The functional architecture of the object vision pathway in the human brain was investigated using functional magnetic resonance imaging to measure patterns of response in ventral temporal cortex while subjects viewed faces, cats, five categories of man-made objects, and nonsense pictures. A distinct pattern of response was found for each stimulus category. The distinctiveness of the response to a given category was not due simply to the regions that responded maximally to that category, because the category being viewed also could be identified on the basis of the pattern of response when those regions were excluded from the analysis. Patterns of response that discriminated among all categories were found even within cortical regions that responded maximally to only one category. These results indicate that the representations of faces and objects in ventral temporal cortex are widely distributed and overlapping.

The neural networks that putatively modulate aspects of normal emotional behavior have been implicated in the pathophysiology of mood disorders by converging evidence from neuroimaging, neuropathological and lesion analysis studies. These networks involve the medial prefrontal cortex (MPFC) and closely related areas in the medial and caudolateral orbital cortex (medial prefrontal network), amygdala, hippocampus, and ventromedial parts of the basal ganglia, where alterations in grey matter volume and neurophysiological activity are found in cases with recurrent depressive episodes. Such findings hold major implications for models of the neurocircuits that underlie depression. In particular evidence from lesion analysis studies suggests that the MPFC and related limbic and striato-pallido-thalamic structures organize emotional expression. The MPFC is part of a larger ''default system'' of cortical areas that include the dorsal PFC, mid-and posterior cingulate cortex, anterior temporal cortex, and entorhinal and parahippocampal cortex, which has been implicated in self-referential functions. Dysfunction within and between structures in this circuit may induce disturbances in emotional behavior and other cognitive aspects of depressive syndromes in humans. Further, because the MPFC and related limbic structures provide forebrain modulation over visceral control structures in the hypothalamus and brainstem, their dysfunction can account for the disturbances in autonomic regulation and neuroendocrine responses that are associated with mood disorders. This paper discusses these systems together with the neurochemical systems that impinge on them and form the basis for most pharmacological therapies.The World Health Organization ranks major depressive disorder (MDD) and bipolar disorder (BD) as the first and fifth leading causes of years lived with disability (WHO 2001), respectively, yet almost nothing is known about their pathogenesis. Because these conditions were not associated with gross brain pathology or with clear animal models for spontaneous, recurrent mood episodes, the availability of tools allowing noninvasive assessment of the human brain proved critical to elucidating their neurobiology. The recent development of neuroimaging technologies that permit in vivo characterization of the anatomical, physiological and neurochemical correlates of mood disorders thus has enabled significant advances toward illuminating the pathophysiology of these conditions. Notably, the results of neuroimaging studies and the post mortem studies that have been guided by neuroimaging results have given rise to neurocircuitry-based models in which both functional and structural brain pathology play roles in the development of mood disorders.The symptomatology of the clinical syndrome shared by MDD and BD, namely the major depressive episode, implicates brain systems involved in the regulation of mood and emotional expression,

We investigated whether the topographically organized, categoryrelated patterns of neural response in the ventral visual pathway are a representation of sensory images or a more abstract representation of object form that is not dependent on sensory modality. We used functional MRI to measure patterns of response evoked during visual and tactile recognition of faces and manmade objects in sighted subjects and during tactile recognition in blind subjects. Results showed that visual and tactile recognition evoked category-related patterns of response in a ventral extrastriate visual area in the inferior temporal gyrus that were correlated across modality for manmade objects. Blind subjects also demonstrated category-related patterns of response in this ''visual'' area, and in more ventral cortical regions in the fusiform gyrus, indicating that these patterns are not due to visual imagery and, furthermore, that visual experience is not necessary for category-related representations to develop in these cortices. These results demonstrate that the representation of objects in the ventral visual pathway is not simply a representation of visual images but, rather, is a representation of more abstract features of object form.haptic perception ͉ fMRI ͉ supramodal cortex

Context Major depressive disorder (MDD) is associated with behavioral and neurophysiological evidence for mood-congruent processing biases toward explicitly presented, emotionally-valenced stimuli. However, few studies have investigated such biases toward implicitly presented stimuli. Objective To investigate differential amygdala responses to sad, happy and neutral faces presented below the level of explicit conscious awareness using a backward masking task in unmedicated subjects with MDD and healthy controls. Design Initial cross-sectional design followed by a longitudinal treatment trial using functional magnetic resonance imaging. Setting Psychiatric outpatient clinic at the National Institute of Mental Health. Participants Twenty-two unmedicated, currently-depressed subjects with MDD (dMDD), 16 unmedicated subjects with MDD in full remission (rMDD), and 25 healthy controls (HC). Interventions Ten dMDD subjects underwent 8 weeks of antidepressant treatment with the selective serotonin reuptake inhibitor, sertraline. Main Outcome Measures Amygdala region-of-interest and whole brain analyses evaluated the hemodynamic response during exposure to masked-sad versus masked-happy faces, to masked-sad versus neutral faces, and to masked-happy versus neutral faces. Results dMDD subjects showed greater amygdala responses than HC to masked-sad faces, while HC subjects showed greater amygdala responses to masked-happy faces. The bias toward sad faces also was evident in the rMDD relative to HC subjects and did not differ between the dMDD and rMDD subjects. This processing bias reversed toward the normative pattern in the dMDD subjects following sertraline treatment. Conclusions Emotional processing biases occur in the amygdala to sad faces presented below conscious awareness in currently-depressed or remitted-MDD subjects and to happy faces in controls. By influencing the salience of social stimuli, mood-congruent processing biases in the amygdala may contribute to dysfunction in conscious perceptions and social interactions in MDD. Our data suggest, however, that the negative bias resolves and a positive bias develops in MDD subjects during selective serotonin reuptake inhibitor treatment.

Context-The need for improved therapeutic agents that more quickly and effectively treat depression is critical. In a pilot study we evaluated the role of the cholinergic system in cognitive symptoms of depression and unexpectedly observed rapid reductions in depression severity following the administration of the antimuscarinic drug scopolamine hydrobromide (4 μg/kg intravenously) compared with placebo (P=.002). Subsequently a clinical trial was designed to assess more specifically the antidepressant efficacy of scopolamine.Objective-To evaluate scopolamine as a potential antidepressant agent.Design-Two studies were conducted: a double-blind, placebo-controlled, dose-finding study followed by a double-blind, placebo-controlled, crossover clinical trial. Setting-The National Institute of Mental Health.Patients-Currently depressed outpatients aged 18 to 50 years meeting DSM-IV criteria for recurrent major depressive disorder or bipolar disorder. Of 39 eligible patients, 19 were randomized and 18 completed the trial.Interventions-Multiple sessions including intravenous infusions of placebo or scopolamine hydrobromide (4 μg/kg). Individuals were randomized to a placebo/ scopolamine or scopolamine/ placebo sequence (series of 3 placebo sessions and series of 3 scopolamine sessions). Sessions occurred 3 to 5 days apart.Main Outcome Measures-Psychiatric evaluations using the Montgomery-Asberg Depression Rating Scale and the Hamilton Anxiety Rating Scale were performed to assess antidepressant and antianxiety responses to scopolamine.Results-The placebo/scopolamine group showed no significant change during placebo infusion vs baseline; reductions in depression and anxiety rating scale scores (P<.001 for both) were observed after the administration of scopolamine compared with placebo. The scopolamine/ placebo group also showed reductions in depression and anxiety rating scale scores (P<.001 for both) after the administration of scopolamine, relative to baseline, and these effects persisted as they received placebo. In both groups, improvement was significant at the first evaluation after scopolamine administration (P≤.002).Conclusion-Rapid, robust antidepressant responses to the antimuscarinic scopolamine occurred in currently depressed patients who predominantly had poor prognoses.Correspondence: Maura L. Furey, PhD, Mood and Anxiety Disorders Program, National Institute of Mental Health, National Institutes of Health, 15K North Dr, Bldg 15K, Room 115B, Bethesda, MD 20892 (mfurey@mail.nih.gov). Additional Information: A use-patent application for the use of scopolamine as an antidepressant agent has been filed. NIH Public Access Author ManuscriptArch Gen Psychiatry. Author manuscript; available in PMC 2012 January 3. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptMajor depression is the leading cause of years lived with disability. 1 A range of antidepressant agents is available, but 30% to 40% of patients with major depressive disorder (MDD) do not respond to initial treatment, 2 an...

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

Using functional magnetic resonance imaging, we investigated the mechanism by which cholinergic enhancement improves working memory. We studied the effect of the cholinesterase inhibitor physostigmine on subcomponents of this complex function. Cholinergic enhancement increased the selectivity of neural responses in extrastriate cortices during visual working memory, particularly during encoding. It also increased the participation of ventral extrastriate cortex during memory maintenance and decreased the participation of anterior prefrontal cortex. These results indicate that cholinergic enhancement improves memory performance by augmenting the selectivity of perceptual processing during encoding, thereby simplifying processing demands during memory maintenance and reducing the need for prefrontal participation.

Background We previously reported that intravenous scopolamine administration produced rapid and robust antidepressant effects in a sample consisting of both unipolar and bipolar depressives. The present study aimed to replicate this finding in an independent sample limited to unipolar depressives. Methods Outpatients with major depressive disorder (MDD) (n=23; 22 were included in analyses) participated in a double-blind, placebo-controlled, cross-over trial. Subjects were randomized into either a P/S or S/P sequence [P=block of three placebo sessions; S= block of three scopolamine sessions (4.0 μg/kg i.v.)]. Sessions occurred 3-to-5 days apart, such that time spent in each block lasted 1½-2 weeks and the interval between blocks was 3 to 5 days. The Montgomery-Asberg Depression Rating Scale (MADRS) served as the primary outcome measure. Results Following the initial block the group receiving scopolamine first (S/P) showed a 32 percent reduction in MADRS scores (p<0.001) which exceeded the corresponding change of 6.5 percent under placebo (P/S) (p=0.009), confirming the a priori hypothesis. Improvement was significant at the first evaluation that followed scopolamine administration (p=0.011). In block 2 the P/S group showed a 53 percent reduction in MADRS scores (p=0.001) following scopolamine versus placebo, while the reduction seen in S/P subjects who received scopolamine during block 1 persisted as they received placebo during block 2. Scopolamine induced drowsiness, blurred vision, dry mouth, light-headedness and reduced blood pressure, which were sufficiently well-tolerated that no subject dropped out due to side effects. Conclusions These results replicate previous finding that scopolamine produces a rapid and robust antidepressant response.