Addiction and the Insula

Wikipedia

Addiction

"The insula also reads body states like hunger and craving and helps push people into reaching for the next sandwich, cigarette or line of cocaine." [55[[12 Anatomy and Physiology#cite_note-54|]]] A number of functional brain imaging studies have shown that the insular cortex is activated when drug abusers are exposed to environmental cues that trigger cravings. This has been shown for a variety of drugs of abuse, including cocaine, alcohol, opiates and nicotine. Despite these findings, the insula has been ignored within the drug addiciton literature, perhaps because it is not known to be a direct target of the mesotelencephalic dopamine system which is central to current dopamine reward theories of addiction. Recent research [56[[12 Anatomy and Physiology#cite_note-55|]]] has shown that cigarette smokers who suffer damage to the insular cortex, from a stroke for instance, have their addiction to cigarettes practically eliminated. However, the study was conducted on average eight years after the strokes, and the author admits recall bias could affect the results[57[[12 Anatomy and Physiology#cite_note-56|]]]
These individuals were found to be up to 136 times more likely to undergo a disruption of smoking addiction than smokers with damage in other areas. Disruption of addiction was evidenced by self-reported behavior changes such as quitting smoking less than one day after the brain injury, quitting smoking with great ease, not smoking again after quitting, and having no urge to resume smoking since quitting. This suggests a significant role for the insular cortex in the neurological mechanisms underlying addiction to nicotine and other drugs, and would make this area of the brain a possible target for novel anti-addiction medication. In addition, this finding suggests that functions mediated by the insula, especially conscious feelings, may be particularly important for maintaining drug addiction, although this view is not represented in any modern research or reviews of the subject.[58[[12 Anatomy and Physiology#cite_note-57|]]]
A recent study in rats by Contreras et al.[59[[12 Anatomy and Physiology#cite_note-58|]]] corroborates these findings by showing that reversible inactivation of the insula disrupts amphetamine conditioned place preference, an animal model of cue-induced drug craving. In this study, insula inactivation also disrupted "malaise" responses to lithium chloride injection, suggesting that the representation of negative interoceptive states by the insula plays a role in addiction. However, in this same study, the conditioned place preference took place immediately after the injection of amphetamine, suggesting that it was the immediate, pleasurable interoceptive effects of amphetamine administration, rather than the delayed, aversive effects of amphetamine withdrawal that are represented within the insula.
A model proposed by Naqvi et al. (see above) is that the insula stores a representation of the pleasurable interoceptive effects of drug use (e.g. the airway sensory effects of nicotine, the cardiovascular effects of amphetamine), and that this representation is activated by exposure to cues that have previously been associated with drug use. A number of functional imaging studies have shown the insula to be activated during the administration of drugs of abuse. Several functional imaging studies have also shown that the insula is activated when drug users are exposed to drug cues, and that this activity is correlated with subjective urges. In the cue-exposure studies, insula activity is elicited when there is no actual change in the level of drug in the body. Therefore, rather than merely representing the interoceptive effects of drug use as it occurs, the insula may play a role in memory for the pleasurable interoceptive effects of past drug use, anticipation of these effects in the future, or both. Such a representation may give rise to conscious urges that feel as if they arise from within the body. This may make addicts feel as if their bodies need to use a drug, and may result in persons with lesions in the insula reporting that their bodies have forgotten the urge to use, according to this study.



Alpha/Theta "Border'

A fascinating possibility is the harmonic association of 40-Hz activity and the Alpha/Theta Neurofeedback training for addictions. If the 40-Hz/subharmonics theory is correct, the objective in addictive work is to teach the brain to open the fifth subharmonic "gate" of 40 Hz (7-8 Hz).
Alpha/Theta may be the frequency correlate of Kenneth Blum's theory of the Cascade Theory of Reward (1990), which leads to the Reward Deficiency Syndrome. In Blum~s theory, because of genetic anomalies, the neurochemistry in some people is satisfied with a drink (or bite) or two while the neurochemistry of the addicted person drives him or her into an unrelenting spiral of craving. Tying the 40-Hz theory with Blunfs theory, it appears that those with genetic anomalies (addictive tendencies) can be "locked out" of certain EEG frequencies, and thus certain neurochemistry (or vice versa). As a result, those with addictive craving are not able to feel rewarded (satisfied) while non-addictive people are.
While there are exceptions in EEG patterning, the alcoholic's EEG while sober often demonstrates a low voltage Beta pattern mixed with low amplitude Theta and Delta activity It is the type of low-voltage fast, "non-Alpha" EEG that is commonly associated with anxiety. If the alcoholic takes a relatively small amount of alcohol, he or she may quickly slip into a relaxed physiologic state and exhibit a relatively high amplitude, well-modulated Alpha rhythm. With that first drink, however, the brain of the alcoholic demands more alcohol. Instead of mellowing into an Alpha/Theta state as "normal" people do, additional amounts of alcohol cause a rapid descent into higher and higher amplitude Theta and Delta activity. The Alpha/Theta border of 78 Hz is seemingly "passed by."
It may be that the addicted person can open 40-Hz's fourth Harmonic gate (Alpha) with the alcohol or drugs. But, whether it is an anomalous gene, aberrant EEG frequencies, inappropriate neurochemistry a neurochemical "lock out," or some other reason, the alcoholic is not able to open the fifth subharmonic 7-8 Hz gate. Instead of entering the Alpha/Theta state, the person sinks into the high-amplitude slow waves of profoundly lowered arousal (unconsciousness).
Alpha/Theta Neurofeedback results in some 80% of those addicts properly trained becoming non-craving, having a mellow personality and significantly adjusted neurochemistry (Peninston & Kulkosky, 1990). Alpha/Theta training may be a process by which the previously closed fifth subharmonic gate (40-Hz divided by 5) can be opened and certain critical neurochemistry accessed.






Abstract This study investigated neurophysiological differences between recovering substance abusers (RSA) and controls while electroencephalogram (EEG) was continuously recorded during completion of a new assessment instrument. The participants consisted of 56 total subjects; 28 RSA and 28 non-clinical controls (C). The participants completed the self-perception and experiential schemata assessment (SPESA) and source localization was compared utilizing standardized low-resolution electromagnetic tomography (sLORETA). The data show significant differences between groups during both the assessment condition and baselines. A pattern of alpha activity as estimated by sLORETA was shown in the right amygdala, uncus, hippocampus, BA37, insular cortex and orbitofrontal regions during the SPESA condition. This activity possibly reflects a circuit related to negative perceptions of self formed in specific neural pathways. These pathways may be responsive to the alpha activity induced by many substances by bringing the brain into synchrony if only for a short time. In effect this may represent the euphoria described by substance abusers.