Neurophysiological Substrates Research Articles

Dreaming: A Neurocognitive Approach

The studies reported in the following articles are aimed at providing a comprehensive, detailed, and quantitative picture of cognition in human dreaming. Our main premises are that waking, REM sleep, and non-REM (NREM) sleep represent physiologically distinct and identifiable brain states and that the differences between waking, REM, and NREM mentation reflect these physiological differences. We have studied dreams at a formal level of analysis and, in these papers, have studied the specific dream properties of emotions, bizarre transformations, scene shifts, and plot coherence, in adults and 4- to 10-year-old children, as part of a larger effort to map state-dependent mental phenomena back onto the varying neurobiological processes that must underlie them. We believe that such efforts will enhance our understanding not only of dreaming and its neurophysiological substrates, but also of the cognitive processes that dreaming shares with other unusual mental states.

Mechanisms of pain in angina pectoris--a critical review of the adenosine hypothesis.

Clinical characteristics: Angina pectoris represents a visceral pain caused by reversible myocardial ischemia. The majority of ischemic attacks are symptomless. When pain is manifested, it appears late during the ischemic event. The pain is complex in its quality and bears little relation to the region of myocardial ischemia. Pain shows a sensitive dependence on initial conditions suggesting a mechanism with deterministic chaotic dynamics for the association between myocardial ischemia and pain. Neurophysiological substrate: Ganglia are present within the heart, particularly in epicardial fat. The blood supply of intrinsic cardiac ganglia arises primarily from branches of the proximal coronary arteries. Both afferent and efferent neurons within the intrinsic cardiac nervous system exist, while the majority of neurons in that location may be local circuit neurons. Integration takes place not only in the intrinsic cardiac nervous system, but also in mediastinal, middle cervical, and stellate ganglia. Cardiac afferent receptors are also connected to cell bodies in dorsal root and nodose ganglia, as well as intrathoracic ganglia. Myocardial regions have no spatial representation in these ganglia. Adenosine, among a number of substances, can modulate the activity generated by cardiac afferent nerve endings and intrinsic cardiac neurons. Such effects appear to be exerted at A1 receptors. Adenosine as a pain messenger: During myocardial ischemia adenosine is released in large quantities into the interstitial space. The endothelium takes up the major amount of adenosine. Thus only small increments of adenosine are detected in the blood-stream. Given as an intravenous bolus to healthy volunteers or to patients with ischemic heart disease and angina pectoris, adenosine provokes angina pectorislike pain, which is similar to habitual angina pectoris with regard to quality and location. Pain is provoked in the absence of ECG signs of ischemia. Patients with asymptomatic myocardial ischemia are less sensitive to adenosine, whereas patients with Syndrome X are more sensitive with respect to adenosine-provoked pain. When adenosine is given intraarterially, including into the coronary arteries, pain is provoked in the corresponding vascular bed. Adenosine-provoked pain and ischemic pain are counteracted by previous administration of the adenosine receptor antagonist theophylline.(ABSTRACT TRUNCATED AT 400 WORDS)

Consciousness, Volition, and the Neuropsychology of Facial Expressions of Emotion

Although we have learned much about the neuropsychological control of facial expressions of emotion, there is still much work to do. We suggest that future work integrate advances in our theoretical understanding of the roles of volition and consciousness in the elicitation of emotion and the production of facial expressions with advances in our understanding of its underlying neurophysiology. We first review the facial musculature and the neural paths thought to innervate it, as well as previous attempts at understanding the neural control of facial expressions of emotion, focusing on the voluntary-involuntary dichotomy and studies of hemispheric specialization. In the second section, we discuss four major aspects of the psychology of facial expressions of emotion that have particular import to their neurophysiological substrates. We offer these as a starting point for a better integration of psychological and neurophysiological perspectives in considering the neuropsychological control of facial expressions of emotion.

Evolutionary epistemology as an overlapping, interlevel theory

I examine the branch of evolutionary epistemology which tries to account for the character of cognitive mechanisms in animals and humans by extending the biological theory of evolution to the neurophysiological substrates of cognition. Like Plotkin, I construe this branch as a struggling science, and attempt to characterize the sort of theory one might expect to find this truly interdisciplinary endeavor, an endeavor which encompasses not only evolutionary biology, cognitive psychology, and developmental neuroscience, but also and especially, the computational modeling of “artificial life” programming; I suggest that extending Schaffner's notion of interlevel theories to include both “horizontal” and “vertical” levels of abstraction best fits the theories currently being developed in cognitive science. Finally, I support this claim with examples drawn from computational modeling data using the genetic algorithm.

Echoes of pain

Any episode of pain is characterized by a complex sequence of events and opportunities to observe them. Explorations of the neurophysiological and biochemical substrates of the experience have been exciting and fruitful over the past several decades. As well, experiential, behavioral, and social parameters are beginning to enjoy the detailed attention required if scientific and clinical objectives of understanding and control are to be achieved. The behavioral perspective, effectively summarized and examined by Keefe and Dunsmore, provides a rigorous intellectual tool for focusing attention upon those overt manifestations of pain that permit inferences about its severity and subjective qualities. It is no surprise that the behavioral paradigm was brought to bear upon pain. While it has its detractors and deficiencies, it does have a long tradition, primarily in North America, and the past three decades have seen the majority of psychologists embrace it, in either its behavioral or more recent cognitive/behavioral form, or incorporate it into an eclectic formulation of human behavior. Many clinicians and scientists interested in pain have ably represented this point of view, but none has been so successful in bringing it to bear upon the development of treatment programs as Fordyceg or upon a sophisticated research program using measurement skills as Keefe. I find it difficult not to respond favorably to the position and most of the details articulated in the Keefe and Dunsmore paper, for the reasons given as well as others. Given that conscious experience cannot be observed directly, whether adopting the behavioral perspective or not, verbal and nonverbal behavior provide the most accessible means of inference about

Seasonality in Psychiatry — A Review*

This paper reviews the literature pertaining to seasonal patterns in psychiatric illnesses. Evidence on the season of birth phenomenon suggests that a greater risk of pre-, peri-, or post-natal damage is associated with the winter months. There is currently insufficient evidence to pinpoint the exact mechanism involved or to ascertain whether the mechanism is common to each condition. Studies of seasonal patterns of incidence of psychiatric disorders have highlighted the role of seasonally regulated environmental factors on internal biological processes. There is growing evidence that serotonin is involved in a variety of psychiatric disorders. Seasonal patterns have been observed in processes involving serotonergic functioning. Furthermore, it has been postulated that these processes may be influenced by photoperiod, suggesting that the seasonal patterns of incidence of several psychiatric conditions may share a common neurophysiological substrate.

Les hallucinations musicales

Musical hallucinations are rarely reported. Acquired deafness play an important role in their development. The anatomical and neurophysiological substrates for the musical hallucinations are unknown. Most authors related the perceptual disturbance to organic origin (central or peripheral).

Surgical Management of Pain

This article presents an overview of the neuroanatomical, neurochemical, and neurophysiological substrates of nociception relevant to the neurosurgical treatment of chronic pain. Consideration is given to the various procedures currently employed in the treatment of patients suffering from medically intractable chronic pain of both benign and malignant diseases, including their indications, techniques, and results. Particular attention is given to the modern neuroaugmentative methods, such as electrical stimulation and CNS drug infusion, that are progressively overshadowing the previously developed ablative procedures.

Neurocognitive deficits of alcoholism: An intervention

This study investigated the impact of cognitive retraining on a sample of neurocognitively impaired alcoholics (N = 45). The treatment group received training on a hierarchical cumulative learning program. In this paradigm, the subjects mastered an isolated concept to automaticity, at which point a second and then a third concept were added. The training group demonstrated significantly improved performance over the practice and control groups on the three measures taken from the Wisconsin Card Sorting Test: total number of categories, perseverative errors, and nonperseverative errors. Neither the practice nor the control group exhibited significantly improved performance. These data lend support to an information processing perspective and are at odds with research that infers that neurophysiological substrates preclude normal functioning in alcoholics and argues that mere exposure of alcoholics to training stimuli prompts significant improvements. Treatment implications are discussed.

Electroencephalographic and evoked potential methods in human marihuana research: Historical review and future trends

AbstractThe sensitivity of electroencephalographic (EEG) signals to variables affecting brain neurophysiological substrate is briefly reviewed. Because this sensitivity extends to numerous pharmacological compounds with central nervous system (CNS) effect, it is suggested that EEG methods may also be useful in studies of human marihuana exposure. EEG investigations of marihuana are grouped by the type of research strategy employed and, within each grouping, the review summarizes salient reported findings as well as methodological issues of concern. The value of using quantitative methods of EEG analyses under blind conditions is stressed. Recent technological developments permitting topographic brain mapping of quantitative EEG variables are described as offering promise for marihuana research and some examples are given. Finally, evoked potential findings in studies of marihuana exposure are reviewed.

The Circadian System and Affective Disorders: Clocks or Rhythms?

There have been a number of proposals that a pathology of the circadian system involving clock functioning underlies the affective disorders. It is argued that neither current findings from research into the neurophysiological substrates of the affective disorders, recent clinical findings regarding these illnesses or their phenomenology support such a contention. This does not mean however that there is not a primary pathological disturbance of the circadian system at the heart of the affective disorders. The same neurophysiological, phenomenological and clinical evidence can be offered in favour of a disturbance of circadian rhythms in the presence of grossly normal clock functioning. The research and remedial implications of this alternative are outlined briefly.

Diagnostic criteria for the hyperventilation syndrome

Hyperventilation is defined as a ventilation in excess of the metabolic needs of the body; therefore hypocapnia is the essential criterium for this condition. The diagnosis “Hyperventilation Syndrome” (HVS) is made in the absence of somatic causes for hyperventilation, together with the presence of a characteristic set of complaints. In patients afflicted by this syndrome, the normal homeostatic mechanism for control of ventilation and of a normal PCO2 is disturbed or “overruled” by other respiratory drives. This disturbance of normal ventilatory control has various aspects, and possible neurophysiological substrates. Understanding these pathophysiological mechanisms facilitates establishing the diagnosis HVS. In normal resting situations the ventilatory rhythm is generated in the “respiratory centres” in the pons and medulla oblongata, and controlled by a chemical feedback loop for the PCO2-pH homeostatis of the organism. The activity of the medullary respiratory neuronal organisation can be stimulated from various other structures in the central nervous system (Fig. 1).

Application of Dual Brain Theory to Cross-Cultural Studies of Cognitive Development and Education

The cognitive structures of children from minority group, poor, rural, aboriginal, or otherwise socially disadvantaged backgrounds are hypothesized to be gestalt-synthetic in mode of thought and field-dependent in cognitive style; cognitive structures of children from dominant, majority, urban, nonaboriginal, or otherwise advantaged backgrounds, to be relatively logical-analytic and field-independent. These cognitive structures are shown by cerebral lateralization theory to have neurophysiological substrates. Individual hemisphericity, the tendency to rely on the resources of the right or left cerebral hemisphere, is interpreted on four distinct levels: performance hemisphericity, hemispheric activation, hemispheric preference (as personality structure), and cognitive style (lateral flexibility). An illustrative comparison of thinking processes of Australian Aborigines and Australian-born whites is developed using primary and secondary data.

Adaption Versus Phylogeny: The Role of Animal Psychology in The Study of Human Behavior

Advocates of Darwinian approaches to the study of behavior are divided over what an evolutionary perspective is thought to entail. Some take "evolution-mindedness" to mean "phylogeny-mindedness," whereas others take it to mean "adaptationmindedness." Historically, comparative psychology began as the search for mental continuities between humans and other animals: a phylogenetic approach. Independently, ethologists and now behavioral ecologists have placed far more emphasis on the nichedifferentiated mental abilities unique to the species being investigated: an adaptive approach. We argue that the output of complex, dynamical systems can be dramatically changed by only minor changes in internal structure. Because selection acts on the consequences of behavior, the behavioral output of the psyche will be easily shaped by adaptive demands over evolutionary time, even though the modification of the neurophysiological substrate necessary to create such adaptive changes may be minor. Thus, adaptation-mindedness will be most illuminating in the study of cognition and behavior, whereas phylogeny-mindedness will be most illuminating in the study of their neurophysiological substrates. Similarly, a phylogenetic approach to cognition and behavior is likely to cause one to overlook our most interesting, complexly designed species-typical traits, whereas using animal psychology to exfoliate general principles of behavioral ecology represents our best hope of understanding humanity's many zoologically unique characteristics.

Auditory event related potentials in violent and nonviolent prisoners.

The neurophysiologic substrates of violence and aggression have been extensively studied. Although the EEG is often normal in violent persons any abnormalities are generally nonspecific in nature. Evoked potentials have been infrequently used to study such behavior disorders. Long latency auditory event-related potentials (AEPs) were studied in prison inmates incarcerated for unmotivated violent crimes or violence during the commission of other crimes, and in prisoners jailed for non-violent offenses. Habitually violent inmates were compared with an equal number of non-violent prisoners and neurologically and audiologically intact controls. AEPs were recorded to an "oddball" paradigm from vertex and left and right temporal electrodes. None of the prisoners had latencies more than 3 standard deviations beyond the normal group mean. N1 and P2 components were longer in latency and lower in amplitude in prisoners than in controls, but this was not statistically significant. Violent and non-violent individuals did not differ in these measures. P3 was significantly prolonged in latency in violent inmates, but not in those who had committed a violent act. All components were longer in latency on the right in violent prisoners, while amplitudes were lower but not significantly so. This asymmetry was not present in non-violent prisoners or control subjects. Caution is needed in identifying differences between criminals and the general population, and in seeking markers of violent behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Chapter 17 Synergistic interactions and functional working range of the visual and vestibular systems in postural control: neuronal correlates

Comparisons between experimental data on visual-vestibular convergences at the neural, motor and perceptual levels yield the following conclusions: (1) synergistic interactions between congruent visual and vestibular signals improve velocity coding during low-frequency and steady-state body motion; (2) visual signals generally predominate over vestibular signals in the low frequency range, while the contrary applies in the higher frequency range of movement; (3) visual and vestibular inputs might be weighted depending on their internal relevance. These common interaction characteristics suggest that visual and vestibular modulation of activity in vestibular neurons might constitute at least part of the neurophy-siological substrate for visual-vestibular cooperation in postural regulation and self-motion perception. In fact, it is well known that the vestibular nuclei are involved in motor control through vestibulospinal influences [22,26,34], Nevertheless visual-vestibular convergences have been found to occur in numerous nervous structures such as the superior colliculus [8], the cerebellum [21,33], and the primary visual cortex [24,29] as well as in the vestibular cortical area [12]. Systematic investigations on the way the two modalities interact in these structures would help to determine whether the complex interactions described in this review actually take place within the vestibular nuclei or are simply reflected there after being integrated in other nervous structures.

Neuroleptic reduction of cocaine-induced paranoia but not euphoria?

Central dopaminergic activation is hypothesized to underly schizophrenia and, paradoxically, stimulant euphoria. Four cocaine abusers with histories of stimulant-induced paranoid psychoses reported selective reduction in psychotic symptoms but not euphoria when treated with dopamine blockers. This provides preliminary evidence against efficacy of neuroleptics in cocaine abuse prevention, and suggests euphoria and paranoia may have discriminable neurophysiological substrates.

Olfactory responses in the gustatory area of the parabrachial pons

Electrophysiological responses to olfactory and gustatory stimuli were recorded in the same neural elements in the parabrachial nuclei (PbN) of rats under Flaxedil. Responses to olfactory stimuli varied in temporal pattern and magnitude from responses to gustatory stimuli. Intravenous infusion of Nembutal while recording from one unit appeared to alter the pattern of responsiveness across stimuli. Most importantly the response to one olfactory stimulus (vanilla) was eliminated by this procedure. Olfactory-gustatory elements were located in the lateral portion of the tasteresponsive area of the PbN, just below the brachium conjunctivum. These results suggest that the PbN receives input from both olfactory and gustatory pathways and that these pathways may converge on the same neural elements within the PbN. This convergence may be part of a neurophysiological substrate for the perception of flavor.

Stability of pathway-hemisphere differences in the auditory event-related potential (ERP) to monaural stimulation.

ABSTRACTThe evidence for ERP manifestations of contralateral dominance in the auditory pathways is not entirely compelling. The effect when found has involved either latency or amplitude of a variety of components obtained from averaged or subtraction waveforms. Also, the effect appears to have as much to do with hemisphere as pathway differences. The objectives of this experiment were to establish whether a specific ERP peak reflected contralateral dominance, to assess its long‐term stability, and to clarify the apparent pathway‐hemisphere interactions which result from monaural stimulation. Ten male subjects were tested on 6 occasions (generally weekly intervals). On each occasion, 76 monaural tones were presented while EEG was recorded at C2, P2, T3, and T4 referred to linked earlobes. P70, N120, and P200 peak amplitudes and latencies and N1–P2 amplitudes were examined. N120 amplitudes proved to be larger at the temporal site contralateral to the ear stimulated. This contralateral dominance effect was observed on all 6 occasions for right ear stimuli and on all but one occasion for left ear stimuli. N1–P2 amplitudes less reliably reflected contralateral dominance because possible hemisphere effects appeared with this measure. Methodological issues related to assessment of ERP contralateral dominance and to the variety of effects seen in the literature are discussed. The data are examined with reference to neurophysiological substrates thought to underlie auditory ERPs. Finally, the utility of a stable ERP phenomenon in assessing drug or pathology effects is evaluated.

Suicide and the dexamethasone suppression test in adolescence

The identification and treatment of adolescents at risk for suicide is one of the most critical issues in adolescent psychiatry. Suicide is the third leading cause of death in the age group and its prevalence appears to be rising (Holinger, 1978). Clinicians see many adolescents with suicidal thoughts or behavior, however, who are not all equally at risk for future lethal attempts. While demographic, diagnostic, and other clinical factors are helpful in identifying adolescents at risk for suicide (Carlson and Cantwell 1982; Garfinkle et al. 1982; Robbins and Alessi 1983) such factors remain limited in their ability to identify individuals at greatest risk (Pokorny 1983). A biological marker of current or future risk for suicide could be an important adjunct to the clinician confronting this dilemma. Furthermore, study of biological markers may help us towards an understanding of the neurophysiological substrates of severe dysphoric mood states. Carroll (1982) has reported an association of nonsuppression in the dexamethasone suppression test (DST) with severe or lethal suicide attempts in adults. Three other groups also observed DST nonsuppression in patients hospitalized for suicide attempts or who subsequently