Electrophysiological assessment of the cranial reflexes

Electrophysiological assessment methods play a key role in the diagnosis of various neurological disorders. Electrophysiological evaluation of cranial reflexes is particularly valuable for neurologists. This article provides an overview of electrophysiological evaluation methods for cranial reflexes, which are most commonly used in clinical practice. They provide objective assessment of the functional integrity of nervous system structures that make up the cranial reflex arc, identify the level and, in some cases, the nature of disease, as well as pathophysiological mechanisms of central and peripheral nervous system disorders. We describe the instruments and main approaches to analysing the results for the standard blink reflex, blink reflex with prepulse inhibition, blink reflex with paired stimuli and recovery curve evaluation, reflex inhibition of the levator palpebrae superioris, jaw jerk reflex, and reflex inhibition (cutaneous silent period) of the masseter muscle.

Can Hybrid Synapse be Formed between Rat Spinal Motor Neurons and Major Pelvic Ganglion Neurons in vitro?

The purpose of this study is to determine whether synapses can be formed between spinal motor neurons (SMNs) and major pelvic ganglion (MPG) neurons of a rat in vitro. The green fluorescent protein (GFP)-labelled MPG cells were cultured together with SMNs in a specific medium. The synaptic-like contacts established between SMNs and MPG neurons were studied in co-cultures using morphologic and immunocytochemistry approaches. Phase-contrast observation of co-cultures showed apparent SMNs-MPG neurons contacts as early as three or four days in vitro. We demonstrate some evidence of synaptic contacts between SMNs and MPG neurons in vitro by immunostaining with antibody directed against postsynaptic density protein 95 (PSD-95). We describe the development process of a defined SMNs-MPG neurons co-culture system. The results suggest that the hybrid synapse formation that may occur between SMNs and MPG neurons in vitro played an essential role in the mechanisms of a regenerated bladder with an artificial somatic-autonomic reflex arc.

Poussin's sign

V. Dosuzkova and Th. Dosuzkov (Revue V. neurologii i psychiatrii, 1928, no. 4). In contrast to Babinsky, Leshchenko and Nemlicher (Proceedings of the Ukrainian psychoneur. Inst., 1927, III), the authors do not consider this reflex part of the fan sign, just as they do not find definite connections of this reflex with the setting and defense reflexes. Poussin occurs with the simultaneous defeat of the pyramidal and extrapyramidal motor pathways and disinhibition of the reflex arc of this reflex.

Psychophysics to Literary Experiments: Gertrude Stein and Neural Composition

The last chapter returns to automatisms and the concept of the reflex arc as they were investigated and rethought in Gertrude Stein’s early writings. Critics frequently analyze Stein’s work by reference to William James, one of her teachers at Harvard. Only a few think it important that Hugo Münsterberg, the German physiological psychologist, supervised most of her work in the Harvard psychology laboratory. I argue that Stein sided with Münsterberg against James’s interest in split personalities and his belief that they explained automatic writing. Stein conducted an experiment to discount such ideas, and in the process she discovered her process of allowing automatism to foster invention in composition. But, eventually recoiling from Münsterberg’s aim to exploit unconscious physiological automatisms for industrial efficiency and social order, Stein later experiments in Tender Buttons with ways to escape such determined responses in the creation of meaning.

Distinct forms of synaptic plasticity during ascending vs descending control of medial olivocochlear efferent neurons

Activity in each brain region is shaped by the convergence of ascending and descending axonal pathways, and the balance and characteristics of these determine neural output. The medial olivocochlear (MOC) efferent system is part of a reflex arc that critically controls auditory sensitivity. Multiple central pathways contact MOC neurons, raising the question of how a reflex arc could be engaged by diverse inputs. We examined functional properties of synapses onto brainstem MOC neurons from ascending (ventral cochlear nucleus, VCN), and descending (inferior colliculus, IC) sources in mice using an optogenetic approach. We found that these pathways exhibited opposing forms of short-term plasticity, with VCN input showing depression and IC input showing marked facilitation. By using a conductance clamp approach, we found that combinations of facilitating and depressing inputs enabled firing of MOC neurons over a surprisingly wide dynamic range, suggesting an essential role for descending signaling to a brainstem nucleus.

Protracted Hiccups Induced by Aripiprazole and Regressed after Administration of Gabapentin

Hiccups are sudden, repeated, and involuntary contractions of the diaphragm muscle (myoclonic contraction). It involves a reflex arc that, once activated, causes a strong contraction of the diaphragm immediately followed by the closure of the glottis translating into the classic “hic” sound. Hiccups can be short, persistent, and intractable depending on the duration. The most disabling hiccups often represent the epiphenomenon of a medical condition such as gastrointestinal and cardiovascular disorders; central nervous system (CNS) abnormalities; ear, nose, and throat (ENT) conditions or pneumological problems; metabolic/endocrine disorders; infections; and psychogenic disorders. Some drugs, such as aripiprazole, a second-generation antipsychotic, can induce the onset of variable hiccups. We describe herein the cases of three hospitalized patients who developed insistent hiccups after taking aripiprazole and who positively responded to low doses of gabapentin. It is probable that aripiprazole, prescribed at a low dosage (<7.5 mg/day), would act as a dopamine agonist by stimulating D2 and D3 receptors at the “hiccup center” level—located in the brain stem—thus triggering the hiccup. On the other hand, gabapentin led to a complete regression of the hiccup probably by reducing the nerve impulse transmission and modulating the diaphragmatic activity. The present case series suggests the use of low doses of gabapentin as an effective treatment for aripiprazole-induced hiccups. However, our knowledge of the neurotransmitter functioning of the hiccup reflex arc is still limited, and further research is needed to characterize the neurotransmitters involved in hiccups for potential novel therapeutic targets.

Philosophical Considerations and Research Ideas About Comparing the Two Approaches: Messer’s Comments Point the Way Forward

In his commentary, Stanley Messer (2021) posed the question of whether it is possible to evaluate the relative merits of different case formulation approaches to psychotherapy. He went on to maintain, based on the pragmatic theory of truth, that it is possible to compare different case formulation approaches, and pointed to a program of research that he and his collaborators conducted as an example for possible future research (Collins Messer, 1991; Holland, Roberts, Messer, 1998; Messer, Tishby, Spillman, 1992; Tishby Messer, 1995). In this reply, we express our appreciation for Messer’s remarks, with which we agree in large measure, and attempt to highlight and build upon some of the points he made. We discuss Dewey’s (1896) classic critique of the reflex arc concept to point out other ways the philosophical perspective of pragmatism supports the view that different approaches to therapy are not incommensurate. We also offer a number of suggestions for future research comparing psychotherapy based on Interpersonal Defense Theory and IRT, or any two case formulation approaches to therapy. At many points, our suggestions follow along the lines of Messer’s research. We also emphasize the value of case formulation-based studies, not only with regard to research comparing approaches to treatment, but for investigating other issues about therapy as well.

Distinct forms of synaptic plasticity during ascending vs. descending control of medial olivocochlear efferent neurons

Activity in each brain region is shaped by the convergence of ascending and descending axonal pathways, and the balance and characteristics of these determine neural output. The medial olivocochlear (MOC) efferent system is part of a reflex arc that critically controls auditory sensitivity. Multiple central pathways contact MOC neurons, raising the question of how a reflex arc could be engaged by diverse inputs. We examined functional properties of synapses onto brainstem MOC neurons from ascending (ventral cochlear nucleus, VCN), and descending (inferior colliculus, IC) sources in mice using an optogenetic approach. We found that these pathways exhibited opposing forms of short-term plasticity, with VCN input showing depression and IC input showing marked facilitation. By using a conductance clamp approach, we found that combinations of facilitating and depressing inputs enabled firing of MOC neurons over a surprisingly wide dynamic range, suggesting an essential role for descending signaling to a brainstem nucleus.