PART 2-Anxiolytic Drugs & Behavioral Inhibition System
Anxiolytic Drugs and the Behavioral Inhibition System (Page 101)
Partial reinforcement acquisition effect:
Increased arousal from secondary frustrative stimuli.
Blocked by anxiolytic drugs (Amsel, 1962, 1992; Gray & Smith, 1969).
Potentiated startle response:
Increased arousal output of the behavioral inhibition system.
Produced by preceding startle stimulus with secondary punishing or frustrative stimulus.
Blocked by benzodiazepines, barbiturates, and buspirone (Chi, 1965; Davis et al., 1993) during the test phase.
Anxiolytic drugs impair the behavioral inhibition system:
Reduce concern about threats of punishment, omens of failure, uncertainties of novel environments.
Leads to reduced behavior inhibition, less attentiveness to threatening stimuli, and decreased arousal.
Anxiolytic drug effects:
Change in mood or disposition.
Cognitive component, evident in complex tasks.
Indirect effects on anxiety expression by interfering with cognitive mechanisms.
Behavioral effects of anxiolytic drugs provide a coherent pattern to be replicated by dysfunction of specific neural systems. Match drug effects to some part or parts of the neurology of defense (see Appendices 2 and 3 for full details).
A Theory of the Behavioral Inhibition System (Page 102)
The ethological, psychological, and pharmacological data identifies the behavioral inhibition system as central to anxiety.
Primary Input: Eliciting Stimuli That Activate the System
Chapter 2 discussed the ethology of threat systems.
Distinguished responses to immediate present threat from responses to a potential threat, producing different types of behaviour.
Active responses to a present threat are directed to avoidance of the source of threat.
Active responses to a potential threat are directed to approach to (and assessment of) the source of potential threat.
Defensive distance:
Small defensive distance produces behavioural inhibition so great that there is no active behaviour.
Larger defensive distance produces behavioural inhibition but also active risk analysis and ‘stretched-attend’ posture.
Very large defensive distance leads to disappearance of both behavioural inhibition and active threat-related behavior.
Active threat-related behavior showed an inverted ∪ relationship to defensive distance.
Anxiolytic drugs had effects consistent with an increase in defensive distance.
Classical Behaviorist Stimulus-Bound Position (Page 103)
Moving to a more contemporary cognitive and functional view.
Fight–flight–freezing system:
Controls behavior when the animal’s primary purpose is to remove itself from a source of danger, its goal is to reach safety.
Behavioral inhibition system:
Controls behavior when the animal’s primary purpose is to achieve some goal requiring it to move towards a source of danger that is when it has concurrent conflicting goals of reaching safety and of satisfying appetite.
The predator/potential predator distinction at the stimulus level is highly correlated with activation of the fight–flight and behavioural inhibition systems but is not necessary.
The fundamental distinction depends on whether the animal’s actions are aimed at entering (behavioural inhibition system) or leaving (fight–flight system) a dangerous situation—a matter of ‘defensive direction’.
Anxiety is identified with activity in the behavioural inhibition system.
Learning-theory analysis:
Categorically differentiate active avoidance from behavioural inhibition.
Expand the concept of the behavioural inhibition system activated by approach–avoidance conflict.
Conflicts could be produced by innate fear stimuli, learned signals of impending punishment, signals of impending frustrative non-reward, and novelty.
It is not the presence of the aversive stimuli themselves which activates the behavioural inhibition system, but their conjunction with appetitive stimuli or other conditions that result in the animal’s having to choose between conflicting, incompatible goals.
Anxiolytic Drugs (Page 104)
Anxiolytic drug impact
The compounds appear to leave the functioning of the fight-flight system while generally impairing the behavioural inhibition system in a manner consistent with an increase in perceived defensive distance.
Matching anxiolytic drug effects with anxiety-related behaviour produces reasonably coherent patterns.
Common actions of different classes of anxiolytic drugs could be used as a probe for anxiety itself.
Congruence between classical and novel anxiolytics is observed, despite different mechanisms of action and profiles of side-effects.
Conflicting goals and behavioural inhibition included a number of effects in tests of memory.
Full analysis of these tests was postponed until Chapter 8; but the effects in them of anxiolytics suggest that their actions may be exerted on the cognitive processes that ultimately lead to emotional responses, as much as directly on the emotional responses themselves.
The anxiolytic drugs are ineffective in reducing innate or conditioned escape or active avoidance responses.
Behavioural inhibition system has been distinguished from the behavioural approach system, since anxiolytics do not affect appetitive learning or a wide variety of other responses which are uncontaminated by the presence of conflicting goals.
Confusion surrounding the results obtained in several of the more recent screening tests for anxiolytic drugs due tests not firmly grounded in classical learning theory and interaction between these compounds and the activity of the pituitary–adrenal system.
The behavioural inhibition system is most characteristically involved in and may have originally evolved to cope with the requirement to enter threatening situations.
Potential predatory threat is not the only situation which engenders approach–avoidance conflict, and all approach–avoidance conflicts have many functional features in common.
The Behavioral Inhibition Model (Page 105)
The behavioural inhibition system broadened its scope from potential predators to all the aversive stimuli which we can at present envisage as requiring resolution of approach–avoidance conflict: innate and acquired signals of punishment, innate and acquired signals of frustration, and initially threatening novel stimuli.
The behavioural inhibition system functions to resolve conflicts between approximately equally activated and incompatible goals.
The presence of stimuli or contingencies is not sufficient to activate this system. The animal’s knowledge of those stimuli and contingencies must be such as to engender a genuine conflict between mutually incompatible goals (e.g. safety and food).
Once an animal has learned to avoid shock, its behavior is controlled by habit and the behavioural inhibition system is no longer involved.
Conflicting Goals and the Output System (Page 106).
outputs of the behavioural inhibition system can be derived from the requirement to correctly resolve conflicting goals.
Neither appetitive nor aversive behavior is appropriate. Approaching the appetitive goal and escape from a potential danger. The first requirement is inhibition of both the behavioural approach and the fight–flight systems.
Increase in arousal: must be prepared for split-second changes between approach to the appetitive goal and escape from a potential danger that may suddenly become manifest.
Increased attention: increased scanning of the environment, a wide range of risk assessment behaviours, increased retrieval of associations from memory combined with their assessment for threatening or otherwise adverse implications.
Evolution, Anxiety, and Rules for the Behavioural System (Page 106)
Try and find its neural substrate.
Where both classical and novel anxiolytics produce a common change in neural function, that change is likely to involve the neural substrate of anxiety.
The behavioural inhibition system is specifically adapted to the processing of one aspect of threat.
The species studied with anxiolytic drugs include fish, birds, mice, cats, dogs, pigs, and monkeys, as well as people. Despite this diversity, there is virtually no need to qualify any of the resulting conclusions with respect to species.
Phylogenetically Old Substrate (Page 107)
The substrate upon which the anxiolytic drugs act includes components that are phylogenetically old, old enough to be present in contemporary mammalian species and to have homologues in all vertebrates.
These data give us good reason in the specific case of anxiety to treat human beings as fundamentally similar to other mammalian species.
If the action of the anxiolytic drugs in so many diverse species is to reduce anxiety It follows that anxiety itself is phylogenetically old which greatly weakens any attempt to explain the fundamental mechanisms of human anxiety in terms that are specific to human beings.
The brain areas which must mediate human anxiety and on which the anxiolytic drugs act are likely to include systems that are common at least to most mammals and likely, therefore, to lie outside the cerebral cortex which has achieved most prominence in ourselves and other primates.
Conditioning and expectation play major roles in the production of anxiety. The range of stimuli which can elicit anxiety must depend on the perceptual and cognitive equipment available to the species in question.
Evolution often proceeds through phylogenetic conservation of simple mechanisms combined with elaboration of function by the progressive addition of further simple mechanisms
This possibility is consistent with ethological analysis.
Emotion and Emotional Reaction (Page 108)
Emotion is best defined as a set of reactions to its own unique historical functional class of situation. First, a large part of the form of the emotional reaction is the result of evolution. Second, most emotions involve action tendencies, autonomic responses, hormonal responses, and probably immune responses.
The pattern of effector output to which we assign a specific emotion label, such as ‘anxiety’, could result more from consistencies in the functional characteristics of the external eliciting stimuli than from the presence of some single locus in the animal’s brain controlling all the outputs of all the co-activated effector systems.
Faced with a dangerous animal motor tension, autonomic hyperactivity, apprehensive expectation, and vigilance and scanning are determined by the fact that ancestors have frequently been faced with predators. Responses are in part due to the prior meeting of random mutation with selective advantage.
The necessary involvement of random mutation has some interesting consequences for emotion.
In particular, the response of each effector system will be subject to its own evolutionary equation; and, to the extent that the response of any effector system is genetically determined, it will be the result of a mutation which in many cases will be specific to that system.
Each response system is under its own private stimulus control.
Separation Anxiety (Page 110)
Separation anxiety may be manifest in both behavioural and autonomic responses. These occur in concert when the mother is removed and appear, therefore, to be different effector outputs of a single, unified central state.
The behavioural reactions can be eliminated by the presence of a non-lactating foster mother, while the autonomic reactions can be eliminated by feeding with milk, but not in either case vice versa (Hofer 1972).
Apparent coherent, integrated activity results from the activation of a number of what have been termed ‘rules of thumb’ (see Krebs et al. 1983).
The tension between this type of relatively fragmented solution to the problem posed by the neuropsychology of anxiety and the more unified position adopted in the first edition of this book will occupy our attention at several later points in the development of our argument
Behavioral Inhibition vs. Learning Theory (Page 110)
A rule of thumb is a simple rule which delivers approximately ‘optimal’ behaviour, usually within a limited stimulus domain. Any one rule of thumb will only deliver adaptive behaviour in a limited domain.
Sufficiently large set of rules of thumb will give the appearance of a single coherent adaptive strategy applied over the whole of the animal’s usual ecological range.
Anxiolytic drugs decrease behavioural inhibition of lever-pressing on schedules of successive discrimination, fixed interval and differential reinforcement of low rates of response (DRL).
In each case the behavioural inhibition can be characterized as resulting from a conflict between a prepotent lever-press response for food and a signal of reward omission.
However, a surprise awaits you if we challenge the effects of anxiolytics in these tasks with the opiate receptor antagonist naloxone. Naloxone blocks the effects of the anxiolytic benzodiazepine chlordiazepoxide on the DRL schedule, does not alter the effect of chlordiazepoxide on successive discrimination. Naloxone blocks the effect of chlordiazepoxide in the early part of the fixed interval, but not the later part.
Behavioural inhibition (as a specific output of the behavioural inhibition system) is mediated by at least two distinct neural pathways, of which one is sensitive to anxiolytics but does not contain an endogenous opiate link while the other is sensitive to anxiolytics and does contain such a link.
The neuropsychology of anxiety, requires we are dealing with a set of parallel systems, or a network of nodes, with distributed control, rather than a system with a linear flow of information through a single neural coordinating centre.
The surprisingly specific effects of the anxiolytic drugs on what we have identified behaviourally as anxiety is, paradoxically, the result of their capacity to affect simultaneously a number of quite separate nodes within such a parallel distributed system.
There need be no central coordinating node. Control will be distributed across a neural network made up of multiple interacting nodes.
The Neural Systems (Page 112)
Search for neural systems, activity in which is altered by the anxiolytic drugs and dysfunction in which produces behavioral effects similar to those of these compounds.
The logical place to start our search will be in the limbic system. Ethological, learning-theory, and pharmacological analyses useful to link the operations of the behavioural inhibition system with those of the fight-flight system, acting, as they do, to control different modes of response to similar classes of situation.
Defence Systems (Page 113)
analysis pursued in Chapters 2 and 3 distinguished two classes of defence resulting from fear and anxiety.
Simplest class of defence requires only escape or aggressive behaviour controlled by the fight–flight–freeze system.
Second class is more complicated, since simple escape or avoidance tendencies are in conflict with a tendency to approach the source of potential threat, this type of approach–avoidance conflict is controlled by the behavioural inhibition system.
Behavioural inhibition system provides an extra, inhibitory, level superimposed upon the fight–flight system
The neurology of fear will be bound up in the neurology of anxiety.
The goal is removing itself from a source of danger.
Detailed analysis of even the primary defence system would require a book at least is to large as the present one.
Anxiolytic Drugs and the Behavioral Inhibition System (Page 101)
Partial reinforcement acquisition effect:
Increased arousal from secondary frustrative stimuli. This effect occurs when a behavior is only sometimes followed by a reinforcer, leading to increased persistence and resistance to extinction. The heightened arousal is attributed to the unexpected absence of the anticipated reward.
Blocked by anxiolytic drugs (Amsel, 1962, 1992; Gray & Smith, 1969). Anxiolytics interfere with the increased arousal, suggesting that anxiety-reducing medications can diminish the impact of unpredictable reinforcement schedules.
Potentiated startle response:
Increased arousal output of the behavioral inhibition system. The startle response is amplified when an aversive stimulus is preceded by a punishing or frustrating stimulus, indicating a heightened state of anxiety or fear.
Produced by preceding startle stimulus with secondary punishing or frustrative stimulus. This potentiation highlights the role of associative learning in amplifying fear responses.
Blocked by benzodiazepines, barbiturates, and buspirone (Chi, 1965; Davis et al., 1993) during the test phase. These drugs reduce the amplified startle response, further supporting their anxiolytic effects by modulating the behavioral inhibition system.
Anxiolytic drugs impair the behavioral inhibition system:
Reduce concern about threats of punishment, omens of failure, uncertainties of novel environments. By diminishing the activity of the behavioral inhibition system, these drugs alleviate anxiety associated with potential negative outcomes and unfamiliar situations.
Leads to reduced behavior inhibition, less attentiveness to threatening stimuli, and decreased arousal. The overall effect is a reduction in anxiety-driven behaviors and vigilance toward potential threats.
Anxiolytic drug effects:
Change in mood or disposition, leading to a more relaxed and less anxious state.
Cognitive component, evident in complex tasks. Anxiolytics can improve cognitive performance in tasks sensitive to anxiety, suggesting a cognitive dimension to their effects.
Indirect effects on anxiety expression by interfering with cognitive mechanisms. Rather than directly suppressing anxiety, these drugs may alter cognitive processes that contribute to the expression of anxiety.
Behavioral effects of anxiolytic drugs provide a coherent pattern to be replicated by dysfunction of specific neural systems. Match drug effects to some part or parts of the neurology of defense (see Appendices 2 and 3 for full details). This underscores the importance of understanding the neural substrates underlying anxiety and defense mechanisms to better comprehend the actions of anxiolytic drugs.
A Theory of the Behavioral Inhibition System (Page 102)
The ethological, psychological, and pharmacological data identifies the behavioral inhibition system as central to anxiety. The behavioral inhibition system is a critical neural circuit involved in mediating responses to potential threats and conflicts.
Primary Input: Eliciting Stimuli That Activate the System- Chapter 2 discussed the ethology of threat systems.
Distinguished responses to immediate present threat from responses to a potential threat, producing different types of behaviour. An immediate threat elicits active avoidance responses, whereas a potential threat triggers assessment behaviors.
Active responses to a present threat are directed to avoidance of the source of threat. The primary goal is to escape from immediate danger.
Active responses to a potential threat are directed to approach to (and assessment of) the source of potential threat. Animals engage in risk assessment to evaluate the nature and magnitude of the potential threat.
Defensive distance:
Small defensive distance produces behavioural inhibition so great that there is no active behaviour. When the threat is very close, freezing or complete inhibition of movement occurs.
Larger defensive distance produces behavioural inhibition but also active risk analysis and ‘stretched-attend’ posture. At a moderate distance, animals display a combination of inhibition and vigilance, carefully monitoring the threat.
Very large defensive distance leads to disappearance of both behavioural inhibition and active threat-related behavior. When the threat is far away, anxiety and threat-related behaviors subside.
Active threat-related behavior showed an inverted ∪ relationship to defensive distance. The relationship between defensive distance and active threat-related behavior follows an inverted U-shaped curve, where intermediate distances elicit the most pronounced responses.
Anxiolytic drugs had effects consistent with an increase in defensive distance. These drugs effectively increase the perceived distance from a threat, reducing anxiety and defensive behaviors.
Classical Behaviorist Stimulus-Bound Position (Page 103)
Moving to a more contemporary cognitive and functional view.
Fight–flight–freezing system:
Controls behavior when the animal’s primary purpose is to remove itself from a source of danger, its goal is to reach safety. This system governs responses aimed at immediate escape or confrontation in the face of danger.
Behavioral inhibition system:
Controls behavior when the animal’s primary purpose is to achieve some goal requiring it to move towards a source of danger that is when it has concurrent conflicting goals of reaching safety and of satisfying appetite. The behavioral inhibition system manages situations where an animal must balance conflicting motivations, such as approaching a reward in the presence of potential danger.
The predator/potential predator distinction at the stimulus level is highly correlated with activation of the fight–flight and behavioural inhibition systems but is not necessary. The type of threat (e.g., predator versus potential risk) influences which system is activated, but it is not the sole determinant.
The fundamental distinction depends on whether the animal’s actions are aimed at entering (behavioural inhibition system) or leaving (fight–flight system) a dangerous situation—a matter of ‘defensive direction’. Whether an animal is moving towards or away from a threat is crucial in determining which defensive system is engaged.
Anxiety is identified with activity in the behavioural inhibition system. Anxiety is closely linked to the functioning of the behavioral inhibition system.
Learning-theory analysis:
Categorically differentiate active avoidance from behavioural inhibition. Active avoidance involves taking actions to prevent exposure to a threat, while behavioral inhibition involves suppressing behavior in the presence of a threat.
Expand the concept of the behavioural inhibition system activated by approach–avoidance conflict. The behavioral inhibition system is activated when there is a conflict between approaching a reward and avoiding a potential threat.
Conflicts could be produced by innate fear stimuli, learned signals of impending punishment, signals of impending frustrative non-reward, and novelty. Various stimuli and situations can trigger approach-avoidance conflicts, including innate fears, learned signals, and novel stimuli.
It is not the presence of the aversive stimuli themselves which activates the behavioural inhibition system, but their conjunction with appetitive stimuli or other conditions that result in the animal’s having to choose between conflicting, incompatible goals. The behavioral inhibition system is activated by the combination of aversive stimuli and conflicting goals, forcing the animal to choose between incompatible actions.
Anxiolytic Drugs (Page 104)
Anxiolytic drug impact- The compounds appear to leave the functioning of the fight-flight system while generally impairing the behavioural inhibition system in a manner consistent with an increase in perceived defensive distance. Anxiolytic drugs primarily affect the behavioral inhibition system, making threats seem farther away without affecting the immediate escape responses controlled by the fight-flight system.
Matching anxiolytic drug effects with anxiety-related behaviour produces reasonably coherent patterns. The effects of anxiolytic drugs align well with observed anxiety-related behaviors, providing a cohesive understanding of their mechanisms.
Common actions of different classes of anxiolytic drugs could be used as a probe for anxiety itself. Common effects among different anxiolytic drugs can serve as a tool to investigate the nature of anxiety.
Congruence between classical and novel anxiolytics is observed, despite different mechanisms of action and profiles of side-effects. Both classic and novel anxiolytics share common effects despite their differing mechanisms and side effect profiles.
Conflicting goals and behavioural inhibition included a number of effects in tests of memory.- Full analysis of these tests was postponed until Chapter 8; but the effects in them of anxiolytics suggest that their actions may be exerted on the cognitive processes that ultimately lead to emotional responses, as much as directly on the emotional responses themselves. Anxiolytics influence cognitive processes linked to emotional responses, as seen in memory tests involving conflicting goals and behavioral inhibition.
The Behavioral Inhibition Model (Page 105)
The behavioural inhibition system broadened its scope from potential predators to all the aversive stimuli which we can at present envisage as requiring resolution of approach–avoidance conflict: innate and acquired signals of punishment, innate and acquired signals of frustration, and initially threatening novel stimuli. The behavioral inhibition system addresses various conflicting situations, including potential predators, punishment signals, frustration signals, and novel stimuli.
The behavioural inhibition system functions to resolve conflicts between approximately equally activated and incompatible goals. The core function of the behavioral inhibition system is to resolve conflicts between equally strong, opposing goals.
The presence of stimuli or contingencies is not sufficient to activate this system. The animal’s knowledge of those stimuli and contingencies must be such as to engender a genuine conflict between mutually incompatible goals (e.g. safety and food). For the behavioral inhibition system to activate, an animal must recognize and experience a genuine conflict between incompatible goals.
Once an animal has learned to avoid shock, its behavior is controlled by habit and the behavioural inhibition system is no longer involved. Once avoidance behavior becomes habitual, the behavioral inhibition system is no longer actively engaged.
Conflicting Goals and the Output System (Page 106).
outputs of the behavioural inhibition system can be derived from the requirement to correctly resolve conflicting goals. The outputs of the behavioral inhibition system arise from the need to properly address conflicting goals.
Neither appetitive nor aversive behavior is appropriate. Approaching the appetitive goal and escape from a potential danger. The first requirement is inhibition of both the behavioural approach and the fight–flight systems. Successfully resolving conflicts requires suppressing both approach and escape behaviors.
Increase in arousal: must be prepared for split-second changes between approach to the appetitive goal and escape from a potential danger that may suddenly become manifest. Heightened arousal prepares the animal for rapid shifts between approaching a reward and escaping danger.
Increased attention: increased scanning of the environment, a wide range of risk assessment behaviours, increased retrieval of associations from memory combined with their assessment for threatening or otherwise adverse implications. Heightened attention involves increased environmental scanning, risk assessment, and memory retrieval to assess potential threats.
Evolution, Anxiety, and Rules for the Behavioural System (Page 106)
Try and find its neural substrate. Identifying the neural substrate is essential for understanding the biological basis of this system.
Where both classical and novel anxiolytics produce a common change in neural function, that change is likely to involve the neural substrate of anxiety. Common neural changes induced by both classical and novel anxiolytics likely involve the neural substrate of anxiety.
The behavioural inhibition system is specifically adapted to the processing of one aspect of threat. The behavioral inhibition system is specialized for processing particular types of threats.
The species studied with anxiolytic drugs include fish, birds, mice, cats, dogs, pigs, and monkeys, as well as people. Despite this diversity, there is virtually no need to qualify any of the resulting conclusions with respect to species. Anxiolytic drug effects are largely consistent across diverse species, indicating a fundamental mechanism.
Phylogenetically Old Substrate (Page 107)
The substrate upon which the anxiolytic drugs act includes components that are phylogenetically old, old enough to be present in contemporary mammalian species and to have homologues in all vertebrates. Anxiolytic drugs act on ancient neural circuits, conserved across mammalian and vertebrate species.
These data give us good reason in the specific case of anxiety to treat human beings as fundamentally similar to other mammalian species. The shared neural substrates suggest that human anxiety mechanisms are similar to those in other mammals.
If the action of the anxiolytic drugs in so many diverse species is to reduce anxiety It follows that anxiety itself is phylogenetically old which greatly weakens any attempt to explain the fundamental mechanisms of human anxiety in terms that are specific to human beings. The broad efficacy of anxiolytics indicates that anxiety is an evolutionarily old phenomenon, challenging human-specific explanations.
The brain areas which must mediate human anxiety and on which the anxiolytic drugs act are likely to include systems that are common at least to most mammals and likely, therefore, to lie outside the cerebral cortex which has achieved most prominence in ourselves and other primates. Brain regions mediating human anxiety and targeted by anxiolytics are likely conserved across mammals, often outside the highly evolved cerebral cortex.
Conditioning and expectation play major roles in the production of anxiety. The range of stimuli which can elicit anxiety must depend on the perceptual and cognitive equipment available to the species in question. Conditioning and expectation significantly influence anxiety, with the range of eliciting stimuli depending on a species’ cognitive abilities.
Evolution often proceeds through phylogenetic conservation of simple mechanisms combined with elaboration of function by the progressive addition of further simple mechanisms. Evolution often conserves basic mechanisms while adding complexity through additional simple processes.
This possibility is consistent with ethological analysis. This aligns with ethological analyses of behavior.
Emotion and Emotional Reaction (Page 108)
Emotion is best defined as a set of reactions to its own unique historical functional class of situation. Emotion is best understood as a set of reactions tailored to specific historical and functional contexts.
First, a large part of the form of the emotional reaction is the result of evolution. A significant portion of emotional reactions is shaped by evolution.
Second, most emotions involve action tendencies, autonomic responses, hormonal responses, and probably immune responses. Emotions encompass action tendencies, autonomic responses, hormonal changes, and immune responses.
The pattern of effector output to which we assign a specific emotion label, such as ‘anxiety’, could result more from consistencies in the functional characteristics of the external eliciting stimuli than from the presence of some single locus in the animal’s brain controlling all the outputs of all the co-activated effector systems. Specific emotion labels like ‘anxiety’ may arise more from consistent external stimuli than from a single brain region controlling all outputs.
Faced with a dangerous animal motor tension, autonomic hyperactivity, apprehensive expectation, and vigilance and scanning are determined by the fact that ancestors have frequently been faced with predators. Responses are in part due to the prior meeting of random mutation with selective advantage.- The necessary involvement of random mutation has some interesting consequences for emotion.
In particular, the response of each effector system will be subject to its own evolutionary equation; and, to the extent that the response of any effector system is genetically determined, it will be the result of a mutation which in many cases will be specific to that system.- Each response system is under its own private stimulus control.
Separation Anxiety (Page 110)
Separation anxiety may be manifest in both behavioural and autonomic responses. These occur in concert when the mother is removed and appear, therefore, to be different effector outputs of a single, unified central state. Separation anxiety presents as both behavioral and autonomic responses, appearing unified when a mother is absent.
The behavioural reactions can be eliminated by the presence of a non-lactating foster mother, while the autonomic reactions can be eliminated by feeding with milk, but not in either case vice versa (Hofer 1972). Behavioral reactions can be mitigated by a non-lactating foster mother, while autonomic reactions are soothed by feeding, but not reciprocally.
Apparent coherent, integrated activity results from the activation of a number of what have been termed ‘rules of thumb’ (see Krebs et al. 1983). Coherent activity arises from the activation of various simple ‘rules of thumb’.
The tension between this type of relatively fragmented solution to the problem posed by the neuropsychology of anxiety and the more unified position adopted in the first edition of this book will occupy our attention at several later points in the development of our argument. The contrast between fragmented and unified explanations in the neuropsychology of anxiety will be addressed later.
Behavioral Inhibition vs. Learning Theory (Page 110)
A rule of thumb is a simple rule which delivers approximately ‘optimal’ behaviour, usually within a limited stimulus domain. Any one rule of thumb will only deliver adaptive behaviour in a limited domain. A ‘rule of thumb’ is a simple, nearly optimal behavior within specific contexts, but it is only adaptive in limited domains.
Sufficiently large set of rules of thumb will give the appearance of a single coherent adaptive strategy applied over the whole of the animal’s usual ecological range. A large set of these rules can mimic a unified adaptive strategy across an animal’s ecological range.
Anxiolytic drugs decrease behavioural inhibition of lever-pressing on schedules of successive discrimination, fixed interval and differential reinforcement of low rates of response (DRL). Anxiolytics reduce behavioral inhibition in lever-pressing tasks involving discrimination, fixed intervals, and differential reinforcement.
In each case the behavioural inhibition can be characterized as resulting from a conflict between a prepotent lever-press response for food and a signal of reward omission. Behavioral inhibition arises from the conflict between pressing a lever for food and signals indicating reward omission.
However, a surprise awaits you if we challenge the effects of anxiolytics in these tasks with the opiate receptor antagonist naloxone. Naloxone blocks the effects of the anxiolytic benzodiazepine chlordiazepoxide on the DRL schedule, does not alter the effect of chlordiazepoxide on successive discrimination. Naloxone blocks the effect of chlordiazepoxide in the early part of the fixed interval, but not the later part. Naloxone, an opiate receptor antagonist, can block the effects of the anxiolytic chlordiazepoxide in certain tasks but not others, revealing complex interactions.
Behavioural inhibition (as a specific output of the behavioural inhibition system) is mediated by at least two distinct neural pathways, of which one is sensitive to anxiolytics but does not contain an endogenous opiate link while the other is sensitive to anxiolytics and does contain such a link. Behavioral inhibition is mediated by at least two neural pathways, one sensitive to anxiolytics without an opiate link, and another sensitive to anxiolytics with an opiate link.
The neuropsychology of anxiety, requires we are dealing with a set of parallel systems, or a network of nodes, with distributed control, rather than a system with a linear flow of information through a single neural coordinating centre. The neuropsychology of anxiety suggests parallel systems or a network with distributed control, rather than a linear, centralized system.
The surprisingly specific effects of the anxiolytic drugs on what we have identified behaviourally as anxiety is, paradoxically, the result of their capacity to affect simultaneously a number of quite separate nodes within such a parallel distributed system. The specific effects of anxiolytics on anxiety result from their action on multiple separate nodes within a parallel distributed system.
There need be no central coordinating node. Control will be distributed across a neural network made up of multiple interacting nodes. No central coordinating node is necessary; control is distributed across an interacting neural network.
The Neural Systems (Page 112)
Search for neural systems, activity in which is altered by the anxiolytic drugs and dysfunction in which produces behavioral effects similar to those of these compounds. We aim to identify neural systems altered by anxiolytics and whose dysfunction leads to similar behavioral effects.
The logical place to start our search will be in the limbic system. The limbic system is a key area to begin exploring.
Ethological, learning-theory, and pharmacological analyses useful to link the operations of the behavioural inhibition system with those of the fight-flight system, acting, as they do, to control different modes of response to similar classes of situation. Ethological, learning-theory, and pharmacological analyses connect the behavioral inhibition system and the fight-flight system, which control different responses to similar situations.
Defence Systems (Page 113)
analysis pursued in Chapters 2 and 3 distinguished two classes of defence resulting from fear and anxiety. Previous analyses have identified two classes of defense arising from fear and anxiety.
Simplest class of defence requires only escape or aggressive behaviour controlled by the fight–flight–freeze system. The simplest defense involves escape or aggression, controlled by the fight-flight-freeze system.
Second class is more complicated, since simple escape or avoidance tendencies are in conflict with a tendency to approach the source of potential threat, this type of approach–avoidance conflict is controlled by the behavioural inhibition system. The more complex defense involves an approach-avoidance conflict, managed by the behavioral inhibition system.
Behavioural inhibition system provides an extra, inhibitory, level superimposed upon the fight–flight system. The behavioral inhibition system adds an inhibitory layer to the fight-flight system.
The neurology of fear will be bound up in the neurology of anxiety. The neurology of fear is intertwined with the neurology of anxiety.
The goal is removing itself from a source of danger.
Detailed analysis of even the primary defence system would require a book at least is to large as the present one. Even a detailed analysis of the primary defense system would require an extensive volume.