisphere. These findings provide evidence that the midventrolateral prefrontal cortical region interacts with specific posterior cortical areas in the human cerebral cortex for the selective retrieval of object and location features of an auditory memory experience. PMID:26831102
Kostopoulos, Penelope; Petrides, Michael
There is evidence from the visual, verbal, and tactile memory domains that the midventrolateral prefrontal cortex plays a critical role in the top-down modulation of activity within posterior cortical areas for the selective retrieval of specific aspects of a memorized experience, a functional process often referred to as active controlled retrieval. In the present functional neuroimaging study, we explore the neural bases of active retrieval for auditory nonverbal information, about which almost nothing is known. Human participants were scanned with functional magnetic resonance imaging (fMRI) in a task in which they were presented with short melodies from different locations in a simulated virtual acoustic environment within the scanner and were then instructed to retrieve selectively either the particular melody presented or its location. There were significant activity increases specifically within the midventrolateral prefrontal region during the selective retrieval of nonverbal auditory information. During the selective retrieval of information from auditory memory, the right midventrolateral prefrontal region increased its interaction with the auditory temporal region and the inferior parietal lobule in the right hemisphere. These findings provide evidence that the midventrolateral prefrontal cortical region interacts with specific posterior cortical areas in the human cerebral cortex for the selective retrieval of object and location features of an auditory memory experience.
Perez-Cruz, Claudia; Müller-Keuker, Jeanine I. H.; Heilbronner, Urs; Fuchs, Eberhard; Flügge, Gabriele
The prefrontal cortex (PFC) plays an important role in the stress response. We filled pyramidal neurons in PFC layer III with neurobiotin and analyzed dendrites in rats submitted to chronic restraint stress and in controls. In the right prelimbic cortex (PL) of controls, apical and distal dendrites were longer than in the left PL. Stress reduced the total length of apical dendrites in right PL and abolished the hemispheric difference. In right infralimbic cortex (IL) of controls, proximal apical dendrites were longer than in left IL, and stress eliminated this hemispheric difference. No hemispheric difference was detected in anterior cingulate cortex (ACx) of controls, but stress reduced apical dendritic length in left ACx. These data demonstrate interhemispheric differences in the morphology of pyramidal neurons in PL and IL of control rats and selective effects of stress on the right hemisphere. In contrast, stress reduced dendritic length in the left ACx. PMID:18253468
Jäncke, Lutz; Cheetham, Marcus; Baumgartner, Thomas
In this review, the neural underpinnings of the experience of presence are outlined. Firstly, it is shown that presence is associated with activation of a distributed network, which includes the dorsal and ventral visual stream, the parietal cortex, the premotor cortex, mesial temporal areas, the brainstem and the thalamus. Secondly, the dorsolateral prefrontal cortex (DLPFC) is identified as a key node of the network as it modulates the activity of the network and the associated experience of presence. Thirdly, children lack the strong modulatory influence of the DLPFC on the network due to their unmatured frontal cortex. Fourthly, it is shown that presence-related measures are influenced by manipulating the activation in the DLPFC using transcranial direct current stimulation (tDCS) while participants are exposed to the virtual roller coaster ride. Finally, the findings are discussed in the context of current models explaining the experience of presence, the rubber hand illusion, and out-of-body experiences.
Goodwin, Shikha J; Blackman, Rachael K; Sakellaridi, Sofia; Chafee, Matthew V
Human cognition is characterized by flexibility, the ability to select not only which action but which cognitive process to engage to best achieve the current behavioral objective. The ability to tailor information processing in the brain to rules, goals, or context is typically referred to as executive control, and although there is consensus that prefrontal cortex is importantly involved, at present we have an incomplete understanding of how computational flexibility is implemented at the level of prefrontal neurons and networks. To better understand the neural mechanisms of computational flexibility, we simultaneously recorded the electrical activity of groups of single neurons within prefrontal and posterior parietal cortex of monkeys performing a task that required executive control of spatial cognitive processing. In this task, monkeys applied different spatial categorization rules to reassign the same set of visual stimuli to alternative categories on a trial-by-trial basis. We found that single neurons were activated to represent spatially defined categories in a manner that was rule dependent, providing a physiological signature of a cognitive process that was implemented under executive control. We found also that neural signals coding rule-dependent categories were distributed between the parietal and prefrontal cortex--however, not equally. Rule-dependent category signals were stronger, more powerfully modulated by the rule, and earlier to emerge in prefrontal cortex relative to parietal cortex. This suggests that prefrontal cortex may initiate the switch in neural representation at a network level that is important for computational flexibility.
Brand, Bodo; Hadlich, Frieder; Brandt, Bettina; Schauer, Nicolas; Graunke, Katharina L; Langbein, Jan; Repsilber, Dirk; Ponsuksili, Siriluk; Schwerin, Manfred
In the past decade the number of studies investigating temperament in farm animals has increased greatly because temperament has been shown not only to affect handling but also reproduction, health and economically important production traits. However, molecular pathways underlying temperament and molecular pathways linking temperament to production traits, health and reproduction have yet to be studied in full detail. Here we report the results of metabolite profiling of the prefrontal cortex and serum of cattle with distinct temperament types that were performed to further explore their molecular divergence in the response to the slaughter procedure and to identify new targets for further research of cattle temperament. By performing an untargeted comprehensive metabolite profiling, 627 and 1097 metabolite features comprising 235 and 328 metabolites could be detected in the prefrontal cortex and serum, respectively. In total, 54 prefrontal cortex and 51 serum metabolite features were indicated to have a high relevance in the classification of temperament types by a sparse partial least square discriminant analysis. A clear discrimination between fearful/neophobic-alert, interested-stressed, subdued/uninterested-calm and outgoing/neophilic-alert temperament types could be observed based on the abundance of the identified relevant prefrontal cortex and serum metabolites. Metabolites with high relevance in the classification of temperament types revealed that the main differences between temperament types in the response to the slaughter procedure were related to the abundance of glycerophospholipids, fatty acyls and sterol lipids. Differences in the abundance of metabolites related to C21 steroid metabolism and oxidative stress indicated that the differences in the metabolite profiles of the four extreme temperament types could be the result of a temperament type specific regulation of molecular pathways that are known to be involved in the stress and fear response.
Brand, Bodo; Hadlich, Frieder; Brandt, Bettina; Schauer, Nicolas; Graunke, Katharina L.; Langbein, Jan; Repsilber, Dirk; Ponsuksili, Siriluk; Schwerin, Manfred
In the past decade the number of studies investigating temperament in farm animals has increased greatly because temperament has been shown not only to affect handling but also reproduction, health and economically important production traits. However, molecular pathways underlying temperament and molecular pathways linking temperament to production traits, health and reproduction have yet to be studied in full detail. Here we report the results of metabolite profiling of the prefrontal cortex and serum of cattle with distinct temperament types that were performed to further explore their molecular divergence in the response to the slaughter procedure and to identify new targets for further research of cattle temperament. By performing an untargeted comprehensive metabolite profiling, 627 and 1097 metabolite features comprising 235 and 328 metabolites could be detected in the prefrontal cortex and serum, respectively. In total, 54 prefrontal cortex and 51 serum metabolite features were indicated to have a high relevance in the classification of temperament types by a sparse partial least square discriminant analysis. A clear discrimination between fearful/neophobic-alert, interested-stressed, subdued/uninterested-calm and outgoing/neophilic-alert temperament types could be observed based on the abundance of the identified relevant prefrontal cortex and serum metabolites. Metabolites with high relevance in the classification of temperament types revealed that the main differences between temperament types in the response to the slaughter procedure were related to the abundance of glycerophospholipids, fatty acyls and sterol lipids. Differences in the abundance of metabolites related to C21 steroid metabolism and oxidative stress indicated that the differences in the metabolite profiles of the four extreme temperament types could be the result of a temperament type specific regulation of molecular pathways that are known to be involved in the stress and fear response
Bouamrane, Lamine; Scheyer, Andrew F.; Lassalle, Olivier; Iafrati, Jillian; Thomazeau, Aurore; Chavis, Pascale
The reelin gene is a strong candidate in the etiology of several psychiatric disorders such as schizophrenia, major depression, bipolar disorders, and autism spectrum disorders. Most of these diseases are accompanied by cognitive and executive-function deficits associated with prefrontal dysfunctions. Mammalian prefrontal cortex (PFC) development is characterized by a protracted postnatal maturation constituting a period of enhanced vulnerability to psychiatric insults. The identification of the molecular components underlying this prolonged postnatal development is necessary to understand the synaptic properties of defective circuits participating in these psychiatric disorders. We have recently shown that reelin plays a key role in the maturation of glutamatergic functions in the postnatal PFC, but no data are available regarding the GABAergic circuits. Here, we undertook a cross-sectional analysis of GABAergic function in deep layer pyramidal neurons of the medial PFC of wild-type and haploinsufficient heterozygous reeler mice. Using electrophysiological approaches, we showed that decreased reelin levels impair the maturation of GABAergic synaptic transmission without affecting the inhibitory nature of GABA. This phenotype consequently impacted the developmental sequence of the synaptic excitation/inhibition (E/I) balance. These data indicate that reelin is necessary for the correct maturation and refinement of GABAergic synaptic circuits in the postnatal PFC and therefore provide a mechanism for altered E/I balance of prefrontal circuits associated with psychiatric disorders. PMID:28127276
Córcoles-Parada, M; Müller, Ncj; Ubero, M; Serrano-Del-Pueblo, V M; Mansilla, F; Marcos-Rabal, P; Artacho-Pérula, E; Dresler, M; Insausti, R; Fernández, G; Muñoz-López, M
The medial prefrontal areas 32, 24, 14, and 25 (mPFC) form part of the limbic memory system, but little is known about their functional specialization in humans. To add anatomical precision to structural and functional MRI data, we aimed to identify these mPFC subareas in histological preparations of human brain tissue, determine sulci most consistently related with mPFC areal boundaries, and use these sulci to delineate mPFC areas in MRIs. To achieve this, we obtained 3D MRI data from 11 ex vivo hemispheres and processed them for cyto- and myelo-architectonic analysis. The architectonic boundaries of mPFC areas were identified in histology and cortical surface length and volumes were measured. Unfolded maps of histologically determined boundaries were generated to identify the association of mPFC areal boundaries with sulci across cases. This analysis showed that cingulate and superior rostral were the sulci most consistently related to mPFC areal boundaries. Based on presence/absence and anastomosis between such sulci, 6 sulci patterns in the 11 hemispheres were found. A further analysis of 102 hemispheres of in vivo MRI scans (N=51 males, mean±sd 24.1±3.1 years of age) showed similar sulci patterns, which allowed us to delineate the mFPC areas in them. The volumes of mPFC areas across histological, ex vivo and in vivo MRI delineations were comparable and probabilistic maps generated from the MRIs of the102 hemispheres. Probabilistic maps of mPFC areas were registered to MNI space and are available for regional analysis of fMRI data. This article is protected by copyright. All rights reserved.
Brincat, Scott L.
As we learn about items in our environment, their neural representations become increasingly enriched with our acquired knowledge. But there is little understanding of how network dynamics and neural processing related to external information changes as it becomes laden with “internal” memories. We sampled spiking and local field potential activity simultaneously from multiple sites in the lateral prefrontal cortex (PFC) and the hippocampus (HPC)—regions critical for sensory associations—of monkeys performing an object paired-associate learning task. We found that in the PFC, evoked potentials to, and neural information about, external sensory stimulation decreased while induced beta-band (∼11–27 Hz) oscillatory power and synchrony associated with “top-down” or internal processing increased. By contrast, the HPC showed little evidence of learning-related changes in either spiking activity or network dynamics. The results suggest that during associative learning, PFC networks shift their resources from external to internal processing. SIGNIFICANCE STATEMENT As we learn about items in our environment, their representations in our brain become increasingly enriched with our acquired “top-down” knowledge. We found that in the prefrontal cortex, but not the hippocampus, processing of external sensory inputs decreased while internal network dynamics related to top-down processing increased. The results suggest that during learning, prefrontal cortex networks shift their resources from external (sensory) to internal (memory) processing. PMID:27629722
Liu, Albert; Jain, Neeraj; Vyas, Ajai; Lim, Lee Wei
Memory dysfunction is a key symptom of age-related dementia. Although recent studies have suggested positive effects of electrical stimulation for memory enhancement, its potential targets remain largely unknown. In this study, we hypothesized that spatially targeted deep brain stimulation of ventromedial prefrontal cortex enhanced memory functions in a middle-aged rat model. Our results show that acute stimulation enhanced the short-, but not the long-term memory in the novel-object recognition task. Interestingly, after chronic high-frequency stimulation, both the short- and long-term memories were robustly improved in the novel-object recognition test and Morris water-maze spatial task compared to sham. Our results also demonstrated that chronic ventromedial prefrontal cortex high-frequency stimulation upregulated neurogenesis-associated genes along with enhanced hippocampal cell proliferation. Importantly, these memory behaviors were strongly correlated with the hippocampal neurogenesis. Overall, these findings suggest that chronic ventromedial prefrontal cortex high-frequency stimulation may serve as a novel effective therapeutic target for dementia-related disorders. DOI: http://dx.doi.org/10.7554/eLife.04803.001 PMID:25768425
Hamamura, T; Fibiger, H C
This study examined the extent to which chronic d-amphetamine administration sensitizes animals to some behavioral and neurochemical effects of foot shock stress. Rats received daily injections of saline for 14 days or d-amphetamine (2 mg/kg 7 days and 4 mg/kg 7 days). After a 7 day drug abstinent period, extracellular dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid concentrations were measured in the medial prefrontal cortex using in vivo microdialysis in freely moving rats. The behavioral responses to mild foot shock stress were enhanced in the d-amphetamine-pretreated subjects. Concomitant with this behavioral sensitization, d-amphetamine-pretreated subjects showed greater stress-induced increases in extracellular dopamine in the medial prefrontal cortex than in controls. d-Amphetamine (2 mg/kg)-induced stereotyped behavior was also enhanced in the amphetamine-pretreated animals compared to controls; however, d-amphetamine-induced increases in extracellular dopamine in the medial prefrontal cortex were not enhanced in the amphetamine-pretreated group. These results suggest that the mesocortical dopaminergic system is involved in cross-sensitization between d-amphetamine and stress, but not in d-amphetamine-induced behavioral sensitization.
Pereira, Elaine Cristina; Lucetti, Daniel Luna; Barbosa-Filho, José Maria; de Brito, Eliane Magalhães; Monteiro, Valdécio Silvano; Patrocínio, Manoel Cláudio Azevedo; de Moura, Rebeca Ribeiro; Leal, Luzia Kalyne Almeida Moreira; Macedo, Danielle Silveira; de Sousa, Francisca Cléa Florenço; de Barros Viana, Glauce Socorro; Vasconcelos, Silvânia Maria Mendes
Coumarin is a compound known to be present in a wide variety of plants, microorganisms and animal species. Most of its effects were studied in organs and systems other than the central nervous system. The present work evaluated the effect of coumarin administration on the levels of gamma-aminobutyric acid (GABA), glutamate (GLU), glycine (GLY) and taurine (TAU) in the prefrontal cortex and hippocampus of mice. Male Swiss mice were treated with distilled water (controls), coumarin (20 or 40 mg/kg, i.p.) or diazepam (1 mg/kg, i.p.). Results showed that in the prefrontal cortex, coumarin at the lowest dose increased the levels of GLU and TAU, while GABA increased with both doses studied and GLY had its levels increased only at the dose of 40 mg/kg. Diazepam (DZP) increased the levels of GABA and TAU and decreased the levels of GLU and GLY in this area. In the hippocampus, only glutamate had its levels decreased after coumarin treatment, while diazepam increased the levels of GABA and TAU and decreased the levels of GLU in this brain region. We concluded that coumarin stimulates the release of endogenous amino acids, increasing the levels of inhibitory and excitatory amino acids in the prefrontal cortex, and decreasing glutamate levels in the hippocampus. Together, these results are of interest, considering that some neurodegenerative diseases and seizures are related to the imbalance of the amino acid levels in the CNS suggesting a perspective of a therapeutic use of coumarins in these disorders.
Rubino, Tiziana; Prini, Pamela; Piscitelli, Fabiana; Zamberletti, Erica; Trusel, Massimo; Melis, Miriam; Sagheddu, Claudia; Ligresti, Alessia; Tonini, Raffaella; Di Marzo, Vincenzo; Parolaro, Daniela
Current concepts suggest that exposure to THC during adolescence may act as a risk factor for the development of psychiatric disorders later in life. However, the molecular underpinnings of this vulnerability are still poorly understood. To analyze this, we investigated whether and how THC exposure in female rats interferes with different maturational events occurring in the prefrontal cortex during adolescence through biochemical, pharmacological and electrophysiological means. We found that the endocannabinoid system undergoes maturational processes during adolescence and that THC exposure disrupts them, leading to impairment of both endocannabinoid signaling and endocannabinoid-mediated LTD in the adult prefrontal cortex. THC also altered the maturational fluctuations of NMDA subunits, leading to larger amounts of gluN2B at adulthood. Adult animals exposed to THC during adolescence also showed increased AMPA gluA1 with no changes in gluA2 subunits. Finally, adolescent THC exposure altered cognition at adulthood. All these effects seem to be triggered by the disruption of the physiological role played by the endocannabinoid system during adolescence. Indeed, blockade of CB1 receptors from early to late adolescence seems to prevent the occurrence of pruning at glutamatergic synapses. These results suggest that vulnerability of adolescent female rats to long-lasting THC adverse effects might partly reside in disruption of the pivotal role played by the endocannabinoid system in the prefrontal cortex maturation.
Zikopoulos, Basilis; Barbas, Helen
Pathways linking the thalamus and cortex mediate our daily shifts from states of attention to quiet rest, or sleep, yet little is known about their architecture in high-order neural systems associated with cognition, emotion and action. We provide novel evidence for neurochemical and synaptic specificity of two complementary circuits linking one such system, the prefrontal cortex with the ventral anterior thalamic nucleus in primates. One circuit originated from the neurochemical group of parvalbumin-positive thalamic neurons and projected focally through large terminals to the middle cortical layers, resembling ‘drivers’ in sensory pathways. Parvalbumin thalamic neurons, in turn, were innervated by small ‘modulatory’ type cortical terminals, forming asymmetric (presumed excitatory) synapses at thalamic sites enriched with the specialized metabotropic glutamate receptors. A second circuit had a complementary organization: it originated from the neurochemical group of calbindin-positive thalamic neurons and terminated through small ‘modulatory’ terminals over long distances in the superficial prefrontal layers. Calbindin thalamic neurons, in turn, were innervated by prefrontal axons through small and large terminals that formed asymmetric synapses preferentially at sites with ionotropic glutamate receptors, consistent with a driving pathway. The largely parallel thalamo-cortical pathways terminated among distinct and laminar-specific neurochemical classes of inhibitory neurons that differ markedly in inhibitory control. The balance of activation of these parallel circuits that link a high-order association cortex with the thalamus may allow shifts to different states of consciousness, in processes that are disrupted in psychiatric diseases. PMID:17786219
Pope, Paul A; Brenton, Jonathan W; Miall, R Chris
We previously speculated that depression of cerebellar excitability using cathodal transcranial direct current stimulation (tDCS) might release extra cognitive resources via the disinhibition of activity in prefrontal cortex. The objective of the present study was to investigate whether anodal tDCS over the prefrontal cortex could similarly improve performance when cognitive demands are high. Sixty-three right-handed participants in 3 separate groups performed the Paced Auditory Serial Addition Task (PASAT) and the more difficult Paced Auditory Serial Subtraction Task (PASST), before and after 20 min of anodal, cathodal, or sham stimulation over the left dorsolateral prefrontal cortex (DLPFC). Performance was assessed in terms of the accuracy, latency, and variability of correct verbal responses. All behavioral measures significantly improved for the PASST after anodal DLPFC stimulation, but not the PASAT. There were smaller practice effects after cathodal and sham stimulation. Subjective ratings of attention and mental fatigue were unchanged by tDCS over time. We conclude that anodal stimulation over the left DLPFC can selectively improve performance on a difficult cognitive task involving arithmetic processing, verbal working memory, and attention. This result might be achieved by focally improving executive functions and/or cognitive capacity when tasks are difficult, rather than by improving levels of arousal/alertness.
Pickering, Chris; Ericson, Mia; Söderpalm, Bo
Phencyclidine (PCP) mimics many aspects of schizophrenia, yet the underlying mechanism of neurochemical adaptation for PCP is unknown. We therefore used proteomics to study changes in the medial prefrontal cortex in animals with PCP-induced behavioural deficits. Male Wistar rats were injected with saline or 5 mg/kg phencyclidine for 5 days followed by two days of washout. Spontaneous alternation behaviour was tested in a Y-maze and then proteins were extracted from the medial prefrontal cortex. 2D-DIGE analysis followed by spot picking and protein identification with mass spectrometry then provided a list of differentially expressed proteins. Treatment with 5 mg/kg phencyclidine decreased the percentage of correct alternations in the Y-maze compared to saline-treated controls. Proteomics analysis of the medial prefrontal cortex found upregulation of 6 proteins (synapsin-1, Dpysl3, Aco2, Fscn1, Tuba1c, and Mapk1) and downregulation of 11 (Bin1, Dpysl2, Sugt1, ApoE, Psme1, ERp29, Pgam1, Uchl1, Ndufv2, Pcmt1, and Vdac1). A trend to upregulation was observed for Gnb4 and Capza2, while downregulation trends were noted for alpha-enolase and Fh. Many of the hits in this study concur with recent postmortem data from schizophrenic patients and this further validates the use of phencyclidine in preclinical translational research. PMID:23738220
Kamphuis, Jeanine; Baichel, Swetlana; Lancel, Marike; de Boer, Sietse F; Koolhaas, Jaap M; Meerlo, Peter
Sleep deprivation has profound effects on cognitive performance, and some of these effects may be mediated by impaired prefrontal cortex function. In search of an animal model to investigate this relationship we studied the influence of restricted sleep on operant conditioning in rats, particularly the performance in a differential reinforcement of low rate responding (DRL) task, which is highly dependent upon an intact prefrontal cortex. Animals were trained to withhold a lever press until an imposed delay of 30 s after the last press had passed in order to achieve a food reward. Once the animals had mastered the task, they were sleep-restricted for 7 days with 20 h of sleep deprivation per day. At the end of each daily sleep deprivation session, performance on the DRL task was assessed. The results show that sleep-restricted animals were less able to time their responses correctly, started pressing the lever more randomly and showed signs of behavioural disinhibition, the latter possibly reflecting enhanced impulsivity. Our data support the hypothesis that a sleep debt has disruptive consequences for the functioning of the prefrontal cortex. This model offers possibilities for future studies investigating the underlying biochemical and molecular mechanisms of this relationship.
Beierholm, Ulrik R.; Bossaerts, Peter; O'Doherty, John P.
Prefrontal cortex has long been implicated in tasks involving higher order inference in which decisions must be rendered, not only about which stimulus is currently rewarded, but also which stimulus dimensions are currently relevant. However, the precise computational mechanisms used to solve such tasks have remained unclear. We scanned human participants with functional MRI, while they performed a hierarchical intradimensional/extradimensional shift task to investigate what strategy subjects use while solving higher order decision problems. By using a computational model-based analysis, we found behavioral and neural evidence that humans solve such problems not by occasionally shifting focus from one to the other dimension, but by considering multiple explanations simultaneously. Activity in human prefrontal cortex was better accounted for by a model that integrates over all available evidences than by a model in which attention is selectively gated. Importantly, our model provides an explanation for how the brain determines integration weights, according to which it could distribute its attention. Our results demonstrate that, at the point of choice, the human brain and the prefrontal cortex in particular are capable of a weighted integration of information across multiple evidences. PMID:21697443
Basso, Julia C; Shang, Andrea; Elman, Meredith; Karmouta, Ryan; Suzuki, Wendy A
The effects of acute aerobic exercise on cognitive functions in humans have been the subject of much investigation; however, these studies are limited by several factors, including a lack of randomized controlled designs, focus on only a single cognitive function, and testing during or shortly after exercise. Using a randomized controlled design, the present study asked how a single bout of aerobic exercise affects a range of frontal- and medial temporal lobe-dependent cognitive functions and how long these effects last. We randomly assigned 85 subjects to either a vigorous intensity acute aerobic exercise group or a video watching control group. All subjects completed a battery of cognitive tasks both before and 30, 60, 90, or 120 min after the intervention. This battery included the Hopkins Verbal Learning Test-Revised, the Modified Benton Visual Retention Test, the Stroop Color and Word Test, the Symbol Digit Modalities Test, the Digit Span Test, the Trail Making Test, and the Controlled Oral Word Association Test. Based on these measures, composite scores were formed to independently assess prefrontal cortex- and hippocampal-dependent cognition. A three-way mixed Analysis of Variance was used to determine whether differences existed between groups in the change in cognitive function from pre- to post-intervention testing. Acute exercise improved prefrontal cortex- but not hippocampal-dependent functioning, with no differences found between delay groups. Vigorous acute aerobic exercise has beneficial effects on prefrontal cortex-dependent cognition and these effects can last for up to 2 hr after exercise.
Réus, Gislaine Z.; Stringari, Roberto B.; de Souza, Bruna; Petronilho, Fabrícia; Dal-Pizzol, Felipe; Hallak, Jaime E.; Zuardi, Antônio W.; Crippa, José A.; Quevedo, João
A growing body of evidence has suggested that reactive oxygen species (ROS) may play an important role in the physiopathology of depression. Evidence has pointed to the β-carboline harmine as a potential therapeutic target for the treatment of depression. The present study we evaluated the effects of acute and chronic administration of harmine (5, 10 and 15 mg/kg) and imipramine (10, 20 and 30 mg/kg) or saline in lipid and protein oxidation levels and superoxide dismutase (SOD) and catalase (CAT) activities in rat prefrontal cortex and hippocampus. Acute and chronic treatments with imipramine and harmine reduced lipid and protein oxidation, compared to control group in prefrontal cortex and hippocampus. The SOD and CAT activities increased with acute and chronic treatments with imipramine and harmine, compared to control group in prefrontal cortex and hippocampus. In conclusion, our results indicate positive effects of imipramine antidepressant and β-carboline harmine of oxidative stress parameters, increasing SOD and CAT activities and decreasing lipid and protein oxidation. PMID:21150338
Heinzel, Sebastian; Dresler, Thomas; Baehne, Christina G; Heine, Monika; Boreatti-Hümmer, Andrea; Jacob, Christian P; Renner, Tobias J; Reif, Andreas; Lesch, Klaus-Peter; Fallgatter, Andreas J; Ehlis, Ann-Christine
The prefrontal cortex plays a major role in cognitive control, but it is unclear how single genes and gene-gene interactions (genetic epistasis) impact neural and behavioral phenotypes. Both dopamine (DA) availability ("inverted U-model") and excitatory versus inhibitory DA receptor stimulation ("dual-state theory") have been linked to important principles of prefrontal processing. Catechol-O-methyltransferase (COMT; Val158Met) and DA D4-receptor (DRD4; 48 bp VNTR) genotypes were analyzed for effects on behavioral and neural correlates of prefrontal response control (NoGo-anteriorization, NGA) using a Go-NoGo task and electroencephalography (114 controls and 181 patients with attention-deficit/hyperactivity disorder). DRD4 and COMT epistatically interacted on the NGA, whereas single genes and diagnosis showed no significant impact. Subjects with presumably relatively increased D4-receptor function (DRD4: no 7R-alleles) displayed an inverted U-relationship between the NGA and increasing COMT-dependent DA levels, whereas subjects with decreased D4-sensitivity (7R) showed a U-relationship. This interaction was supported by 7R-allele dose effects and mirrored by reaction time variability (non-significant after multiple testing correction). Combining previous theories of prefrontal DA functioning, neural stability at intermediate DA levels may be accompanied by the risk of overly decreased neural flexibility if inhibitory DA receptor function is additionally decreased. Our findings might help to disentangle the genetic basis of dopaminergic mechanisms underlying prefrontal (dys)function.
Takahara, Daisuke; Inoue, Ken-Ichi; Hirata, Yoshihiro; Miyachi, Shigehiro; Nambu, Atsushi; Takada, Masahiko; Hoshi, Eiji
Lines of evidence indicate that both the ventrolateral prefrontal cortex (vlPFC) (areas 45/12) and dorsal premotor cortex (PMd) (rostral F2 in area 6) are crucially involved in conditional visuomotor behavior, in which it is required to determine an action based on an associated visual object. However, virtually no direct projections appear to exist between the vlPFC and PMd. In the present study, to elucidate possible multisynaptic networks linking the vlPFC to the PMd, we performed a series of neuroanatomical tract-tracing experiments in macaque monkeys. First, we identified cortical areas that send projection fibers directly to the PMd by injecting Fast Blue into the PMd. Considerable retrograde labeling occurred in the dorsal prefrontal cortex (dPFC) (areas 46d/9/8B/8Ad), dorsomedial motor cortex (dmMC) (F7 and presupplementary motor area), rostral cingulate motor area, and ventral premotor cortex (F5 and area 44), whereas the vlPFC was virtually devoid of neuronal labeling. Second, we injected the rabies virus, a retrograde transneuronal tracer, into the PMd. At 3 days after the rabies injections, second-order neurons were labeled in the vlPFC (mainly area 45), indicating that the vlPFC disynaptically projects to the PMd. Finally, to determine areas that connect the vlPFC to the PMd indirectly, we carried out an anterograde/retrograde dual-labeling experiment in single monkeys. By examining the distribution of axon terminals labeled from the vlPFC and cell bodies labeled from the PMd, we found overlapping labels in the dPFC and dmMC. These results indicate that the vlPFC outflow is directed toward the PMd in a multisynaptic fashion through the dPFC and/or dmMC.
Procyk, Emmanuel; Dominey, Peter Ford
Primates display a remarkable ability to adapt to novel situations. Determining what is most pertinent in these situations is not always possible based only on the current sensory inputs, and often also depends on recent inputs and behavioral outputs that contribute to internal states. Thus, one can ask how cortical dynamics generate representations of these complex situations. It has been observed that mixed selectivity in cortical neurons contributes to represent diverse situations defined by a combination of the current stimuli, and that mixed selectivity is readily obtained in randomly connected recurrent networks. In this context, these reservoir networks reproduce the highly recurrent nature of local cortical connectivity. Recombining present and past inputs, random recurrent networks from the reservoir computing framework generate mixed selectivity which provides pre-coded representations of an essentially universal set of contexts. These representations can then be selectively amplified through learning to solve the task at hand. We thus explored their representational power and dynamical properties after training a reservoir to perform a complex cognitive task initially developed for monkeys. The reservoir model inherently displayed a dynamic form of mixed selectivity, key to the representation of the behavioral context over time. The pre-coded representation of context was amplified by training a feedback neuron to explicitly represent this context, thereby reproducing the effect of learning and allowing the model to perform more robustly. This second version of the model demonstrates how a hybrid dynamical regime combining spatio-temporal processing of reservoirs, and input driven attracting dynamics generated by the feedback neuron, can be used to solve a complex cognitive task. We compared reservoir activity to neural activity of dorsal anterior cingulate cortex of monkeys which revealed similar network dynamics. We argue that reservoir computing is a
Enel, Pierre; Procyk, Emmanuel; Quilodran, René; Dominey, Peter Ford
Primates display a remarkable ability to adapt to novel situations. Determining what is most pertinent in these situations is not always possible based only on the current sensory inputs, and often also depends on recent inputs and behavioral outputs that contribute to internal states. Thus, one can ask how cortical dynamics generate representations of these complex situations. It has been observed that mixed selectivity in cortical neurons contributes to represent diverse situations defined by a combination of the current stimuli, and that mixed selectivity is readily obtained in randomly connected recurrent networks. In this context, these reservoir networks reproduce the highly recurrent nature of local cortical connectivity. Recombining present and past inputs, random recurrent networks from the reservoir computing framework generate mixed selectivity which provides pre-coded representations of an essentially universal set of contexts. These representations can then be selectively amplified through learning to solve the task at hand. We thus explored their representational power and dynamical properties after training a reservoir to perform a complex cognitive task initially developed for monkeys. The reservoir model inherently displayed a dynamic form of mixed selectivity, key to the representation of the behavioral context over time. The pre-coded representation of context was amplified by training a feedback neuron to explicitly represent this context, thereby reproducing the effect of learning and allowing the model to perform more robustly. This second version of the model demonstrates how a hybrid dynamical regime combining spatio-temporal processing of reservoirs, and input driven attracting dynamics generated by the feedback neuron, can be used to solve a complex cognitive task. We compared reservoir activity to neural activity of dorsal anterior cingulate cortex of monkeys which revealed similar network dynamics. We argue that reservoir computing is a
Simone, Luciano; Rozzi, Stefano; Bimbi, Marco; Fogassi, Leonardo
Grasping actions require the integration of two neural processes, one enabling the transformation of object properties into corresponding motor acts, and the other involved in planning and controlling action execution on the basis of contextual information. The first process relies on parieto-premotor circuits, whereas the second is considered to be a prefrontal function. Up to now, the prefrontal cortex has been mainly investigated with conditional visuomotor tasks requiring a learned association between cues and behavioural output. To clarify the functional role of the prefrontal cortex in grasping actions, we recorded the activity of ventrolateral prefrontal (VLPF) neurons while monkeys (Macaca mulatta) performed tasks requiring reaching-grasping actions in different contextual conditions (in light and darkness, memory-guided, and in the absence of abstract learned rules). The results showed that the VLPF cortex contains neurons that are active during action execution (movement-related neurons). Some of them showed grip selectivity, and some also responded to object presentation. Most movement-related neurons discharged during action execution both with and without visual feedback, and this discharge typically did not change when the action was performed with object mnemonic information and in the absence of abstract rules. The findings of this study indicate that a population of VLPF neurons play a role in controlling goal-directed grasping actions in several contexts. This control is probably exerted within a wider network, involving parietal and premotor regions, where the role of VLPF movement-related neurons would be that of activating, on the basis of contextual information, the representation of the motor goal of the intended action (taking possession of an object) during action planning and execution.
Bordner, Kelly A.; Kitchen, Robert R.; Carlyle, Becky; George, Elizabeth D.; Mahajan, Milind C.; Mane, Shrikant M.; Taylor, Jane R.; Simen, Arthur A.
Aging in humans is associated with parallel changes in cognition, motivation, and motoric performance. Based on the human aging literature, we hypothesized that this constellation of age-related changes is mediated by the medial prefrontal cortex and that it would be observed in aging mice. Toward this end, we performed detailed assessments of cognition, motivation, and motoric behavior in aging mice. We assessed behavioral and cognitive performance in C57Bl/6 mice aged 6, 18, and 24 months, and followed this with microarray analysis of tissue from the medial prefrontal cortex and analysis of serum cytokine levels. Multivariate modeling of these data suggested that the age-related changes in cognition, motivation, motor performance, and prefrontal immune gene expression were highly correlated. Peripheral cytokine levels were also correlated with these variables, but less strongly than measures of prefrontal immune gene upregulation. To determine whether the observed immune gene expression changes were due to prefrontal microglial cells, we isolated CD11b-positive cells from the prefrontal cortex and subject them to next-generation RNA sequencing. Many of the immune changes present in whole medial prefrontal cortex were enriched in this cell population. These data suggest that, as in humans, cognition, motivation, and motoric performance in the mouse change together with age and are strongly associated with CNS immune gene upregulation. PMID:21453768
Anderson, John R.; Anderson, John F.; Ferris, Jennifer L.; Fincham, Jon M.; Jung, Kwan-Jin
Two studies used puzzles that required participants to find a word that satisfied a set of constraints. The first study used a remote-association task, where participants had to find a word that would form compound words with 3 other words. The second study required participants to complete a word fragment with an associate of another word. Both studies produced distinct patterns of activity in the lateral inferior prefrontal cortex (LIPFC) and the anterior cingulate cortex (ACC). Activation in the LIPFC rose only as long as the participants were trying to retrieve the solution and dropped off as soon as the solution was obtained. However, activation in the ACC increased upon the retrieval of a solution, reflecting the need to process that solution. The data of the second experiment are fit by an information-processing model that interprets the activity in the LIPFC as reflecting retrieval operations and the activity in the ACC as reflecting subgoal setting. PMID:19541657
Kühn, Andrea A; Sharott, Andrew; Trottenberg, Thomas; Kupsch, Andreas; Brown, Peter
The influence of the brainstem motor system on cerebral motor areas may play an important role in motor control in health and disease. A new approach to investigate this interaction in man is combining acoustic stimulation activating the startle system with transcranial magnetic stimulation (TMS) over the motor cortex. However, it is unclear whether the inhibition of TMS responses following acoustic stimulation occurs at the level of the motor cortex through reticulo-cortical projections or subcortically, perhaps through reticulo-spinal projections. We compared the influence of acoustic stimulation on motor effects elicited by TMS over motor cortical areas to those evoked with subcortical electrical stimulation (SES) through depth electrodes in five patients treated with deep brain stimulation for Parkinson's disease. SES bypasses the motor cortex, demonstrating any interaction with acoustic stimuli at the subcortical level. EMG was recorded from the contralateral biceps brachii muscle. Acoustic stimulation was delivered binaurally through headphones and used as a conditioning stimulus at an interstimulus interval of 50 ms. When TMS was used as the test stimulus, the area and amplitude of the conditioned motor response was significantly inhibited (area: 57.5+/-12.9%, amplitude: 47.9+/-7.4%, as percentage of unconditioned response) whereas facilitation occurred with SES (area: 110.1+/-4.3%, amplitude: 116.9+/-6.9%). We conclude that a startle-evoked activation of reticulo-cortical projections transiently inhibits the motor cortex.
Wang, Yin; Ramsey, Richard; Hamilton, Antonia F de C
Spontaneous mimicry of other people's actions serves an important social function, enhancing affiliation and social interaction. This mimicry can be subtly modulated by different social contexts. We recently found behavioral evidence that direct eye gaze rapidly and specifically enhances mimicry of intransitive hand movements (Wang et al., 2011). Based on past findings linking medial prefrontal cortex (mPFC) to both eye contact and the control of mimicry, we hypothesized that mPFC might be the neural origin of this behavioral effect. The present study aimed to test this hypothesis. During functional magnetic resonance imaging (fMRI) scanning, 20 human participants performed a simple mimicry or no-mimicry task, as previously described (Wang et al., 2011), with direct gaze present on half of the trials. As predicted, fMRI results showed that performing the task activated mirror systems, while direct gaze and inhibition of the natural tendency to mimic both engaged mPFC. Critically, we found an interaction between mimicry and eye contact in mPFC, superior temporal sulcus (STS) and inferior frontal gyrus. We then used dynamic causal modeling to contrast 12 possible models of information processing in this network. Results supported a model in which eye contact controls mimicry by modulating the connection strength from mPFC to STS. This suggests that mPFC is the originator of the gaze-mimicry interaction and that it modulates sensory input to the mirror system. Thus, our results demonstrate how different components of the social brain work together to on-line control mimicry according to the social context.
Liu, Wenhua; Yuen, Eunice Y.; Allen, Patrick B.; Feng, Jian; Greengard, Paul; Yan, Zhen
The noradrenergic system in the prefrontal cortex (PFC) is involved in many physiological and psychological processes, including working memory and mood control. To understand the functions of the noradrenergic system, we examined the regulation of NMDA receptors (NMDARs), key players in cognition and emotion, by α1- and α2-adrenergic receptors (α1-ARs, α2-ARs) in PFC pyramidal neurons. Applying norepinephrine or a norepinephrine transporter inhibitor reduced the amplitude but not paired-pulse ratio of NMDAR-mediated excitatory postsynaptic currents (EPSC) in PFC slices. Specific α1-AR or α2-AR agonists also decreased NMDAR-EPSC amplitude and whole-cell NMDAR current amplitude in dissociated PFC neurons. The α1-AR effect depended on the phospholipase C–inositol 1,4,5-trisphosphate–Ca2+ pathway, whereas the α2-AR effect depended on protein kinase A and the microtubule-based transport of NMDARs that is regulated by ERK signaling. Furthermore, two members of the RGS family, RGS2 and RGS4, were found to down-regulate the effect of α1-AR on NMDAR currents, whereas only RGS4 was involved in inhibiting α2-AR regulation of NMDAR currents. The regulating effects of RGS2/4 on α1-AR signaling were lost in mutant mice lacking spinophilin, which binds several RGS members and G protein-coupled receptors, whereas the effect of RGS4 on α2-AR signaling was not altered in spinophilin-knockout mice. Our work suggests that activation of α1-ARs or α2-ARs suppresses NMDAR currents in PFC neurons by distinct mechanisms. The effect of α1-ARs is modified by RGS2/4 that are recruited to the receptor complex by spinophilin, whereas the effect of α2-ARs is modified by RGS4 independent of spinophilin. PMID:17101972
Willcocks, Andrea L; McNally, Gavan P
The prelimbic (PL) and infralimbic (IL) medial prefrontal cortex (mPFC) are thought to play opposing roles in drug-seeking behaviour. Specifically, the PL promotes drug-seeking whereas the IL is necessary for the inhibition of drug-seeking during extinction. We studied the roles of the PL, IL and dorsal peduncular PFC (DP) in the expression of context-induced reinstatement, reacquisition and extinction of alcoholic beer-seeking. In context-induced reinstatement (renewal), animals were trained to nosepoke for alcoholic beer (context A), extinguished (context B) and then tested in context A and B. In reacquisition, animals received the same instrumental training and extinction without any contextual manipulation. On test, alcoholic beer was again available and responding was compared with naive controls. Just prior to the test, rats received bilateral infusion of baclofen/muscimol into the PL, IL or DP. Reversible inactivation of the PL attenuated ABA renewal but augmented reacquisition. Reversible inactivation of IL had no effect on the reinstatement or reacquisition of alcoholic beer-seeking and had no effect on extinction expression (ABB and AAA). IL inactivation did, however, increase the latencies with which animals responded on test but only when animals were tested in the extinction context. DP inactivation had no effect on reinstatement or reacquisition. These studies are inconsistent with the view that PL and IL exert opposing effects on drug-seeking. Rather, they support the view that PL is important for retrieval of drug-seeking contingency information and that the use of contextual information is enhanced with IL manipulation.
Thierry, Guillaume; Ibarrola, Danielle; Démonet, Jean-François; Cardebat, Dominique
Event-related functional magnetic resonance imaging was used to test the involvement of the inferior prefrontal cortex in verbal working memory. Pairs of French nouns were presented to ten native French speakers who had to make semantic or grammatical gender decisions. Verbal working memory involvement was manipulated by making the categorization of the second noun optional. Decisions could be made after processing the first noun only (RELEASE condition) or after processing the two nouns (HOLD condition). Reaction times suggested faster processing for gender than for semantic category in RELEASE. Despite the absence of anatomical difference across tasks and conditions in the wide activated network, the haemodynamic response peak latencies of the inferior prefrontal cortex were significantly delayed in HOLD versus RELEASE while no such peak delay was observed in the superior temporal gyrus. Interestingly, this pattern did not interact with language tasks. This study shows that cognitive manipulation can influence haemodynamic time-course and suggests that the main cognitive process determining inferior prefrontal activation is verbal working memory rather than specific linguistic processes such as grammatical or semantic analysis.
Romanski, Lizabeth M
The integration of facial gestures and vocal signals is an essential process in human communication and relies on an interconnected circuit of brain regions, including language regions in the inferior frontal gyrus (IFG). Studies have determined that ventral prefrontal cortical regions in macaques [e.g., the ventrolateral prefrontal cortex (VLPFC)] share similar cytoarchitectonic features as cortical areas in the human IFG, suggesting structural homology. Anterograde and retrograde tracing studies show that macaque VLPFC receives afferents from the superior and inferior temporal gyrus, which provide complex auditory and visual information, respectively. Moreover, physiological studies have shown that single neurons in VLPFC integrate species-specific face and vocal stimuli. Although bimodal responses may be found across a wide region of prefrontal cortex, vocalization responsive cells, which also respond to faces, are mainly found in anterior VLPFC. This suggests that VLPFC may be specialized to process and integrate social communication information, just as the IFG is specialized to process and integrate speech and gestures in the human brain.
Satpute, Ajay B.; Badre, David; Ochsner, Kevin N.
Research in social neuroscience has uncovered a social knowledge network that is particularly attuned to making social judgments. However, the processes that are being performed by both regions within this network and those outside of this network that are nevertheless engaged in the service of making a social judgment remain unclear. To help address this, we drew upon research in semantic memory, which suggests that making a semantic judgment engages 2 distinct control processes: A controlled retrieval process, which aids in bringing goal-relevant information to mind from long-term stores, and a selection process, which aids in selecting the information that is goal-relevant from the information retrieved. In a neuroimaging study, we investigated whether controlled retrieval and selection for social information engage distinct portions of both the social knowledge network and regions outside this network. Controlled retrieval for social information engaged an anterior ventrolateral portion of the prefrontal cortex, whereas selection engaged both the dorsomedial prefrontal cortex and temporoparietal junction within the social knowledge network. These results suggest that the social knowledge network may be more involved with the selection of social information than the controlled retrieval of it and incorporates lateral prefrontal regions in accessing memory for making social judgments. PMID:23300111
Ciaramelli, Elisa; Muccioli, Michela; Làdavas, Elisabetta
Recent fMRI evidence has detected increased medial prefrontal activation during contemplation of personal moral dilemmas compared to impersonal ones, which suggests that this cortical region plays a role in personal moral judgment. However, functional imaging results cannot definitively establish that a brain area is necessary for a particular cognitive process. This requires evidence from lesion techniques, such as studies of human patients with focal brain damage. Here, we tested 7 patients with lesions in the ventromedial prefrontal cortex and 12 healthy individuals in personal moral dilemmas, impersonal moral dilemmas and non-moral dilemmas. Compared to normal controls, patients were more willing to judge personal moral violations as acceptable behaviors in personal moral dilemmas, and they did so more quickly. In contrast, their performance in impersonal and non-moral dilemmas was comparable to that of controls. These results indicate that the ventromedial prefrontal cortex is necessary to oppose personal moral violations, possibly by mediating anticipatory, self-focused, emotional reactions that may exert strong influence on moral choice and behavior. PMID:18985127
Schaefer, Michael; Heinze, Hans-Jochen; Rotte, Michael
Increasing evidence suggests that somatosensory information is modulated cortically for task-specific sensory inflow: Several studies report short-term adaptation of representational maps in primary somatosensory cortex (SI) due to attention or induced by task-related motor activity such as handwriting. Recently, it has been hypothesized that the frontal or prefrontal cortex may modulate SI. In order to test this hypothesis, we studied the functional organization of SI while subjects performed the Tower of Hanoi task. This task is known to be related to activation of frontal or prefrontal areas. The functional organization of SI while performing the Tower of Hanoi task was compared to the organization of SI during performing the same movements but without the Tower of Hanoi task and with rest. Topography of SI was assessed using neuromagnetic source imaging based on tactile stimulation of the first (D1) and fifth digits (D5). Performing the Tower of Hanoi task was accompanied by plastic changes in SI as indicated by significant shifts in the cortical representations of D1 and D5: They moved further apart during the Tower of Hanoi task compared to the control task containing the same movements but without the cognitive characteristic. Thus, we conclude that SI maps undergo dynamic modulation depending on motor tasks with different cognitive demands. The results suggest that this short-term plasticity may be regulated by a prefrontal-cortical sensory gating system.
Modirrousta, Mandana; Fellows, Lesley K.
The frontal lobes are thought to play a role in the monitoring of memory performance, or "meta-memory," but the specific circuits involved have yet to be definitively established. Medial prefrontal cortex in general and the anterior cingulate cortex in particular, have been implicated in other forms of monitoring, such as error and conflict…
Vartanian, O; Jobidon, M-E; Bouak, F; Nakashima, A; Smith, I; Lam, Q; Cheung, B
Working memory (WM) training has been shown to lead to improvements in WM capacity and fluid intelligence. Given that divergent thinking loads on WM and fluid intelligence, we tested the hypothesis that WM training would improve performance and moderate neural function in the Alternate Uses Task (AUT)-a classic test of divergent thinking. We tested this hypothesis by administering the AUT in the functional magnetic resonance imaging scanner following a short regimen of WM training (experimental condition), or engagement in a choice reaction time task not expected to engage WM (active control condition). Participants in the experimental group exhibited significant improvement in performance in the WM task as a function of training, as well as a significant gain in fluid intelligence. Although the two groups did not differ in their performance on the AUT, activation was significantly lower in the experimental group in ventrolateral prefrontal and dorsolateral prefrontal cortices-two brain regions known to play dissociable and critical roles in divergent thinking. Furthermore, gain in fluid intelligence mediated the effect of training on brain activation in ventrolateral prefrontal cortex. These results indicate that a short regimen of WM training is associated with lower prefrontal activation-a marker of neural efficiency-in divergent thinking.
Tranel, Daniel; Manzel, Kenneth; Anderson, Steven W.
Patients with prefrontal damage and severe defects in decision making and emotional regulation often have a remarkable absence of intellectual impairment, as measured by conventional IQ tests such as the WAIS/WAIS-R. This enigma might be explained by shortcomings in the tests, which tend to emphasize measures of “crystallized” (e.g., vocabulary, fund of information) more than “fluid” (e.g., novel problem solving) intelligence. The WAIS-III added the Matrix Reasoning subtest to enhance measurement of fluid reasoning. In a set of four studies, we investigated Matrix Reasoning performances in 80 patients with damage to various sectors of the prefrontal cortex, and contrasted these with the performances of 80 demographically matched patients with damage outside the frontal lobes. The results failed to support the hypothesis that prefrontal damage would disproportionately impair fluid intelligence, and every prefrontal subgroup we studied (dorsolateral, ventromedial, dorsolateral + ventromedial) had Matrix Reasoning scores (as well as IQ scores more generally) that were indistinguishable from those of the brain-damaged comparison groups. Our findings do not support a connection between fluid intelligence and the frontal lobes, although a viable alternative interpretation is that the Matrix Reasoning subtest lacks construct validity as a measure of fluid intelligence. PMID:17853146
Baxter, Mark G; Browning, Philip G F; Mitchell, Anna S
Surgical disconnection of the frontal cortex and inferotemporal cortex severely impairs many aspects of visual learning and memory, including learning of new object-in-place scene memory problems, a monkey model of episodic memory. As part of a study of specialization within prefrontal cortex in visual learning and memory, we tested monkeys with bilateral ablations of ventrolateral prefrontal cortex in object-in-place scene learning. These monkeys were mildly impaired in scene learning relative to their own preoperative performance, similar in severity to that of monkeys with bilateral ablation of orbital prefrontal cortex. An analysis of response types showed that the monkeys with lesions were specifically impaired in responding to negative feedback during learning: The post-operative increase in errors was limited to trials in which the first response to each new problem, made on the basis of trial and error, was incorrect. This perseverative pattern of deficit was not observed in the same analysis of response types in monkeys with bilateral ablations of the orbital prefrontal cortex, who were equally impaired on trials with correct and incorrect first responses. This may represent a specific signature of ventrolateral prefrontal involvement in episodic learning and memory.
Liy-Salmeron, Gustavo; Meneses, Alfredo
This article describes a series of experiments investigating the effects of systemic or intraprefrontal administration of serotonergic agents on ketamine induced memory deficits in rats. First, rats were trained on an operant autoshaping task. Immediately after training, rats were injected with different doses of drug or saline. Following drug administration, rats were tested after 1.5 h for short-term memory (STM) and 24 h for long-term memory (LTM) of conditioned response. An increase or decrease in number of conditioned responses was an index of retention. The major results of this work show that ketamine impaired STM and this effect was reversed, by either systemic or intraprefrontal cortex administration of the agonist 5-HT(1A/7) 8-OH-DPAT, the 5-HT receptor antagonists MDL100907 (5-HT(2A)), SB-399885 (5-HT(6)), and SB-269970 (5-HT(7)). The ketamine STM-impairment effect was not altered by the 5-HT(1A) antagonist WAY 100635 or the 5-HT(1B) antagonist SB-224289. Notably, prefrontal cortex inhibition of translation or transcription interrupted STM without affecting LTM suggesting different signaling mechanisms. The interacting effect of NMDA and serotonin agents in memory function is an interesting and important area of study; both receptors are considered to be important targets for the development of antipsychotic medication. Particularly, 5-HT(1A/7), 5-HT(2A) 5-HT(6), and 5-HT(7) receptors present in prefrontal cortex, represent important targets for development of drugs for the treatment of SMT-deficits.
Garcia-Oscos, Francisco; Peña, David; Housini, Mohammad; Cheng, Derek; Lopez, Diego; Borland, Michael S.; Salgado-Delgado, Roberto; Salgado, Humberto; D’Mello, Santosh; Kilgard, Michael P.; Rose-John, Stefan; Atzori, Marco
The ratio between synaptic inhibition and excitation (sI/E) is a critical factor in the pathophysiology of neuropsychiatric disease. We recently described a stress-induced interleukin-6 dependent mechanism leading to a decrease in sI/E in the rodent temporal cortex. The aim of the present study was to determine whether a similar mechanism takes place in the prefrontal cortex, and to elaborate strategies to prevent or attenuate it. We used aseptic inflammation (single acute injections of lipopolysaccharide, LPS, 10 mg/kg) as stress model, and patch-clamp recording on a prefrontal cortical slice preparation from wild-type rat and mice, as well as from transgenic mice in which the inhibitor of IL-6 trans-signaling sgp130Fc was produced in a brain-specific fashion (sgp130Fc mice). The anti-inflammatory reflex was activated either by vagal nerve stimulation or peripheral administration of the nicotinic α7 receptor agonist PHA543613. We found that the IL-6-dependent reduction in prefrontal cortex synaptic inhibition was blocked in sgp130Fc mice, or – in wild-type animals – upon application sgp130Fc. Similar results were obtained by activating the “anti-inflammatory reflex” – a neural circuit regulating peripheral immune response – by stimulation of the vagal nerve or through peripheral administration of the α7 nicotinic receptor agonist PHA543613. Our results indicate that the prefrontal cortex is an important potential target of IL-6 mediated trans-signaling, and suggest a potential new avenue in the treatment of a large class of hyperexcitable neuropsychiatric conditions, including epilepsy, schizophrenic psychoses, anxiety disorders, autism spectrum disorders, and depression. PMID:25128387
Murray, Andrew J; Woloszynowska-Fraser, Marta U; Ansel-Bollepalli, Laura; Cole, Katy L H; Foggetti, Angelica; Crouch, Barry; Riedel, Gernot; Wulff, Peer
Dysfunction of parvalbumin (PV)-positive GABAergic interneurons (PVIs) within the prefrontal cortex (PFC) has been implicated in schizophrenia pathology. It is however unclear, how impaired signaling of these neurons may contribute to PFC dysfunction. To identify how PVIs contribute to PFC-dependent behaviors we inactivated PVIs in the PFC in mice using region- and cell-type-selective expression of tetanus toxin light chain (TeLC) and compared the functional consequences of this manipulation with non-cell-type-selective perturbations of the same circuitry. By sampling for behavioral alterations that map onto distinct symptom categories in schizophrenia, we show that dysfunction of PVI signaling in the PFC specifically produces deficits in the cognitive domain, but does not give rise to PFC-dependent correlates of negative or positive symptoms. Our results suggest that distinct aspects of the complex symptomatology of PFC dysfunction in schizophrenia can be attributed to specific prefrontal circuit elements.
Murray, Andrew J.; Woloszynowska-Fraser, Marta U.; Ansel-Bollepalli, Laura; Cole, Katy L. H.; Foggetti, Angelica; Crouch, Barry; Riedel, Gernot; Wulff, Peer
Dysfunction of parvalbumin (PV)-positive GABAergic interneurons (PVIs) within the prefrontal cortex (PFC) has been implicated in schizophrenia pathology. It is however unclear, how impaired signaling of these neurons may contribute to PFC dysfunction. To identify how PVIs contribute to PFC-dependent behaviors we inactivated PVIs in the PFC in mice using region- and cell-type-selective expression of tetanus toxin light chain (TeLC) and compared the functional consequences of this manipulation with non-cell-type-selective perturbations of the same circuitry. By sampling for behavioral alterations that map onto distinct symptom categories in schizophrenia, we show that dysfunction of PVI signaling in the PFC specifically produces deficits in the cognitive domain, but does not give rise to PFC-dependent correlates of negative or positive symptoms. Our results suggest that distinct aspects of the complex symptomatology of PFC dysfunction in schizophrenia can be attributed to specific prefrontal circuit elements. PMID:26608841
Marcos, Encarni; Tsujimoto, Satoshi; Genovesio, Aldo
The estimation of space and time can interfere with each other, and neuroimaging studies have shown overlapping activation in the parietal and prefrontal cortical areas. We used duration and distance discrimination tasks to determine whether space and time share resources in prefrontal cortex (PF) neurons. Monkeys were required to report which of two stimuli, a red circle or blue square, presented sequentially, were longer and farther, respectively, in the duration and distance tasks. In a previous study, we showed that relative duration and distance are coded by different populations of neurons and that the only common representation is related to goal coding. Here, we examined the coding of absolute duration and distance. Our results support a model of independent coding of absolute duration and distance metrics by demonstrating that not only relative magnitude but also absolute magnitude are independently coded in the PF.
Desrochers, Theresa M.; Chatham, Christopher H.; Badre, David
Summary Frontal neocortex is thought to support our highest intellectual abilities, including our ability to plan and enact a sequence of tasks toward a desired goal. In everyday life, such task sequences are abstract in that they do not require consistent movement sequences and are often assembled “on the fly”. Yet, remarkably little is known about the necessity of frontal sub-regions for such control. Participants repeatedly completed sequences of simple tasks during fMRI scanning. Rostrolateral prefrontal cortex (RLPFC) activation ramped over sequence position, and reset at the initiation of each new sequence. To establish the necessity and function of RLPFC in this task, participants performed the sequential task while undergoing transcranial magnetic stimulation (TMS) of the RLPFC versus two prefrontal control regions. Across two independent experiments, only RLPFC stimulation increasingly disrupted task performance as each sequence progressed. These data establish RLPFC as necessary for uncertainty resolution during sequence-level control. PMID:26402612
Watanabe, Kei; Funahashi, Shintaro
Simultaneous performance of two tasks often leads to performance deficits in the component tasks. This effect, known as dual-task interference, is thought to be a proof of capacity limitation in cognition, and the lateral prefrontal cortex (LPFC) has been highlighted as its putative neural substrate. Here we recorded single-neuron activities in LPFC while monkeys performed dual tasks that required the simultaneous performance of a varying-load spatial attention task and a spatial memory task. We found that the performance of the monkeys exhibited dual-task interference, and prefrontal neuron activities showed a decreased ability to represent task-relevant information to a degree proportional to the increased demand of the concurrent counterpart task. The locus of the interference was shown to originate in the simultaneous, overloaded recruitment of the same LPFC neural population by the two tasks. These results provide direct neurophysiological evidence for, and constraints to, psychological models of dual-task interference and capacity limitation.
Eden, Annuschka Salima; Schreiber, Jan; Anwander, Alfred; Keuper, Katharina; Laeger, Inga; Zwanzger, Peter; Zwitserlood, Pienie; Kugel, Harald; Dobel, Christian
Diffusion tensor imaging revealed that trait anxiety predicts the microstructural properties of a prespecified fiber tract between the amygdala and the perigenual anterior cingulate cortex. Besides this particular pathway, it is likely that other pathways are also affected. We investigated white matter differences in persons featuring an anxious or a nonanxious personality, taking into account all potential pathway connections between amygdala and anxiety-related regions of the prefrontal cortex (PFC). Diffusion-weighted images, measures of trait anxiety and of reappraisal use (an effective emotion-regulation style), were collected in 48 females. With probabilistic tractography, pathways between the amygdala and the dorsolateral PFC, dorsomedial PFC, ventromedial PFC, and orbitofrontal cortex (OFC) were delineated. The resulting network showed a direct ventral connection between amygdala and PFC and a second limbic connection following the fornix and the anterior limb of the internal capsule. Reappraisal use predicted the microstructure of pathways to all calculated PFC regions in the left hemisphere, indicating stronger pathways for persons with high reappraisal use. Trait anxiety predicted the microstructure in pathways to the ventromedial PFC and OFC, indexing weaker connections in trait-anxious persons. These effects appeared in the right hemisphere, supporting lateralization and top-down inhibition theories of emotion processing. Whereas a specific microstructure is associated with an anxious personality, a different structure subserves emotion regulation. Both are part of a broad fiber tract network between amygdala and PFC.
Hartmann, Christian J.; Lujan, J. Luis; Chaturvedi, Ashutosh; Goodman, Wayne K.; Okun, Michael S.; McIntyre, Cameron C.; Haq, Ihtsham U.
Background: Medication resistant obsessive-compulsive disorder (OCD) patients can be successfully treated with Deep Brain Stimulation (DBS) which targets the anterior limb of the internal capsule (ALIC) and the nucleus accumbens (NA). Growing evidence suggests that in patients who respond to DBS, axonal fiber bundles surrounding the electrode are activated, but it is currently unknown which discrete pathways are critical for optimal benefit. Our aim was to identify axonal pathways mediating clinical effects of ALIC-NA DBS. Methods: We created computational models of ALIC-NA DBS to simulate the activation of fiber tracts and to identify connected cerebral regions. The pattern of activated axons and their cortical targets was investigated in six OCD patients who underwent ALIC-NA DBS. Results: Modulation of the right anterior middle frontal gyrus (dorsolateral prefrontal cortex) was associated with an excellent response. In contrast, non-responders showed high activation in the orbital part of the right inferior frontal gyrus (lateral orbitofrontal cortex/anterior ventrolateral prefrontal cortex). Factor analysis followed by step-wise linear regression indicated that YBOCS improvement was inversely associated with factors that were predominantly determined by gray matter activation results. Discussion: Our findings support the hypothesis that optimal therapeutic results are associated with the activation of distinct fiber pathways. This suggests that in DBS for OCD, focused stimulation of specific fiber pathways, which would allow for stimulation with lower amplitudes, may be superior to activation of a wide array of pathways, typically associated with higher stimulation amplitudes. PMID:26834544
Lee, Jeongmi; Geng, Joy J
The efficiency of finding an object in a crowded environment depends largely on the similarity of nontargets to the search target. Models of attention theorize that the similarity is determined by representations stored within an "attentional template" held in working memory. However, the degree to which the contents of the attentional template are individually unique and where those idiosyncratic representations are encoded in the brain are unknown. We investigated this problem using representational similarity analysis of human fMRI data to measure the common and idiosyncratic representations of famous face morphs during an identity categorization task; data from the categorization task were then used to predict performance on a separate identity search task. We hypothesized that the idiosyncratic categorical representations of the continuous face morphs would predict their distractability when searching for each target identity. The results identified that patterns of activation in the lateral prefrontal cortex (LPFC) as well as in face-selective areas in the ventral temporal cortex were highly correlated with the patterns of behavioral categorization of face morphs and search performance that were common across subjects. However, the individually unique components of the categorization behavior were reliably decoded only in right LPFC. Moreover, the neural pattern in right LPFC successfully predicted idiosyncratic variability in search performance, such that reaction times were longer when distractors had a higher probability of being categorized as the target identity. These results suggest that the prefrontal cortex encodes individually unique components of categorical representations that are also present in attentional templates for target search.
Vargo, J M; Corwin, J V; King, V; Reep, R L
Unilateral lesions of the medial precentral prefrontal cortex produce severe polymodal neglect which reaches a stable level of recovery over 3 to 4 weeks. Previous research has indicated that neglect is produced by unilateral destruction of this region in either hemisphere, but that the nature of the neglect produced is dependent on the hemisphere damaged. The present study is a further examination of behavioral laterality produced by this unilateral destruction. The results indicated that destruction of medial precentral cortex in the left hemisphere (n = 12) produced severe contralateral multimodal neglect of visual, somatosensory, and auditory stimuli. Identical destruction in the right hemisphere (n = 18) also produced severe neglect, but unlike the left hemisphere operates which always demonstrated contralateral neglect, there were two distinct populations of right hemisphere operates. These subjects demonstrated either ipsilateral neglect or a "switching" response pattern characterized by the initial demonstration of contralateral or ipsilateral neglect and then, during the course of recovery, severe neglect on the opposite body side. Histological analysis indicated that the left and right hemisphere lesions were equivalent, as were the lesions in the two behavioral subcategories of right hemisphere operates. Operated controls (n = 12) did not demonstrate long-standing neglect or this switching pattern. The behavioral laterality observed following unilateral destruction of medial precentral prefrontal cortex is discussed in relationship to the anatomical and neurochemical asymmetries which have been demonstrated in this cortical region.
Leopold, Anne; dal Monte, Olga; Pardini, Matteo; Pulaski, Sarah J.; Solomon, Jeffrey; Grafman, Jordan
Studies investigating theory of mind (ToM) abilities (i.e. ability to understand and predict others’ mental states) have revealed that affective and cognitive functions play a significant role and that each of those functions are associated with distinct neural networks. Cognitive facets of ToM have implicated the medial prefrontal cortex, temporo-parietal junction and the anterior paracingulate cortex, whereas affective facets have implicated the ventromedial prefrontal cortex (vmPFC). Although the vmPFC has repeatedly shown to be critical for affective functions, knowledge regarding the exact role of the left and right vmPFC in affective ToM is still obscure. Here, we compared performances of 30 patients with left, right and bilateral vmPFC lesions to two comparison groups (one without and one with brain injuries) on the Faux Pas Recognition task measuring the facets of ToM. We also investigated whether any deficits may be associated with other emotional measures, namely emotional empathy and emotional intelligence. Our results extend earlier findings by showing that the vmPFC is associated with abilities in affective ToM. More importantly, our results revealed that the left, and not the right vmPFC as indicated previously, is involved in affective ToM and that this deficit is associated with emotional intelligence. PMID:22021651
Seminowicz, David A.; Shpaner, Marina; Keaser, Michael L.; Krauthamer, G. Michael; Mantegna, John; Dumas, Julie A.; Newhouse, Paul A.; Filippi, Christopher; Keefe, Francis J.; Naylor, Magdalena R.
Several studies have reported reduced cerebral gray matter (GM) volume/density in chronic pain conditions, but there is limited research on plasticity of the human cortex in response to psychological interventions. We investigated GM changes after cognitive behavioral therapy (CBT) in patients with chronic pain. We used voxel based morphometry (VBM) to compare anatomical MRI scans of 13 patients with mixed chronic pain types before and after an 11-week CBT treatment and to 13 healthy control participants. CBT led to significant improvements in clinical measures. Patients did not differ from healthy controls in GM anywhere in the brain. After treatment, patients had increased GM in bilateral dorsolateral prefrontal (DLPFC), posterior parietal (PPC), subgenual anterior cingulate (ACC)/orbitofrontal, and sensorimotor cortices, as well as hippocampus, and reduced GM in supplementary motor area. In most of these areas showing GM increases, GM became significantly higher than in controls. Decreased pain catastrophizing was associated with increased GM in left DLPFC and ventrolateral prefrontal (VLPFC), right PPC, somatosensory cortex, and pregenual ACC. While future studies with additional control groups will be needed to determine the specific roles of CBT on GM and brain function, we propose that increased GM in the PFC and PPC reflects greater top-down control over pain and cognitive reappraisal of pain, and that changes in somatosensory cortices reflect alterations in the perception of noxious signals. Perspective An 11-week CBT intervention for coping with chronic pain resulted in increased gray matter volume in prefrontal and somatosensory brain regions, as well as increased dorsolateral prefrontal volume associated with reduced pain catastrophizing. These results add to mounting evidence that CBT can be a valuable treatment option for chronic pain. PMID:24135432
Milella, Michele S.; Fotros, Aryandokht; Gravel, Paul; Casey, Kevin F.; Larcher, Kevin; Verhaeghe, Jeroen A.J.; Cox, Sylvia M.L.; Reader, Andrew J.; Dagher, Alain; Benkelfat, Chawki; Leyton, Marco
Background Accumulating evidence indicates that drug-related cues can induce dopamine (DA) release in the striatum of substance abusers. Whether these same cues provoke DA release in the human prefrontal cortex remains unknown. Methods We used high-resolution positron emission tomography with [18F]fallypride to measure cortical and striatal DA D2/3 receptor availability in the presence versus absence of drug-related cues in volunteers with current cocaine dependence. Results Twelve individuals participated in our study. Among participants reporting a craving response (9 of 12), exposure to the cocaine cues significantly decreased [18F]fallypride binding potential (BPND) values in the medial orbitofrontal cortex and striatum. In all 12 participants, individual differences in the magnitude of craving correlated with BPND changes in the medial orbitofrontal cortex, dorsolateral prefrontal cortex, anterior cingulate, and striatum. Consistent with the presence of autoreceptors on mesostriatal but not mesocortical DA cell bodies, midbrain BPND values were significantly correlated with changes in BPND within the striatum but not the cortex. The lower the midbrain D2 receptor levels, the greater the striatal change in BPND and self-reported craving. Limitations Limitations of this study include its modest sample size, with only 2 female participants. Newer tracers might have greater sensitivity to cortical DA release. Conclusion In people with cocaine use disorders, the presentation of drug-related cues induces DA release within cortical and striatal regions. Both effects are associated with craving, but only the latter is regulated by midbrain autoreceptors. Together, the results suggest that cortical and subcortical DA responses might both influence drug-focused incentive motivational states, but with separate regulatory mechanisms. PMID:26900792
Kawamichi, Hiroaki; Sasaki, Akihiro T; Matsunaga, Masahiro; Yoshihara, Kazufumi; Takahashi, Haruka K; Tanabe, Hiroki C; Sadato, Norihiro
The reputation of others influences partner selection in human cooperative behaviors through verbal reputation representation. Although the way in which humans represent the verbal reputations of others is a pivotal issue for social neuroscience, the neural correlates underlying the representation of verbal reputations of others are unclear. Humans primarily depend on self-evaluation when assessing reputation of self. Likewise, humans might primarily depend on self-evaluation of others when representing their reputation. As interaction promotes the formation of more nuanced, individualized impressions of an interaction partner, humans tend to form self-evaluations of persons with whom they are intimate in their daily life. Thus, we hypothesized that the representation of reputation of others is modulated by intimacy due to one's own evaluation formation of that person. To test this hypothesis, we conducted a functional magnetic resonance imaging experiment with 11 pairs of romantic partners while they viewed an evaluation of a target person (self, partner [intimate other], or stranger [non-intimate other]), made by other evaluators. When compared with strangers, viewing evaluations of self and partner activated overlapping regions in the medial prefrontal cortex. Verbal reputation of self-specific activation was found in the precuneus, which represents self-related processing. The data suggest that midline structures represent reputation of self. In addition, intimacy-modulated activation in the medial prefrontal cortex suggests that the verbal reputation of intimate others is represented similarly to reputation of self. These results suggest that the reputation representation in the medial prefrontal cortex is engaged by verbal reputation of self and intimate others stemming from both own and other evaluators' judgments.
Hatam, Masoumeh; Sheybanifar, Mehrnoosh; Nasimi, Ali
The anterior claustrum (CLa) has bilateral connections with the areas involved in cardiovascular regulation, though its role in cardiovascular control is not yet understood. This study was performed to find the cardiovascular responsive region of the CLa by stimulating all parts of the CLa with l-glutamate, and to find the possible mechanisms mediating its responses in urethane-anesthetized rats. We also investigated the possible involvement of the medial prefrontal cortex in the cardiovascular responses of the CLa. The effect of microinjection of l-glutamate (50-100 nl, 0.25 M) was tested throughout the Cla and only in one area at 2.7 mm rostral to bregma, 1.8-2.0 midline and 4.5-5.6mm vertical, significant decreases in arterial pressure were elicited (-21.71±2.1 mmHg, P<0.001, t-test) with no significant change in heart rate. Administration (i.v.) of the muscarinic receptor blocker, atropine, had no effect on the change in mean arterial pressure in response to glutamate stimulation, suggesting that the parasympathetic system was not involved in this response. However, administration (i.v.) of the nicotinic receptor blocker, hexamethonium dichloride abolished the depressor response to glutamate, suggesting that CLa stimulation decreases sympathetic outflow to the cardiovascular system. In addition, microinjection of the reversible synaptic blocker, cobalt chloride, into the medial prefrontal cortex greatly attenuated the depressor response elicited by microinjection of glut into the CLa. Thus for the first time, we found the cardiovascular responsive region of the anterior claustrum. Also we showed that its response is mediated through the medial prefrontal cortex.
Lomber, Stephen G.; Everling, Stefan
Following unilateral brain injury, patients are often unable to detect a stimulus presented in the contralesional field when another is presented simultaneously ipsilesionally. This phenomenon has been referred to as extinction and has been conceptualized as a deficit in selective attention. Although most commonly observed following damage to posterior parietal areas, extinction has been observed following lesions of prefrontal cortex (PFC) in both humans and nonhuman primates. To date, most studies in nonhuman primates have examined lesions of multiple PFC subregions, including the frontal eye fields (FEF). Theoretical accounts of attentional disturbances from human patients, however, also implicate other PFC areas, including the middle frontal gyrus. Here, we investigated the effects of deactivating PFC areas anterior to the FEF on stimulus selection using a free-choice task. Macaque monkeys were presented with two peripheral stimuli appearing either simultaneously, or at varying stimulus onset asynchronies, and their performance was evaluated during unilateral cryogenic deactivation of part of dorsolateral prefrontal cortex or the cortex lining the caudal principal sulcus, the likely homologue of the human middle frontal gyrus. A decreased proportion of saccades was made to stimuli presented in the hemifield contralateral to the deactivated PFC. We also observed increases in reaction times to contralateral stimuli and decreases for stimuli presented in the hemifield ipsilateral to the deactivated hemisphere. In both cases, these results were greatest when both PFC subregions were deactivated. These findings demonstrate that selection biases result from PFC deactivation and support a role of dorsolateral prefrontal subregions anterior to FEF in stimulus selection. PMID:26792881
Musazzi, Laura; Treccani, Giulia; Popoli, Maurizio
Increasing evidence has shown that the pathophysiology of neuropsychiatric disorders, including mood disorders, is associated with abnormal function and regulation of the glutamatergic system. Consistently, preclinical studies on stress-based animal models of pathology showed that glucocorticoids and stress exert crucial effects on neuronal excitability and function, especially in cortical and limbic areas. In prefrontal and frontal cortex, acute stress was shown to induce enhancement of glutamate release/transmission dependent on activation of corticosterone receptors. Although the mechanisms whereby stress affects glutamate transmission have not yet been fully understood, it was shown that synaptic, non-genomic action of corticosterone is required to increase the readily releasable pool of glutamate vesicles, but is not sufficient to enhance transmission in prefrontal and frontal cortex. Slower, partly genomic mechanisms are probably necessary for the enhancement of glutamate transmission induced by stress. Combined evidence has suggested that the changes in glutamate release and transmission are responsible for the dendritic remodeling and morphological changes induced by stress and it has been argued that sustained alterations of glutamate transmission may play a key role in the long-term structural/functional changes associated with mood disorders in patients. Intriguingly, modifications of the glutamatergic system induced by stress in the prefrontal cortex seem to be biphasic. Indeed, while the fast response to stress suggests an enhancement in the number of excitatory synapses, synaptic transmission and working memory, long-term adaptive changes - including those consequent to chronic stress - induce opposite effects. Better knowledge of the cellular effectors involved in this biphasic effect of stress may be useful to understand the pathophysiology of stress-related disorders, and open new paths for the development of therapeutic approaches.
Musazzi, Laura; Treccani, Giulia; Popoli, Maurizio
Increasing evidence has shown that the pathophysiology of neuropsychiatric disorders, including mood disorders, is associated with abnormal function and regulation of the glutamatergic system. Consistently, preclinical studies on stress-based animal models of pathology showed that glucocorticoids and stress exert crucial effects on neuronal excitability and function, especially in cortical and limbic areas. In prefrontal and frontal cortex, acute stress was shown to induce enhancement of glutamate release/transmission dependent on activation of corticosterone receptors. Although the mechanisms whereby stress affects glutamate transmission have not yet been fully understood, it was shown that synaptic, non-genomic action of corticosterone is required to increase the readily releasable pool of glutamate vesicles, but is not sufficient to enhance transmission in prefrontal and frontal cortex. Slower, partly genomic mechanisms are probably necessary for the enhancement of glutamate transmission induced by stress. Combined evidence has suggested that the changes in glutamate release and transmission are responsible for the dendritic remodeling and morphological changes induced by stress and it has been argued that sustained alterations of glutamate transmission may play a key role in the long-term structural/functional changes associated with mood disorders in patients. Intriguingly, modifications of the glutamatergic system induced by stress in the prefrontal cortex seem to be biphasic. Indeed, while the fast response to stress suggests an enhancement in the number of excitatory synapses, synaptic transmission and working memory, long-term adaptive changes – including those consequent to chronic stress – induce opposite effects. Better knowledge of the cellular effectors involved in this biphasic effect of stress may be useful to understand the pathophysiology of stress-related disorders, and open new paths for the development of therapeutic approaches. PMID
Dupree, Jeffrey L.; Gacias, Mar; Frawley, Rebecca; Sikder, Tamjeed; Naik, Payal; Casaccia, Patrizia
Altered myelin structure and oligodendrocyte function have been shown to correlate with cognitive and motor dysfunction and deficits in social behavior. We and others have previously demonstrated that social isolation in mice induced behavioral, transcriptional, and ultrastructural changes in oligodendrocytes of the prefrontal cortex (PFC). However, whether enhancing myelination and oligodendrocyte differentiation could be beneficial in reversing such changes remains unexplored. To test this hypothesis, we orally administered clemastine, an antimuscarinic compound that has been shown to enhance oligodendrocyte differentiation and myelination in vitro, for 2 weeks in adult mice following social isolation. Clemastine successfully reversed social avoidance behavior in mice undergoing prolonged social isolation. Impaired myelination was rescued by oral clemastine treatment, and was associated with enhanced oligodendrocyte progenitor differentiation and epigenetic changes. Clemastine induced higher levels of repressive histone methylation (H3K9me3), a marker for heterochromatin, in oligodendrocytes, but not neurons, of the PFC. This was consistent with the capability of clemastine in elevating H3K9 histone methyltransferases activity in cultured primary mouse oligodendrocytes, an effect that could be antagonized by cotreatment with muscarine. Our data suggest that promoting adult myelination is a potential strategy for reversing depressive-like social behavior. SIGNIFICANCE STATEMENT Oligodendrocyte development and myelination are highly dynamic processes influenced by experience and neuronal activity. However, whether enhancing myelination and oligodendrocyte differentiation is beneficial to treat depressive-like behavior has been unexplored. Mice undergoing prolonged social isolation display impaired myelination in the prefrontal cortex. Clemastine, a Food and Drug Administration-approved antimuscarinic compound that has been shown to enhance myelination under
Inoue, Masato; Mikami, Akichika
To investigate the neuronal mechanism of the process of selection of a target from an array of stimuli, we analysed neuronal activity of the lateral prefrontal cortex during the response period of a serial probe reproduction task. During the response period of this task, monkeys were trained to select a memorized target object from an array of three objects and make a saccadic eye movement toward it. Of 611 neurons, 74 neurons showed visual response and 56 neurons showed presaccadic activity during the response period. Among visual neurons, 27 showed array- and target-selectivity. All of these array- and target-selective visual responses were recorded from the ventrolateral prefrontal cortex (VLPFC). Among 56 neurons with presaccadic activity, nine showed target-selective activity, 17 showed target- and direction-selective activity, and 23 showed direction-selective activity. The target-selective, and the target- and direction-selective activities were recorded from the VLPFC, and the direction-selective activities were recorded from VLPFC and dorsolateral prefrontal cortex (DLPFC). The starting time of the activity was earlier for the target-selective, and target- and direction-selective activities in VLPFC, intermediate for the direction-selective activities in VLPFC, and later for the direction-selective activities in DLPFC. These results suggest that VLPFC plays a role in the process of selection of a target object from an array of stimuli, VLPFC and DLPFC play a role in determining the location of the target in space, and DLPFC plays a role in selecting a direction and making a decision to generate a saccadic eye movement.
Murakami, Gen; Nakamura, Masato; Takita, Masatoshi; Ishida, Yasushi; Ueki, Takatoshi; Nakahara, Daiichiro
Growing evidence implicates a critical involvement of prefrontal glial modulation of extracellular glutamate (GLU) in aversive behaviors. However, nothing is known about whether prefrontal glial cells modulate GLU levels in rewarding behaviors. To address this question, we measured GLU efflux in the medial prefrontal cortex (PFC) of rats associated with rewarding behaviors. We used intracranial self-stimulation (ICSS) of the medial forebrain bundle (MFB) as the rewarding behavior. GLU was indirectly measured using microdialysis combined with on-line fluorometric detection of NADH resulting from the reaction of GLU and NAD(+) catalyzed by GLU dehydrogenase with a time resolution of 1 min. ICSS caused a minute-by-minute change of extracellular GLU in the medial PFC, with a slight decrease during the stimulation, followed by an increase afterward. This bidirectional change was tetrodotoxin insensitive and abolished by the gliotoxin fluorocitrate. To confirm and extend the previous studies of aversion-induced increase of extracellular GLU in the medial PFC, we also measured prefrontal GLU efflux associated with an aversive stimulation, immobilization stress. The temporal change in extracellular GLU caused by this stress was markedly different from that observed during ICSS. A rapid increase in GLU was detected during the aversive stimulation, followed by a large increase afterward. This bimodal change was tetrodotoxin insensitive, similar to that detected for ICSS. These findings indicate a bidirectional regulation of extracellular GLU by prefrontal glial cells associated with rat ICSS behavior, and reveal that glial modulation of GLU neurochemistry in the medial PFC contributes to rewarding as well as aversive behaviors in rats.
Kwapis, Janine L; Jarome, Timothy J; Helmstetter, Fred J
The extinction of delay fear conditioning relies on a neural circuit that has received much attention and is relatively well defined. Whether this established circuit also supports the extinction of more complex associations, however, is unclear. Trace fear conditioning is a better model of complex relational learning, yet the circuit that supports extinction of this memory has received very little attention. Recent research has indicated that trace fear extinction requires a different neural circuit than delay extinction; trace extinction requires the participation of the retrosplenial cortex, but not the amygdala, as noted in a previous study. Here, we tested the roles of the prelimbic and infralimbic regions of the medial prefrontal cortex in trace and delay fear extinction by blocking NMDA receptors during extinction learning. We found that the prelimbic cortex is necessary for trace, but not for delay fear extinction, whereas the infralimbic cortex is involved in both types of extinction. These results are consistent with the idea that trace fear associations require plasticity in multiple cortical areas for successful extinction. Further, the infralimbic cortex appears to play a role in extinction regardless of whether the animal was initially trained in trace or delay conditioning. Together, our results provide new information about how the neural circuits supporting trace and delay fear extinction differ.
Sakatani, Kaoru; Takemoto, N; Tsujii, T; Yanagisawa, K; Tsunashima, H
The aim of this study was to develop a NIRS-based neurofeedback system to modulate activity in the prefrontal cortex (PFC). We evaluated the effectiveness of the system in terms of separability of changes in oxy-Hb and its derivative. Training with neurofeedback resulted in higher separability than training without neurofeedback or no training, suggesting that the neurofeedback system could enhance self-control of PFC activity. Interestingly, the dorsolateral PFC exhibited enhanced activity and high separability after neurofeedback training. These observations suggest that the neurofeedback system might be useful for training subjects to regulate emotions by self-control of dorsolateral PFC activity.
Gonzalez, Maria Carolina; Villar, Maria Eugenia; Igaz, Lionel M; Viola, Haydée; Medina, Jorge H
The medial prefrontal cortex (mPFC) is known for its role in decision making and memory processing, including the participation in the formation of extinction memories. However, little is known regarding its contribution to aversive memory consolidation. Here we demonstrate that neural activity and protein synthesis are required in the dorsal mPFC for memory formation of a conditioned taste aversion (CTA) task and that this region is involved in the retrieval of recent and remote long-term CTA memory. In addition, both NMDA receptor and CaMKII activity in dorsal mPFC are needed for CTA memory consolidation, highlighting the complexity of mPFC functions.
Winters, Bradley D.; Huang, Yanhua H.; Dong, Yan; Krueger, James M.
Despite sleep-loss-induced cognitive deficits, little is known about the cellular adaptations that occur with sleep loss. We used brain slices obtained from mice that were sleep deprived for 8 h to examine the electrophysiological effects of sleep deprivation (SD). We employed a modified pedestal (flowerpot) over water method for SD that eliminated rapid eye movement sleep and greatly reduced non-rapid eye movement sleep. In layer V/VI pyramidal cells of the medial prefrontal cortex, miniature excitatory post synaptic current amplitude was slightly reduced, miniature inhibitory post synaptic currents were unaffected, and intrinsic membrane excitability was increased after SD. PMID:21962531
Barbey, Aron K.; Krueger, Frank; Grafman, Jordan
We propose that counterfactual representations for reasoning about the past or predicting the future depend on structured event complexes (SECs) in the human prefrontal cortex (PFC; ‘What would happen if X were performed in the past or enacted in the future?’). We identify three major categories of counterfactual thought (concerning action versus inaction, the self versus other and upward versus downward thinking) and propose that each form of inference recruits SEC representations in distinct regions of the medial PFC. We develop a process model of the regulatory functions these representations serve and draw conclusions about the importance of SECs for explaining the past and predicting the future. PMID:19528010
Soutschek, Alexander; Sauter, Marian; Schubert, Torsten
Previous functional imaging studies investigating the neural basis of strategic decision making in the prisoner's dilemma reported a correlation between cooperative behavior and dorsolateral prefrontal cortex (DLPFC) activity; however, the precise function of the DLPFC in establishing cooperation remains unclear so far. The present study investigated the causal role of the DLPFC in an iterative prisoner's dilemma game with transcranial magnetic stimulation (TMS). We discovered that disrupting the DLPFC with TMS decreased cooperation rates in comparison to control conditions, with this effect being most pronounced when the partner had defected previously. Thus, the current results suggest that the DLPFC contributes to strategic decision making in the prisoner's dilemma game.
Walton, Mark E; Chau, Bolton K H; Kennerley, Steven W
Our environment and internal states are frequently complex, ambiguous and dynamic, meaning we need to have selection mechanisms to ensure we are basing our decisions on currently relevant information. Here, we review evidence that orbitofrontal (OFC) and ventromedial prefrontal cortex (VMPFC) play conserved, critical but distinct roles in this process. While OFC may use specific sensory associations to enhance task-relevant information, particularly in the context of learning, VMPFC plays a role in ensuring irrelevant information does not impinge on the decision in hand. PMID:26937446
Winters, Bradley D; Huang, Yanhua H; Dong, Yan; Krueger, James M
Despite sleep-loss-induced cognitive deficits, little is known about the cellular adaptations that occur with sleep loss. We used brain slices obtained from mice that were sleep deprived for 8h to examine the electrophysiological effects of sleep deprivation (SD). We employed a modified pedestal (flowerpot) over water method for SD that eliminated rapid eye movement sleep and greatly reduced non-rapid eye movement sleep. In layer V/VI pyramidal cells of the medial prefrontal cortex, miniature excitatory post synaptic current amplitude was slightly reduced, miniature inhibitory post synaptic currents were unaffected, and intrinsic membrane excitability was increased after SD.
Woodward, John J; Pava, Matthew
Background The prefrontal cortex (PFC) is critically involved in working memory, cognition and decision-making; processes significantly affected by ethanol. During quiet restfulness or sleep, prefrontal cortical neurons show synaptically-evoked oscillations in membrane potential between hyperpolarized down-states and depolarized up-states. Previous studies from this laboratory used whole-cell electrophysiology and demonstrated that in individual neurons, ethanol inhibited PFC up-states at concentrations associated with behavioral impairment. While those studies monitored activity in one or two neurons at a time, it is likely that in vivo, larger networks of neurons participate in the complex functions of the prefrontal cortex. In the present study, we used imaging and a genetically encoded calcium sensor to examine the effects of ethanol on the activity of multiple neurons simultaneously during up-states. Methods Slice cultures of mouse prefrontal cortex were infected with an AAV virus encoding the calcium indicator GCaMP3 whose expression was driven by the neuron-specific synapsin promoter. After 2–3 weeks in culture, a fast CCD-camera imaging system was used to capture changes in GCaMP3 fluorescence before, during and after exposure to ethanol. Results PFC neurons displayed robust and reproducible changes in GCaMP3 fluorescence during evoked and spontaneous up-states. Simultaneous whole-cell patch-clamp recording and GCaMP3 imaging verified that neurons transitioned into and out of up-states together. Acute application of ethanol reliably depressed up-state calcium signals with lower doses having a greater effect on up-state duration than amplitude. These effects of ethanol on up-state parameters were reversed during washout. Conclusions The results of the present study indicate that ethanol has profound effects on upstate activity in prefrontal neurons and suggest that this action may underlie some of the cognitive impairment associated with acute alcohol
Jacob, Simon N.; Stalter, Maximilian; Nieder, Andreas
The prefrontal cortex (PFC) is crucial for maintaining relevant information in working memory and resisting interference. PFC neurons are strongly regulated by dopamine, but it is unknown whether dopamine receptors are involved in protecting target memories from distracting stimuli. We investigated the prefrontal circuit dynamics and dopaminergic modulation of targets and distractors in monkeys trained to ignore interfering stimuli in a delayed-match-to-numerosity task. We found that dopamine D1 receptors (D1Rs) modulate the recovery of task-relevant information following a distracting stimulus. The direction of modulation is cell-type-specific: in putative pyramidal neurons, D1R inhibition enhances and D1R stimulation attenuates coding of the target stimulus after the interference, while the opposite pattern is observed in putative interneurons. Our results suggest that dopaminergic neuromodulation of PFC circuits regulates mental representations of behaviourally relevant stimuli that compete with task-irrelevant input and could play a central role for cognitive functioning in health and disease. PMID:27807366
Fajardo, C; Escobar, M I; Buriticá, E; Arteaga, G; Umbarila, J; Casanova, M F; Pimienta, H
Von Economo neurons (VENs), also known as spindle cells, have been described in layer V of the anterior cingulate (BA 24) and frontoinsular cortex (FI) of humans and other great apes. In the present study we used immunohistochemistry against two specific neuronal markers (NeuN and MAP2) in order to establish the presence of these cell types in Brodmann area 9 (BA 9) of the human prefrontal cortex. We evaluated tissue samples of eight human postmortem brains (age range 26-50) from BAs 9, 24, 4, 46, 45, 10 and 17. We identified a group of cells with similar morphology to that previously described for VENs in all specimens of BA 9 examined, albeit less frequently than in BA 24. This is the first description of this cell type in a human brain area with well developed granular layers (BA 9).
Fuentes-Claramonte, Paola; Ávila, César; Rodríguez-Pujadas, Aina; Ventura-Campos, Noelia; Bustamante, Juan C; Costumero, Víctor; Rosell-Negre, Patricia; Barrós-Loscertales, Alfonso
Current perspectives on cognitive control acknowledge that individual differences in motivational dispositions may modulate cognitive processes in the absence of reward contingencies. This work aimed to study the relationship between individual differences in Behavioral Activation System (BAS) sensitivity and the neural underpinnings involved in processing a switching cue in a task-switching paradigm. BAS sensitivity was hypothesized to modulate brain activity in frontal regions, ACC and the striatum. Twenty-eight healthy participants underwent fMRI while performing a switching task, which elicited activity in fronto-striatal regions during the processing of the switch cue. BAS sensitivity was negatively associated with activity in the lateral prefrontal cortex, anterior cingulate cortex and the ventral striatum. Combined with previous results, our data indicate that BAS sensitivity modulates the neurocognitive processes involved in task switching in a complex manner depending on task demands. Therefore, individual differences in motivational dispositions may influence cognitive processing in the absence of reward contingencies.
Fuentes-Claramonte, Paola; Ávila, César; Rodríguez-Pujadas, Aina; Ventura-Campos, Noelia; Bustamante, Juan C.; Costumero, Víctor; Rosell-Negre, Patricia; Barrós-Loscertales, Alfonso
Current perspectives on cognitive control acknowledge that individual differences in motivational dispositions may modulate cognitive processes in the absence of reward contingencies. This work aimed to study the relationship between individual differences in Behavioral Activation System (BAS) sensitivity and the neural underpinnings involved in processing a switching cue in a task-switching paradigm. BAS sensitivity was hypothesized to modulate brain activity in frontal regions, ACC and the striatum. Twenty-eight healthy participants underwent fMRI while performing a switching task, which elicited activity in fronto-striatal regions during the processing of the switch cue. BAS sensitivity was negatively associated with activity in the lateral prefrontal cortex, anterior cingulate cortex and the ventral striatum. Combined with previous results, our data indicate that BAS sensitivity modulates the neurocognitive processes involved in task switching in a complex manner depending on task demands. Therefore, individual differences in motivational dispositions may influence cognitive processing in the absence of reward contingencies. PMID:25875640
Katsuki, Fumi; Constantinidis, Christos
The dorsolateral prefrontal cortex (PFC) and posterior parietal cortex (PPC) are two parts of a broader brain network involved in the control of cognitive functions such as working-memory, spatial attention, and decision-making. The two areas share many functional properties and exhibit similar patterns of activation during the execution of mental operations. However, neurophysiological experiments in non-human primates have also documented subtle differences, revealing functional specialization within the fronto-parietal network. These differences include the ability of the PFC to influence memory performance, attention allocation, and motor responses to a greater extent, and to resist interference by distracting stimuli. In recent years, distinct cellular and anatomical differences have been identified, offering insights into how functional specialization is achieved. This article reviews the common functions and functional differences between the PFC and PPC, and their underlying mechanisms. PMID:22563310
Noda, Yoshihiro; Zomorrodi, Reza; Cash, Robin F. H.; Barr, Mera S.; Farzan, Faranak; Rajji, Tarek K.; Chen, Robert; Daskalakis, Zafiris J.; Blumberger, Daniel M.
Gamma-aminobutyric acid (GABA)ergic and glutamatergic neurotransmissions in the prefrontal cortex decreases with age. Further, cognitive function mediated through the dorsolateral prefrontal cortex (DLPFC) also declines with age. Although neuroimaging studies have demonstrated decreased levels of these substances, direct neurophysiological data investigating the effect of aging in the DLPFC in human subjects is lacking. The advent of transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG) has allowed for the assessment of functional neurotransmission in vivo. In the present study, we examined short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) in a group of older adults (> 60 yrs) to evaluate the strength of GABAA and glutamate-mediated neurotransmission in the DLPFC, compared to younger adults (18-59 yrs). Older adults showed an increase of amplitude of N100 by the SICI paradigm, while N45 amplitude was increased and N100 amplitude was decreased by ICF. Moreover, these modulations significantly correlated with age. Our findings provide evidence for age-related alterations of excitatory and inhibitory functions in the prefrontal cortex in healthy adults. Future studies may aim to explore these neurophysiological relationships in the DLPFC in pathological forms of aging that affect cortical functioning such as mild cognitive impairment and Alzheimer's disease. PMID:28209926
Noda, Yoshihiro; Zomorrodi, Reza; Cash, Robin F H; Barr, Mera S; Farzan, Faranak; Rajji, Tarek K; Chen, Robert; Daskalakis, Zafiris J; Blumberger, Daniel M
Gamma-aminobutyric acid (GABA)ergic and glutamatergic neurotransmissions in the prefrontal cortex decreases with age. Further, cognitive function mediated through the dorsolateral prefrontal cortex (DLPFC) also declines with age. Although neuroimaging studies have demonstrated decreased levels of these substances, direct neurophysiological data investigating the effect of aging in the DLPFC in human subjects is lacking. The advent of transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG) has allowed for the assessment of functional neurotransmission in vivo. In the present study, we examined short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) in a group of older adults (> 60 yrs) to evaluate the strength of GABAA and glutamate-mediated neurotransmission in the DLPFC, compared to younger adults (18-59 yrs). Older adults showed an increase of amplitude of N100 by the SICI paradigm, while N45 amplitude was increased and N100 amplitude was decreased by ICF. Moreover, these modulations significantly correlated with age. Our findings provide evidence for age-related alterations of excitatory and inhibitory functions in the prefrontal cortex in healthy adults. Future studies may aim to explore these neurophysiological relationships in the DLPFC in pathological forms of aging that affect cortical functioning such as mild cognitive impairment and Alzheimer's disease.
Wang, Zhuo; Guo, Yumei; Myers, Kalisa G.; Heintz, Ryan; Holschneider, Daniel P.
Exercise modality and complexity play a key role in determining neurorehabilitative outcome in Parkinson’s disease (PD). Exercise training (ET) that incorporates both motor skill training and aerobic exercise has been proposed to synergistically improve cognitive and automatic components of motor control in PD patients. Here we introduced such a skilled aerobic ET paradigm in a rat model of dopaminergic deafferentation. Rats with bilateral, intra-striatal 6-hydroxydopamine lesions were exposed to forced ET for 4 weeks, either on a simple running wheel (non-skilled aerobic exercise, NSAE) or on a complex wheel with irregularly spaced rungs (skilled aerobic exercise, SAE). Cerebral perfusion was mapped during horizontal treadmill walking or at rest using [14C]-iodoantipyrine 1 week after the completion of ET. Regional cerebral blood flow (rCBF) was quantified by autoradiography and analyzed in 3-dimensionally reconstructed brains by statistical parametric mapping. SAE compared to NSAE resulted in equal or greater recovery in motor deficits, as well as greater increases in rCBF during walking in the prelimbic area of the prefrontal cortex, broad areas of the somatosensory cortex, and the cerebellum. NSAE compared to SAE animals showed greater activation in the dorsal caudate-putamen and dorsal hippocampus. Seed correlation analysis revealed enhanced functional connectivity in SAE compared to NSAE animals between the prelimbic cortex and motor areas, as well as altered functional connectivity between midline cerebellum and sensorimotor regions. Our study provides the first evidence for functional brain reorganization following skilled aerobic exercise in Parkinsonian rats, and suggests that SAE compared to NSAE results in enhancement of prefrontal cortex- and cerebellum-mediated control of motor function. PMID:25747184
Wang, Zhuo; Guo, Yumei; Myers, Kalisa G; Heintz, Ryan; Holschneider, Daniel P
Exercise modality and complexity play a key role in determining neurorehabilitative outcome in Parkinson's disease (PD). Exercise training (ET) that incorporates both motor skill training and aerobic exercise has been proposed to synergistically improve cognitive and automatic components of motor control in PD patients. Here we introduced such a skilled aerobic ET paradigm in a rat model of dopaminergic deafferentation. Rats with bilateral, intra-striatal 6-hydroxydopamine lesions were exposed to forced ET for 4weeks, either on a simple running wheel (non-skilled aerobic exercise, NSAE) or on a complex wheel with irregularly spaced rungs (skilled aerobic exercise, SAE). Cerebral perfusion was mapped during horizontal treadmill walking or at rest using [(14)C]-iodoantipyrine 1week after the completion of ET. Regional cerebral blood flow (rCBF) was quantified by autoradiography and analyzed in 3-dimensionally reconstructed brains by statistical parametric mapping. SAE compared to NSAE resulted in equal or greater recovery in motor deficits, as well as greater increases in rCBF during walking in the prelimbic area of the prefrontal cortex, broad areas of the somatosensory cortex, and the cerebellum. NSAE compared to SAE animals showed greater activation in the dorsal caudate-putamen and dorsal hippocampus. Seed correlation analysis revealed enhanced functional connectivity in SAE compared to NSAE animals between the prelimbic cortex and motor areas, as well as altered functional connectivity between midline cerebellum and sensorimotor regions. Our study provides the first evidence for functional brain reorganization following skilled aerobic exercise in Parkinsonian rats, and suggests that SAE compared to NSAE results in enhancement of prefrontal cortex- and cerebellum-mediated control of motor function.
Minamoto, Takehiro; Osaka, Mariko; Yaoi, Ken; Osaka, Naoyuki
Different people make different responses when they face a frustrating situation: some punish others (extrapunitive), while others punish themselves (intropunitive). Few studies have investigated the neural structures that differentiate extrapunitive and intropunitive individuals. The present fMRI study explored these neural structures using two different frustrating situations: an ego-blocking situation which blocks a desire or goal, and a superego-blocking situation which blocks self-esteem. In the ego-blocking condition, the extrapunitive group (n = 9) showed greater activation in the bilateral ventrolateral prefrontal cortex, indicating that these individuals prefer emotional processing. On the other hand, the intropunitive group (n = 9) showed greater activation in the left dorsolateral prefrontal cortex, possibly reflecting an effortful control for anger reduction. Such patterns were not observed in the superego-blocking condition. These results indicate that the prefrontal cortex is the source of individual differences in aggression direction in the ego-blocking situation. PMID:24454951
Minamoto, Takehiro; Osaka, Mariko; Yaoi, Ken; Osaka, Naoyuki
Different people make different responses when they face a frustrating situation: some punish others (extrapunitive), while others punish themselves (intropunitive). Few studies have investigated the neural structures that differentiate extrapunitive and intropunitive individuals. The present fMRI study explored these neural structures using two different frustrating situations: an ego-blocking situation which blocks a desire or goal, and a superego-blocking situation which blocks self-esteem. In the ego-blocking condition, the extrapunitive group (n = 9) showed greater activation in the bilateral ventrolateral prefrontal cortex, indicating that these individuals prefer emotional processing. On the other hand, the intropunitive group (n = 9) showed greater activation in the left dorsolateral prefrontal cortex, possibly reflecting an effortful control for anger reduction. Such patterns were not observed in the superego-blocking condition. These results indicate that the prefrontal cortex is the source of individual differences in aggression direction in the ego-blocking situation.
Large, Adam M.; Vogler, Nathan W.; Mielo, Samantha; Oswald, Anne-Marie M.
Throughout the brain, the recruitment of feedforward and recurrent inhibition shapes neural responses. However, disentangling the relative contributions of these often-overlapping cortical circuits is challenging. The piriform cortex provides an ideal system to address this issue because the interneurons responsible for feedforward and recurrent inhibition are anatomically segregated in layer (L) 1 and L2/3 respectively. Here we use a combination of optical and electrical activation of interneurons to profile the inhibitory input received by three classes of principal excitatory neuron in the anterior piriform cortex. In all classes, we find that L1 interneurons provide weaker inhibition than L2/3 interneurons. Nonetheless, feedforward inhibitory strength covaries with the amount of afferent excitation received by each class of principal neuron. In contrast, intracortical stimulation of L2/3 evokes strong inhibition that dominates recurrent excitation in all classes. Finally, we find that the relative contributions of feedforward and recurrent pathways differ between principal neuron classes. Specifically, L2 neurons receive more reliable afferent drive and less overall inhibition than L3 neurons. Alternatively, L3 neurons receive substantially more intracortical inhibition. These three features—balanced afferent drive, dominant recurrent inhibition, and differential recruitment by afferent vs. intracortical circuits, dependent on cell class—suggest mechanisms for olfactory processing that may extend to other sensory cortices. PMID:26858458
Junghofer, Markus; Winker, Constantin; Rehbein, Maimu A; Sabatinelli, Dean
Depressive patients typically show biased attention towards unpleasant and away from pleasant emotional material. Imaging studies suggest that dysfunctions in a distributed neural network, including the ventromedial prefrontal cortex (vmPFC), are associated with this processing bias. Accordingly, changes in vmPFC activation should mediate changes in processing of emotional stimuli. Here, we investigated the effect of inhibitory and excitatory transcranial direct current stimulation (tDCS) of the vmPFC on emotional scene processing in two within-subject experiments using functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG). Both studies showed that excitatory relative to inhibitory tDCS amplifies processing of pleasant compared to unpleasant scenes in healthy participants. This modulatory effect occurred in a distributed network including sensory and prefrontal cortex regions and was visible during very early to late processing stages. Findings are discussed with regard to neurophysiological models of emotional processing. The convergence of stimulation effects across independent groups of healthy participants and complementary neuroimaging methods (fMRI, MEG) provides a basis for further investigation of a potentially therapeutic use of this novel stimulation approach in patients with depression or other affective disorders.
Leitman, David I; Wolf, Daniel H; Loughead, James; Valdez, Jeffrey N; Kohler, Christian G; Brensinger, Colleen; Elliott, Mark A; Turetsky, Bruce I; Gur, Raquel E; Gur, Ruben C
Schizophrenia patients display impaired performance and brain activity during facial affect recognition. These impairments may reflect stimulus-driven perceptual decrements and evaluative processing abnormalities. We differentiated these two processes by contrasting responses to identical stimuli presented under different contexts. Seventeen healthy controls and 16 schizophrenia patients performed an fMRI facial affect detection task. Subjects identified an affective target presented amongst foils of differing emotions. We hypothesized that targeting affiliative emotions (happiness, sadness) would create a task demand context distinct from that generated when targeting threat emotions (anger, fear). We compared affiliative foil stimuli within a congruent affiliative context with identical stimuli presented in an incongruent threat context. Threat foils were analysed in the same manner. Controls activated right orbitofrontal cortex (OFC)/ventrolateral prefrontal cortex (VLPFC) more to affiliative foils in threat contexts than to identical stimuli within affiliative contexts. Patients displayed reduced OFC/VLPFC activation to all foils, and no activation modulation by context. This lack of context modulation coincided with a 2-fold decrement in foil detection efficiency. Task demands produce contextual effects during facial affective processing in regions activated during affect evaluation. In schizophrenia, reduced modulation of OFC/VLPFC by context coupled with reduced behavioural efficiency suggests impaired ventral prefrontal control mechanisms that optimize affective appraisal.
Bault, Nadège; Joffily, Mateus; Rustichini, Aldo; Coricelli, Giorgio
We compared private and social decision making to investigate the neural underpinnings of the effect of social comparison on risky choices. We measured brain activity using functional MRI while participants chose between two lotteries: in the private condition, they observed the outcome of the unchosen lottery, and in the social condition, the outcome of the lottery chosen by another person. The striatum, a reward-related brain structure, showed higher activity when participants won more than their counterpart (social gains) compared with winning in isolation and lower activity when they won less than their counterpart (social loss) compared with private loss. The medial prefrontal cortex, implicated in social reasoning, was more activated by social gains than all other events. Sensitivity to social gains influenced both brain activity and behavior during subsequent choices. Specifically, striatal activity associated with social gains predicted medial prefrontal cortex activity during social choices, and experienced social gains induced more risky and competitive behavior in later trials. These results show that interplay between reward and social reasoning networks mediates the influence of social comparison on the decision process. PMID:21896760
Sagliano, Laura; D'Olimpio, Francesca; Panico, Francesco; Gagliardi, Serena; Trojano, Luigi
Previous studies demonstrated that excitatory (high frequency) offline transcranial magnetic stimulation (TMS) over the left and right dorsolateral prefrontal cortex (DLPFC) modulates attention allocation on threatening stimuli in non-clinical samples. These studies only employed offline TMS protocol that did not allow investigating the effect of the stimulation on the early stage of threat processing. In this study, the role of the right and left dorsolateral prefrontal cortex in early threat processing was investigated in high and low anxious individuals by means of an inhibitory single-pulse online TMS protocol. Our results demonstrated the role of the left DLPFC in an early stage of threat processing and that this effect is modulated by individuals' anxiety level. The inhibitory stimulation of the left DLPFC determined a disengagement bias in high anxious individuals, while the same stimulation determined an attentional avoidance in low anxious individuals. The findings of the present study suggest that right and left DLPFC are differently involved in early threat processing of healthy individuals.
Gacias, Mar; Gaspari, Sevasti; Santos, Patricia-Mae G; Tamburini, Sabrina; Andrade, Monica; Zhang, Fan; Shen, Nan; Tolstikov, Vladimir; Kiebish, Michael A; Dupree, Jeffrey L; Zachariou, Venetia; Clemente, Jose C; Casaccia, Patrizia
Gene-environment interactions impact the development of neuropsychiatric disorders, but the relative contributions are unclear. Here, we identify gut microbiota as sufficient to induce depressive-like behaviors in genetically distinct mouse strains. Daily gavage of vehicle (dH2O) in nonobese diabetic (NOD) mice induced a social avoidance behavior that was not observed in C57BL/6 mice. This was not observed in NOD animals with depleted microbiota via oral administration of antibiotics. Transfer of intestinal microbiota, including members of the Clostridiales, Lachnospiraceae and Ruminococcaceae, from vehicle-gavaged NOD donors to microbiota-depleted C57BL/6 recipients was sufficient to induce social avoidance and change gene expression and myelination in the prefrontal cortex. Metabolomic analysis identified increased cresol levels in these mice, and exposure of cultured oligodendrocytes to this metabolite prevented myelin gene expression and differentiation. Our results thus demonstrate that the gut microbiota modifies the synthesis of key metabolites affecting gene expression in the prefrontal cortex, thereby modulating social behavior. DOI: http://dx.doi.org/10.7554/eLife.13442.001 PMID:27097105
Rao, Hengyi; Han, Shihui; Jiang, Yi; Xue, Yanping; Gu, Hua; Cui, Yong; Gao, Dingguo
Behavioral studies have identified a robust phenomenon that an observer's memory of the final position of a moving target is shifted a little further in its motion direction, which is usually called representational momentum (RM). However, the neural substrates underlying RM are poorly understood. The current study measured hemodynamic responses in association with RM using functional magnetic resonance imaging (fMRI). Two experiments using block and event-related designs, respectively, were conducted in which subjects compared the orientation of a probe rectangle with the remembered orientation of the final inducing figures in a set of rotating rectangles. Both experiments showed that, relative to the control task in which behavioral data did not show RM effects, RM task induced stronger activation in the prefrontal cortex. However, no activation was found in MT/MST complex in association with RM. The fMRI results suggest that RM may not simply reflect implicit motion perception and high level cognitive mechanisms underpinned by the prefrontal cortex may be involved in the RM effect.
Khamassi, Mehdi; Quilodran, René; Enel, Pierre; Dominey, Peter F; Procyk, Emmanuel
To explain the high level of flexibility in primate decision-making, theoretical models often invoke reinforcement-based mechanisms, performance monitoring functions, and core neural features within frontal cortical regions. However, the underlying biological mechanisms remain unknown. In recent models, part of the regulation of behavioral control is based on meta-learning principles, for example, driving exploratory actions by varying a meta-parameter, the inverse temperature, which regulates the contrast between competing action probabilities. Here we investigate how complementary processes between lateral prefrontal cortex (LPFC) and dorsal anterior cingulate cortex (dACC) implement decision regulation during exploratory and exploitative behaviors. Model-based analyses of unit activity recorded in these 2 areas in monkeys first revealed that adaptation of the decision function is reflected in a covariation between LPFC neural activity and the control level estimated from the animal's behavior. Second, dACC more prominently encoded a reflection of outcome uncertainty useful for control regulation based on task monitoring. Model-based analyses also revealed higher information integration before feedback in LPFC, and after feedback in dACC. Overall the data support a role of dACC in integrating reinforcement-based information to regulate decision functions in LPFC. Our results thus provide biological evidence on how prefrontal cortical subregions may cooperate to regulate decision-making.
Hvizdosova, Natalia; Tomasova, Lenka; Bolekova, Adriana; Kolesar, Dalibor; Kluchova, Darina
The presence of nitrergic cells in the prefrontal cortex has been confirmed, however little is known about the postnatal development of these cells. Nitrergic neurons were studied histochemically by using NADPH-diaphorase staining in the prefrontal cortex of male Wistar rats from postnatal day 7-21 (P7-21). Neuronal NADPH-diaphorase is a nitric oxide synthase that provides a specific histochemical marker for neurons producing nitric oxide (NO). NO acts as a neurotransmitter and intracellular signaling molecule in the nervous system. We observed in 7 day old rats NADPH-d containing neurons that were intensely stained. These neurons were bipolar with a short dendrite with average length of 23 μm. During the second postnatal week, the neurons were mainly bipolar and were rarely multipolar. By P14 the cells were located primarily in cortical layers III-VI. Nitrergic neurons of the 21 day old rats were histochemically identified as multipolar cells with long radial extending dendrites. Dendrites of neurons in 14 and 21 day old rats were a similar length with an average of 57 μm. These results suggest that nitrergic neurons differentiate during a relatively short period of time and reach their structural maturity by the end of the second week of postnatal development.
Rostral prefrontal cortex (RPFC) has increased in size and changed in terms of its cellular organisation during primate evolution. In parallel emerged the ability to detach oneself from the immediate environment to process abstract thoughts and solve problems and to understand other individuals' thoughts and intentions. Rostrolateral prefrontal cortex (RLPFC) is thought to play an important role in supporting the integration of abstract, often self-generated, thoughts. Thoughts can be temporally abstract and relate to long term goals, or past or future events, or relationally abstract and focus on the relationships between representations rather than simple stimulus features. Behavioural studies have provided evidence of a prolonged development of the cognitive functions associated with RLPFC, in particular logical and relational reasoning, but also episodic memory retrieval and prospective memory. Functional and structural neuroimaging studies provide further support for a prolonged development of RLPFC during adolescence, with some evidence of increased specialisation of RLPFC activation for relational integration and aspects of episodic memory retrieval. Topics for future research will be discussed, such as the role of medial RPFC in processing abstract thoughts in the social domain, the possibility of training abstract thinking in the domain of reasoning, and links to education.
Medvedev, Andrei V.; Kainerstorfer, Jana M.; Borisov, Sergey V.; Gandjbakhche, Amir H.; Vanmeter, John
Near-infrared spectroscopy is a novel imaging technique potentially sensitive to both brain hemodynamics (slow signal) and neuronal activity (fast optical signal, FOS). The big challenge of measuring FOS noninvasively lies in the presumably low signal-to-noise ratio. Thus, detectability of the FOS has been controversially discussed. We present reliable detection of FOS from 11 individuals concurrently with electroencephalogram (EEG) during a Go-NoGo task. Probes were placed bilaterally over prefrontal cortex. Independent component analysis (ICA) was used for artifact removal. Correlation coefficient in the best correlated FOS-EEG ICA pairs was highly significant (p < 10-8), and event-related optical signal (EROS) was found in all subjects. Several EROS components were similar to the event-related potential (ERP) components. The most robust ``optical N200'' at t = 225 ms coincided with the N200 ERP; both signals showed significant difference between targets and nontargets, and their timing correlated with subject's reaction time. Correlation between FOS and EEG even in single trials provides further evidence that at least some FOS components ``reflect'' electrical brain processes directly. The data provide evidence for the early involvement of prefrontal cortex in rapid object recognition. EROS is highly localized and can provide cost-effective imaging tools for cortical mapping of cognitive processes.
Yamagishi, Toshio; Takagishi, Haruto; Fermin, Alan de Souza Rodrigues; Kanai, Ryota; Li, Yang; Matsumoto, Yoshie
Human prosociality has been traditionally explained in the social sciences in terms of internalized social norms. Recent neuroscientific studies extended this traditional view of human prosociality by providing evidence that prosocial choices in economic games require cognitive control of the impulsive pursuit of self-interest. However, this view is challenged by an intuitive prosociality view emphasizing the spontaneous and heuristic basis of prosocial choices in economic games. We assessed the brain structure of 411 players of an ultimatum game (UG) and a dictator game (DG) and measured the strategic reasoning ability of 386. According to the reflective norm-enforcement view of prosociality, only those capable of strategically controlling their selfish impulses give a fair share in the UG, but cognitive control capability should not affect behavior in the DG. Conversely, we support the intuitive prosociality view by showing for the first time, to our knowledge, that strategic reasoning and cortical thickness of the dorsolateral prefrontal cortex were not related to giving in the UG but were negatively related to giving in the DG. This implies that the uncontrolled choice in the DG is prosocial rather than selfish, and those who have a thicker dorsolateral prefrontal cortex and are capable of strategic reasoning (goal-directed use of the theory of mind) control this intuitive drive for prosociality as a means to maximize reward when there are no future implications of choices. PMID:27140622
Amemori, Ken-ichi; Amemori, Satoko
The judgment of whether to accept or to reject an offer is determined by positive and negative affect related to the offer, but affect also induces motivational responses. Rewarding and aversive cues influence the firing rates of many neurons in primate prefrontal and cingulate neocortical regions, but it still is unclear whether neurons in these regions are related to affective judgment or to motivation. To address this issue, we recorded simultaneously the neuronal spike activities of single units in the dorsolateral prefrontal cortex (dlPFC) and the anterior cingulate cortex (ACC) of macaque monkeys as they performed approach–avoidance (Ap–Av) and approach–approach (Ap–Ap) decision-making tasks that can behaviorally dissociate affective judgment and motivation. Notably, neurons having activity correlated with motivational condition could be distinguished from neurons having activity related to affective judgment, especially in the Ap–Av task. Although many neurons in both regions exhibited similar, selective patterns of task-related activity, we found a larger proportion of neurons activated in low motivational conditions in the dlPFC than in the ACC, and the onset of this activity was significantly earlier in the dlPFC than in the ACC. Furthermore, the temporal onsets of affective judgment represented by neuronal activities were significantly slower in the low motivational conditions than in the other conditions. These findings suggest that motivation and affective judgment both recruit dlPFC and ACC neurons but with differential degrees of involvement and timing. PMID:25653353
Morozov, Yury M; Datta, Dibyadeep; Paspalas, Constantinos D; Arnsten, Amy F T
Dorsolateral prefrontal cortex mediates high-order cognitive functions that are impaired early in the aging process in monkeys and humans. Here, we report pronounced changes in mitochondrial morphology in dendrites of dorsolateral prefrontal cortex neurons from aged rhesus macaques. Electron microscopy paired with 3D reconstruction from serial sections revealed an age-related increase in mitochondria with thin segments that intermingled with enlarged ones, the 'mitochondria-on-a-string' phenotype, similar to those recently reported in patients with Alzheimer's disease. The thin mitochondrial segments were associated with endoplasmic reticulum cisterns, and the mitochondrial proteins Fis1 and Drp1, all of which initiate mitochondrial fission. These data suggest that the 'mitochondria-on-a-string' phenotype may reflect malfunction in mitochondrial dynamics, whereby fission is initiated, but the process is incomplete due to malfunction of subsequent step(s). Thus, aged rhesus monkeys may be particularly helpful in exploring the age-related changes that render higher cortical circuits so vulnerable to degeneration.
Loggia, Marco L.; Berna, Chantal; Kim, Jieun; Cahalan, Christine M.; Martel, Marc-Olivier; Gollub, Randy L.; Wasan, Ajay D.; Napadow, Vitaly; Edwards, Robert R.
While high levels of negative affect and cognitions have been associated in chronic pain conditions with greater pain sensitivity, the neural mechanisms mediating the hyperalgesic effect of psychological factors in patients with pain disorders are largely unknown. In this cross-sectional study, we hypothesized that 1) catastrophizing modulates brain responses to pain anticipation, and that 2) anticipatory brain activity mediates the hyperalgesic effect of different levels of catastrophizing, in fibromyalgia (FM) patients. Using functional Magnetic Resonance Imaging, we scanned the brains of 31 FM patients exposed to visual cues anticipating the onset of moderately intense deep-tissue pain stimuli. Our results indicated the existence of a negative association between catastrophizing and pain-anticipatory brain activity, including in the right lateral prefrontal cortex (IPFC). A bootstrapped mediation analysis revealed that pain-anticipatory activity in lateral prefrontal cortex (IPFC) mediates the association between catastrophizing and pain sensitivity. These findings highlight the role of IPFC in the pathophysiology of FM related hyperalgesia, and suggest that deficits in the recruitment of pain-inhibitory brain circuitry during pain-anticipatory periods may play an important contributory role in the association between various degrees of widespread hyperalgesia in FM and levels of catastrophizing, a well validated measure of negative cognitions and psychological distress. Perspective This article highlights the presence of alterations in pain-anticipatory brain activity in FM. These findings provide the rationale for the development of psychological or neurofeedback-based techniques aimed at modifying patients' negative affect and cognitions towards pain. PMID:25937162
Zhu, Bi; Chen, Chuansheng; Xue, Gui; Lei, Xuemei; Wang, Yunxin; Li, Jin; Moyzis, Robert K; Li, Jun; Dong, Qi; Lin, Chongde
The CNTNAP2 (contactin-associated protein-like 2) gene, highly expressed in the human prefrontal cortex, has been linked with autism and language impairment. Potential relationships between CNTNAP2, dorsolateral prefrontal cortex (DLPFC), and cognition have been suggested by previous clinical studies, but have not been directly examined in the same study. The current study collected structural MRI, genetic, and behavioral data in 317 healthy Chinese adults, and examined associations between CNTNAP2 variants, DLPFC, and cognitive performance (measured by the Stroop task). After controlling for intracranial volume, sex, and age, the CNTNAP2 genetic polymorphism at SNP rs7809486 had the strongest association with bilateral DLPFC volume (p=0.00015 and 0.00014 for left and right DLPFC volumes, respectively), with GG homozygotes having greater bilateral DLPFC volumes and surface areas than the other genotypes. Furthermore, TT homozygotes of CNTNAP2 rs4726946 (a nearby SNP that had moderate linkage disequilibrium with rs7809486) had greater left DLPFC volume and surface area, and better cognitive performance than the other genotypes. Subjects with greater left DLPFC surface area had better cognitive performance. Importantly, the left DLPFC surface area mediated the association between the CNTNAP2 rs4726946 genotype and cognitive performance. This study provides the first evidence for associations among the CNTNAP2 gene, left DLPFC structure, and cognitive control.
Fujiki, Ryo; Morita, Kiichiro; Sato, Mamoru; Kamada, Yuji; Kato, Yusuke; Inoue, Masayuki; Shoji, Yoshihisa; Uchimura, Naohisa
Schizophrenia has been associated with a deficit of the prefrontal cortex, which is involved in attention, executive processes, and working memory. The Trail Making Test (TMT) is administered in two parts, TMT-A and TMT-B. It is suggested that the difference in performance between part A and part B reflects executive processes. In this study, we compared the characteristics of hemodynamic changes during TMT tasks between 14 outpatients with schizophrenia and 14 age- and gender-matched healthy control subjects. Using multichannel near-infrared spectroscopy, we measured relative changes in oxygenated hemoglobin concentration, which reflects brain activity of the prefrontal cortex during this task. In both tasks, patients showed significantly smaller activation than controls and, in an assessment of executive functions, a subtraction of oxygenated hemoglobin (oxy-Hb) changes during TMT-A from those of TMT-B showed a decrease in cerebral lateralization and hypoactivity in patients. There was a significant negative correlation between oxy-Hb changes and the severity of psychiatric symptoms. These findings may characterize disease-related features, suggesting the usefulness of oxy-Hb change measurement during TMT tasks for assessing functional outcomes in schizophrenic patients. PMID:23696704
Yamagishi, Toshio; Takagishi, Haruto; Fermin, Alan de Souza Rodrigues; Kanai, Ryota; Li, Yang; Matsumoto, Yoshie
Human prosociality has been traditionally explained in the social sciences in terms of internalized social norms. Recent neuroscientific studies extended this traditional view of human prosociality by providing evidence that prosocial choices in economic games require cognitive control of the impulsive pursuit of self-interest. However, this view is challenged by an intuitive prosociality view emphasizing the spontaneous and heuristic basis of prosocial choices in economic games. We assessed the brain structure of 411 players of an ultimatum game (UG) and a dictator game (DG) and measured the strategic reasoning ability of 386. According to the reflective norm-enforcement view of prosociality, only those capable of strategically controlling their selfish impulses give a fair share in the UG, but cognitive control capability should not affect behavior in the DG. Conversely, we support the intuitive prosociality view by showing for the first time, to our knowledge, that strategic reasoning and cortical thickness of the dorsolateral prefrontal cortex were not related to giving in the UG but were negatively related to giving in the DG. This implies that the uncontrolled choice in the DG is prosocial rather than selfish, and those who have a thicker dorsolateral prefrontal cortex and are capable of strategic reasoning (goal-directed use of the theory of mind) control this intuitive drive for prosociality as a means to maximize reward when there are no future implications of choices.
Ianov, Lara; Rani, Asha; Beas, Blanca S.; Kumar, Ashok; Foster, Thomas C.
Cognitive function depends on transcription; however, there is little information linking altered gene expression to impaired prefrontal cortex function during aging. Young and aged F344 rats were characterized on attentional set shift and spatial memory tasks. Transcriptional differences associated with age and cognition were examined using RNA sequencing to construct transcriptomic profiles for the medial prefrontal cortex (mPFC), white matter, and region CA1 of the hippocampus. The results indicate regional differences in vulnerability to aging. Age-related gene expression in the mPFC was similar to, though less robust than, changes in the dorsolateral PFC of aging humans suggesting that aging processes may be similar. Importantly, the pattern of transcription associated with aging did not predict cognitive decline. Rather, increased mPFC expression of genes involved in regulation of transcription, including transcription factors that regulate the strength of excitatory and inhibitory inputs, and neural activity-related immediate-early genes was observed in aged animals that exhibit delayed set shift behavior. The specificity of impairment on a mPFC-dependent task, associated with a particular mPFC transcriptional profile indicates that impaired executive function involves altered transcriptional regulation and neural activity/plasticity processes that are distinct from that described for impaired hippocampal function. PMID:27242522
Farahmandfar, Maryam; Akbarabadi, Ardeshir; Bakhtazad, Atefeh; Zarrindast, Mohammad-Reza
Ketamine and other noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonists are known to induce deficits in learning and cognitive performance sensitive to prefrontal cortex (PFC) functions. The interaction of a glutamatergic and GABAergic systems is essential for many cognitive behaviors. In order to understand the effect of γ-aminobutyric acid (GABA)/glutamate interactions on learning and memory, we investigated the effects of intra medial prefrontal cortex (mPFC) injections of GABAergic agents on ketamine-induced amnesia using a one-trial passive avoidance task in mice. Pre-training systemic administration of ketamine (5, 10 and 15mg/kg, i.p.) dose-dependently decreased the memory acquisition of a one-trial passive avoidance task. Pre-training intra-mPFC injection of muscimol, GABAA receptor agonist (0.05, 0.1 and 0.2μg/mouse) and baclofen GABAB receptor agonist (0.05, 0.1, 0.5 and 1μg/mouse), impaired memory acquisition. However, co-pretreatment of different doses of muscimol and baclofen with a lower dose of ketamine (5mg/kg), which did not induce amnesia by itself, caused inhibition of memory formation. Our data showed that sole pre-training administration of bicuculline, GABA-A receptor antagonist and phaclofen GABA-B receptor antagonist into the mPFC, did not affect memory acquisition. In addition, the amnesia induced by pre-training ketamine (15mg/kg) was significantly decreased by the pretreatment of bicuculline (0.005, 0.1 and 0.5μg/mouse). It can be concluded that GABAergic system of the mPFC is involved in the ketamine-induced impairment of memory acquisition.
Lang, Simone; Kroll, Alexander; Lipinski, Slawomira J; Wessa, Michèle; Ridder, Stephanie; Christmann, Christoph; Schad, Lothar R; Flor, Herta
Functional magnetic resonance imaging was used to investigate the role of the hippocampus, amygdala and medial prefrontal cortex (mPFC) in a contextual conditioning and extinction paradigm provoking anxiety. Twenty-one healthy persons participated in a differential context conditioning procedure with two different background colours as contexts. During acquisition increased activity to the conditioned stimulus (CS+) relative to the CS− was found in the left hippocampus and anterior cingulate cortex (ACC). The amygdala, insula and inferior frontal cortex were differentially active during late acquisition. Extinction was accompanied by enhanced activation to CS+ vs. CS− in the dorsal anterior cingulate cortex (dACC). The results are in accordance with animal studies and provide evidence for the important role of the hippocampus in contextual learning in humans. Connectivity analyses revealed correlated activity between the left posterior hippocampus and dACC (BA32) during early acquisition and the dACC, left posterior hippocampus and right amygdala during extinction. These data are consistent with theoretical models that propose an inhibitory effect of the mPFC on the amygdala. The interaction of the mPFC with the hippocampus may reflect the context-specificity of extinction learning. PMID:19200075
Wang, Hui-Dong; Deutch, Ariel Y
Dystrophic changes in dendrites of cortical neurons are present in several neuro-psychiatric disorders, including schizophrenia. The mechanisms that account for dendritic changes in the prefrontal cortex (PFC) in schizophrenia are unclear. Cognitive deficits in schizophrenia have been linked to compromised cortical dopamine function, and the density of the PFC dopamine innervation is decreased in schizophrenia. We determined if 6-hydroxydopamine lesions of the ventral tegmental area that disrupt the PFC dopamine innervation cause dystrophic changes in cortical neurons. Three weeks post-operatively we observed a marked decrease in basal dendritic length and spine density of layer V pyramidal cells in the prelimbic cortex; no change was seen in neurons of the motor cortex. We then examined rats in which the PFC dopamine innervation was lesioned and 3 weeks later were started on chronic treatment with an atypical (olanzapine) or typical (haloperidol) antipsychotic drug. Olanzapine but not haloperidol reversed lesion-induced changes in PFC pyramidal cell dendrites. These data suggest that dopamine regulates dendritic structure in PFC neurons. Moreover, the findings are consistent with a decrease in cortical dopaminergic tone contributing to the pathological changes in the cortex of schizophrenia, and suggest that the progressive cortical loss in schizophrenia may be slowed or reversed by treatment with atypical antipsychotic drugs.
Kirk, Ulrich; Harvey, Ann; Montague, P. Read
Recent work using an art-viewing paradigm shows that monetary sponsorship of the experiment by a company (a favor) increases the valuation of paintings placed next to the sponsoring corporate logo, an effect that correlates with modulation of the ventromedial prefrontal cortex (VMPFC). We used the same art-viewing paradigm to test a prevailing idea in the domain of conflict-of-interest: that expertise in a domain insulates against judgment bias even in the presence of a monetary favor. Using a cohort of art experts, we show that monetary favors do not bias the experts’ valuation of art, an effect that correlates with a lack of modulation of the VMPFC across sponsorship conditions. The lack of sponsorship effect in the VMPFC suggests the hypothesis that their brains remove the behavioral sponsorship effect by censoring sponsorship-dependent modulation of VMPFC activity. We tested the hypothesis that prefrontal regions play a regulatory role in mediating the sponsorship effect. We show that the dorsolateral prefrontal cortex (DLPFC) is recruited in the expert group. Furthermore, we tested the hypothesis in nonexpert controls by contrasting brain responses in controls who did not show a sponsorship effect to controls who did. Changes in effective connectivity between the DLPFC and VMPFC were greater in nonexpert controls, with an absence of the sponsorship effect relative to those with a presence of the sponsorship effect. The role of the DLPFC in cognitive control and emotion regulation suggests that it removes the influence of a monetary favor by controlling responses in known valuation regions of the brain including the the VMPFC. PMID:21646526
Nakamura, Koyo; Kawabata, Hideaki
Neuroaesthetics has been searching for the neural bases of the subjective experience of beauty. It has been demonstrated that neural activities in the medial prefrontal cortex (mPFC) and the left primary motor cortex (lPMC) correlate with the subjective experience of beauty. Although beauty and ugliness seem to be semantically and conceptually opposite, it is still unknown whether these two evaluations represent extreme opposites in unitary or bivariate dimensions. In this study, we applied transcranial direct current stimulation (tDCS) to examine whether non-invasive brain stimulation modulates two types of esthetic evaluation; evaluating beauty and ugliness. Participants rated the subjective beauty and ugliness of abstract paintings before and after the application of tDCS. Application of cathodal tDCS over the mPFC with anode electrode over the lPMC, which induced temporal inhibition of neural excitability of the mPFC, led to a decrease in beauty ratings but not ugliness ratings. There were no changes in ratings of both beauty and ugliness when applying anodal tDCS or sham stimulation over the mPFC. Results from our experiment indicate that the mPFC and the lPMC have a causal role in generating the subjective experience of beauty, with beauty and ugliness evaluations constituting two distinct dimensions. PMID:26696865
Nakamura, Koyo; Kawabata, Hideaki
Neuroaesthetics has been searching for the neural bases of the subjective experience of beauty. It has been demonstrated that neural activities in the medial prefrontal cortex (mPFC) and the left primary motor cortex (lPMC) correlate with the subjective experience of beauty. Although beauty and ugliness seem to be semantically and conceptually opposite, it is still unknown whether these two evaluations represent extreme opposites in unitary or bivariate dimensions. In this study, we applied transcranial direct current stimulation (tDCS) to examine whether non-invasive brain stimulation modulates two types of esthetic evaluation; evaluating beauty and ugliness. Participants rated the subjective beauty and ugliness of abstract paintings before and after the application of tDCS. Application of cathodal tDCS over the mPFC with anode electrode over the lPMC, which induced temporal inhibition of neural excitability of the mPFC, led to a decrease in beauty ratings but not ugliness ratings. There were no changes in ratings of both beauty and ugliness when applying anodal tDCS or sham stimulation over the mPFC. Results from our experiment indicate that the mPFC and the lPMC have a causal role in generating the subjective experience of beauty, with beauty and ugliness evaluations constituting two distinct dimensions.
Large, Adam M.; Kunz, Nicholas A.; Mielo, Samantha L.; Oswald, Anne-Marie M.
Inhibitory circuitry plays an integral role in cortical network activity. The development of transgenic mouse lines targeting unique interneuron classes has significantly advanced our understanding of the functional roles of specific inhibitory circuits in neocortical sensory processing. In contrast, considerably less is known about the circuitry and function of interneuron classes in piriform cortex, a paleocortex responsible for olfactory processing. In this study, we sought to utilize transgenic technology to investigate inhibition mediated by somatostatin (SST) interneurons onto pyramidal cells (PCs), parvalbumin (PV) interneurons, and other interneuron classes. As a first step, we characterized the anatomical distributions and intrinsic properties of SST and PV interneurons in four transgenic lines (SST-cre, GIN, PV-cre, and G42) that are commonly interbred to investigate inhibitory connectivity. Surprisingly, the distributions SST and PV cell subtypes targeted in the GIN and G42 lines were sparse in piriform cortex compared to neocortex. Moreover, two-thirds of interneurons recorded in the SST-cre line had electrophysiological properties similar to fast spiking (FS) interneurons rather than regular (RS) or low threshold spiking (LTS) phenotypes. Nonetheless, like neocortex, we find that SST-cells broadly inhibit a number of unidentified interneuron classes including putatively identified PV cells and surprisingly, other SST cells. We also confirm that SST-cells inhibit pyramidal cell dendrites and thus, influence dendritic integration of afferent and recurrent inputs to the piriform cortex. Altogether, our findings suggest that SST interneurons play an important role in regulating both excitation and the global inhibitory network during olfactory processing. PMID:27582691
Inui, Koji; Nakagawa, Kei; Nishihara, Makoto; Motomura, Eishi; Kakigi, Ryusuke
Despite their indispensable roles in sensory processing, little is known about inhibitory interneurons in humans. Inhibitory postsynaptic potentials cannot be recorded non-invasively, at least in a pure form, in humans. We herein sought to clarify whether prepulse inhibition (PPI) in the auditory cortex reflected inhibition via interneurons using magnetoencephalography. An abrupt increase in sound pressure by 10 dB in a continuous sound was used to evoke the test response, and PPI was observed by inserting a weak (5 dB increase for 1 ms) prepulse. The time course of the inhibition evaluated by prepulses presented at 10–800 ms before the test stimulus showed at least two temporally distinct inhibitions peaking at approximately 20–60 and 600 ms that presumably reflected IPSPs by fast spiking, parvalbumin-positive cells and somatostatin-positive, Martinotti cells, respectively. In another experiment, we confirmed that the degree of the inhibition depended on the strength of the prepulse, but not on the amplitude of the prepulse-evoked cortical response, indicating that the prepulse-evoked excitatory response and prepulse-evoked inhibition reflected activation in two different pathways. Although many diseases such as schizophrenia may involve deficits in the inhibitory system, we do not have appropriate methods to evaluate them; therefore, the easy and non-invasive method described herein may be clinically useful. PMID:27219470
Oemisch, Mariann; Westendorff, Stephanie; Everling, Stefan; Womelsdorf, Thilo
The anterior cingulate cortex (ACC) and prefrontal cortex (PFC) are believed to coactivate during goal-directed behavior to identify, select, and monitor relevant sensory information. Here, we tested whether coactivation of neurons across macaque ACC and PFC would be evident at the level of pairwise neuronal correlations during stimulus selection in a spatial attention task. We found that firing correlations emerged shortly after an attention cue, were evident for 50-200 ms time windows, were strongest for neuron pairs in area 24 (ACC) and areas 8 and 9 (dorsal PFC), and were independent of overall firing rate modulations. For a subset of cell pairs from ACC and dorsal PFC, the observed functional spike-train connectivity carried information about the direction of the attention shift. Reliable firing correlations were evident across area boundaries for neurons with broad spike waveforms (putative excitatory neurons) as well as for pairs of putative excitatory neurons and neurons with narrow spike waveforms (putative interneurons). These findings reveal that stimulus selection is accompanied by slow time scale firing correlations across those ACC/PFC subfields implicated to control and monitor attention. This functional coupling was informative about which stimulus was selected and thus indexed possibly the exchange of task-relevant information. We speculate that interareal, transient firing correlations reflect the transient coordination of larger, reciprocally interacting brain networks at a characteristic 50-200 ms time scale. Significance statement: Our manuscript identifies interareal spike-train correlations between primate anterior cingulate and dorsal prefrontal cortex during a period where attentional stimulus selection is likely controlled by these very same circuits. Interareal correlations emerged during the covert attention shift to one of two peripheral stimuli, proceeded on a slow 50-200 ms time scale, and occurred between putative pyramidal and
Hamazaki, Kei; Maekawa, Motoko; Toyota, Tomoko; Dean, Brian; Hamazaki, Tomohito; Yoshikawa, Takeo
Postmortem brain studies have shown abnormal levels of n-3 polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid, in the frontal cortex (particularly the orbitofrontal cortex) of patients with depression, schizophrenia, or bipolar disorder. However, the results from regions in the frontal cortex other than the orbitofrontal cortex are inconsistent. In this study we investigated whether patients with schizophrenia, bipolar disorder, or major depressive disorder have abnormalities in PUFA levels in the prefrontal cortex [Brodmann area (BA) 8]. In postmortem studies, fatty acids in the phospholipids of the prefrontal cortex (BA8) were evaluated by thin layer chromatography and gas chromatography. Specimens were evaluated for patients with schizophrenia (n=15), bipolar disorder (n=15), or major depressive disorder (n=15) and compared with unaffected controls (n=15). In contrast to previous studies, we found no significant differences in the levels of PUFAs or other fatty acids in the prefrontal cortex (BA8) between patients and controls. Subanalysis by sex also showed no significant differences. No significant differences were found in any individual fatty acids between suicide and non-suicide cases. These psychiatric disorders might be characterized by very specific fatty acid compositions in certain areas of the brain, and BA8 might not be involved in abnormalities of PUFA metabolism.
Tomasino, Barbara; Fabbro, Franco
Mindfulness meditation is a form of attention control training. The training exercises the ability to repeatedly focus attention. We addressed the activation changes related to an 8-weeks mindfulness-oriented focused attention meditation training on an initially naïve subject cohort. Before and after training participants underwent an fMRI experiment, thus, although not strictly a cross over design, they served as their internal own control. During fMRI they exercised focused attention on breathing and body scan as compared to resting. We found increased and decreased activation in different parts of the prefrontal cortex (PFC) by comparing pre- vs. post-mindfulness training (MT) during breathing and body scan meditation exercises that were compared against their own resting state. In the post-MT (vs. pre-MT) meditation increased activation in the right dorsolateral PFC and in the left caudate/anterior insula and decreased activation in the rostral PFC and right parietal area 3b. Thus a brief mindfulness training caused increased activation in areas involved in sustaining and monitoring the focus of attention (dorsolateral PFC), consistent with the aim of mindfulness that is exercising focused attention mechanisms, and in the left caudate/anterior insula involved in attention and corporeal awareness and decreased activation in areas part of the "default mode" network and is involved in mentalizing (rostral PFC), consistent with the ability trained by mindfulness of reducing spontaneous mind wandering.
Vallortigara, Julie; Rangarajan, Sindhoo; Whitfield, David; Alghamdi, Amani; Howlett, David; Hortobágyi, Tibor; Johnson, Mary; Attems, Johannes; Ballard, Clive; Thomas, Alan; O'Brien, John; Aarsland, Dag; Francis, Paul
Dementia with Lewy Bodies (DLB) and Parkinson's Disease Dementia (PDD) together, represent the second most common cause of dementia, after Alzheimer's disease (AD). The synaptic dysfunctions underlying the cognitive decline and psychiatric symptoms observed throughout the development of PDD and DLB are still under investigation. In this study we examined the expression level of Dynamin1 and phospho-CaMKII, key proteins of endocytosis and synaptic plasticity respectively, as potential markers of molecular processes specifically deregulated with DLB and/or PDD. In order to measure the levels of these proteins, we isolated grey matter from post-mortem prefrontal cortex area (BA9), anterior cingulated gyrus (BA24) and parietal cortex (BA40) from DLB and PDD patients in comparison to age-matched controls and a group of AD cases. Clinical and pathological data available included the MMSE score, neuropsychiatric history, and semi-quantitative scores for AD pathology (plaques - tangles) and for α-synuclein (Lewy bodies). Changes in the expression of the synaptic markers, and correlates with neuropathological features and cognitive decline were predominantly found in the prefrontal cortex. On one hand, levels of Dynamin1 were significantly reduced, and correlated with a higher rate of cognitive decline observed in cases from three dementia groups. On the other hand, the fraction of phospho-CaMKII was decreased, and correlated with a high score of plaques and tangles in BA9. Interestingly, the correlation between the rate of cognitive decline and the level of Dynamin1 remained when the analysis was restricted to the PDD and DLB cases, highlighting an association of Dynamin1 with cognitive decline in people with Lewy Body dementia.
Kang, Pyungwon; Lee, Jongbin; Sul, Sunhae; Kim, Hackjin
The ability to accurately estimate another person's preferences is crucial for a successful social life. In daily interactions, we often do this on the basis of minimal information. The aims of the present study were (a) to examine whether people can accurately judge others based only on a brief exposure to their appearances, and (b) to reveal the underlying neural mechanisms with functional magnetic resonance imaging (fMRI). Participants were asked to make guesses about unfamiliar target individuals' preferences for various items after looking at their faces for 3 s. The behavioral results showed that participants estimated others' preferences above chance level. The fMRI data revealed that higher accuracy in preference estimation was associated with greater activity in the dorsomedial prefrontal cortex (DMPFC) when participants were guessing the targets' preferences relative to thinking about their own preferences. These findings suggest that accurate estimations of others' preferences may require increased activity in the DMPFC. A functional connectivity analysis revealed that higher accuracy in preference estimation was related to increased functional connectivity between the DMPFC and the brain regions that are known to be involved in theory of mind processing, such as the temporoparietal junction (TPJ) and the posterior cingulate cortex (PCC)/precuneus, during correct vs. incorrect guessing trials. On the contrary, the tendency to refer to self-preferences when estimating others' preference was related to greater activity in the ventromedial prefrontal cortex. These findings imply that the DMPFC may be a core region in estimating the preferences of others and that higher accuracy may require stronger communication between the DMPFC and the TPJ and PCC/precuneus, part of a neural network known to be engaged in mentalizing. PMID:24324419
Lim, Manyoel; Kim, June Sic; Kim, Dajung J.; Chung, Chun Kee
Recent human neuroimaging studies have suggested that fibromyalgia (FM), a chronic widespread pain disorder, exhibits altered thalamic structure and function. Since the thalamus has extensive reciprocal connection with the cortex, structural and functional thalamic alterations in FM might be linked to aberrant thalamocortical oscillation. This study investigated the presence of abnormal brain rhythmicity in low- and high-frequency bands during resting state in patients with FM and their relationship to clinical pain symptom. Spontaneous magnetoencephalography (MEG) activity was recorded in 18 females with FM and 18 age- and sex-matched healthy control (HC) subjects. The most remarkable finding was that FM patients had general increases in theta, beta and gamma power along with a slowing of the dominant alpha peak. Increased spectral powers in the theta-band were primarily localized to the left dorsolateral prefrontal (DLPFC) and orbitofrontal cortex (OFC). Beta and gamma over-activation were localized to insular, primary motor and primary and secondary somatosensory (S2) cortices, as well as the DLPFC and OFC. Furthermore, enhanced high-frequency oscillatory activities in the DLPFC and OFC were associated with higher affective pain scores in patients with FM. Our results demonstrate that FM patients feature enhanced low- and high-frequency oscillatory activity in the brain areas related to cognitive and emotional modulation of pain. Increased low- and high-frequency activity of the prefrontal cortex may contribute to persistent perception of pain in FM. Therapeutic intervention based on manipulating neural oscillation to restore normal thalamocortical rhythmicity may be beneficial to pain relief in FM. PMID:27014041
Mackey, Wayne E.; Devinsky, Orrin; Doyle, Werner K.; Meager, Michael R.
A dominant theory, based on electrophysiological and lesion evidence from nonhuman primate studies, posits that the dorsolateral prefrontal cortex (dlPFC) stores and maintains working memory (WM) representations. Yet, neuroimaging studies have consistently failed to translate these results to humans; these studies normally find that neural activity persists in the human precentral sulcus (PCS) during WM delays. Here, we attempt to resolve this discrepancy. To test the degree to which dlPFC is necessary for WM, we compared the performance of patients with dlPFC lesions and neurologically healthy controls on a memory-guided saccade task that was used in the monkey studies to measure spatial WM. We found that dlPFC damage only impairs the accuracy of memory-guided saccades if the damage impacts the PCS; lesions to dorsolateral dlPFC that spare the PCS have no effect on WM. These results identify the necessary subregion of the frontal cortex for WM and specify how this influential animal model of human cognition must be revised. SIGNIFICANCE STATEMENT High-level cognition depends on working memory (WM) as a critical building block, and many symptoms of psychiatric disorders may be the direct result of impaired WM. Canonical theory posits a critical role for the dorsolateral prefrontal cortex (dlPFC) in WM based on studies of nonhuman primates. However, we find that spatial WM in humans is intact after dlPFC damage unless it impacts the more caudal PCS. Therefore, the human dlPFC is not necessary for spatial WM and highlights the need for careful translation of animal models of human cognition. PMID:26961941
Winter, Sabrina; Dieckmann, Marco; Schwabe, Kerstin
Prefrontocortical dopamine (DA) plays an essential role in the representation of reward value and is implicated in behavioral flexibility. We here tested the effect of systemic and local blockade of DA D1- and D2-receptors in the medial prefrontal cortex (mPFC) and orbitofrontal cortex (OFC) by using an operant paradigm, where rats have to adjust their behavior to changing reward value. Rats were trained in a Skinner box, where different numbers of lever-presses for pellet-rewards were assigned to and switched between two levers. After rats commit to the efficient lever the lever-occupancy reversed and rats had to switch to the now efficient one. Rats were either intraperitoneally injected with the DA D1-receptor antagonist SCH23390 (40 microg/kg), the DA D2-receptor antagonist sulpiride (10mg/kg), or phosphate buffered saline (PBS). Two other groups received bilateral local mPFC- or OFC-infusions of SCH23390, sulpiride (both 3 microg/0.5 microl), or PBS (0.5 microl) through previously implanted cannulae. After initial detection of reverse of lever-occupancy, systemic and local blockade of D1-receptors increased the number of switches back to the previously efficient lever, thus reducing the total number of reverses completed. D2-receptor blockade deteriorated this measure after local mPFC-infusion. Notably, initial detection of reverse of lever-occupancy was not affected. Blockade of DA receptors within the prefrontal cortex do not deteriorate the detection of changes in reward value, whereas maintenance of behavioral adaptation is disturbed. Interestingly, blockade of DA receptors in the mPFC and OFC had similar effects, i.e., these regions apparently act in a cooperative manner.
Dauvermann, Maria R; Mukherjee, Prerona; Moorhead, William T; Stanfield, Andrew C; Fusar-Poli, Paolo; Lawrie, Stephen M; Whalley, Heather C
Measures of cortical folding ('gyrification') and connectivity are both reported to be disrupted in schizophrenia. There are also reports that increases in prefrontal gyrification may be predictive of subsequent illness in individuals at familial risk of the disorder. Such measures therefore have important potential clinical relevance. The nature of the relationship between cortical morphology and underlying connectivity is however unclear. In the current study we sought to explore the relationship between measures of gyrification and functional connectivity in a cohort of individuals at high genetic risk for the disorder. The theoretical background is based on the hypothesis that increased gyrification index (GI) in the prefrontal cortex may reflect increased short range regional connectivity. The cohort comprised 68 young unaffected relatives of schizophrenia patients and 21 healthy controls. Cortical folding was assessed using an automated Gyrification Index method (A-GI). Participants performed the Hayling sentence completion paradigm in the scanner and measures of functional connectivity were assessed using a correlation based approach. In the high risk subjects significant positive associations were found between prefrontal GI and prefrontal lateral-medial connectivity, while a negative correlation was found between prefrontal GI and prefrontal-thalamic connectivity. These associations indicate that measures describing morphological features of the brain surface relate to measures of underlying functional connectivity in the high risk subjects. Correlations in high risk people were more pronounced than in control subjects. We suggest our previous finding of increased prefrontal gyrification may therefore relate to increased local short range prefrontal connectivity and reduced long range connectivity.
Yuen, Eunice Y; Yan, Zhen
GABAergic interneurons in prefrontal cortex (PFC) play a critical role in cortical circuits by providing feedforward and feedback inhibition and synchronizing neuronal activity. Impairments in GABAergic inhibition to PFC pyramidal neurons have been implicated in the abnormal neural synchrony and working memory disturbances in schizophrenia. The dopamine D(4) receptor, which is strongly linked to neuropsychiatric disorders, such as attention deficit-hyperactivity disorder (ADHD) and schizophrenia, is highly expressed in PFC GABAergic interneurons, while the physiological role of D(4) in these interneurons is largely unknown. In this study, we found that D(4) activation caused a persistent suppression of AMPAR-mediated synaptic transmission in PFC interneurons. This effect of D(4) receptors on AMPAR-EPSC was via a mechanism dependent on actin/myosin V motor-based transport of AMPA receptors, which was regulated by cofilin, a major actin depolymerizing factor. Moreover, we demonstrated that the major cofilin-specific phosphatase Slingshot, which was activated by calcineurin downstream of D(4) signaling, was required for the D(4) regulation of glutamatergic transmission. Thus, D(4) receptors, by using the unique calcineurin/Slingshot/cofilin signaling mechanism, regulate actin dynamics and AMPAR trafficking in PFC GABAergic interneurons. It provides a potential mechanism for D(4) receptors to control the excitatory synaptic strength in local-circuit neurons and GABAergic inhibition in the PFC network, which may underlie the role of D(4) receptors in normal cognitive processes and mental disorders.
Yates, M.A.; Markham, J.A.; Anderson, S.E.; Morris, J.R.; Juraska, J.M.
During aging, changes in the structure of the cerebral cortex of the rat have been seen, but potential changes in neuron number remain largely unexplored. In the present study, stereological methods were used to examine neuron number in the medial prefrontal cortex and primary visual cortex of young adult (85–90 days of age) and aged (19–22 months old) male and female rats in order to investigate any age-related losses. Possible sex differences in aging were also examined since sexually dimorphic patterns of aging have been seen in other measures. An age-related loss of neurons (18–20%), which was mirrored in volume losses, was found to occur in the primary visual cortex in both sexes in all layers except IV. Males, but not females, also lost neurons (15 %) from layer V/VI of the ventral medial prefrontal cortex and showed an overall decrease in volume of this region. In contrast, dorsal medial prefrontal cortex showed no age-related changes. The effects of aging clearly differ among regions of the rat brain and to some degree, between the sexes. PMID:18513705
Kwon, Diana; Maillet, David; Pasvanis, Stamatoula; Ankudowich, Elizabeth; Grady, Cheryl L; Rajah, M Natasha
The ability to encode and retrieve spatial and temporal contextual details of episodic memories (context memory) begins to decline at midlife. In the current study, event-related fMRI was used to investigate the neural correlates of context memory decline in healthy middle aged adults (MA) compared with young adults (YA). Participants were scanned while performing easy and hard versions of spatial and temporal context memory tasks. Scans were obtained at encoding and retrieval. Significant reductions in context memory retrieval accuracy were observed in MA, compared with YA. The fMRI results revealed that overall, both groups exhibited similar patterns of brain activity in parahippocampal cortex, ventral occipito-temporal regions and prefrontal cortex (PFC) during encoding. In contrast, at retrieval, there were group differences in ventral occipito-temporal and PFC activity, due to these regions being more activated in MA, compared with YA. Furthermore, only in YA, increased encoding activity in ventrolateral PFC, and increased retrieval activity in occipital cortex, predicted increased retrieval accuracy. In MA, increased retrieval activity in anterior PFC predicted increased retrieval accuracy. These results suggest that there are changes in PFC contributions to context memory at midlife.
Kingsbury, Marcy A; Gleason, Erin D; Ophir, Alexander G; Phelps, Steven M; Young, Larry J; Marler, Catherine A
Limbic-associated cortical areas, such as the medial prefrontal and retrosplenial cortex (mPFC and RS, respectively), are involved in the processing of emotion, motivation, and various aspects of working memory and have been implicated in mating behavior. To determine whether the independent evolution of mating systems is associated with a convergence in cortical mechanisms, we compared the size of mPFC and RS between the monogamous prairie vole (Microtus ochrogaster) and the promiscuous meadow vole (Microtus pennsylvanicus), and between the monogamous California mouse (Peromyscus californicus) and the promiscuous white-footed mouse (Peromyscus leucopus). For both promiscuous mice and voles, the mPFC occupied a significantly larger percentage of total cortex than in the monogamous species. No significant differences were observed for the RS or overall cortex size with respect to mating system, supporting the convergent evolution of mPFC size, specifically. Individual differences in the mating behavior of male prairie voles (wandering versus pair-bonding), presumably facultative tactics, were not reflected in the relative size of the mPFC, which is likely a heritable trait. Given the importance of the mPFC for complex working memory, particularly object-place and temporal order memory, we hypothesize that the relatively greater size of the mPFC in promiscuous species reflects a greater need to remember multiple individuals and the times and locations in which they have been encountered in the home range.
Crippa, G. E.; Lewis, S. J.; Johnson, A. K.; Correa, F. M.
The injection of acetylcholine (ACh) into the cingulate region of the medial prefrontal cortex (MPFC) causes a marked fall in arterial blood pressure which is not accompanied by changes in heart rate. The purpose of the present study was to investigate the hemodynamic basis for this stimulus-induced hypotension in Sprague-Dawley rats. The study was designed to determine whether a change in the vascular resistance of hindlimb, renal or mesenteric vascular beds contributes to the fall in arterial pressure in response to ACh injection into the cingulate cortex. Miniature pulsed-Doppler flow probes were used to measure changes in regional blood flow and vascular resistance. The results indicated that the hypotensive response was largely due to a consistent and marked vasodilation in the hindlimb vascular bed. On this basis, an additional experiment was then undertaken to determine the mechanisms that contribute to hindlimb vasodilation. The effect of interrupting the autonomic innervation of one leg on the hindlimb vasodilator response was tested. Unilateral transection of the lumbar sympathetic chain attenuated the cingulate ACh-induced vasodilation in the ipsilateral, but not in the contralateral hindlimb. These results suggest that the hypotensive response to cingulate cortex-ACh injection is caused by skeletal muscle vasodilation mediated by a sympathetic chain-related vasodilator system.
Hassan, Sarah F; Cornish, Jennifer L; Goodchild, Ann K
The prefrontal cortex (PFC) is referred to as the visceral motor cortex; however, little is known about whether this region influences respiratory or metabolic outflows. The aim of this study was to describe simultaneous changes in respiratory, metabolic and cardiovascular functions evoked by disinhibition of the medial PFC (mPFC) and adjacent lateral septal nucleus (LSN). In urethane-anaesthetized rats, bicuculline methiodide was microinjected (2 mm; GABA-A receptor antagonist) into 90 sites in the mPFC at 0.72–4.00 mm from bregma. Phrenic nerve amplitude and frequency, arterial pressure, heart rate, splanchnic and lumbar sympathetic nerve activities (SNA), expired CO2, and core and brown adipose tissue temperatures were measured. Novel findings included disturbances to respiratory rhythm evoked from all subregions of the mPFC. Injections into the cingulate cortex evoked reductions in central respiratory function exclusively, whereas in ventral sites, particularly the infralimbic region, increases in respiratory drive and frequency, and metabolic and cardiac outflows were evoked. Disinhibition of sites in surrounding regions revealed that the LSN could evoke cardiovascular changes accompanied by distinct oscillations in SNA, as well as increases in respiratory amplitude. We show that activation of neurons within the mPFC and LSN influence respiratory, metabolic and cardiac outflows in a site-dependent manner. This study has implications with respect to the altered PFC neuronal activity seen in stress-related and mental health disorders, and suggests how basic physiological systems may be affected. PMID:24042503
Pomarol-Clotet, E; Canales-Rodríguez, E J; Salvador, R; Sarró, S; Gomar, J J; Vila, F; Ortiz-Gil, J; Iturria-Medina, Y; Capdevila, A; McKenna, P J
Neuroimaging studies have found evidence of altered brain structure and function in schizophrenia, but have had complex findings regarding the localization of abnormality. We applied multimodal imaging (voxel-based morphometry (VBM), functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) combined with tractography) to 32 chronic schizophrenic patients and matched healthy controls. At a conservative threshold of P=0.01 corrected, structural and functional imaging revealed overlapping regions of abnormality in the medial frontal cortex. DTI found that white matter abnormality predominated in the anterior corpus callosum, and analysis of the anatomical connectivity of representative seed regions again implicated fibres projecting to the medial frontal cortex. There was also evidence of convergent abnormality in the dorsolateral prefrontal cortex, although here the laterality was less consistent across techniques. The medial frontal region identified by these three imaging techniques corresponds to the anterior midline node of the default mode network, a brain system which is believed to support internally directed thought, a state of watchfulness, and/or the maintenance of one's sense of self, and which is of considerable current interest in neuropsychiatric disorders. PMID:20065955
Castner, Stacy A.; Williams, Graham V.
The prefrontal cortex of the primate frontal lobes provides the capacity for judgment which can constantly adapt behavior in order to optimize its outcome. Adjudicating between long-term memory programs and prepotent responses, this capacity reviews all incoming information and provides an interpretation dependent on the events that have just…
Brennan, Avis R.; Dolinsky, Beth; Vu, Mai-Anh T.; Stanley, Marion; Yeckel, Mark F.; Arnsten, Amy F. T.
Planning and directing thought and behavior require the working memory (WM) functions of prefrontal cortex. WM is compromised by stress, which activates phosphatidylinositol (PI)-mediated IP[subscript 3]-PKC intracellular signaling. PKC overactivation impairs WM operations and in vitro studies indicate that IP[subscript 3] receptor (IP[subscript…
Baratta, Michael V.; Lucero, Thomas R.; Amat, Jose; Watkins, Linda R.; Maier, Steven F.
A prior experience of behavioral control over a stressor interferes with subsequent Pavlovian fear conditioning, and this effect is dependent on the activation of the ventral medial prefrontal cortex (mPFCv) at the time of the initial experience with control. It is unknown whether mPFCv activity is necessary during fear learning and/or testing for…
Gilmartin, Marieke R.; Helmstetter, Fred J.
The contribution of the medial prefrontal cortex (mPFC) to the formation of memory is a subject of considerable recent interest. Notably, the mechanisms supporting memory acquisition in this structure are poorly understood. The mPFC has been implicated in the acquisition of trace fear conditioning, a task that requires the association of a…
Garcia, Rene; Chang, Chun-hui; Maren, Stephen
Lesion studies indicate that rats without the medial prefrontal cortex (mPFC) have difficulty recalling fear extinction acquired the previous day. Several electrophysiological studies have also supported this observation by demonstrating that extinction-related increases in neuronal activity in the mPFC participate in expression of fear…
do Prado, Carine H; Narahari, Tanya; Holland, Freedom H; Lee, Ha-Neul; Murthy, Shashi K; Brenhouse, Heather C
Early postnatal stress such as maternal separation causes cognitive dysfunction later in life, including working memory deficits that are largely mediated by the prefrontal cortex. Maternal separation in male rats also yields a loss of parvalbumin-containing prefrontal cortex interneurons in adolescence, which may occur via inflammatory or oxidative stress mechanisms. Environmental enrichment can prevent several effects of maternal separation; however, effects of enrichment on prefrontal cortex development are not well understood. Here, we report that enrichment prevented cognitive dysfunction in maternally separated males and females, and prevented elevated circulating pro-inflammatory cytokines that was evident in maternally separated males, but not females. However, enrichment did not prevent parvalbumin loss or adolescent measures of oxidative stress. Significant correlations indicated that adolescents with higher oxidative damage and less prefrontal cortex parvalbumin in adolescence committed more errors on the win-shift task; therefore, maternal separation may affect cognitive dysfunction via aberrant interneuron development. © 2015 Wiley Periodicals, Inc. Dev Psychobiol 58: 482-491, 2016.
Li, Xiaojing; Yang, Juan; Li, Peng; Li, Hong
The weighing of intentions and consequences is inconsistent in adult's moral judgments, and this is particularly prominent when assigning blame to the immoral intentions in the absence of negative outcomes. The current study extends previous research by examining how individual differences in moral judgment competence are reflected in the cortical network when making judgments about immoral intentions. Twenty-four participants were scanned, using functional magnetic resonance imaging, while making judgments about three kinds of moral scenarios: a neutral condition, an immoral intention condition, and an immoral condition. The result showed that comparing with making judgments about the other two conditions, making judgments about the immoral intentions takes longer time and was associated with significantly elevated activity in the dorsolateral prefrontal cortex and the ventrolateral prefrontal cortex. Additionally, moral judgment competence scores were inversely correlated with activity in the right dorsolateral prefrontal cortex when assigning blame to the immoral intentions. Greater activity in the right dorsolateral prefrontal cortex in participants with lower moral judgment competence possibly reflected increased recruitment of cognitive resource applied to control impulsive response and integrate competitive information in making judgments about the immoral intention.
Keistler, Colby; Barker, Jacqueline M.; Taylor, Jane R.
Although several studies have examined the subcortical circuitry underlying Pavlovian-to-instrumental transfer (PIT), the role of medial prefrontal cortex in this behavior is largely unknown. Elucidating the cortical contributions to PIT will be key for understanding how reward-paired cues control behavior in both adaptive and maladaptive context…
Balaguer-Ballester, Emili; Seamans, Jeremy K.; Phillips, Anthony G.; Durstewitz, Daniel
Modulation of neural activity by monoamine neurotransmitters is thought to play an essential role in shaping computational neurodynamics in the neocortex, especially in prefrontal regions. Computational theories propose that monoamines may exert bidirectional (concentration-dependent) effects on cognition by altering prefrontal cortical attractor dynamics according to an inverted U-shaped function. To date, this hypothesis has not been addressed directly, in part because of the absence of appropriate statistical methods required to assess attractor-like behavior in vivo. The present study used a combination of advanced multivariate statistical, time series analysis, and machine learning methods to assess dynamic changes in network activity from multiple single-unit recordings from the medial prefrontal cortex (mPFC) of rats while the animals performed a foraging task guided by working memory after pretreatment with different doses of d-amphetamine (AMPH), which increases monoamine efflux in the mPFC. A dose-dependent, bidirectional effect of AMPH on neural dynamics in the mPFC was observed. Specifically, a 1.0 mg/kg dose of AMPH accentuated separation between task-epoch-specific population states and convergence toward these states. In contrast, a 3.3 mg/kg dose diminished separation and convergence toward task-epoch-specific population states, which was paralleled by deficits in cognitive performance. These results support the computationally derived hypothesis that moderate increases in monoamine efflux would enhance attractor stability, whereas high frontal monoamine levels would severely diminish it. Furthermore, they are consistent with the proposed inverted U-shaped and concentration-dependent modulation of cortical efficiency by monoamines. PMID:26180194
Antzoulatos, Evan G.; Miller, Earl K.
Summary Learning to classify diverse experiences into meaningful groups, like categories, is fundamental to normal cognition. To understand its neural basis, we simultaneously recorded from multiple electrodes in the lateral prefrontal cortex and dorsal striatum, two interconnected brain structures critical for learning. Each day, monkeys learned to associate novel, abstract dot-based categories with a right vs. left saccade. Early on, when they could acquire specific stimulus-response associations, striatum activity was an earlier predictor of the corresponding saccade. However, as the number of exemplars was increasing, and monkeys had to learn to classify them, PFC began predicting the saccade associated with each category before the striatum. While monkeys were categorizing novel exemplars at a high rate, PFC activity was a strong predictor of their corresponding saccade early in the trial, before the striatal neurons. These results suggest that striatum plays a greater role in stimulus-response association and PFC in abstraction of categories. PMID:21791284
Amaral, A.C.; Jakovcevski, M.; McGaughy, J.A.; Calderwood, S.K.; Mokler, D.J.; Rushmore, R.J.; Galler, J.R.; Akbarian, S.A.; Rosene, D.L.
Prenatal protein malnutrition (PPM) in rats causes enduring changes in brain and behavior including increased cognitive rigidity and decreased inhibitory control. A preliminary gene microarray screen of PPM rat prefrontal cortex (PFC) identified alterations in KCNJ3 (GIRK1/Kir3.1), a gene important for regulating neuronal excitability. Follow-up with polymerase chain reaction and Western blot showed decreased KCNJ3 expression in PFC, but not hippocampus or brainstem. To verify localization of the effect to the PFC, baseline regional brain activity was assessed with 14C-2-deoxyglucose. Results showed decreased activation in PFC but not hippocampus. Together these findings point to the unique vulnerability of the PFC to the nutritional insult during early brain development, with enduring effects in adulthood on KCNJ3 expression and baseline metabolic activity. PMID:25446346
Amaral, A C; Jakovcevski, M; McGaughy, J A; Calderwood, S K; Mokler, D J; Rushmore, R J; Galler, J R; Akbarian, S A; Rosene, D L
Prenatal protein malnutrition (PPM) in rats causes enduring changes in brain and behavior including increased cognitive rigidity and decreased inhibitory control. A preliminary gene microarray screen of PPM rat prefrontal cortex (PFC) identified alterations in KCNJ3 (GIRK1/Kir3.1), a gene important for regulating neuronal excitability. Follow-up with polymerase chain reaction and Western blot showed decreased KCNJ3 expression in the PFC, but not hippocampus or brainstem. To verify localization of the effect to the PFC, baseline regional brain activity was assessed with (14)C-2-deoxyglucose. Results showed decreased activation in the PFC but not hippocampus. Together these findings point to the unique vulnerability of the PFC to the nutritional insult during early brain development, with enduring effects in adulthood on KCNJ3 expression and baseline metabolic activity.
Green, Anders C.; Bærentsen, Klaus B.; Stødkilde-Jørgensen, Hans; Roepstorff, Andreas; Vuust, Peter
We used functional magnetic resonance imaging to investigate the neural basis of the mere exposure effect in music listening, which links previous exposure to liking. Prior to scanning, participants underwent a learning phase, where exposure to melodies was systematically varied. During scanning, participants rated liking for each melody and, later, their recognition of them. Participants showed learning effects, better recognising melodies heard more often. Melodies heard most often were most liked, consistent with the mere exposure effect. We found neural activations as a function of previous exposure in bilateral dorsolateral prefrontal and inferior parietal cortex, probably reflecting retrieval and working memory-related processes. This was despite the fact that the task during scanning was to judge liking, not recognition, thus suggesting that appreciation of music relies strongly on memory processes. Subjective liking per se caused differential activation in the left hemisphere, of the anterior insula, the caudate nucleus, and the putamen. PMID:22548168
Nee, Derek Evan; Jahn, Andrew; Brown, Joshua W.
The functions of the prefrontal cortex (PFC) underlie higher-level cognition. Varying proposals suggest that the PFC is organized along a rostral-caudal gradient of abstraction with more abstract representations/processes associated with more rostral areas. However, the operational definition of abstraction is unclear. Here, we contrasted 2 prominent theories of abstraction—temporal and relational—using fMRI. We further examined whether integrating abstract rules—a function common to each theory—recruited the PFC independently of other abstraction effects. While robust effects of relational abstraction were present in the PFC, temporal abstraction effects were absent. Instead, we found activations specific to the integration of relational rules in areas previously shown to be associated with temporal abstraction. We suggest that previous effects of temporal abstraction were due to confounds with integration demands. We propose an integration framework to understand the functions of the PFC that resolves discrepancies in prior data. PMID:23563962
Negrón-Oyarzo, Ignacio; Aboitiz, Francisco; Fuentealba, Pablo
Chronic stress-related psychiatric diseases, such as major depression, posttraumatic stress disorder, and schizophrenia, are characterized by a maladaptive organization of behavioral responses that strongly affect the well-being of patients. Current evidence suggests that a functional impairment of the prefrontal cortex (PFC) is implicated in the pathophysiology of these diseases. Therefore, chronic stress may impair PFC functions required for the adaptive orchestration of behavioral responses. In the present review, we integrate evidence obtained from cognitive neuroscience with neurophysiological research with animal models, to put forward a hypothesis that addresses stress-induced behavioral dysfunctions observed in stress-related neuropsychiatric disorders. We propose that chronic stress impairs mechanisms involved in neuronal functional connectivity in the PFC that are required for the formation of adaptive representations for the execution of adaptive behavioral responses. These considerations could be particularly relevant for understanding the pathophysiology of chronic stress-related neuropsychiatric disorders. PMID:26904302
Coricelli, Giorgio; Nagel, Rosemarie
We used functional MRI (fMRI) to investigate human mental processes in a competitive interactive setting—the “beauty contest” game. This game is well-suited for investigating whether and how a player's mental processing incorporates the thinking process of others in strategic reasoning. We apply a cognitive hierarchy model to classify subject's choices in the experimental game according to the degree of strategic reasoning so that we can identify the neural substrates of different levels of strategizing. According to this model, high-level reasoners expect the others to behave strategically, whereas low-level reasoners choose based on the expectation that others will choose randomly. The data show that high-level reasoning and a measure of strategic IQ (related to winning in the game) correlate with the neural activity in the medial prefrontal cortex, demonstrating its crucial role in successful mentalizing. This supports a cognitive hierarchy model of human brain and behavior. PMID:19470476
Tada, Hirobumi; Miyazaki, Tomoyuki; Takemoto, Kiwamu; Takase, Kenkichi; Jitsuki, Susumu; Nakajima, Waki; Koide, Mayu; Yamamoto, Naoko; Komiya, Kasane; Suyama, Kumiko; Sano, Akane; Taguchi, Akiko; Takahashi, Takuya
Social separation early in life can lead to the development of impaired interpersonal relationships and profound social disorders. However, the underlying cellular and molecular mechanisms involved are largely unknown. Here, we found that isolation of neonatal rats induced glucocorticoid-dependent social dominance over nonisolated control rats in juveniles from the same litter. Furthermore, neonatal isolation inactivated the actin-depolymerizing factor (ADF)/cofilin in the juvenile medial prefrontal cortex (mPFC). Isolation-induced inactivation of ADF/cofilin increased stable actin fractions at dendritic spines in the juvenile mPFC, decreasing glutamate synaptic AMPA receptors. Expression of constitutively active ADF/cofilin in the mPFC rescued the effect of isolation on social dominance. Thus, neonatal isolation affects spines in the mPFC by reducing actin dynamics, leading to altered social behavior later in life. PMID:27791080
Stumbrys, Tadas; Erlacher, Daniel; Schredl, Michael
Recent studies suggest that lucid dreaming (awareness of dreaming while dreaming) might be associated with increased brain activity over frontal regions during rapid eye movement (REM) sleep. By applying transcranial direct current stimulation (tDCS), we aimed to manipulate the activation of the dorsolateral prefrontal cortex (DLPFC) during REM sleep to increase dream lucidity. Nineteen participants spent three consecutive nights in a sleep laboratory. On the second and third nights they randomly received either 1 mA tDCS for 10 min or sham stimulation during each REM period starting with the second one. According to the participants' self-ratings, tDCS over the DLPFC during REM sleep increased lucidity in dreams. The effects, however, were not strong and found only in frequent lucid dreamers. While this indicates some preliminary support for the involvement of the DLPFC in lucid dreaming, further research, controlling for indirect effects of stimulation and including other brain regions, is needed.
Eiselt, Anne-Kathrin; Nieder, Andreas
Processing quantity information based on abstract principles is central to intelligent behavior. Neural correlates of quantitative rule selectivity have been identified previously in the prefrontal cortex (PFC). However, whether individual neurons represent rules applied to multiple magnitude types is unknown. We recorded from PFC neurons while monkeys switched between "greater than/less than" rules applied to spatial and numerical magnitudes. A majority of rule-selective neurons responded only to the quantitative rules applied to one specific magnitude type. However, another population of neurons generalized the magnitude principle and represented the quantitative rules related to both magnitudes. This indicates that the primate brain uses rule-selective neurons specialized in guiding decisions related to a specific magnitude type only, as well as generalizing neurons that respond abstractly to the overarching concept "magnitude rules."
Gamo, Nao J.; Arnsten, Amy F.T.
Dysfunction of the prefrontal cortex (PFC) is a central feature of many psychiatric disorders, such as attention deficit hyperactivity disorder (ADHD), post-traumatic stress disorder (PTSD), schizophrenia and bipolar disorder. Thus, understanding molecular influences on PFC function through basic research in animals is essential to rational drug development. In this review, we discuss the molecular signaling events initiated by norepinephrine and dopamine that strengthen working memory function mediated by the dorsolateral PFC under optimal conditions, and weaken working memory function during uncontrollable stress. We also discuss how these intracellular mechanisms can be compromised in psychiatric disorders, and how novel treatments based on these findings may restore a molecular environment conducive to PFC regulation of behavior, thought and emotion. Examples of successful translation from animals to humans include guanfacine for the treatment of ADHD and related PFC disorders, and prazosin for the treatment of PTSD. PMID:21480691
Fermin, Alan S. R.; Sakagami, Masamichi; Kiyonari, Toko; Li, Yang; Matsumoto, Yoshie; Yamagishi, Toshio
Social value orientations (SVOs) are economic preferences for the distribution of resources – prosocial individuals are more cooperative and egalitarian than are proselfs. Despite the social and economic implications of SVOs, no systematic studies have examined their neural correlates. We investigated the amygdala and dorsolateral prefrontal cortex (DLPFC) structures and functions in prosocials and proselfs by functional magnetic resonance imaging and evaluated cooperative behavior in the Prisoner’s Dilemma game. We found for the first time that amygdala volume was larger in prosocials and positively correlated with cooperation, while DLPFC volume was larger in proselfs and negatively correlated with cooperation. Proselfs’ decisions were marked by strong DLPFC and weak amygdala activity, and prosocials’ decisions were marked by strong amygdala activity, with the DLPFC signal increasing only in defection. Our findings suggest that proselfs’ decisions are controlled by DLPFC-mediated deliberative processes, while prosocials’ decisions are initially guided by automatic amygdala processes. PMID:26876988
Baron, Sean G; Gobbini, M I; Engell, Andrew D; Todorov, Alexander
We explored the neural correlates of learning about people when the affective value of both facial appearance and behavioral information is manipulated. Participants were presented with faces that were either rated as high or low on trustworthiness. Subsequently, we paired these faces with positive, negative, or no behavioral information. Prior to forming face-behavior associations, a cluster in the right amygdala responded more strongly to untrustworthy than to trustworthy faces. During learning, a cluster in the dorsomedial prefrontal cortex (dmPFC) responded more strongly to faces paired with behaviors than faces not paired with behaviors. We also observed that the activity in the dmPFC was correlated with behavioral learning performance assessed after scanning. Interestingly, individual differences in the initial amygdala response to face trustworthiness prior to learning modulated the relationship between dmPFC activity and learning. This finding suggests that the activity of the amygdala can affect the interaction between dmPFC activity and learning.
Michael, Nikolaus; Erfurth, Andreas; Pfleiderer, Bettina
Metabolites within the left dorsolateral prefrontal cortex (DLPFC) of six inpatients with bipolar II rapid cycling (RC) during various mood states (depressed, hypomanic, and euthymic), six depressed inpatients with non-RC bipolar disorder (BIPD), and six healthy controls (HC) were assessed by proton magnetic resonance spectroscopy (MRS). We hypothesized that glutamate/glutamine levels should be altered in RC compared with HC. Patients with RC in contrast to BIPD and HC exhibited elevated levels of N-acetylaspartate (NAA), choline (Cho), creatine (Cr), and glutamate/glutamine (Glx) during all mood states. The Glx levels of BIPD compared with HC did not differ significantly; the other metabolites were increased, though less than in RC patients. Our findings of elevated metabolites in patients with RC, especially Glx as a possible marker of cortical activity, indicate that increased neuronal activity may constitute an important neurobiological feature of RC.
Vierheilig, Nina; Mühlberger, Andreas; Polak, Thomas; Herrmann, Martin J
Both functional imaging or EEG studies and studies including neurological patients found the dorsolateral prefrontal cortex (dLPFC) to be an important brain area for the processing of emotion and attention. The aim of the present study was to investigate whether emotion and attention can be modulated through bilateral transcranial direct current stimulation (tDCS) of the dLPFC. Therefore, we measured electroencephalographic occipital (early posterior negativity, EPN) and parietal ERPs (late positive potential, LPP) during an emotional picture viewing paradigm with an additional attentional instruction while applying bilateral anodal and cathodal tDC-stimulation to the left and right dLPFC. Beyond the well-known emotion and attention effects for both EPN and LPP, we found that left cathodal/right anodal tDCS leads to increased LPP amplitudes to target stimuli. In contrast to our hypothesis bilateral tDCS over the dLPFC did not influence emotional processing.
Tsutsui, Ken-Ichiro; Grabenhorst, Fabian; Kobayashi, Shunsuke; Schultz, Wolfram
Neuronal reward valuations provide the physiological basis for economic behaviour. Yet, how such valuations are converted to economic decisions remains unclear. Here we show that the dorsolateral prefrontal cortex (DLPFC) implements a flexible value code based on object-specific valuations by single neurons. As monkeys perform a reward-based foraging task, individual DLPFC neurons signal the value of specific choice objects derived from recent experience. These neuronal object values satisfy principles of competitive choice mechanisms, track performance fluctuations and follow predictions of a classical behavioural model (Herrnstein's matching law). Individual neurons dynamically encode both, the updating of object values from recently experienced rewards, and their subsequent conversion to object choices during decision-making. Decoding from unselected populations enables a read-out of motivational and decision variables not emphasized by individual neurons. These findings suggest a dynamic single-neuron and population value code in DLPFC that advances from reward experiences to economic object values and future choices. PMID:27618960
Davis, Tyler; Goldwater, Micah; Giron, Josue
The ability to form relational categories for objects that share few features in common is a hallmark of human cognition. For example, anything that can play a preventative role, from a boulder to poverty, can be a "barrier." However, neurobiological research has focused solely on how people acquire categories defined by features. The present functional magnetic resonance imaging study examines how relational and feature-based category learning compare in well-matched learning tasks. Using a computational model-based approach, we observed a cluster in left rostrolateral prefrontal cortex (rlPFC) that tracked quantitative predictions for the representational distance between test and training examples during relational categorization. Contrastingly, medial and dorsal PFC exhibited graded activation that tracked decision evidence during both feature-based and relational categorization. The results suggest that rlPFC computes an alignment signal that is critical for integrating novel examples during relational categorization whereas other PFC regions support more general decision functions.
Gonzalez, María C.; Kramar, Cecilia P.; Tomaiuolo, Micol; Katche, Cynthia; Weisstaub, Noelia; Cammarota, Martín; Medina, Jorge H.
Medial prefrontal cortex (mPFC) is essential for initial memory processing and expression but its involvement in persistent memory storage has seldom been studied. Using the hippocampus dependent inhibitory avoidance learning task and the hippocampus-independent conditioned taste aversion paradigm together with specific dopamine receptor agonists and antagonists we found that persistence but not formation of long-term aversive memories requires dopamine D1/D5 receptors activation in mPFC immediately after training and, depending on the task, between 6 and 12 h later. Our results indicate that besides its well-known participation in retrieval and early consolidation, mPFC also modulates the endurance of long-lasting aversive memories regardless of whether formation of the aversive mnemonic trace requires the participation of the hippocampus. PMID:25506318
Vollbrecht, Peter J.; Simmler, Linda D.; Blakely, Randy D.; Deutch, Ariel Y.
Both dopamine and glutamate are critically involved in cognitive processes such as working memory. Astrocytes, which express dopamine receptors, are essential elements in the termination of glutamatergic signaling: the astrocytic glutamate transporter GLT-1 is responsible for >90% of cortical glutamate uptake. The effect of dopamine depletion on glutamate transporters in the prefrontal cortex (PFC) is unknown. In an effort to determine if astrocytes are a locus of cortical dopamine-glutamate interactions, we examined the effects of chronic dopamine denervation on PFC protein and mRNA levels of glutamate transporters. PFC dopamine denervation elicited a marked increase in GLT-1 protein levels, but had no effect on levels of other glutamate transporters; high affinity glutamate transport was positively correlated with the extent of dopamine depletion. GLT-1 gene expression was not altered. Our data suggests that dopamine depletion may lead to post-translational modifications that result in increased expression and activity of GLT-1 in PFC astrocytes. PMID:24611756
Kang, Hyo Jung; Adams, David H; Simen, Arthur; Simen, Birgitte B; Rajkowska, Grazyna; Stockmeier, Craig A; Overholser, James C; Meltzer, Herbert Y; Jurjus, George J; Konick, Lisa C; Newton, Samuel S; Duman, Ronald S
Investigations of the molecular mechanisms underlying major depressive disorder (MDD) have been hampered by the complexity of brain tissue and sensitivity of gene expression profiling approaches. To address these issues, we used discrete microdissections of postmortem dorsolateral prefrontal cortex (DLPFC) (area 9) and an oligonucleotide (60mer) microarray hybridization procedure that increases sensitivity without RNA amplification. Mixed-effects statistical methods were used to rigorously control for medication usage in the subset of medicated depressed subjects. These analyses yielded a rich profile of dysregulated genes. Two of the most highly dysregulated genes of interest were stresscopin, a neuropeptide involved in stress responses, and Forkhead box D3 (FOXD3), a transcription factor. Secondary cell-based analysis demonstrated that stresscopin and FoxD3 are increased in neurons of DLPFC gray matter of MDD subjects. These findings identify abnormal gene expression in a discrete region of MDD subjects and contribute to further elucidation of the molecular alterations of this complex mood disorder.
Ries, S. K; Karzmark, C. R.; Navarrete, E.; Knight, R. T.; Dronkers, N. F.
Word selection allows us to choose words during language production. This is often viewed as a competitive process wherein a lexical representation is retrieved among semantically-related alternatives. The left prefrontal cortex (LPFC) is thought to help overcome competition for word selection through top-down control. However, whether the LPFC is always necessary for word selection remains unclear. We tested 6 LPFC-injured patients and controls in two picture naming paradigms varying in terms of item repetition. Both paradigms elicited the expected semantic interference effects (SIE), reflecting interference caused by semantically-related representations in word selection. However, LPFC patients as a group showed a larger SIE than controls only in the paradigm involving item repetition. We argue that item repetition increases interference caused by semantically-related alternatives, resulting in increased LPFC-dependent cognitive control demands. The remaining network of brain regions associated with word selection appears to be sufficient when items are not repeated. PMID:26291289
Cole, Michael W; Etzel, Joset A; Zacks, Jeffrey M; Schneider, Walter; Braver, Todd S
Flexible, adaptive behavior is thought to rely on abstract rule representations within lateral prefrontal cortex (LPFC), yet it remains unclear how these representations provide such flexibility. We recently demonstrated that humans can learn complex novel tasks in seconds. Here we hypothesized that this impressive mental flexibility may be possible due to rapid transfer of practiced rule representations within LPFC to novel task contexts. We tested this hypothesis using functional MRI and multivariate pattern analysis, classifying LPFC activity patterns across 64 tasks. Classifiers trained to identify abstract rules based on practiced task activity patterns successfully generalized to novel tasks. This suggests humans can transfer practiced rule representations within LPFC to rapidly learn new tasks, facilitating cognitive performance in novel circumstances.
Cole, Michael W.; Etzel, Joset A.; Zacks, Jeffrey M.; Schneider, Walter; Braver, Todd S.
Flexible, adaptive behavior is thought to rely on abstract rule representations within lateral prefrontal cortex (LPFC), yet it remains unclear how these representations provide such flexibility. We recently demonstrated that humans can learn complex novel tasks in seconds. Here we hypothesized that this impressive mental flexibility may be possible due to rapid transfer of practiced rule representations within LPFC to novel task contexts. We tested this hypothesis using functional MRI and multivariate pattern analysis, classifying LPFC activity patterns across 64 tasks. Classifiers trained to identify abstract rules based on practiced task activity patterns successfully generalized to novel tasks. This suggests humans can transfer practiced rule representations within LPFC to rapidly learn new tasks, facilitating cognitive performance in novel circumstances. PMID:22125519
There is an important hemispheric distinction in the functional organization of prefrontal cortex (PFC) that has not been fully recognized and explored. Research with split-brain patients provides considerable evidence for a left hemisphere (LH) “interpreter” that abhors indeterminacy and automatically draws inferences to complete patterns (real or imaginary). It is suggested that this “interpreter” function may be a byproduct of the linguistic capabilities of the LH. This same literature initially limited the role of the right hemisphere (RH) to little more than visual organization. Recent reviews have garnered evidence for several different roles for the right PFC in reasoning, problem solving, and decision-making. We here focus on the beneficial but neglected role of indeterminacy in real-world problem solving and argue that the right PFC complements the left PFC “interpreter” by maintaining, and even enhancing indeterminacy. Successful real-world functioning is a delicate balancing act between these two systems. PMID:26136673
Galloway, Evan M; Woo, Newton H; Lu, Bai
Working memory is the ability to maintain representations of task-relevant information for short periods of time to guide subsequent actions or make decisions. Neurons of the prefrontal cortex exhibit persistent firing during the delay period of working memory tasks. Despite extensive studies, the mechanisms underlying this persistent neural activity remain largely obscure. The neurotransmitter systems of dopamine, NMDA, and GABA have been implicated, but further investigations are necessary to establish their precise roles and relationships. Recent research has suggested a new component: brain-derived neurotrophic factor (BDNF) and its high-affinity receptor, TrkB. We review the research on persistent activity and suggest that BDNF/TrkB signaling in a distinct class of interneurons plays an important role in organizing persistent neural activity at the single-neuron and network levels.
Chavez, Robert S.; Heatherton, Todd F.
The capacity to accurately infer the thoughts and intentions of other people is critical for effective social interaction, and neural activity in dorsomedial prefrontal cortex (dmPFC) has long been linked with the extent to which people engage in mental state attribution. In this study, we combined functional neuroimaging and experience sampling methodologies to test the predictive value of this neural response for daily social behaviors. We found that individuals who displayed greater activity in dmPFC when viewing social scenes spent more time around other people on a daily basis. These findings suggest a specific role for the neural mechanisms that support the capacity to mentalize in guiding individuals toward situations containing valuable social outcomes. PMID:26206505
Coricelli, Giorgio; Nagel, Rosemarie
We used functional MRI (fMRI) to investigate human mental processes in a competitive interactive setting--the "beauty contest" game. This game is well-suited for investigating whether and how a player's mental processing incorporates the thinking process of others in strategic reasoning. We apply a cognitive hierarchy model to classify subject's choices in the experimental game according to the degree of strategic reasoning so that we can identify the neural substrates of different levels of strategizing. According to this model, high-level reasoners expect the others to behave strategically, whereas low-level reasoners choose based on the expectation that others will choose randomly. The data show that high-level reasoning and a measure of strategic IQ (related to winning in the game) correlate with the neural activity in the medial prefrontal cortex, demonstrating its crucial role in successful mentalizing. This supports a cognitive hierarchy model of human brain and behavior.
Knoch, Daria; Schneider, Frédéric; Schunk, Daniel; Hohmann, Martin; Fehr, Ernst
Reputation formation pervades human social life. In fact, many people go to great lengths to acquire a good reputation, even though building a good reputation is costly in many cases. Little is known about the neural underpinnings of this important social mechanism, however. In the present study, we show that disruption of the right, but not the left, lateral prefrontal cortex (PFC) with low-frequency repetitive transcranial magnetic stimulation (rTMS) diminishes subjects' ability to build a favorable reputation. This effect occurs even though subjects' ability to behave altruistically in the absence of reputation incentives remains intact, and even though they are still able to recognize both the fairness standards necessary for acquiring and the future benefits of a good reputation. Thus, subjects with a disrupted right lateral PFC no longer seem to be able to resist the temptation to defect, even though they know that this has detrimental effects on their future reputation. This suggests an important dissociation between the knowledge about one's own best interests and the ability to act accordingly in social contexts. These results link findings on the neural underpinnings of self-control and temptation with the study of human social behavior, and they may help explain why reputation formation remains less prominent in most other species with less developed prefrontal cortices.
Joensson, Morten; Thomsen, Kristine Rømer; Andersen, Lau M.; Gross, Joachim; Mouridsen, Kim; Sandberg, Kristian; Østergaard, Leif
Abstract When experiences become meaningful to the self, they are linked to synchronous activity in a paralimbic network of self‐awareness and dopaminergic activity. This network includes medial prefrontal and medial parietal/posterior cingulate cortices, where transcranial magnetic stimulation may transiently impair self‐awareness. Conversely, we hypothesize that dopaminergic stimulation may improve self‐awareness and metacognition (i.e., the ability of the brain to consciously monitor its own cognitive processes). Here, we demonstrate improved noetic (conscious) metacognition by oral administration of 100 mg dopamine in minimal self‐awareness. In a separate experiment with extended self‐awareness dopamine improved the retrieval accuracy of memories of self‐judgment (autonoetic, i.e., explicitly self‐conscious) metacognition. Concomitantly, magnetoencephalography (MEG) showed increased amplitudes of oscillations (power) preferentially in the medial prefrontal cortex. Given that electromagnetic activity in this region is instrumental in self‐awareness, this explains the specific effect of dopamine on explicit self‐awareness and autonoetic metacognition. Hum Brain Mapp 36:1866–1877, 2015. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.. PMID:25627861
Chadick, James Z.; Zanto, Theodore P.; Gazzaley, Adam
Older adults experience deficits in working memory (WM) that are acutely exacerbated by the presence of distracting information. Human neurophysiological studies have revealed that these changes are accompanied by a diminished ability to suppress visual cortical activity associated with task-irrelevant information. Although this is often attributed to deficits in top-down control from a prefrontal cortical source, this has not yet been directly demonstrated. Here we evaluate the neural basis of distraction’s negative impact on WM and the impairment in neural suppression in older adults by performing structural and functional MRIs while older participants engage in tasks that require remembering relevant visual stimuli in the context of overlapping irrelevant stimuli. Analysis supports both an age-related distraction effect and neural suppression deficit, and extends our understanding by revealing an alteration in functional connectivity between visual cortices and a region in the default network, the medial prefrontal cortex (mPFC). Moreover, within the older population, the magnitude of WM distractibility and neural suppression are both associated with individual differences in cortical volume and activity of the mPFC, as well as its associated white-matter tracts. PMID:24979364
Suzuki, Atsunobu; Ito, Yuichi; Kiyama, Sachiko; Kunimi, Mitsunobu; Ohira, Hideki; Kawaguchi, Jun; Tanabe, Hiroki C.; Nakai, Toshiharu
A bad reputation can persistently affect judgments of an individual even when it turns out to be invalid and ought to be disregarded. Such indelible distrust may reflect that the negative evaluation elicited by a bad reputation transfers to a person. Consequently, the person him/herself may come to activate this negative evaluation irrespective of the accuracy of the reputation. If this theoretical model is correct, an evaluation-related brain region will be activated when witnessing a person whose bad reputation one has learned about, regardless of whether the reputation is deemed valid or not. Here, we tested this neural hypothesis with functional magnetic resonance imaging (fMRI). Participants memorized faces paired with either a good or a bad reputation. Next, they viewed the faces alone and inferred whether each person was likely to cooperate, first while retrieving the reputations, and then while trying to disregard them as false. A region of the left ventrolateral prefrontal cortex (vlPFC), which may be involved in negative evaluation, was activated by faces previously paired with bad reputations, irrespective of whether participants attempted to retrieve or disregard these reputations. Furthermore, participants showing greater activity of the left ventrolateral prefrontal region in response to the faces with bad reputations were more likely to infer that these individuals would not cooperate. Thus, once associated with a bad reputation, a person may elicit evaluation-related brain responses on their own, thereby evoking distrust independently of their reputation. PMID:26869908
Ackerman, Christopher M.
Item-specific spatial information is essential for interacting with objects and for binding multiple features of an object together. Spatial relational information is necessary for implicit tasks such as recognizing objects or scenes from different views but also for explicit reasoning about space such as planning a route with a map and for other distinctively human traits such as tool construction. To better understand how the brain supports these two different kinds of information, we used functional MRI to directly contrast the neural encoding and maintenance of spatial relations with that for item locations in equivalent visual scenes. We found a double dissociation between the two: whereas item-specific processing implicates a frontoparietal attention network, including the superior frontal sulcus and intraparietal sulcus, relational processing preferentially recruits a cognitive control network, particularly lateral prefrontal cortex (PFC) and inferior parietal lobule. Moreover, pattern classification revealed that the actual meaning of the relation can be decoded within these same regions, most clearly in rostrolateral PFC, supporting a hierarchical, representational account of prefrontal organization. PMID:22896722
Genovesio, Aldo; Tsujimoto, Satoshi; Navarra, Giulia; Falcone, Rossella; Wise, Steven P
Two rhesus monkeys performed a distance discrimination task in which they reported whether a red square or a blue circle had appeared farther from a fixed reference point. Because a new pair of distances was chosen randomly on each trial, and because the monkeys had no opportunity to correct errors, no information from the previous trial was relevant to a current one. Nevertheless, many prefrontal cortex neurons encoded the outcome of the previous trial on current trials. A smaller, intermingled population of cells encoded the spatial goal on the previous trial or the features of the chosen stimuli, such as color or shape. The coding of previous outcomes and goals began at various times during a current trial, and it was selective in that prefrontal cells did not encode other information from the previous trial. The monitoring of previous goals and outcomes often contributes to problem solving, and it can support exploratory behavior. The present results show that such monitoring occurs autonomously and selectively, even when irrelevant to the task at hand.
Suzuki, Atsunobu; Ito, Yuichi; Kiyama, Sachiko; Kunimi, Mitsunobu; Ohira, Hideki; Kawaguchi, Jun; Tanabe, Hiroki C; Nakai, Toshiharu
A bad reputation can persistently affect judgments of an individual even when it turns out to be invalid and ought to be disregarded. Such indelible distrust may reflect that the negative evaluation elicited by a bad reputation transfers to a person. Consequently, the person him/herself may come to activate this negative evaluation irrespective of the accuracy of the reputation. If this theoretical model is correct, an evaluation-related brain region will be activated when witnessing a person whose bad reputation one has learned about, regardless of whether the reputation is deemed valid or not. Here, we tested this neural hypothesis with functional magnetic resonance imaging (fMRI). Participants memorized faces paired with either a good or a bad reputation. Next, they viewed the faces alone and inferred whether each person was likely to cooperate, first while retrieving the reputations, and then while trying to disregard them as false. A region of the left ventrolateral prefrontal cortex (vlPFC), which may be involved in negative evaluation, was activated by faces previously paired with bad reputations, irrespective of whether participants attempted to retrieve or disregard these reputations. Furthermore, participants showing greater activity of the left ventrolateral prefrontal region in response to the faces with bad reputations were more likely to infer that these individuals would not cooperate. Thus, once associated with a bad reputation, a person may elicit evaluation-related brain responses on their own, thereby evoking distrust independently of their reputation.
Cheng, Gordon L F; Lee, Tatia M C
The prefrontal cortex (PFC) subserves complex cognitive abilities, including risky decision-making; the modulation of this brain area is shown to alter the way people take risks. Yet, neuromodulation of the PFC in relation to risk-taking behavior remains relatively less well-studied. Moreover, the psychological variables that influence such neuromodulation remain poorly understood. To address these issues, 16 participants took part in 3 experimental sessions on separate days. They received: (i) left anodal-right cathodal transcranial direct current stimulation (tDCS); (ii) left cathodal-right anodal stimulation; or (iii) sham stimulation while they completed two risk-taking tasks. They also measured on several cognitive-affective abilities and personality traits. It was revealed that left cathodal-right anodal stimulation led to significantly reduced risk-taking under a context of haste. The reduction of risk-taking (relative to sham) correlated with state and trait impulsivity, such that the effect was larger in more impulsive individuals. For these individuals, the tDCS effect size was considered to be large (generalized partial η(2) > .17). The effect of prefrontal-neuromodulation in reducing risk-taking was influenced by baseline impulsivity, reflecting a state-dependent effect of neuromodulation on the PFC. The results of this study carry important insights into the use of neuromodulation to alter higher cognition.
Berman, K.F.; Illowsky, B.P.; Weinberger, D.R.
In previous studies we found that patients with chronic schizophrenia had lower regional cerebral blood flow (rCBF) in dorsolateral prefrontal cortex (DLPFC) than did normal subjects during performance of the Wisconsin Card Sort Test, an abstract reasoning task linked to DLPFC function. This was not the case during less complex tasks. To examine further whether this finding represented regionally circumscribed pathophysiology or a more general correlate of abstract cognition, 24 medication-free patients and 25 age- and sex-matched normal control subjects underwent rCBF measurements with the xenon 133 technique while they performed two tasks: Raven's Progressive Matrices (RPM) and an active baseline control task. While performing RPM, normal subjects activated posterior cortical areas over baseline, but did not activate DLPFC, as had been seen during the Wisconsin Card Sort Test. Like normal subjects, patients showed maximal rCBF elevations posteriorly and, moreover, they had no significant DLPFC or other cortical deficit while performing RPM. These results suggest that DLPFC dysfunction in schizophrenia is linked to pathophysiology of a regionally specific neural system rather than to global cortical dysfunction, and that this pathophysiology is most apparent under prefrontally specific cognitive demand.
Kumaran, Dharshan; Warren, David E.; Tranel, Daniel
Individuals learn both from the outcomes of their own internally generated actions (“experiential learning”) and from the observation of the consequences of externally generated actions (“observational learning”). While neuroscience research has focused principally on the neural mechanisms by which brain structures such as the ventromedial prefrontal cortex (vmPFC) support experiential learning, relatively less is known regarding how learning proceeds through passive observation. We explored the necessity of the vmPFC for observational learning by testing a group of patients with damage to the vmPFC as well as demographically matched normal comparison and brain-damaged comparison groups—and a single patient with bilateral dorsal prefrontal damage—using several value-learning tasks that required learning from direct experience, observational learning, or both. We found a specific impairment in observational learning in patients with vmPFC damage manifest in the reduced influence of previously observed rewards on current choices, despite a relatively intact capacity for experiential learning. The current study provides evidence that the vmPFC plays a critical role in observational learning, suggests that there are dissociable neural circuits for experiential and observational learning, and offers an important new extension of how the vmPFC contributes to learning and memory. PMID:25911415
Vollbrecht, Peter J; Simmler, Linda D; Blakely, Randy D; Deutch, Ariel Y
Both dopamine and glutamate are critically involved in cognitive processes such as working memory. Astrocytes, which express dopamine receptors, are essential elements in the termination of glutamatergic signaling: the astrocytic glutamate transporter GLT-1 is responsible for > 90% of cortical glutamate uptake. The effect of dopamine depletion on glutamate transporters in the prefrontal cortex (PFC) remains unknown. In an effort to determine if astrocytes are a locus of cortical dopamine-glutamate interactions, we examined the effects of chronic dopamine denervation on PFC protein and mRNA levels of glutamate transporters. PFC dopamine denervation elicited a marked increase in GLT-1 protein levels, but had no effect on levels of other glutamate transporters; high-affinity glutamate transport was positively correlated with the extent of dopamine depletion. GLT-1 gene expression was not altered. Our data suggest that dopamine depletion may lead to post-translational modifications that result in increased expression and activity of GLT-1 in PFC astrocytes. The glutamate transporter GLT-1 is expressed by astrocytes, which also express dopamine receptors. Regulation of prefrontal cortical (PFC) GLT-1 potentially offers a novel treatment approach to the cognitive deficits of schizophrenia. Partial PFC dopamine deafferentation increased membrane expression of GLT-1 protein and glutamate uptake, but did not alter levels of the other two neocortical glutamate transporters, GLAST and EAAC1.
Joensson, Morten; Thomsen, Kristine Rømer; Andersen, Lau M; Gross, Joachim; Mouridsen, Kim; Sandberg, Kristian; Østergaard, Leif; Lou, Hans C
When experiences become meaningful to the self, they are linked to synchronous activity in a paralimbic network of self-awareness and dopaminergic activity. This network includes medial prefrontal and medial parietal/posterior cingulate cortices, where transcranial magnetic stimulation may transiently impair self-awareness. Conversely, we hypothesize that dopaminergic stimulation may improve self-awareness and metacognition (i.e., the ability of the brain to consciously monitor its own cognitive processes). Here, we demonstrate improved noetic (conscious) metacognition by oral administration of 100 mg dopamine in minimal self-awareness. In a separate experiment with extended self-awareness dopamine improved the retrieval accuracy of memories of self-judgment (autonoetic, i.e., explicitly self-conscious) metacognition. Concomitantly, magnetoencephalography (MEG) showed increased amplitudes of oscillations (power) preferentially in the medial prefrontal cortex. Given that electromagnetic activity in this region is instrumental in self-awareness, this explains the specific effect of dopamine on explicit self-awareness and autonoetic metacognition.
Huang, Hui; Ya, Jinrong; Wu, Zhe; Wen, Chunmei; Zheng, Suyue; Tian, Chaoyang; Ren, Hui; Carlson, Synnöve; Yu, Hualin; Chen, Feng; Wang, Jianhong
Background Sensory gating, often described as the ability to filter out irrelevant information that is repeated in close temporal proximity, is essential for the selection, processing, and storage of more salient information. This study aimed to test the effect of sensory gating under anesthesia in the prefrontal cortex (PFC) of monkeys following injection of bromocriptine, haloperidol, and phencyclidine (PCP). Material/Methods We used an auditory evoked potential that can be elicited by sound to examine sensory gating during treatment with haloperidol, bromocriptine, and PCP in the PFC in the cynomolgus monkey. Scalp electrodes were located in the bilateral PFC and bilateral temporal, bilateral parietal, and occipital lobes. Administration of bromocriptine (0.313 mg/kg, 0.625 mg/kg, and 1.25 mg/kg), haloperidol (0.001 mg/kg, 0.01 mg/kg, and 0.05 mg/kg), and the N-methyl-D-aspartic acid receptor antagonist PCP (0.3 mg/kg) influenced sensory gating. Results We demonstrated the following: (1) Administration of mid-dose bromocriptine disrupted sensory gating (N100) in the right temporal lobe, while neither low-dose nor high-dose bromocriptine impaired gating. (2) Low-dose haloperidol impaired gating in the right prefrontal cortex. Mid-dose haloperidol disrupted sensory gating in left occipital lobe. High-dose haloperidol had no obvious effect on sensory gating. (3) Gating was impaired by PCP in the left parietal lobe. Conclusions Our studies showed that information processing was regulated by the dopaminergic system, which might play an important role in the PFC. The dopaminergic system influenced sensory gating in a dose- and region-dependent pattern, which might modulate the different stages that receive further processing due to novel information. PMID:27218151
Kim, Airee; Mandyam, Chitra D
Methamphetamine addicts demonstrate impaired frontal cortical-dependent cognitive function that could result from methamphetamine-induced maladaptive plasticity in the prefrontal cortex. Reduced adult gliogenesis observed in a rodent model of compulsive methamphetamine self-administration could contribute to the maladaptive plasticity in the medial prefrontal cortex (mPFC) as excessive methamphetamine intake is associated with loss of gliogenesis. The present study explored the vulnerability of mPFC progenitors to the duration of various sessions of methamphetamine self-administration in limited and extended access schedule of reinforcement. Proliferation of progenitors via Ki-67 labeling and apoptosis via activated caspase-3 labeling were studied in rats that intravenously self-administered methamphetamine in a limited access (1h/day: short access (ShA)) or extended access (6h/day: long access (LgA)) paradigm over 4, 13, 22 or 42 sessions, and in rats that experienced 22 sessions and were withdrawn from self-administration for a period of 4weeks. Four sessions of LgA methamphetamine enhanced proliferation and apoptosis and forty-two sessions of ShA and LgA methamphetamine reduced proliferation without effecting apoptosis. Withdrawal from twenty-two sessions of methamphetamine enhanced proliferation in LgA animals. Our findings demonstrate that proliferation of mPFC progenitors is vulnerable to psychostimulant exposure and withdrawal with distinct underlying mechanisms relating to methamphetamine toxicity. The susceptibility of mPFC progenitors to even modest doses of methamphetamine could account for the pronounced neuroadaptation in the mPFC linked to methamphetamine abuse.
Conflict adaptation – a conflict-triggered improvement in the resolution of conflicting stimulus or response representations – has become a widely used probe of cognitive control processes in both healthy and clinical populations. Previous functional magnetic resonance imaging (fMRI) studies have localized activation foci associated with conflict resolution to dorsolateral prefrontal cortex (dlPFC). The traditional group-analysis approach employed in these studies highlights regions that are, on average, activated during conflict resolution, but does not necessarily reveal areas mediating individual differences in conflict resolution, because between-subject variance is treated as noise. Here, we employed a complementary approach in order to elucidate the neural bases of variability in the proficiency of conflict-driven cognitive control. We analyzed two independent fMRI data sets of face-word Stroop tasks by using individual variability in the behavioral expression of conflict adaptation as the metric against which brain activation was regressed, while controlling for individual differences in mean reaction time and Stroop interference. Across the two experiments, a replicable neural substrate of individual variation in conflict adaptation was found in ventrolateral prefrontal cortex (vlPFC), specifically, in the right inferior frontal gyrus, pars orbitalis (BA 47). Unbiased regression estimates showed that variability in activity in this region accounted for ~40% of the variance in behavioral expression of conflict adaptation across subjects, thus documenting a heretofore unsuspected key role for vlPFC in mediating conflict-driven adjustments in cognitive control. We speculate that vlPFC plays a primary role in conflict control that is supplemented by dlPFC recruitment under conditions of suboptimal performance. PMID:21568631
Andreazza, Ana C; Wang, Jun-Feng; Salmasi, Faraz; Shao, Li; Young, Lionel T
Previously, we found decreased mitochondrial complex I subunits levels and increased protein oxidation and nitration in postmortem prefrontal cortex (PFC) from patients with bipolar disorder (BD) and schizophrenia (SCZ). The objectives of this study were to replicate our findings in an independent sample of subjects with BD, and to examine more specifically oxidative and nitrosative damage to mitochondrial and synaptosomal proteins and lipid peroxidation in myelin. We isolated mitochondria, synaptosomes, and myelin using a percoll gradient from postmortem PFC from patients with BD, SCZ, and healthy controls. Levels of mitochondrial complex I and III proteins, protein oxidation (carbonylation), and nitration (3-nitrotyrosine) were assessed using immunobloting analysis. Lipid peroxidation [lipid hydroperoxides (LPH), 8-isoprostane (8-Iso), 4-hydroxy-2-nonenal (4-HNE)] were measured using colorimetric or ELISA assays. We found decreased complex I subunits levels in BD subjects compared with control (CTL), but no difference in complex III subunits. Carbonylation was increased in synaptosomes from BD group while 3-nitrotyrosine was increased in mitochondria from BD and SCZ groups. 8-Iso was found increased in the BD group while 4-HNE was increased in both SCZ and BD when compared with controls with no differences in LPH. Our results suggest that in BD mitochondrial proteins are more susceptible to potentially reversible nitrosative damage while more longstanding oxidative damage occurs to synaptic proteins. Oxidative stress has been shown to be higher in the brain of patients with bipolar disorder (BD). Here, we demonstrated increased levels of protein oxidation in synaptosomes from postmortem prefrontal cortex from patients from BD group, while 3-nitrotyrosine was increased in mitochondria from BD and schizophrenia (SCZ) groups. Moreover, lipid peroxidation was found increased in the BD when compared with controls; suggesting that in BD mitochondrial proteins are more
Parikh, Vinay; Man, Kingson; Decker, Michael W; Sarter, Martin
Because modulation of cortical cholinergic neurotransmission has been hypothesized to represent a necessary mechanism mediating the beneficial cognitive effects of nicotine and nicotinic acetylcholine receptor (nAChR) subtype-selective agonists, we used choline-sensitive microelectrodes for the real-time measurement of ACh release in vivo, to characterize cholinergic transients evoked by nicotine and the alpha4beta2*-selective nAChR partial agonist 2-methyl-3-(2-(S)-pyrrolindinylmethoxy)pyridine dihydrochloride (ABT-089), a clinically effective cognition enhancer. In terms of cholinergic signal amplitudes, ABT-089 was significantly more potent than nicotine in evoking ACh cholinergic transients. Moreover, cholinergic signals evoked by ABT-089 were characterized by faster signal rise time and decay rate. The nAChR antagonist mecamylamine attenuated the cholinergic signals evoked by either compound. Cholinergic signals evoked by ABT-089 were more efficaciously attenuated by the relatively beta2*-selective nAChR antagonist dihydro-beta-erythroidine. The alpha7 antagonist methyllycaconitine did not affect choline signal amplitudes but partly attenuated the relatively slow decay rate of nicotine-evoked cholinergic signals. Furthermore, the AMPA receptor antagonist DNQX as well as the NMDA receptor antagonist APV more potently attenuated cholinergic signals evoked by ABT-089. Using glutamate-sensitive microelectrodes to measure glutamatergic transients, ABT-089 was more potent than nicotine in evoking glutamate release. Glutamatergic signals were highly sensitive to tetrodotoxin-induced blockade of voltage-regulated sodium channels. Together, the present evidence indicates that compared with nicotine, ABT-089 evokes more potent and sharper cholinergic transients in prefrontal cortex. Glutamatergic mechanisms necessarily mediate the cholinergic effects of nAChR agonists in the prefrontal cortex.
Ross, Ashley E; Nguyen, Michael D; Privman, Eve; Venton, B Jill
Mechanical perturbations can release ATP, which is broken down to adenosine. In this work, we used carbon-fiber microelectrodes and fast-scan cyclic voltammetry to measure mechanically stimulated adenosine in the brain by lowering the electrode 50 μm. Mechanical stimulation evoked adenosine in vivo (average: 3.3 ± 0.6 μM) and in brain slices (average: 0.8 ± 0.1 μM) in the prefrontal cortex. The release was transient, lasting 18 ± 2 s. Lowering a 15-μm-diameter glass pipette near the carbon-fiber microelectrode produced similar results as lowering the actual microelectrode. However, applying a small puff of artificial cerebral spinal fluid was not sufficient to evoke adenosine. Multiple stimulations within a 50-μm region of a slice did not significantly change over time or damage cells. Chelating calcium with EDTA or blocking sodium channels with tetrodotoxin significantly decreased mechanically evoked adenosine, signifying that the release is activity dependent. An alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione, did not affect mechanically stimulated adenosine; however, the nucleoside triphosphate diphosphohydrolase 1,2 and 3 (NTDPase) inhibitor POM-1 significantly reduced adenosine so a portion of adenosine is dependent on extracellular ATP metabolism. Thus, mechanical perturbations from inserting a probe in the brain cause rapid, transient adenosine signaling which might be neuroprotective. We have discovered immediate changes in adenosine concentration in the prefrontal cortex following mechanical stimulation. The adenosine increase lasts only about 20 s. Mechanically stimulated adenosine was activity dependent and mostly because of extracellular ATP metabolism. This rapid, transient increase in adenosine may help protect tissue and would occur during implantation of any electrode, such as during deep brain stimulation.
Romcy-Pereira, Rodrigo N.; Erraji-Benchekroun, Loubna; Smyrniotopoulos, Peggy; Ogawa, Sonoko; Mello, Claudio V.; Sibille, Etienne; Pavlides, Constantine
The activity-dependent transcription factor zif268 is re-activated in sleep following hippocampal long-term potentiation (LTP). However, the activation of secondary genes, possibly involved in modifying local synaptic strengths and ultimately stabilizing memory traces during sleep, has not yet been studied. Here, we investigated changes in hippocampal and cortical gene expression at a time point subsequent to the previously reported initial zif268 re-activation during sleep. Rats underwent unilateral hippocampal LTP and were assigned to SLEEP or AWAKE groups. Eighty minutes after a long rapid-eye-movement sleep (REMS) episode (or an equivalent amount of time for awake group) animals had their hippocampi dissected and processed for gene microarray hybridization. Prefrontal and parietal cortices were also collected for qRT-PCR analysis. The microarray analysis identified 28 up-regulated genes in the hippocampus: 11 genes were enhanced in the LTPed hemisphere of sleep animals; 13 genes were enhanced after sleep, regardless of hemisphere; and 4 genes were enhanced in LTPed hemisphere, regardless of behavioral state. qRT-PCR analysis confirmed the upregulation of aif-1 and sc-65 during sleep. Moreover, we observed a down-regulation of the purinergic receptor, P2Y4R in the LTP hemisphere of awake animals and a trend for the protein kinase, CaMKI to be up-regulated in the LTP hemisphere of sleep animals. In the prefrontal cortex, we showed a significant LTP-dependent down-regulation of gluR1 and spinophilin specifically during sleep. Zif268 was downregulated in sleep regardless of the hemisphere. No changes in gene expression were observed in the parietal cortex. Our findings indicate that a set of synaptic plasticity-related genes have their expression modulated during sleep following LTP, which can reflect biochemical events associated with reshaping of synaptic connections in sleep following learning. PMID:19389414
Hegarty, A.A.; Vogel, W.H. )
Both stress and ethanol, when administered individually, have been shown to affect dopamine (DA) and its metabolite (DOPAC) in the central nervous system. Stress can increase DA efflux in several areas of the brain, whereas ethanol has been shown to have variable effects on extracellular DA, either increasing DA or having no apparent effect. Furthermore, ethanol has been shown in microdissection studies to antagonize the effect of stress on the dopaminergic system, indicating an anxiety-reducing property of ethanol. However, the influence of the combination of stress and ethanol on the dopaminergic system has not been studied extensively with the newer technique of microdialysis. In this study, microdialysis was again used to characterize the interaction of immobilization stress and ethanol in the prefrontal cortex. Two groups of rats received either ethanol or saline in the resting state. A third group was immobilization stress and ethanol in the prefrontal cortex. Two groups of rats received either ethanol or saline in the resting state. A third group was immobilization Saline-treated animals showed essentially no changes in levels of DA or DOPAC. Ethanol had no effect on DA overflow in resting animals and caused only a small increase in DOPAC levels. Immobilization caused marked increases in DA levels and smaller increases in DOPAC. Ethanol pretreatment strongly reduced and antagonized the stress-induced increases in DA. However, ethanol potentiated the stress-induced increase in extracellular DOPAC. The authors data add biochemical evidence to the tension-reduction hypothesis of ethanol by perhaps implicating a reduction in the DA stress response by ethanol as a contributing factor in the development of alcoholism.
Kaping, Daniel; Vinck, Martin; Hutchison, R Matthew; Everling, Stefan; Womelsdorf, Thilo
Attentional control ensures that neuronal processes prioritize the most relevant stimulus in a given environment. Controlling which stimulus is attended thus originates from neurons encoding the relevance of stimuli, i.e. their expected value, in hand with neurons encoding contextual information about stimulus locations, features, and rules that guide the conditional allocation of attention. Here, we examined how these distinct processes are encoded and integrated in macaque prefrontal cortex (PFC) by mapping their functional topographies at the time of attentional stimulus selection. We find confined clusters of neurons in ventromedial PFC (vmPFC) that predominantly convey stimulus valuation information during attention shifts. These valuation signals were topographically largely separated from neurons predicting the stimulus location to which attention covertly shifted, and which were evident across the complete medial-to-lateral extent of the PFC, encompassing anterior cingulate cortex (ACC), and lateral PFC (LPFC). LPFC responses showed particularly early-onset selectivity and primarily facilitated attention shifts to contralateral targets. Spatial selectivity within ACC was delayed and heterogeneous, with similar proportions of facilitated and suppressed responses during contralateral attention shifts. The integration of spatial and valuation signals about attentional target stimuli was observed in a confined cluster of neurons at the intersection of vmPFC, ACC, and LPFC. These results suggest that valuation processes reflecting stimulus-specific outcome predictions are recruited during covert attentional control. Value predictions and the spatial identification of attentional targets were conveyed by largely separate neuronal populations, but were integrated locally at the intersection of three major prefrontal areas, which may constitute a functional hub within the larger attentional control network.
Wolfensteller, Uta; von Cramon, D Yves
All of us regularly face situations that require the integration of the available information at hand with the established rules that guide behavior in order to generate the most appropriate action. But where individuals differ from one another is most certainly in terms of the different strategies that are adopted during this process. A previous study revealed differential brain activation patterns for the implementation of well established higher-order stimulus-response (S-R) rules depending on inter-individual strategy differences (Wolfensteller and von Cramon, 2010). This raises the question of how these strategies evolve or which neurocognitive mechanisms underlie these inter-individual strategy differences. Using functional magnetic resonance imaging (fMRI), the present study revealed striking strategy-effects across regions of the lateral prefrontal cortex during the implementation of higher-order S-R rules at an early stage of learning. The left rostrolateral prefrontal cortex displayed a quantitative strategy-effect, such that activation during rule integration based on a mismatch was related to the degree to which participants continued to rely on rule integration. A quantitative strategy ceiling effect was observed for the left inferior frontal junction area. Conversely, the right inferior frontal gyrus displayed a qualitative strategy-effect such that participants who at a later point relied on an item-based strategy showed stronger activations in this region compared to those who continued with the rule integration strategy. Together, the present findings suggest that a certain amount of rule integration is mandatory when participants start to learn higher-order rules. The more efficient item-based strategy that evolves later appears to initially require the recruitment of additional cognitive resources in order to shield the currently relevant S-R association from interfering information.
Li, Kang; Jia, Hengchuan; She, Xiaojun; Cui, Bo; Zhang, Na; Chen, Xuewei; Xu, Chuanxiang; An, Gaihong; Ma, Qiang
Chronic noise exposure has been associated with abnormalities in glutamate (Glu)-NMDAR signaling and tau hyperphosphorylation. However, further studies are necessary to clarify potential causal relationships. The aim of the present study was to evaluate the role of NMDA receptors in noise-induced tau hyperphosphorylation in the rat hippocampus and prefrontal cortex. Male Wistar rats were randomly divided into three groups in the present study: control with isotonic saline instillation (n=10); noise exposure (100 dB SPL white noise, 4h/d × 14d) and treated with saline (n=10); and noise exposure and treated with MK-801 (0.5mg/kg, intraperitoneally; n=10). The levels of tau phosphorylated at Ser202 and Ser396, and proteins involved in hyperphosphorylation, namely glycogen synthase kinase 3β (GSK3β) and protein phosphatase 2A (PP2A), were measured in the hippocampus and prefrontal cortex (PFC) after the last noise exposure. We showed that phosphorylated tau levels were enhanced in noise-exposed-rat hippocampus and PFC. MK-801 decreased the hyperphosphorylation of tau at Ser202 and Ser396 sites in the hippocampus and PFC. Furthermore, MK-801 reversed noise-induced GSK3β overexpression but had no significant effect on PP2A levels. This suggests that MK-801 protects against chronic-noise-induced tau hyperphosphorylation in the hippocampus and PFC. These findings demonstrate that Glu-NMDAR signaling may be involved in triggering aberrant tau hyperphosphorylation in the hippocampus and PFC after chronic noise exposure.
Lazarus, Matthew S; Krishnan, Keerthi; Huang, Z Josh
In mammalian neocortex, the delicate balance of neural circuits is regulated by a rich repertoire of inhibitory control mechanisms mediated by diverse classes of GABAergic interneurons. A key step common to all GABAergic neurons is the synthesis of GABA, catalyzed by 2 isoforms of glutamic acid decarboxylases (GAD). Among these, GAD67 is the rate-limiting enzyme. GAD67 level is regulated by neural activity and is altered in multiple neuropsychiatric disorders. The significance of altered GAD67 levels on inhibitory transmission, however, remains unclear. The presence of GAD65, postsynaptic GABA receptor regulation, and the diversity of cortical interneurons make the link from GAD67 levels to GABA transmission less than straightforward. Here, we selectively removed one allele of the GAD67 gene, Gad1, in PV interneurons in juvenile mice. We found substantial deficits in transmission from PV to pyramidal neurons in prefrontal cortex, along with increases of pyramidal cell excitability and excitation/inhibition balance in PV cells. Synaptic deficits recovered in adult mice, suggesting engagement of homeostatic and compensatory mechanisms. These results demonstrate that GAD67 levels directly influence synaptic inhibition. Thus, GAD67 deficiency in PV cells likely contributes to cortical dysfunction in disease states; the reversibility of synaptic deficits suggests nonpermanent damage to inhibitory circuitry.
Prefrontal neurons exhibit saccade-related activity and pre-saccadic memory-related activity often encodes the directions of forthcoming eye movements, in line with demonstrated prefrontal contribution to flexible control of voluntary eye movements. However, many prefrontal neurons exhibit post-saccadic activity that is initiated well after the initiation of eye movement. Although post-saccadic activity has been observed in the frontal eye field, this activity is thought to be a corollary discharge from oculomotor centers, because this activity shows no directional tuning and is observed whenever the monkeys perform eye movements regardless of goal-directed or not. However, prefrontal post-saccadic activities exhibit directional tunings similar as pre-saccadic activities and show context dependency, such that post-saccadic activity is observed only when monkeys perform goal-directed saccades. Context-dependency of prefrontal post-saccadic activity suggests that this activity is not a result of corollary signals from oculomotor centers, but contributes to other functions of the prefrontal cortex. One function might be the termination of memory-related activity after a behavioral response is done. This is supported by the observation that the termination of memory-related activity coincides with the initiation of post-saccadic activity in population analyses of prefrontal activities. The termination of memory-related activity at the end of the trial ensures that the subjects can prepare to receive new and updated information. Another function might be the monitoring of behavioral performance, since the termination of memory-related activity by post-saccadic activity could be associated with informing the correctness of the response and the termination of the trial. However, further studies are needed to examine the characteristics of saccade-related activities in the prefrontal cortex and their functions in eye movement control and a variety of cognitive functions
Prefrontal neurons exh