Numerical Architecture

The idea that there is a “Number Sense” (Dehaene, 1997) or “Core Knowledge” of number ensconced in a modular processing system (Carey, 2009) has gained popularity as the study of numerical cognition has matured. However, these claims are generally made with little, if any, detailed examination of which modular properties are instantiated in numerical processing. In this article, I aim to rectify this situation by detailing the modular properties on display in numerical cognitive processing. In the process, I review literature from across the cognitive sciences and describe how the evidence reported in these works supports the hypothesis that numerical cognitive processing is modular. I outline the properties that would suffice for deeming a certain processing system a modular processing system. Subsequently, I use behavioral, neuropsychological, philosophical, and anthropological evidence to show that the number module is domain specific, informationally encapsulated, neurally localizable, subject to specific pathological breakdowns, mandatory, fast, and inaccessible at the person level; in other words, I use the evidence to demonstrate that some of our numerical capacity is housed in modular casing.     

Electrical and contractile consequences of Na+ or Ca2+ gradient reduction in cultured heart cells

The normal electrical and contractile activity of cultured neonatal rat ventricular cells is characterized and compared to activity seen in low [Ca²⁺]₀ and low [Na⁺]₀ solutions. In 0 Ca²⁺/0.5 mm EGTA solutions electrical activity is altered: the maximum diastolic potential (m.d.p.), maximum rate of rise ($\text{+}\text{V}\text{?}{}_{\mathrm{<mtext>max</mtext>}}$), and overshoot (o.s.) are reduced, while duration is increased. Low [Ca²⁺]₀ activity is insensitive to TTX and blocked by La³⁺. In low [Na⁺]₀ solutions electrical activity is generally absent; when present $\text{+}\text{V}\text{?}{}_{\mathrm{<mtext>max</mtext>}}$ and o.s. are decreased while duration is increased. Low [Na⁺]₀ activity is blocked by La³⁺. These data suggest the presence of one La³⁺-sensitive slow inward current channel. The absence of spontaneous electrical activity in low [Na⁺]₀ solutions suggests an inhibition of automaticity. To determine if this inhibition is due to a reduction of the Na⁺ gradient, drugs which raise [Na⁺]_i were examined. Both monensin (a Na⁺ ionophore) and ouabain inhibit the occurrence of spontaneous action potentials (cells respond to stimulation) indicating a dependence of pacemaker activity on a normal Na⁺ gradient. During Na⁺ gradient reduction, asynchronous subcellular contractile activity occurs independent of membrane potential fluctuation. This asynchronous activity is inhibited by La³⁺ or when Ca²⁺₀ is absent, but continues in the presence of verapamil (normal activity is blocked by all three conditions). The Na⁺Ca²⁺ exchange system is unaffected by verapamil but blocked by La³⁺, while both these drugs block the slow inward current. These data indicate that the Na⁺Ca²⁺ exchange system can directly supply Ca²⁺ (independent of electrical activity at the membrane) to intracellular sites that support contractile activity.     

Barium-induced spontaneous activity in sheep cardiac Purkinje fibers

We used intracellular microelectrodes to study the electrophysiological effects of low barium concentrations (1 ? 4 × 10 ⁵m) on sheep cardiac Purkinje fibers. The main effect of barium was an increase in action potential duration (APD) both at ?60 mV (APD_?60) and at 100% repolarization (APD₁₀₀). The prolongation of APD was greater at a lower (30/min) than at a higher driving rate (120/min). Barium significantly modified the normal linear relationship between driving rate and APD. The effects of barium on APD were enhanced by lowering [K⁺]₀ and antagonized by increasing [Ca²⁺]₀. Barium caused a slowing of phase 3 repolarization, a steepening of diastolic depolarization and induced spontaneous activity in the resting potential range during the interruption of the drive. The first spontaneous action potential was usually preceded by an oscillatory potential. By means of several procedures (lowering [K⁺]₀, increasing [Ca^2?]₀, increasing the driving rate) it was possible to identify two separate mechanisms underlying the initiation of spontaneous activity: (1) enhancement of normal diastolic depolarization and (2) induction of oscillatory afterpotentials. Finally, barium induced repetitive activity through early afterdepolarizations. We conclude that in Purkinje fibers low barium concentrations cause a lengthening of APD and can induce spontaneous activity by means of at least three different mechanisms. The main factor underlying the barium effects seems to be a reduction in potassium conductance.     

The role of Ca2+ release from sarcoplasmic reticulum in the regulation of sinoatrial node automaticity

Summary The role of Ca²⁺ release channels in the sarcoplasmic reticulum in modulating physiological automaticity of the sinoatrial (SA) node was studied by recording transmembrane action potentials and membrane ionic currents in small preparations of the rabbit SA node. Ryanodine, which modifies the conductance and gating behavior of the Ca²⁺ release channels, was used to block Ca²⁺ release from the sarcoplasmic reticulum. Superfusion of 1-mM ryanodine decreased the spontaneous firing frequency as well as the maximal rate of depolarization of the SA, and these reductions reached a steady state within approximately 5min. The action potential recordings revealed that the latter part of diastolic depolarization was depressed and that the take-off potential became less negative. This suggested that the negative chronotropic effect of ryanodine resulted from the blockade of physiological Ca²⁺ release from the sarcoplasmic reticulum. In voltage clamp experiments, using double-microelectrode techniques, ryanodine did not markedly reduce the Ca²⁺ current (I_Ca) but decreased the delayed rectifying K+ current (I_K), the steady-state inward current (I_ss), and the hyperpolarization-activated inward current (I_h). These observations suggest that, even when the function of Ca²⁺ channels in the cell membrane is normally maintained, depression of Ca²⁺ release channels in the sarcoplasmic reticulum would prevent sufficient elevation of the Ca²⁺ concentration in SA node cells for the activation of various ionic currents, and, thus adversely affect the physiological automaticity of this primary cardiac pacemaker.     

Alcohol-related effects on automaticity due to experimentally manipulated conditioning

Background: The use of alcohol is associated with various forms of automatic processing, such as approach tendencies and attentional biases, which may play a role in addictive behavior. The development of such automaticity has generally occurred well before subjects perform tasks designed to detect them. Although it seems plausible that this development involves some form of alcohol‐related conditioning, this process is not usually included in the experimental procedure. Methods: The development of automaticity involving alcoholic or nonalcoholic stimuli was experimentally manipulated via a conditioning task. Subjects were presented with pairs of stimuli from a set of 4 stimuli: 2 pictures of alcoholic beverages, and 2 pictures of nonalcoholic beverages. One of the alcoholic and 1 of the nonalcoholic beverages was associated with reward, the other stimuli with punishment. Subjects had to learn to select the rewarded stimuli from pairs of 1 rewarded and 1 punished stimulus. The task, thus experimentally established reward versus punishment stimulus–response–outcome associations, for alcoholic and for nonalcoholic stimuli. Subsequently, a cued reversal task was used to test automaticity involving alcoholic versus nonalcoholic, and rewarded versus punished stimuli. Results: An association was found between heavier drinking and an alcohol‐related conditioning bias: heavier drinkers had more difficulty overcoming a conditioned response when it involved selecting a previously punished nonalcoholic stimulus over a previously rewarded alcoholic stimulus. Conclusions: The study provided novel information on secondary reinforcement involving alcoholic stimuli: heavier drinkers may more easily develop automaticity related to alcohol‐reward contingencies. This may have implications for interventions and the interpretation of findings concerning alcohol‐related automatic processing.     

心房耳尖部持续性房性心动过速的临床特点和射频消融

目的：报道心房耳尖部房性心动过速（房速）的临床特点和射频消融结果。方法：对7例[男性2例，女性5例，平均年龄（24．8±7．9）岁]房速患者进行体表心电图和动态心电图检查。采用三维电解剖（Carto）标测系统，确定房速病灶的起源部位和指导经导管射频消融。结果：7例房速均为持续性发作（5～432个月，中位数96个月），未发现器质性心脏病。房速起源于右心房耳尖部（1例）和左心房耳尖部（6例），呈局灶性和异常自律性增高机制。7例房速均消融成功，无并发症。随访7～28个月（中位数15个月），无一例房速复发。结论：心房耳尖部房速表现为持续性发作和异常自律性增高机制。采用三维电解剖标测系统和盐水灌注消融导管，可提高病灶定位的准确性和消融的成功率。     

Transcutaneous auricular vagus nerve stimulation enhances learning of novel letter-sound relationships in adults

BackgroundReading is a critical skill in modern society but is significantly more difficult to acquire during adulthood. Many adults are required to learn a new orthography after this window closes for personal or vocational reasons and while many programs and training methods exist for learning to read in adulthood, none result in native-like fluency. Implantable cervical vagus nerve stimulation is capable of driving neural plasticity but is invasive and not practical as a reading intervention.ObjectiveThe goal of the current study was to evaluate whether non-invasive transcutaneous auricular vagus nerve stimulation (taVNS) is effective at enhancing novel orthography acquisition in young adults.MethodsWe enrolled 37 typically developing participants and randomly assigned them to a computer control, device sham control, earlobe stimulation control, or experimental transcutaneous auricular stimulation (taVNS) group. Participants then learned novel letter-sound correspondences in Hebrew over five training lessons. Performance was assessed using three measures to evaluate various aspects of reading: Letter ID, Automaticity, and Decoding.ResultsThe taVNS group significantly outperformed the three control groups on both the Automaticity and Decoding tasks. There was no difference on the Letter ID task.ConclusionsThese results demonstrate, for the first time, that taVNS is capable of improving aspects of reading acquisition in adults. These findings have potential implications for a wide range of cognitive tasks.     

Intact performance on an indirect measure of race bias following amygdala damage

Recent brain imaging and lesion studies provide converging evidence for amygdala involvement in judgments of fear and trust based on facial expression [Adolphs et al., Nature 393 (1998) 470; Adolphs et al., Neuropsychologia 37 (1999) 1111; Breiter et al., Neuron 17 (1996) 875; Winston et al., Nat. Neurosci. 5 (3) (2002) 277]. Another type of social information apparent in face stimuli is social group membership. Imaging studies have reported amygdala activation to face stimuli of different racial groups [Hart et al., NeuroReport 11 (11) (2000) 2351]. In White American subjects, amygdala activation to Black versus White faces was correlated with indirect, implicit measures of racial evaluation [Phelps et al., J. Cogn. Neurosci. 12 (5) (2000) 729]. To determine if the amygdala plays a critical role in indirect social group evaluation, as suggested by the imaging results, a patient with bilateral amygdala damage and control subjects were given two measures of race bias. All subjects were female, White Americans. The Modern Racism Scale (MRS) is a direct, self-report measure of race attitudes and beliefs. The Implicit Association Test (IAT) is an indirect, automatic evaluation task. Performance on the two tasks did not differ between the patient with amygdala damage and control subjects. All subjects showed a pro-Black bias on the direct, explicit measure of race beliefs, the MRS, and a negative evaluation towards Black faces on the indirect measure of race evaluation, the IAT. These results indicate that even though amygdala activation to Black versus White faces is correlated with performance on indirect measures of race bias [Phelps et al., J. Cogn. Neurosci. 12 (5) (2000) 729], the amygdala is not critical for normal performance on the IAT.     

碘杂环化合物对豚鼠心乳头肌生理特性的影响

本文研究了碘杂环化合物(IHC—64)对豚鼠心乳头肌生理特性的影响。IHC—64可抑制心肌收缩力、降低自律性、延长有效不应期,但不影响心肌兴奋性。IHC—64降低心肌收缩力与细胞外Ca~(2+)有关,并显著抑制高钾除极后异丙肾上腺素诱发的乳头肌收缩,对β受体无影响。初步表明IHC—64抗心律失常可能与拮抗Ca~(2+)有关。     

Do novices display automaticity during simulator training?

BACKGROUND: The objective of this study was to investigate whether novices improve their ability to develop multitask (ie, automaticity) with accumulating experience on a simulated laparoscopic task. METHODS: In this prospective study, novices (12 premed students) trained for 4 months in laparoscopic suturing. Simultaneously with suturing, participants performed a visual-spatial secondary task to assess their spare attentional capacity. Trainees were required to achieve expert-derived levels in both suturing (520 score) and the secondary task (target 73%). Their performance was assessed with objective scores, and their ability to multitask during training was examined. RESULTS: After 10 +/- 5 hours and 84 +/- 41 repetitions, participants demonstrated improvements in their suturing (70%, P < 0.001) and secondary-task performance (16%, P = 0.08) compared with their baseline scores. During the study period, 11 of 12 participants achieved suturing proficiency, but no one achieved secondary-task proficiency. Longer training times correlated with higher secondary-task scores (r = .68, P < 0.02), and participants who performed >100 repetitions (n = 4) achieved higher secondary-task scores (P < 0.03). COMMENTS: This study provides evidence for improved automaticity at advanced stages of simulator training. Although novices achieve simulator proficiency after relatively short training durations, the attainment of automaticity requires substantially longer training periods. Further study of this concept is warranted and is currently underway.