Prevalence,and intellectual outcome of unilateral focal cortical brain damage as a function of age,sex and aetiology

Neurologists and neuropsychologists are aware that aging men are more at risk than women for brain damage, principally because of the well known male-predominant risk for cardiovascular disease and related cerebrovascular accidents. However, a disproportion in prevalence of brain damage between the sexes in childhood may be less suspected. Furthermore, sex-specific risk for other aetiologies of brain damage may be little known, whether in the pediatric or adult populations. Proposals of a sex difference in cognitive recovery from brain damage have also been controversial. Six hundred and thirty five "consecutive" cases with cortical focal lesions including cases of all ages and both sexes were reviewed. Aetiology of the lesion was determined for each case as was postlesion IQ. Risk was highly male prevalent in all age groups, with a predominance of cardiovascular aetiology explaining much of the adult male prevalence. However, several other aetiological categories were significantly male prevalent in juveniles (mitotic, traumatic, dysplasic) and adults (mitotic, traumatic). There was no sex difference in outcome (i.e., postlesion IQ) of these cortical brain lesions for the cohort as a whole, after statistical removal of the influence of lesion extent, aetiology and presence of epilepsy. Mechanisms potentially responsible for sex differences in prevalence, aetiology of brain damage, and recovery, are reviewed and discussed.     

Differences in neuronal activity explain differences in memory forming abilities of different populations of Lymnaea stagnalis

The ability to learn and form long-term memory (LTM) can enhance an animal's fitness, for example, by allowing them to remember predators, food sources or conspecific interactions. Here we use the pond snail, Lymnaea stagnalis, to assess whether variability between natural populations (i.e., strains) in memory forming capabilities correlates with electrophysiological properties at the level of a single neuron, RPeD1. RPeD1 is a necessary site of LTM formation of aerial respiratory behaviour following operant conditioning. We used strains from two small, separate permanent ponds (TC1 and TC2). A comparison of the two populations showed that the TC1 strain had enhanced memory forming capabilities. Further, the behavioural phenotype of enhanced memory strain was explained, in part, by differences in the electrophysiology of RPeD1. Compared to RPeD1 from the naive TC2 strain, RPeD1 from the TC1 strain has both a decreased resistance and decreased excitability. Moreover, 24h after a single 0.5h training session, those membrane properties, as well as the firing and bursting rate, decrease further in the TC1 strain but not in the TC2 strain. The initial differences in RPeD1 properties in the TC1 strain coupled with their ability to further change these properties with a single training session suggests that RPeD1 neurons from the TC1 strain are "primed" to rapidly form memory.     

Is anorexia nervosa a neuropsychological disease?

Evidence for central nervous system, and more particularly cortical, etiology of anorexia nervosa is reviewed. Topics covered are neuropsychiatric comorbidity, inheritance patterns, the neurobiology of body-image disturbance and of the eating function, perinatal and alcoholic insult to the brain, neurochemical and neuroelectric disturbance, anatomic and metabolic brain imaging, and neuropsychological impairment. It is concluded that there is indeed an important neuropsychological etiological dimension to anorexia nervosa. The profile most frequently associated with anorexia nervosa is right posterior hypometabolism, followed by right anterior hypermetabolism, both associated with right-sided abnormal electroencephalogram spiking. It is also proposed that bulimia consists of a positive neurological subtype and that restricting anorexia represents a negative neurological subtype. Priorities for further research into anorexia nervosa are specified to include twin adoption studies, brain electrical topography studies, postmortem histological studies, and experimentally inspired neuropsychological studies.     

Sensory memory of illusory depth in structure-from-motion

When multistable displays (stimuli consistent with two or more equally plausible perceptual interpretations) are presented intermittently, their perceptions are stabilized by sensory memory. Independent memory traces are generated not only for different types of multistable displays (Maier, Wilke, Logothetis, & Leopold, Current Biology 13:1076–1085, 2003), but also for different ambiguous features of binocular rivalry (Pearson & Clifford, Journal of Vision 4:196–202, 2004). In the present study, we examined whether a similar independence of sensory memories is observed in structure-from-motion (SFM), a multistable display with two ambiguous properties. In SFM, a 2-D planar motion creates a vivid impression of a rotating 3-D volume. Both the illusory rotation and illusory depth (i.e., how close parts of an object appear to the observer) of an SFM object are ambiguous. We dissociated the sensory memories of these two ambiguous properties by using an intermittent presentation in combination with a forced-ambiguous-switch paradigm (Pastukhov, Vonau, & Braun, PLoS ONE 7:e37734, 2012). We demonstrated that the illusory depth of SFM generates a sensory memory trace that is independent from that of illusory rotation. Despite this independence, the specificities levels of the sensory memories were identical for illusory depth and illusory rotation. The history effect was weakened by a change in the volumetric property of a shape (whether it was a hollow band or a filled drum volume), but not by changes in color or size. We discuss how these new results constrain models of sensory memory and SFM processing.     

Inhibition of mTOR by rapamycin in the amygdala or hippocampus impairs formation and reconsolidation of inhibitory avoidance memory

Mammalian target of rapamycin (mTOR), a central regulator of protein synthesis in neurons, has been implicated in synaptic plasticity and memory. Here we show that mTOR inhibition by rapamycin in the basolateral amygdala (BLA) or dorsal hippocampus (DH) impairs both formation and reconsolidation of memory for inhibitory avoidance (IA) in rats. Male Wistar rats received bilateral infusions of vehicle or rapamycin into the BLA or DH before or after IA training or retrieval. Memory retention was tested at different time points after drug infusion. Rapamycin impaired long-term IA retention when given before or immediately after training or retrieval into the BLA. When infused into the DH, rapamycin produced memory impairment when given before training or immediately after retrieval. The impairing effects of post-retrieval rapamycin required memory retrieval and were not reversed by a reminder shock. The results provide the first evidence that mTOR in the BLA and DH might play a role in IA memory reconsolidation.     

Syntactic structure building in the anterior temporal lobe during natural story listening

The neural basis of syntax is a matter of substantial debate. In particular, the inferior frontal gyrus (IFG), or Broca’s area, has been prominently linked to syntactic processing, but the anterior temporal lobe has been reported to be activated instead of IFG when manipulating the presence of syntactic structure. These findings are difficult to reconcile because they rely on different laboratory tasks which tap into distinct computations, and may only indirectly relate to natural sentence processing. Here we assessed neural correlates of syntactic structure building in natural language comprehension, free from artificial task demands. Subjects passively listened to Alice in Wonderland during functional magnetic resonance imaging and we correlated brain activity with a word-by-word measure of the amount syntactic structure analyzed. Syntactic structure building correlated with activity in the left anterior temporal lobe, but there was no evidence for a correlation between syntactic structure building and activity in inferior frontal areas. Our results suggest that the anterior temporal lobe computes syntactic structure under natural conditions.     

Contours of time: topographic construals of past, present, and future in the Yupno valley of Papua New Guinea

Time, an everyday yet fundamentally abstract domain, is conceptualized in terms of space throughout the world's cultures. Linguists and psychologists have presented evidence of a widespread pattern in which deictic time-past, present, and future-is construed along the front/back axis, a construal that is linear and ego-based. To investigate the universality of this pattern, we studied the construal of deictic time among the Yupno, an indigenous group from the mountains of Papua New Guinea, whose language makes extensive use of allocentric topographic (uphill/downhill) terms for describing spatial relations. We measured the pointing direction of Yupno speakers' gestures-produced naturally and without prompting-as they explained common expressions related to the past, present, and future. Results show that the Yupno spontaneously construe deictic time spatially in terms of allocentric topography: the past is construed as downhill, the present as co-located with the speaker, and the future as uphill. Moreover, the Yupno construal is not linear, but exhibits a particular geometry that appears to reflect the local terrain. The findings shed light on how, our universal human embodiment notwithstanding, linguistic, cultural, and environmental pressures come to shape abstract concepts.     

Feeling before knowing why: The role of the orbitofrontal cortex in intuitive judgments—an MEG study

In theory, intuitive decisions are made immediately, without conscious, reasoned thought. They are experienced as decisions based on hunches that cannot be explicitly described but, nevertheless, guide subsequent action. Investigating the underlying neural mechanisms, previous research has found the orbitofrontal cortex (OFC) to be crucial to intuitive processes, but its specific role has remained unclear. On the basis of a two-stage conceptualization of intuition suggested by Bowers, Regehr, Balthazard, and Parker Cognitive Psychology, 22, 72-110 (1990), we attempt to clarify the OFC’s role in intuitive processing. We propose that it functions as an early integrator of incomplete stimulus input guiding subsequent processing by means of a coarse representation of the gist of the information. On the subjective level, this representation would be perceived as a (gut) feeling biasing the decision. Our aim in the present study was to test this neural model and rule out alternative explanations of OFC activation in intuitive judgments. We used magnetoencephalography (MEG) to record participants' electromagnetic brain responses during a visual coherence judgment task. As in earlier studies, the OFC was found to be activated when participants perceived coherence. Using MEG, it could be shown that this increase in activation began earlier in the OFC than in temporal object recognition areas. Moreover, the present study demonstrated that OFC activation was independent of physical stimulus characteristics, task requirements, and participants’ explicit recognition of the stimuli presented. These results speak to the OFC’s fundamental role in the early steps of intuitive judgments and suggest the proposed neural model as a promising starting point for future investigations.     

Personality Disorders Are Not as We Thought: Hierarchical Factor Structure at the Criterion Level

The use of personality disorder (PD) categories persists, despite the evidence against them. An often overlooked reason for this is the fact that the true structure underlying the Diagnostic and Statistical Manual of Mental Disorders (DSM) taxonomy is still unknown: We cannot be certain which disorders are valid, and which ones are arbitrary mixtures of heterogeneous traits. To address this gap, we factor analyzed the Personality Diagnostic Questionnaire (PDQ–4+; Hyler, 1994 Hyler, S. E. (1994). PDQ–4+ Personality Diagnostic Questionnaire–4+. New York, NY: New York State Psychiatric Institute. [Google Scholar]) at the criterion level in a mixed clinical and nonclinical sample of 2,519 individuals. The resulting structure was more similar to current dimensional taxonomies than to the DSM classification at all hierarchical levels. Whereas paranoid and antisocial PDs—and to a lesser extent avoidant, dependent, depressive, and schizoid PDs—were fairly homogeneous, all other disorders turned out to be combinations of 2 or 3 unrelated dimensions. Our results strongly support the structure of empirically based dimensional taxonomies and relocate DSM criteria within this emerging framework, thus contributing to preserving much of the knowledge accumulated to date.