I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

Principles of Neural Science

Rationale: Since the mid-1970s, cross-species translational studies of prepulse inhibition (PPI) have increased at an astounding pace as the value of this neurobiologically informative measure has been optimized. PPI occurs when a relatively weak sensory event (the prepulse) is presented 30–500 ms before a strong startle-inducing stimulus, and reduces the magnitude of the startle response. In humans, PPI occurs in a robust, predictable manner when the prepulse and startling stimuli occur in either the same or different modalities (acoustic, visual, or cutaneous). Objective: This review covers three areas of interest in human PPI studies. First, we review the normal influences on PPI related to the underlying construct of sensori- (prepulse) motor (startle reflex) gating. Second, we review PPI studies in psychopathological disorders that form a family of gating disorders. Third, we review the relatively limited but interesting and rapidly expanding literature on pharmacological influences on PPI in humans. Methods: All studies identified by a computerized literature search that addressed the three topics of this review were compiled and evaluated. The principal studies were summarized in appropriate tables. Results: The major influences on PPI as a measure of sensorimotor gating can be grouped into 11 domains. Most of these domains are similar across species, supporting the value of PPI studies in translational comparisons across species. The most prominent literature describing deficits in PPI in psychiatrically defined groups features schizophrenia-spectrum patients and their clinically unaffected relatives. These findings support the use of PPI as an endophenotype in genetic studies. Additional groups of psychopathologically disordered patients with neuropathology involving cortico-striato-pallido-pontine circuits exhibit poor gating of motor, sensory, or cognitive information and corresponding PPI deficits. These groups include patients with obsessive compulsive disorder, Tourette's syndrome, blepharospasm, temporal lobe epilepsy with psychosis, enuresis, and perhaps post-traumatic stress disorder (PTSD). Several pharmacological manipulations have been examined for their effects on PPI in healthy human subjects. In some cases, the alterations in PPI produced by these drugs in animals correspond to similar effects in humans. Specifically, dopamine agonists disrupt and nicotine increases PPI in at least some human studies. With some other compounds, however, the effects seen in humans appear to differ from those reported in animals. For example, the PPI-increasing effects of the glutamate antagonist ketamine and the serotonin releaser MDMA in humans are opposite to the PPI-disruptive effects of these compounds in rodents. Conclusions: Considerable evidence supports a high degree of homology between measures of PPI in rodents and humans, consistent with the use of PPI as a cross-species measure of sensorimotor gating. Multiple investigations of PPI using a variety of methods and parameters confirm that deficits in PPI are evident in schizophrenia-spectrum patients and in certain other disorders in which gating mechanisms are disturbed. In contrast to the extensive literature on clinical populations, much more work is required to clarify the degree of correspondence between pharmacological effects on PPI in healthy humans and those reported in animals.

Human studies of prepulse inhibition of startle: normal subjects, patient groups, and pharmacological studies.

Studies reveal that when people are exposed to emotional facial expressions, they spontaneously react with distinct facial elec- tromyographic (EMG) reactions in emotion-relevant facial muscles. These reactions reflect, in part, a tendency to mimic the facial stimuli. We investigated whether corresponding facial reactions can be elic- ited when people are unconsciously exposed to happy and angry facial expressions. Through use of the backward-masking technique, the subjects were prevented from consciously perceiving 30-ms expo- sures of happy, neutral, and angry target faces, which immediately were followed and masked by neutral faces. Despite the fact that exposure to happy and angry faces was unconscious, the subjects reacted with distinct facial muscle reactions that corresponded to the happy and angry stimulus faces. Our results show that both positive and negative emotional reactions can be unconsciously evoked, and particularly that important aspects of emotional face-to-face commu- nication can occur on an unconscious level.

/pdf/unconscious-facial-reactions-to-emotional-facial-expressions-1x9idxrahz.pdf

Unconscious Facial Reactions to Emotional Facial Expressions

https://webs.wofford.edu/pittmandw/psy230/lab/koch.pdf

The neurobiology of startle.

Placebo

The human startle response is a sensitive, noninvasive measure of central nervous system activity that is currently used in a wide variety of research and clinical settings. In this article, we raise methodological issues and present recommendations for optimal methods of startle blink electromyographic (EMG) response elicitation, recording, quantification, and reporting. It is hoped that this report will foster more methodological validity and reliability in research using the startle response, as well as increase the detail with which relevant methodology is reported in publications using this measure.

/pdf/committee-report-guidelines-for-human-startle-eyeblink-3wopiiqcru.pdf

Committee report: Guidelines for human startle eyeblink electromyographic studies.

This chapter deals with the modification of startle caused by a lead stimulus presented at a lead interval of less than 1 s. This modification of startle can be affected by a variety of parameters of the lead stimulus, such as duration, intensity, and lead interval. Startle modification at short lead intervals can also be affected by the intensity of the startle stimulus itself. The modification of startle decreases as a testing session progresses, and this is due either to habituation of the inhibitory mechanism or to a decrease in control startle reactivity. In some cases, lead stimuli can facilitate the startle response at short lead intervals, usually when the lead and startle stimuli are presented in different sensory systems. Short lead interval modification of startle may serve to protect the processing of the lead stimulus from interruption, but this reflex modification also illustrates automatic sensory gating and the influences of attentional mechanisms early in stimulus processing. Introduction The startle reflex can be elicited by sufficiently sudden and intense stimuli in several sensory modalities, and this reflex has been studied in a wide variety of animals, including humans, across the life span (see Chapter 2). Graham (1975) suggested that the modification of the startle reflex could be useful in identifying the neural mechanisms, at several levels of the central nervous system, that underlie a variety of information-processing functions (see Chapter 1). This chapter will focus on the effects of lead stimulus presentation or change on startle responding, when those lead stimuli are presented within a few hundred milliseconds of the startle stimulus.

Short Lead Interval Startle Modification

For whom the bell (curve) tolls: Cortisol rapidly affects memory retrieval by an inverted U-shaped dose–response relationship

The amplitude and probability of periorbital EMG responses were assessed for a variety of stimuli. In Experiment 1, 50-ms duration broadband noise (20–20K Hz) and tones (1000 Hz), at 95 and 100 dB(A), with rise/fall times of 2.5, 10, and 25 ms, were presented. Noise stimuli were more effective than tones for both response amplitude and probability. Stimulus intensity affected both measures for tones, but only response amplitude for noise. Increasing stimulus rise/fall time had no significant effect for noise, but resulted in lower probability for tones. In Experiment 2, 50-ms duration 1000 Hz tones, at 98 and 102 dB(A), with rise/fall times of 1, 2.5, 5, and 10 ms were presented. Response amplitude was not affected by rise/fall time changes, but increasing rise/fall time from 5 to 10 ms resulted in lower probability. These data show that the startle response can reflect manipulations of stimulus bandwidth, intensity, and rise/fall time, and that startle amplitude and probability reflect these manipulations in different ways. The two response measures may indicate the activity of partially independent underlying mechanisms, with a startle “trigger’ determining response probability and a startle “amplifier’ determining response amplitude for suprathreshold stimuli.

Terry D. Blumenthal

Papers

Committee report: Guidelines for human startle eyeblink electromyographic studies.

Short Lead Interval Startle Modification

For whom the bell (curve) tolls: Cortisol rapidly affects memory retrieval by an inverted U-shaped dose–response relationship

Stimulus rise time, intensity, and bandwidth effects on acoustic startle amplitude and probability

Inhibition of the human startle response is affected by both prepulse intensity and eliciting stimulus intensity