The Prefrontal Cortex—An Update: Time Is of the Essence

Some patients awaken from coma (that is, open the eyes) but remain unresponsive (that is, only showing reflex movements without response to command). This syndrome has been coined vegetative state. We here present a new name for this challenging neurological condition: unresponsive wakefulness syndrome (abbreviated UWS). Many clinicians feel uncomfortable when referring to patients as vegetative. Indeed, to most of the lay public and media vegetative state has a pejorative connotation and seems inappropriately to refer to these patients as being vegetable-like. Some political and religious groups have hence felt the need to emphasize these vulnerable patients' rights as human beings. Moreover, since its first description over 35 years ago, an increasing number of functional neuroimaging and cognitive evoked potential studies have shown that physicians should be cautious to make strong claims about awareness in some patients without behavioral responses to command. Given these concerns regarding the negative associations intrinsic to the term vegetative state as well as the diagnostic errors and their potential effect on the treatment and care for these patients (who sometimes never recover behavioral signs of consciousness but often recover to what was recently coined a minimally conscious state) we here propose to replace the name. Since after 35 years the medical community has been unsuccessful in changing the pejorative image associated with the words vegetative state, we think it would be better to change the term itself. We here offer physicians the possibility to refer to this condition as unresponsive wakefulness syndrome or UWS. As this neutral descriptive term indicates, it refers to patients showing a number of clinical signs (hence syndrome) of unresponsiveness (that is, without response to commands) in the presence of wakefulness (that is, eye opening).

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Unresponsive wakefulness syndrome: a new name for the vegetative state or apallic syndrome

In phylogeny as in ontogeny, the association cortex of the frontal lobe, also known as the prefrontal cortex, is a late-developing region of the neocortex. It is also one of the cortical regions to undergo the greatest expansion in the course of both evolution and individual maturation. In the human adult, the prefrontal cortex constitutes as much as nearly one-third of the totality of the neocortex. The protracted, relatively large, development of the prefrontal cortex is manifest in gross morphology as well as fine structure. In the developing individual, its late maturation is made most apparent by the late myelination of its axonal connections. This and other indices of morphological development of the prefrontal cortex correlate with the development of cognitive functions that neuropsychological studies in animals and humans have ascribed to this cortex. In broad outline, the ventromedial areas of the prefrontal cortex, which with respect to other prefrontal areas develop relatively early, are involved in the expression and control of emotional and instinctual behaviors. On the other hand, the late maturing areas of the lateral prefrontal convexity are principally involved in higher executive functions. The most general executive function of the lateral prefrontal cortex is the temporal organization of goal-directed actions in the domains of behavior, cognition, and language. In all three domains, that global function is supported by a fundamental role of the lateral prefrontal cortex in temporal integration, that is, the integration of temporally discontinuous percepts and neural inputs into coherent structures of action. Temporal integration is in turn served by at least three cognitive functions of somewhat different prefrontal topography: working memory, preparatory set, and inhibitory control. These functions engage the prefrontal cortex in interactive cooperation with other neocortical regions. The development of language epitomizes the development of temporal integrative cognitive functions and their underlying neural substrate, notably the lateral prefrontal cortex and other late-developing cortical regions.

Frontal lobe and cognitive development.

This paper reviews the actual and potential benefits of a marriage between cognitive psychology and psychophysiology. Psychophysiological measures, particularly those of the event-related brain potential, can be used as markers for psychological events and physiological events. Thus, they can serve as "windows" on the mind and as "windows" on the brain. These ideas are illustrated in the context of a series of studies utilizing the lateralized readiness potential, a measure of electrical brain activity that is related to preparation for movement. This measure has been used to illuminate presetting processes that prepare the motor system for action, to demonstrate the presence of the transmission of partial information in the cognitive system, and to identify processes responsible for the inhibition of responses. The lateralized readiness potential appears to reflect activity in motor areas of cortex. Thus, this measure, along with other psychophysiological measures, can be used to understand how the functions of the mind are implemented in the brain.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8986.1989.tb01916.x

Modern Mind‐Brain Reading: Psychophysiology, Physiology, and Cognition

Wait and see.

Primary objective. The Rehabilitation Centre Leijpark in the Netherlands provides an Early Intensive Neurorehabilitation Programme (EINP) to children and young adults in a prolonged unconscious state after severe brain injury. In an extensive research project the effects of EINP were studied. This part of the project focused on the outcome in terms of level of consciousness (LOC) in relation to the specific characteristics of a retrospectively studied cohort. Research design. This study was executed according to a one-group archived pre-test–post-test design. Subjects. Subjects were all consecutively admitted patients (n = 145, 72% male) between December 1987–January 2001. Inclusion criteria were: age 0–25 years, within 6 months after injury, LOC at admission vegetative state (VS) or minimally conscious state (MCS). One hundred and four patients (72%) suffered a traumatic injury and 41 patients (28%) a non-traumatic injury. Methods and procedures. All patients had received EINP until they reached consciou...

Children and young adults in a prolonged unconscious state due to severe brain injury : Outcome after an early intensive neurorehabilitation programme

Sex differences in crying: Empirical findings and possible explanations

Background and aims: Caregivers or relatives of mental patients often show increased levels of psychological distress. This study investigated whether this is also the case for caregivers of patients with borderline personality disorder. Methods: The Symptom Check List (SCL-90) was administered to 64 Dutch volunteers, who were either biologically related (parents or siblings) or biologically unrelated caregivers (partners or friends) of patients with borderline personality disorder. Results: The group of caregivers as a whole scored higher on all symptom dimensions of the SCL-90 than the general population. When controlling for caregiver sex and age, as well as for patient sex, there were no significant differences between the biologically related and unrelated caregiver groups on any dimension. Conclusions: The results are in line with findings concerning distress in caregivers of patients suffering from personality disorders in general, posttraumatic stress disorder or schizophrenia. The mechanism behind the increased levels of distress in our sample is not clear, however. Either exposure to the problematic behaviour of the patient, selective mating or a combination of both might have been responsible for the effect.

Psychological Distress in Caretakers or Relatives of Patients With Borderline Personality Disorder

Waiting for the moment to react to an impending stimulus is accompanied by electrophysiological processes in the central nervous system (CNS) that can be measured from the surface of the body. In this chapter we will discuss electroencephalographic (EEG) and electromyographic (EMG) changes related to preparation for a movement. Most of the results originate from fixed foreperiod reaction time (RT) experiments. When a subject is informed about the moment the imperative (reaction) stimulus (RS) will be presented, the RT is shorter than when the subject is not informed. This information is provided by a warning stimulus (WS), with which the foreperiod starts. The WS has to be detected by the subject. Its significance has to be evaluated and a decision has to be made to prepare for the response. This preparation for the response might imply the presence of processes such as time estimation, anticipation, and response programming. The information processing in the CNS which takes place during the foreperiod and which results in the final response is reflected in electrophysiological changes at two different levels of the CNS: the cortex and the spinal cord. Although all kinds of subcortical and brain stem structures play an important role in the preparation for and the execution of movements, the cortical and spinal electrophysiological changes are the only ones which can be recorded from the surface of the body.

Waiting to Respond: Electrophysiological Measurements in Man During Preparation for a Voluntary Movement

Preparation for a voluntary foot or finger response was studied by evoking Achilles tendon (T) reflexes. Reflexes were evoked simultaneously in both legs at 13 points between 100 and 4300 msec after the warning signal. With this paradigm, the time course of changes in reflex amplitudes related to preparatory processes could be measured simultaneously in the leg involved in the response and in the uninvolved leg. Immediately following the warning stimulus, the reflex amplitudes increased in both involved and non-involved muscles, presumably reflecting a general non-specific arousal. During the second half of the foreperiod, reflex amplitudes in non-involved muscles remained elevated, perhaps reflecting a general activation of the motor system, but returned to baseline in the involved muscles. It is hypothesized that the consistently smaller reflex amplitudes in the involved leg during the entire ISI reflect a presynaptic inhibition of the la afferents to the motoneurons involved in the response. Following the response stimulus, reflex amplitudes increased in both involved and non-involved muscles, although in the former at an earlier point and to a greater extent. It is suggested that this increase following the response stimulus is a manifestation of the transition from motor preparation to response execution.

J.G.M. Scheirs

Papers

Children and young adults in a prolonged unconscious state due to severe brain injury : Outcome after an early intensive neurorehabilitation programme

Sex differences in crying: Empirical findings and possible explanations

Psychological Distress in Caretakers or Relatives of Patients With Borderline Personality Disorder

Waiting to Respond: Electrophysiological Measurements in Man During Preparation for a Voluntary Movement

Changes of Achilles Tendon Reflex Amplitudes During a Fixed Foreperiod of Four Seconds