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PubMed2005

Cortical glutamatergic markers in schizophrenia.

Post-mortem studies have yet to produce consistent findings on cortical glutamatergic markers in schizophrenia; therefore, it is not possible to fully understand the role of abnormal glutamatergic function in the pathology of the disorder. To better understand the changes in cortical glutamatergic markers in schizophrenia, we measured the binding of radioligands to the ionotropic glutamate receptors (N-methyl D-aspartate, [3H]CGP39653, [3H]MK-801), amino-3-hydroxy-5-methyl-4-isoxazole ([3H]AMPA), kainate ([3H]kainate), and the high-affinity glutamate uptake site ([3H]aspartate) using in situ radioligand binding with autoradiography and levels of mRNA for kainate receptors using in situ hybridization in the dorsolateral prefrontal cortex from 20 subjects with schizophrenia and 20 controls matched for age and sex. Levels of [3H]kainate binding were significantly decreased in cortical laminae I-II (p = 0.01), III-IV (p < 0.05), and V-VI (p < 0.01) from subjects with schizophrenia. By contrast, levels of [3H]MK-801, [3H]AMPA, [3H]aspartate, or [3H]CGP39653 binding did not differ between the diagnostic cohorts. Levels of mRNA for the GluR5 subunit were decreased overall (p < 0.05), with no changes in levels of mRNA for GluR6, GluR7, KA1, or KA2 in tissue from subjects with schizophrenia. These data indicate that the decreased number of kainate receptors in the dorsolateral prefrontal cortex in schizophrenia may result, in part, from reduced expression of the GluR5 receptor subunits.

2-Amino-5-phosphonovalerate↗

PubMed2006

Effects of transcranial direct current stimulation on working memory in patients with Parkinson's disease.

OBJECTIVES: Cognitive impairment is a common feature in Parkinson's disease (PD) and is an important predictor of quality of life. Past studies showed that some aspects of cognition, such as working memory, can be enhanced following dopaminergic therapy and transcranial magnetic stimulation. The aim of our study was to investigate whether another form of noninvasive brain stimulation, anodal transcranial direct current stimulation (tDCS), which increases cortical excitability, is associated with a change in a working memory task performance in PD patients. METHODS: We studied 18 patients (12 men and 6 women) with idiopathic PD. The patients performed a three-back working memory task during active anodal tDCS of the left dorsolateral prefrontal cortex (LDLPFC), anodal tDCS of the primary motor cortex (M1) or sham tDCS. In addition, patients underwent two different types of stimulation with different intensities: 1 and 2 mA. RESULTS: The results of this study show a significant improvement in working memory as indexed by task accuracy, after active anodal tDCS of the LDLPFC with 2 mA. The other conditions of stimulation: sham tDCS, anodal tDCS of LDLPFC with 1 mA or anodal tDCS of M1 did not result in a significant task performance change. CONCLUSION: tDCS may exert a beneficial effect on working memory in PD patients that depends on the intensity and site of stimulation. This effect might be explained by the local increase in the excitability of the dorsolateral prefrontal cortex.

Aged↗

PubMed2006

Effect of task difficulty on the functional anatomy of temporal processing.

Temporal processing underlies many aspects of human perception, performance and cognition. The present study used fMRI to examine the functional neuroanatomy of a temporal discrimination task and to address two questions highlighted by previous studies: (1) the effect of task difficulty on neuronal activation and (2) the involvement of the dorsolateral prefrontal cortex (DLPFC) in timing. Twenty healthy subjects were scanned while either judging whether the second in a pair of tones was shorter or longer in duration than the standard tone or simply responding to the presentation of two identical tones as a control condition. Two levels of difficulty were studied. Activation during the less difficult condition was observed only in the cerebellum and superior temporal gyrus. As difficulty increased, additional activation of the supplementary motor area, insula/operculum, DLPFC, thalamus and striatum was observed. These results suggest the cerebellum plays a critical role in timing, particularly in gross temporal discrimination. These results also suggest that recruitment of frontal and striatal regions during timing tasks is load-dependent. Additionally, robust activation of the dorsolateral prefrontal cortex under conditions of minimal working memory involvement supports the specific involvement of this region in temporal processing rather than a more general involvement in working memory.

Acoustic Stimulation↗

PubMed2004

Heat shock protein 12A shows reduced expression in the prefrontal cortex of subjects with schizophrenia.

BACKGROUND: Deoxyribonucleic acid microarray analyses of dorsolateral prefrontal cortex (DLPFC) area 9 from 10 matched pairs of schizophrenic and control subjects revealed a consistent and significant decrease (p = .001; mean log2 signal difference = -.58) in transcript expression for a gene clone KIAA0417. This database entry has been recently annotated as two highly homologous members of a heat-shock protein family (HSPA12A and HSPA12B). METHODS: We followed up our initial results by in situ hybridization in subjects with schizophrenia, major depression, and a chronic haloperidol-treated nonhuman primate model. Furthermore, we investigated the distribution of HSPA12A and HSPA12B transcripts across the human and nonhuman primate brain. RESULTS: We found that HSPA12A (but not HSPA12B) is highly expressed in the human brain and shows a neuron- and region-specific transcript distribution, with strongest expression in the frontal and occipital cortical regions. HSPA12A messenger ribonucleic acid was significantly reduced (p < .01; mean log2 optical density difference = -.84) across subjects with schizophrenia but not in the DLPFC of subjects with major depression or in monkeys chronically treated with haloperidol. CONCLUSIONS: The data are consistent with metabolic alterations in schizophrenia, reflected in selective changes in the expression of certain genes encoding proteins involved in cellular metabolism or metabolic responsiveness.

Adult↗

PubMed2005

Spatial working memory deficit correlates with disorganization symptoms and social functioning in schizophrenia.

Both spatial working memory deficit and disorganization symptoms have been considered significant components of schizophrenic impairment involved with the dorsolateral prefrontal cortex. The purpose of the present study was to investigate the relationships among spatial working memory, psychiatric symptoms including disorganization symptoms, and social functioning in schizophrenia. Fifty clinically stable patients with schizophrenia and 34 healthy controls participated in the study. Patients were rated with the Brief Psychiatric Rating Scale and the Rehabilitation Evaluation Hall and Baker. The Advanced Trail Making Test was used to evaluate spatial working memory. Patients demonstrated significantly reduced spatial working memory compared to that of healthy controls. Spatial working memory in patients correlated significantly with social functioning such as self-care skills, community skills and speech disturbance, and with disorganization symptoms. Disorganization symptoms also correlated with these aspects of social functioning. In conclusion it is suggested that both spatial working memory deficit and disorganization symptoms, which are impairments involved with the dorsolateral prefrontal cortex dysfunction, can serve as effective predictors of social functioning.

Adult↗

PubMed1992

Schizophrenics show spatial working memory deficits.

The present study demonstrates that schizophrenics are impaired on spatial delayed-response tasks, analogous to those that have been used to assess the working memory function of the dorsolateral prefrontal cortex in rhesus monkeys. Schizophrenic patients and two control groups, normal subjects and bipolar psychiatric patients, were tested on the oculomotor version of the memory task, a haptic version of the same task, and two control tasks: a sensory task that did not require working memory and a digit span test. The schizophrenic patients showed marked deficits relative to the two control groups in both the oculomotor and haptic delayed-response tasks. They were not, however, impaired on the digit span test, which taps verbal working memory as well as voluntary attention, and on the sensory control task, in which their responses were guided by external cues rather than by spatial working memory. These findings provide direct evidence that schizophrenics suffer a loss in representational processing and that this deficit is modality independent. These data on spatial working memory add to the growing evidence for involvement of the dorsolateral prefrontal cortex in schizophrenic disease.

Adult↗

PubMed2026

Multiomic single-nucleus profiling reveals cell-type-specific epigenetic and transcriptional dysregulation in major depressive disorder brain.

OBJECTIVE: Major depressive disorder (MDD) is a leading global cause of disability, marked by persistent mood disturbances, cognitive deficits, and changes in prefrontal cortex neural circuitry. In this study, we aimed to define cell-type-specific molecular and regulatory mechanisms underlying MDD by mapping gene-expression and chromatin-accessibility changes in the dorsolateral prefrontal cortex (PFC) (dlPFC). METHODS: Postmortem dlPFC (BA9) tissue from 7 MDD and 8 well-matched controls was analyzed using 10× Genomics snRNA-seq and paired ATAC+RNA multiome sequencing. Sequencing data were processed with Cell Ranger pipelines, nuclei were filtered for quality and doublets/debris, and datasets were integrated and clustered using Seurat/Signac packages. Differential gene expression, chromatin accessibility, and transcription factor motif activity were tested between MDD and controls within each cell type, followed by peak-to-gene linkage and Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and PsyGeNET enrichment to interpret dysregulated regulatory mechanisms. RESULTS: A total of 20 distinct clusters encompassing major neuronal and non-neuronal populations were identified. Differential analyses uncovered extensive cell type-specific changes in chromatin accessibility and gene expression, particularly within excitatory layer 5/6 and inhibitory Pvalb neurons, as well as glial and vascular populations. Functional enrichment indicated dysregulation of synaptic organization, neurotransmission, myelination, stress-response, and immune-regulatory pathways across neuronal and non-neuronal cells. Notably, glucocorticoid-responsive transcription factors NR3C1/NR3C2 exhibited conserved regulatory networks implicating stress signaling in MDD pathophysiology. CONCLUSIONS: Together, these findings provide a comprehensive single-nucleus atlas of gene regulation in the MDD PFC, highlighting coordinated dysfunction across neurons, glia, and vascular cells.

Major Depressive Disorder↗

PubMed2005

rTMS evidence of different delay and decision processes in a fronto-parietal neuronal network activated during spatial working memory.

The existence of a specific and widely distributed network for spatial working memory (WM) in humans, involving the posterior parietal cortex and the prefrontal cortex, is supported by a number of neuroimaging studies. We used a repetitive transcranial magnetic stimulation (rTMS) approach to investigate the temporal dynamics and the reciprocal interactions of the different areas of the parieto-frontal network in normal subjects performing a spatial WM task, with the aim to compare neural activity of the different areas in the delay and decision phases of the task. Trains of rTMS at 25 Hz were delivered over the posterior parietal cortex (PPC), the premotor cortex (SFG) and the dorsolateral prefrontal cortex (DLPFC) of the right hemisphere alternatively during the two phases. We found a pattern of interference of TMS during the delay phase for both parietal and DLPFC sites of stimulation, with no effect observed for the SFG site. When rTMS trains were applied during the decision phase, an interference was observed selectively for DLPFC. The present study shows the existence of a parallel processing in the parieto-frontal network of spatial WM during the delay phase. Furthermore, it provides new evidence of the critical role of the DLPFC during both the delay and the decision phases. We suggest that in DLPFC, two different networks coexist: A local neural network subserving the decisional processes and a second neural population functionally interconnected with the PPC and activated when a certain spatial information has to be kept in memory, available to use.

Adult↗

PubMed1982

Prefrontal unit activity of macaque monkeys during auditory and visual reaction time tasks.

During a simple reaction time task using auditory or visual stimuli, a total of 96 single units were recorded from the dorsolateral prefrontal cortex of macaque monkeys. These monkeys were trained to depress a lever for a fixed period which produced a tone burst or a small spot of light. After a variable period, the stimulus intensity changed, and then, the monkey released the lever. Eighty-one cue-related units were classified into 3 types according to their decay time; that is, phasic, tonic and mixed. Phasic units (n = 19) showed a transient increase of discharge rate with a relatively short peak latency (70-300 ms). Of these, 17 units responded exclusively to either visual or auditory stimuli and two to both. Tonic units (n = 55) showed enhanced or suppressed activity, with longer latencies, which was sustained as long as the cue period continued. The temporal pattern of the discharge in 23 tonic units was found to be similar for both the auditory and visual cues. Seven mixed-type units showed combined phasic and tonic patterns. Lever release-related units (n = 15) were activated only during the period of lever release with no distinction in cue modality. It is suggested that the dorsolateral prefrontal cortex receives sensory inputs fairly discretely on the phasic-type neurons and that these sensory activities are transmitted to the tonic-type neurons which lead to an initiation of the lever release behavior.

Animals↗

PubMed2004

Integrated technology for evaluation of brain function and neural plasticity.

The study of neural plasticity has expanded rapidly in the past decades and has shown the remarkable ability of the developing, adult, and aging brain to be shaped by environmental inputs in health and after a lesion. Robust experimental evidence supports the hypothesis that neuronal aggregates adjacent to a lesion in the sensorimotor brain areas can take over progressively the function previously played by the damaged neurons. It definitely is accepted that such a reorganization modifies sensibly the interhemispheric differences in somatotopic organization of the sensorimotor cortices. This reorganization largely subtends clinical recovery of motor performances and sensorimotor integration after a stroke. Brain functional imaging studies show that recovery from hemiplegic strokes is associated with a marked reorganization of the activation patterns of specific brain structures. To regain hand motor control, the recovery process tends over time to bring the bilateral motor network activation toward a more normal intensity/extent, while overrecruiting simultaneously new areas, perhaps to sustain this process. Considerable intersubject variability exists in activation/hyperactivation pattern changes over time. Some patients display late-appearing dorsolateral prefrontal cortex activation, suggesting the development of "executive" strategies to compensate for the lost function. The AH in stroke often undergoes a significant "remodeling" of sensory and motor hand somatotopy outside the "normal" areas, or enlargement of the hand representation. The UH also undergoes reorganization, although to a lesser degree. Although absolute values of the investigated parameters fluctuate across subjects, secondary to individual anatomic variability, variation is minimal with regards to interhemispheric differences, due to the fact that individual morphometric characters are mirrored in the two hemispheres. Excessive interhemispheric asymmetry of the sensorimotor hand areas seems to be the parameter with highest sensitivity in describing brain reorganization after a monohemispheric lesion, and mapping motor and somatosensory cortical areas through focal TMS, fMRI, PET, EEG, and MEG is useful in studying hand representation and interhemispheric asymmetries in normal and pathologic conditions. TMS and MEG allow the detection of sensorimotor areas reshaping, as a result of either neuronal reorganization or recovery of the previously damaged neural network. These techniques have the advantage of high temporal resolution but also have limitations. TMS provides only bidimensional scalp maps, whereas MEG, even if giving three-dimensional mapping of generator sources, does so by means of inverse procedures that rely on the choice of a mathematical model of the head and the sources. These techniques do not test movement execution and sensorimotor integration as used in everyday life. fMRI and PET may provide the ideal means to integrate the findings obtained with the other two techniques. This multitechnology combined approach is at present the best way to test the presence and amount of plasticity phenomena underlying partial or total recovery of several functions, sensorimotor above all. Dynamic patterns of recovery are emerging progressively from the relevant literature. Enhanced recruitment of the affected cortex, be it spared perilesional tissue, as in the case of cortical stroke, or intact but deafferented cortex, as in subcortical strokes, seems to be the rule, a mechanism especially important in early postinsult stages. The transfer over time of preferential activation toward contralesional cortices, as observed in some cases, seems, however, to reflect a less efficient type of plastic reorganization, with some aspects of maladaptive plasticity. Reinforcing the use of the affected side can cause activation to increase again in the affected side with a corresponding enhancement of clinical function. Activation of the UH MI may represent recruitment of direct (uncrossed) corticospinal tracts and relate more to mirror movements, but it more likely reflects activity redistribution within preexisting bilateral, large-scale motor networks. Finally, activation of areas not normally engaged in the dysfunctional tasks, such as the dorsolateral prefrontal cortex or the superior parietal cortex in motor paralysis, might reflect the implication of compensatory cognitive strategies. An integrated approach with technologies able to investigate functional brain imaging is of considerable value in providing information on the excitability, extension, localization, and functional hierarchy of cortical brain areas. Deepening knowledge of the mechanisms regulating the long-term recovery (even if partial), observed for most neurologic sequelae after neural damage, might prompt newer and more efficacious therapeutic and rehabilitative strategies for neurologic diseases.

Animals↗

PubMed1995

Human prefrontal lesions increase distractibility to irrelevant sensory inputs.

Neurological patients with focal lesions in either the dorsolateral prefrontal cortex, temporal-parietal junction or the posterior hippocampus, and control subjects, were tested on a task requiring short-term retention of environmental sounds. Subjects had to indicate whether initial and subsequent test sounds were identical in two conditions. The initial and test sounds were separated by either a silent period varying from 4 to 12.6 s (no-distractor condition) or a series of irrelevant tones (distractor condition). Prefrontal patients were significantly impaired by distractors at all delays, hippocampal patients were impaired only at longer delays, while temporal-parietal patients performed similar to controls. The findings suggest that dorsolateral prefrontal cortex is crucial for gating of distracting information during delay tasks.

Aged↗

PubMed2004

Executive and prefrontal dysfunction in unipolar depression: a review of neuropsychological and imaging evidence.

This paper reviews recent empirical findings related to prefrontal and executive function in unipolar depression. While a number of reviews have dealt with either the neuropsychological literature or findings from imaging studies, the present review addresses both, as well as findings from studies that have combined brain-imaging techniques with neuropsychological measures. This combined approach is of great interest as the performance of a structured task may act to load the areas of interest and reduce variance, thus making the imaging evidence more valuable; while the use of imaging provides a check that the neuropsychological tasks are indeed engaging the structures whose performance they are intended to assess. Prominent models of the neurobiology of depression implicate involvement of the anterior cingulate cortex (ACC) and the dorsolateral prefrontal cortex (DLPFC). The evidence from combined imaging and neuropsychological studies supports the involvement of the ACC, but is less clear in the case of the DLPFC. However, the limited number of such studies conducted to date means that conclusions must be tentative and further studies employing this combined approach may be of great value.

Animals↗

PubMed1988

Prefrontal representation of stimulus attributes during delay tasks. I. Unit activity in cross-temporal integration of sensory and sensory-motor information.

The activity of 294 single units was recorded from the dorsolateral prefrontal cortex of monkeys performing two visual discrimination tasks with delayed response. One task, delayed matching-to-sample (DMS), required memory of a colored cue for later (18 s) matching and choice of color; the cue did not connote the location of the delayed response. The other task, delayed conditional position discrimination (DCPD), required memory of a colored cue for later (18 s) choice of spatial response; the cue did connote delayed-response location. All 4 cues (red and green in DMS, yellow and blue in DCPD) were isoluminous and appeared in identical location at trial start. Differential unit reactions to the two DCPD cues were more common than those to the two DMS cues (samples). During the delay period, 15% of all units showed, in one task or the other, differential discharge depending on the cue. In DCPD, a large proportion of the units showing direction-related activity at the time of motor response also reacted with a firing frequency change to one or both (spatially identical) trial-initiating cues. Some units showed coherence of cue-related and response-related changes in accord with the behavioral association between color and direction of response (i.e., yellow-right, blue-left). The reactivity of some units was correlated with the behavioral performance of the tasks in terms of correctness or incorrectness of response. The results indicate that, during visual delay tasks, neurons in the dorsolateral prefrontal cortex may process both spatial and non-spatial information. Because of their protracted differential discharge between cue and response (i.e., during the delay), some units seem involved in the transfer of sensory information across time. These findings suggest the role of prefrontal neurons in the representation of multiple attributes of sensory stimuli, including their associated motor connotations, and the overlap of the cortical representations of different attributes. They are also consistent with the role of the prefrontal cortex in the cross-temporal mediation of sensory-motor contingencies and, therefore, the temporal organization of behavior.

Animals↗

PubMed1994

Encoding of behavioral significance of visual stimuli by primate prefrontal neurons: relation to relevant task conditions.

Single-unit activity was recorded from the inferior dorsolateral prefrontal cortex of two monkeys while they performed a symmetrically rewarded go/no-go discrimination task. Three different task conditions were used in which the monkeys had to base their response on (1) the color, or (2) the shape, or (3) the position of a cue that was presented during fixation of a light spot. The colors of the fixation spot informed the monkeys which condition was relevant. The monkeys had to make an immediate release (go) or a delayed release (no-go) at the time of the fixation color change (imperative stimulus) depending on the currently relevant condition and the discriminative cue previously presented. The effect of changing the relevant condition on neuronal responses to the discriminative cue was analyzed. Out of 328 neurons tested in two or three conditions, 249 responded differentially at the cue period depending on the particular behavioral meaning of the stimulus (go or no-go) in at least one of the task conditions. This differential cue-period activity was examined across the different task conditions: the majority of neurons (111/154, 72%) showed such activity in all three conditions. In the remaining 43 neurons (28%) the differential activity was observed in two conditions (27/154, 18%) or in one condition (16/154, 10%). A few neurons (n = 7) showed feature-specific cue-period activity. In addition, 27 neurons displayed condition-dependent anticipatory activity prior to the cue onset. It is suggested that neurons in the inferior dorsolateral prefrontal cortex may participate in the conversion of sensory information from different visual channels into behavioral information (information on the upcoming response).

Animals↗

PubMed2004

Neural correlates of switching set as measured in fast, event-related functional magnetic resonance imaging.

Attentional switching has shown to involve several prefrontal and parietal brain regions. Most cognitive paradigms used to measure cognitive switching such as the Wisconsin Card Sorting Task (WCST) involve additional cognitive processes besides switching, in particular working memory (WM). It is, therefore, questionable whether prefrontal brain regions activated in these conditions, especially dorsolateral prefrontal cortex (DLPFC), are involved in cognitive switching per se, or are related to WM components involved in switching tasks. Functional magnetic resonance imaging (fMRI) was used to examine neural correlates of pure switching using a paradigm purposely designed to minimize WM functions. The switching paradigm required subjects to switch unpredictably between two spatial dimensions, clearly indicated throughout the task before each trial. Fast, event-related fMRI was used to compare neural activation associated with switch trials to that related to repeat trials in 20 healthy, right-handed, adult males. A large cluster of activation was observed in the right hemisphere, extending from inferior prefrontal and pre- and postcentral gyri to superior temporal and inferior parietal cortices. A smaller and more caudal cluster of homologous activation in the left hemisphere was accompanied by activation of left dorsolateral prefrontal cortex (DLPFC). We conclude that left DLPFC activation is involved directly in cognitive switching, in conjunction with parietal and temporal brain regions. Pre- and postcentral gyrus activation may be related to motor components of switching set.

Adult↗

PubMed1997

Differential activation of the caudate nucleus in primates performing spatial and nonspatial working memory tasks.

The caudate nucleus is part of an anatomical network subserving functions associated with the dorsolateral prefrontal cortex (DLPFC). The aim of the present study was to investigate whether the metabolic activity in the striatum reflects specific changes in working memory tasks, which are known to be dependent on the DLPFC, and whether these changes reflect the topographic ordering of prefrontal connections within the striatum. Local cerebral glucose utilization (LCGU) rates were assessed in the striatum by the 14C-2-deoxyglucose method in monkeys that performed a spatial (delayed spatial alternation), a nonspatial (delayed object alternation) visual working memory task, or tasks that did not involve working memory, i.e., a visual pattern discrimination or sensorimotor paradigm. The results show a topographic segregation of activation related to spatial and nonspatial working memory, respectively. The delayed spatial alternation task increases LCGU rates bilaterally by 33-43% in the head of the caudate nucleus, where efferents from the dorsolateral prefrontal cortex project most densely. The delayed object alternation task enhances LCGU rates bilaterally by 32-37% in the body of the caudate nucleus, which is innervated by the temporal cortex. The visual pattern discrimination task similarly activated the body of the caudate, but in a smaller region and only in the right hemisphere. These findings provide the first evidence for metabolic activation of the caudate nuclei in working memory, supporting the role of this nucleus as a node in a neural network mediating DLPFC-dependent working memory processes. The double dissociation of activation observed suggests an anatomical and functional segregation of cortico-striatal circuits subserving spatial and nonspatial cognitive operations.

Animals↗

PubMed1993

Association of working memory deficit and eye tracking dysfunction in schizophrenia.

This study replicates our earlier findings that schizophrenic but not bipolar patients are impaired on oculomotor delayed response tasks, analogous to those used to assess spatial working memory functions of the dorsolateral prefrontal cortex (DLPFC) in monkeys (Park and Holzman, 1992). In addition, we examined the relation between working memory deficits and smooth pursuit eye movement (SPEM) dysfunction, since data from human neuropsychological and animal lesion studies implicate prefrontal pathology in both deficits. Schizophrenic patients showed marked deficits in the oculomotor memory task and the SPEM task relative to the control groups. However, they were not impaired on the oculomotor sensory task in which their responses were guided by external cues rather than by working memory. This result from outpatients replicates our earlier study which was conducted with inpatients. Within the schizophrenic group those patients with good eye tracking performed better than those with impaired pursuit on the oculomotor memory task but there was no correlation between SPEM and performance on the sensory task. These findings support the hypothesis that schizophrenics show a deficit in representational processes and add to the growing evidence for involvement of the dorsolateral prefrontal cortex in schizophrenic pathology.

Attention↗

PubMed1974

The magnet reaction, a symptom of prefrontal ablation.

After bilateral ablation of the medial precruciate cortex in dogs and cats, or dorsolateral prefrontal cortex in monkeys, the animals approach the source of the conditional stimulus (CS) indicating availability of food either before or instead of approaching the food itself. This behavior is designated the "magnet reaction". It is particularly evident when the source of the CS is located in a direction different from that taken to reach the food. Lesions elsewhere in the frontal lobes do not produce this effect.

Animals↗