Le legs de Hebb.

Discusses the influence of Donald Olding Hebb (1904–1985) on the discipline of psychology. The author notes that Hebb's principled opposition to radical behaviourism and emphasis on understanding what goes on between stimulus and response (perception, learning, thinking) helped clear the way for the cognitive revolution. His view of psychology as a biological science and his neuropsychological cell-assembly proposal rejuvenated interest in physiological psychology. Since his death, Hebb's seminal ideas exert an ever-growing influence on those interested in mind (cognitive science), brain (neuroscience), and how brains implement mind (cognitive neuroscience). Specific events in Hebb's career are outlined, with particular attention to the influence on psychology of his book The Organization of Behavior: A Neuropsychological Theory (1949). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Hebb legacy.

Discusses the influence of Donald Olding Hebb (1904–1985) on the discipline of psychology. The author notes that Hebb's principled opposition to radical behaviourism and emphasis on understanding what goes on between stimulus and response (perception, learning, thinking) helped clear the way for the cognitive revolution. His view of psychology as a biological science and his neuropsychological cell-assembly proposal rejuvenated interest in physiological psychology. Since his death, Hebb's seminal ideas exert an ever-growing influence on those interested in mind (cognitive science), brain (neuroscience), and how brains implement mind (cognitive neuroscience). Specific events in Hebb's career are outlined, with particular attention to the influence on psychology of his book The Organization of Behavior: A Neuropsychological Theory (1949). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synaptic plasticity and the organization of behaviour after early and late brain injury.

D. O. Hebb (1949) proposed that synaptic change underlies behavioural and cognitive plasticity. When applied to recovery from brain injury, the general hypothesis is that if there is recovery following brain injury, then there ought to be a correlated synaptic change, which is presumed to be responsible for recovery. In contrast, if recovery fails to occur, or expected recovery is blocked in some manner, then the synaptic change will likely not be present. Systematic study of functional recovery and synaptic change following brain injury at different ages supports these predictions. Good recovery is always correlated with enhanced connectivity whereas poor recovery is always correlated with an absence of reorganized connectivity. Furthermore, factors that stimulate recovery, such as neurotrophins or experience, stimulate synaptic change and functional recovery. Factors that retard recovery, such as depletion of neuromodulators, also block synaptic change. These results thus support Hebb's general idea that synaptic plasticity is related to behavioural change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coherence of gamma-band EEG activity as a basis for associative learning

Different regions of the brain must communicate with each other to provide the basis for the integration of sensory information, sensory-motor coordination and many other functions that are critical for learning, memory, information processing, perception and the behaviour of organisms. Hebb suggested that this is accomplished by the formation of assemblies of cells whose synaptic linkages are strengthened whenever the cells are activated or 'ignited' synchronously. Hebb's seminal concept has intrigued investigators since its formulation, but the technology to demonstrate its existence had been lacking until the past decade. Previous studies have shown that very fast electroencephalographic activity in the gamma band (20-70 Hz) increases during, and may be involved in, the formation of percepts and memory, linguistic processing, and other behavioural and perceptual functions. We show here that increased gamma-band activity is also involved in associative learning. In addition, we find that another measure, gamma-band coherence, increases between regions of the brain that receive the two classes of stimuli involved in an associative-learning procedure in humans. An increase in coherence could fulfil the criteria required for the formation of hebbian cell assemblies, binding together parts of the brain that must communicate with one another in order for associative learning to take place. In this way, coherence may be a signature for this and other types of learning.     

Trains of neural thought.

The neural implementation of concepts, as postulated by Hebb (1949), has become obsolete due to the advances in neuroscience during the last half-century, but the basic idea revolutionized psychology, and remains valuable. This paper charts changes that have been imposed on Hebb's cell assembly by our greater understanding of the anatomy and neurophysiology of the visual system and our better recognition of the influence of "top-down" attention on perception. Difficulties encountered in trying to find neural explanations for the association of ideas are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A brief history of the Hebbian learning rule.

Notes that D. O. Hebb included a version of his neural postulate of learning in his MA thesis (1932). It seems to be a translation of Pavlovian conditioning into neural terms. The version that appears in his book, The Organization of Behavior (1949), speaks of synapses rather than routes, but the idea of simultaneous firing of afferent and efferent elements is common to both versions. The postulate was adopted by groups interested in programming computers to learn and think. It was also one of the hypotheses tested by neurophysiologists in their search for the synaptic mechanism of learning. So far the neurophysiologists have had more success than the logicians; the NMDA synapse appears to explain the main features of Hebb's postulate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The organization of behaviour revisited.

Provides an overview of major themes in D. O. Hebb's thought in behavioural neuroscience. Hebbs saw psychology as a biological science, but one in which the organization of behaviour must remain the central concern. Through penetrating theoretical concepts, including the "cell assembly," "phase sequence," and "Hebb synapse," he offered a way to bridge the gap between cells, circuits and behaviour. He saw the brain as a dynamically organized system of multiple distributed parts, with roots that extend into foundations of development and evolutionary heritage. He understood that behaviour, as brain, can be sliced at various levels and that one of the challenges is to bring these levels into both conceptual and empirical register. He could move between theory and fact with an ease that continues to inspire both students and professional investigators. Although facts continue to accumulate at an accelerating rate in both psychology and neuroscience, and although these facts continue to force revision in the details of Hebb's earlier contributions, his overall insistence that we look at behaviour and brain together, within a dynamic, relational and multilayered framework, remains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When learning met memory.

The first sentence of the introduction to Hebb's (1949) classic monograph, The organization of behavior, is “It might be argued that the task of the psychologist, the task of understanding behaviour and reducing the vagaries of human thought to a mechanical process of cause and effect, is a more difficult one than that of any other scientist” (p. xi). Nowhere is this more true than in the realm of human learning and memory, given our truly remarkable ability to acquire and retain prodigious amounts of information. This article is divided into two parts. The first part sketches my lifelong fascination with learning that led me to study first memory, then attention, and then their interplay, with examples of a few interesting findings along that path. The second part details recent work in my laboratory exploring a simple yet quite powerful encoding technique: Saying things aloud improves memory for them. This benefit, which we call the production effect, likely occurs by enhancing the distinctiveness of the things said aloud, and may constitute a beneficial study method. Understanding how we learn and remember is ultimately a crucial step in understanding ourselves. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotional memory systems in the brain

The neural mechanisms of emotion and memory have long been thought to reside side by side, if not in overlapping structures, of the limbic system. However, the limbic system concept is no longer acceptable as an account of the neural basis of memory or emotion and is being replaced with specific circuit accounts of specific emotional and memory processes. Emotional memory, a special category of memory involving the implicit (probably unconscious) learning and storage of information about the emotional significance of events, is modeled in rodent experiments using aversive classical conditioning techniques. The neural system underlying emotional memory critically involves the amygdala and structures with which it is connected. Afferent inputs from sensory processing areas of the thalamus and cortex mediate emotional learning in situations involving specific sensory cues, whereas learning about the emotional significance of more general, contextual cues involves projections to the amygdala from the hippocampal formation. Within the amygdala, the lateral nucleus (AL) is the sensory interface and the central nucleus the linkage with motor systems involved in the control of species-typical emotional behaviors and autonomic responses. Studies of cellular mechanisms in these pathways have focused on the direct relay to the lateral amygdala from the auditory thalamus. These studies show that single cells in AL respond to both conditioned stimulus and unconditioned stimulus inputs, leading to the notion that AL might be a critical site of sensory-sensory integration in emotional learning. The thalamo-amygdala pathway also exhibits long-term potentiation, a form of synaptic plasticity that might underlie the emotional learning functions of the circuit. The thalamo-amygdala pathway contains and uses the amino acid glutamate in synaptic transmission, suggesting the possibility that an amino-acid mediated form of synaptic plasticity is involved in the emotional learning functions of the pathway. We are thus well on the way to a systems level and a cellular understanding of at least one form of emotional learning and memory.     

Self-administered subcutaneous human menopausal gonadotrophin for the stimulation of testicular growth and the initiation of spermatogenesis in hypogonadotrophic hypogonadism

How can higher level aspects of cognition, such as figure-ground segregation, object recognition, selective focal attention and ultimately even awareness, be implemented at the level of synapses and neurons? A number of theoretical studies emerging out of the connectionist and the computational neuroscience communities are starting to address these issues using neural plausible models.     

Comparison of cognitive function in human and non-human primates

Fundamental to any comparative study of cognitive function in monkey and man is the demonstration of behavioral homology, viz. that the same cognitive function is being studied in both species. This paper considers a variety of psychological issues that need to be taken into account when attempting to demonstrate behavioural homology. Examples are taken from studies of attentional set-shifting, discrimination reversal learning, spatial working memory and episodic memory. Whilst highlighting the pitfalls to be avoided in the future, these examples also demonstrate the enormous contribution that such studies have had to our understanding of the functions of the temporal lobes and frontal lobes. Moreover, they also illustrate the enormous potential in defining the cognitive functions and dysfunctions of the prefronto-striatal circuitry which underlie so many neurodegenerative and neuropsychiatric disorders.     

Hebb's Neural Networks Support the Integration of Psychological Science.

In a recent paper and forthcoming volume, the former President of the American Psychological Association, Robert Sternberg, calls for an effort to reintegrate psychological science (Sternberg, in press; Sternberg & Grigorenko, 2001). In this paper we argue that D. O. Hebb, beginning with his technical volume in 1949 and continuing through a series of introductory textbooks, has convincingly presented the basis for such integration. The basis for this integration lies in understanding how genes and experience shape neural networks underlying human thoughts, feelings, and actions. Why has not Hebb's accomplishment been generally recognized as providing the needed integration for psychology? We suggest that the methods available to Hebb, mostly animal research and behavioural human experiments, were not sufficient to provide empirical methods for linking his conceptual nervous system to real events in the human brain. This methodology has now been provided by neuroimaging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fears, phobias, and preparedness: Toward an evolved module of fear and fear learning.

An evolved module for fear elicitation and fear learning with 4 characteristics is proposed. (a) The fear module is preferentially activated in aversive contexts by stimuli that are fear relevant in an evolutionary perspective. (b) Its activation to such stimuli is automatic. (c) It is relatively impenetrable to cognitive control. (d) It originates in a dedicated neural circuitry, centered on the amygdala. Evidence supporting these propositions is reviewed from conditioning studies, both in humans and in monkeys; illusory correlation studies; studies using unreportable stimuli; and studies from animal neuroscience. The fear module is assumed to mediate an emotional level of fear learning that is relatively independent and dissociable from cognitive learning of stimulus relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning, retention, and conceptual usage in elderly patients with memory disorder.

Elderly patients clinically judged to be suffering from memory disorder show difficulty in learning paired-associates and the kind of tasks found in the Wechsler Performance Scale. The learning difficulty extends to other kinds of learning problems and retention processes are also affected. The relevance of some of Hebb's notions concerning the likely relations between learning and cognitive functioning in human adults was also examined. The results confirmed expectations and suggested that the sort of neuropsychological model elaborated by Hebb may be a useful source of working hypotheses in this area. 18 refs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Theories of artificial grammar learning.

Artificial grammar learning (AGL) is one of the most commonly used paradigms for the study of implicit learning and the contrast between rules, similarity, and associative learning. Despite five decades of extensive research, however, a satisfactory theoretical consensus has not been forthcoming. Theoretical accounts of AGL are reviewed, together with relevant human experimental and neuroscience data. The author concludes that satisfactory understanding of AGL requires (a) an understanding of implicit knowledge as knowledge that is not consciously activated at the time of a cognitive operation; this could be because the corresponding representations are impoverished or they cannot be concurrently supported in working memory with other representations or operations, and (b) adopting a frequency-independent view of rule knowledge and contrasting rule knowledge with specific similarity and associative learning (co-occurrence) knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Similar involvement of VIP receptor type I and type II in lymphocyte chemotaxis

The fundamental concept that synapse growth and change are associated with learning is considered a "replay" of early neurodevelopmental principles that instruct neural connectivity pattern. Common mechanisms suggested to link the process of memory formation through synaptic elaboration are exemplified by the activity of cell adhesion molecules following learning and that center on waves of glycoprotein synthesis occurring in the 6- to 8-h and 10- to 12-h posttraining periods of consolidation. These are associated with spatially clustered granule cells in the adult rat hippocampus that show a transient time-dependent increase in ribosome production and greater microtubular complexity and dendritic spine number 6 to 8 h following training. The elimination and/or selection of the synapses to be retained in the memory trace is proposed to be dependent on cell adhesion molecule glycosylation events in the 10- to 12-h posttraining period. The existence of similar cell adhesion molecule glycosylation mechanisms within a corticohippocampal pathway is used to contribute to a model of memory in which sensory representations are eventually consolidated through relative change in synaptic weightings.     

Communication neuroscience as a tool for health psychologists.

Comments on the original article, "Increased attention but more efficient disengagement: Neuroscientific evidence for defensive processing of threatening health information" by L. T. E. Kessels, R. A. C. Ruiter, and B. M. Jansma (see record 2010-14873-005). Kessler et al present an example of Communication Neuroscience as a tool for understanding the mechanisms that lead some health messages to be processed in a way that facilitates impact whereas other messages are ignored. Kessels et al used event-related brain potentials (ERPs), a high temporal resolution method, to monitor neural activity in the moment that messages are presented. They use this technology to provide insight about the low-level attention processes through which individuals at highest risk (in this case, smokers) disengage from self-relevant health messages (threatening and nonthreatening smoking images). The findings of Kessels et al are convergent with prior theory and empirical work demonstrating that high threat messages may not achieve the desired effect if presented in isolation (Brown & Locker, 2009; Leventhal, Safer, & Panagis, 1983; Liberman & Chaiken, 1992). By using the tools of neuroscience, however, Kessels et al elucidate a mechanism that was not apparent through self-report or implicit (reaction time) measures. They demonstrate that high threat messages lead to increased attention capture, but more efficient disengagement when threatening messages are self-relevant; this in turn helps to explain why high threat messages may not have the desired effect, despite successfully capturing people’s attention. As such, this study illustrates one benefit of combining the tools of neuroscience with more familiar methods in health psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester on spatial and cued leaning

An investigation was made of the effects of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on the acquisition and retention of two operantly conditioned discrimination tasks. Twenty Long-Evans rats were conditioned to approach one of two spatial locations that was either held constant across trials (spatial task) or was associated with a visual cue (illuminated lamp) that was randomly assigned to one of the locations on each trial (cued task). Rats were assigned to one of two treatment groups in which they received intraperitoneal injections of either NG-nitro-L-arginine methyl ester or saline approximately 2 h before sessions on each day of training. Analysis was made of the trial-by-trial performance in order to identify the characteristics of learning under each condition. Assessment of learning acquisition was based on the number of trials required to reach a criterion of 80% correct responses, whereas retention was assessed by the number of trials to criterion on each day after the criterion was initially reached. Analysis indicated that treatment groups did not differ significantly on acquisition or retention of either the spatial or cued task. These results indicate that inhibition of nitric oxide synthase does not interfere with the learning or retention of basic operant tasks that involve simple spatial or visual analysis. Whereas results from biochemical and physiological investigations have suggested an impact of nitric oxide synthase on behavioural function, behavioural investigations indicate a limited impact of nitric oxide synthase inhibition on learning and memory. Although these results do not discount the role of nitric oxide synthase in a hippocampal mechanism, they illustrate that behavioural analysis should be made in the context of multiple interacting neural systems. Viewed with previous behavioural research on the effects of NG-nitro-L-arginine methyl ester, these results indicate that nitric oxide synthase inhibition results in impairment of certain forms of learning whereas other forms are preserved.     

Behaviorism and neuroscience.

The influence of the methods and theories of behaviorism on theory and research in the neurosciences is examined, partly in light of J. B. Watson's (1913; see also PA, Vol 81:27851) original call-to-arms. Behaviorist approaches to animal behavior, particularly in the study of processes of learning and memory, have had a profound and continual influence in the area of neuroscience concerned with animal studies of brain substrates of behavior. Similarly, contemporary behaviorists have not been opposed to the study of neurobiological substrates of behavior. On the other hand, classical behaviorist views of thinking (i.e., as reflex chains) have been largely discounted by developments in neuroscience. Classical behaviorism is viewed by many as being most at odds with the modern fields of cognitive psychology and cognitive neuroscience, particularly regarding "mind" and "consciousness." A modest attempt at reconciliation is offered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

From the Neuroscience of Memory to Psychoanalytic Interaction: Clinical Implications.

The neuroscience of memory enriches and expands our theory of psychoanalytic interaction. There are 2 broad modes of processing memory: implicit (never experienced in symbolic form) and explicit (which is symbolic). Memory is not a thing, but a process, activated by a retrieval cue that is either external or internal. Each memory is an amalgam of the memory itself and the retrieval cue. Using these phenomena derived from the neuroscience of memory, the authors argue that (a) the analyst acts as a retrieval cue making any memory a coconstructed phenomenon; (b) each memory is constructed, transformed, and expanded anew, incrementally leading to new networks and change; and (c) implicit memory, lacking symbolic content, is an underutilized component of psychoanalytic attention. Clinical examples are used as illustrations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)