Response inhibition and impulsivity: an fMRI study

Aggressive, suicidal and violent behaviour have been associated with impulsive personality and difficulty in inhibiting responses. We used functional magnetic resonance imaging (fMRI) of the whole brain to examine the neural correlates of response inhibition in 19 normal subjects as they performed a Go/NoGo task. Subjects completed Eysenck's Impulsivity Scale, Barratt's Impulsivity Scale (BIS) and behavioural impulsivity tasks. Associations between blood oxygen level dependent (BOLD) response, trait impulsivity, task performance and National Adult Reading Test (NART) IQ were investigated. Neural response during response inhibition was most prominent in the right lateral orbitofrontal cortex. Responses were also seen in superior temporal gyrus, medial orbitofrontal cortex, cingulate gyrus, and inferior parietal lobule, predominantly on the right side. Subjects with greater scores on impulsivity scales and who made more errors had greater activation of paralimbic areas during response inhibition, while less impulsive individuals and those with least errors activated higher order association areas. Exploratory factor analysis of orbital activations, personality measures and errors of commission did not reveal a unitary dimension of impulsivity. However, the strong association between posterior orbital activation and Eysenck's impulsivity score on a single factor suggests that greater engagement of right orbitofrontal cortex was needed to maintain behavioural inhibition in impulsive individuals. Lower IQ was more important than impulsivity scores in determining errors of commission during the task. Neuroimaging of brain activity during the Go/NoGo task may be useful in understanding the functional neuroanatomy and associated neurochemistry of response inhibition. It may also allow study of the effects of physical and psychological interventions on response inhibition in clinical conditions such as antisocial personality disorder.

5-HT(2C) receptor activation by m-chlorophenylpiperazine detected in humans with fMRI

Functional brain imaging using selective drug probes offers the opportunity to investigate regional neuronal activation linked to receptor stimulation or inhibition. In a placebo-controlled, balanced order design in eight male volunteers, the 5-HT(2c) agonist, m-chlorophenylpiperazine (mCPP) increased blood oxygen level dependent (BOLD) signal in the hypothalamus, caudate, pallidum, amygdala and pyriform cortex, anterior cingulate gyrus and choroid plexus (p < 0.001 uncorrected), areas with high density of 5-HT(2c) receptors. Activation in the hypothalamus correlated significantly with the prolactin response (p < 0.05 small volume corrected). In a subsequent Go/NoGo task, mCPP enhanced activation in right lateral orbitofrontal cortex (p < 0.05 small volume corrected). These findings suggest that pharmacoMRI is a potentially powerful tool for investigating neurotransmitter function in humans.

HIV testing & treatment of children

In the last year, courts in Canada, the US, and the UK have decided cases in which child welfare authorities have disputed parents' decisions to refuse HIV testing or treatment for their children. This article reviews recent US developments regarding refusal of treatment, and reports the outcome of a recent UK decision compelling the HIV testing of a minor against her parents' wishes. It then provides an update on two recent Canadian cases concerning a parent's refusal to treat an HIV-positive child with antiretroviral therapy, and a brief overview of the current state of Canadian law on the issue of minors and medical treatment.

Newfoundland man pleads guilty to criminal harassment

In May 1999, a Newfoundland trial court sentenced a 30-year-old man after he pleaded guilty to one count of criminal harassment for posting public notices that his ex-girlfriend was HIV-positive and had unprotected sex without disclosing this fact.

Criminalization of assisted suicide challenged

In September 1999, Jim Wakeford, a Toronto man with HIV/AIDS, launched a civil action against the Attorney General of Canada, challenging the constitutionality of sections of the Criminal Code that criminalize assisted suicide.

Allegations of HIV infection raised in criminal trial of escort agency owner

At the beginning of October 1999, a Toronto man who owned an escort agency went to trial in the Ontario Superior Court of Justice on numerous charges of living off the avails of prostitution and procuring for the purpose of prostitution. On the first day of trial, the prosecutor indicated he would be introducing evidence suggesting that three of the women who worked as escorts for Mark Lucacko's agency may be HIV-positive.

AIDS organizations denied leave to intervene in insurance case

In October 1999, the BC Court of Appeal denied the request of the Canadian AIDS Society (CAS) and the BC Persons with AIDS Society (BCPWA) to intervene in the appellate hearing of a case raising questions about the responsibilities of employers and employees to preserve entitlement to life insurance coverage. In this case, the issue of the mental capacity of a man with AIDS-related dementia was a key issue.

No duty to preserve benefits for employee with dementia

In August 1999, an Ontario trial court granted an employer's motion for a summary judgment dismissing a claim against it by the estate of a former employee who died of AIDS-related illness.

Criminal law and HIV/AIDS: update II

This article reviews new developments in the area of criminal prosecutions for HIV transmission or exposure, or developments that have come to our attention since the last issue of the Newsletter. This column will continue to be a regular feature. However, we will not continue to report cases or legislation from jurisdictions other than Canada unless they represent a significant development, either in this area of the law or for the jurisdiction in question.

Appeal board denies public health insurance coverage to immigrants on Minister's Permits

In a decision released in August 1999, the Health Services Appeal Board in Ontario upheld the decision to deny provincial health coverage to an HIV-positive woman who had been denied permanent resident status on the basis of "medical inadmissibility" but was living in Canada on an Immigration Minister's Permit issued on "humanitarian and compassionate grounds."

BC human rights tribunal rules on discrimination by London life

In June 1999, a British Columbia human rights tribunal ruled that London Life Insurance Company had violated the province's Human Rights Act in 1994 by refusing to sell life insurance (on his own life) to an HIV-negative man on the basis that his wife is HIV-positive.

The rate of aneuploidy is altered in spermatids from infertile mice

BACKGROUND

It is now possible for infertile males to father their own genetic children through the technique of ICSI. This prospect has consequently prompted several investigations into the quality of sperm being retrieved from infertile males. One potential risk is the use of aneuploid sperm or spermatids, which might then be transferred to the fertilized oocyte.

METHODS

In this investigation, aneuploidy of spermatids was assessed through immunocytochemistry using antibodies directed against chromosome centromeric regions and complexes. Three different types of infertile male mice with phenotypes closely resembling those described in human non-obstructive azoospermia [PP1cgamma-deficient mice, CREM-deficient mice and C57BL/6J.MAC-17(0--23) mice] were examined for chromosome numbers by counting the number of kinetochores in round spermatids using a CREST antiserum.

RESULTS

PP1cgamma(-/-) and CREM(-/-) spermatids from infertile mice showed highly significant elevated levels in the rate of aneuploidy compared with wild-type animals (P < 0.0001). Thus infertile males with independent genetic mutations resulting in different histopathologies showed a high risk in the level of aneuploidy in their spermatids.

CONCLUSIONS

These results suggest that impaired spermatogenesis may lead to production of aneuploid gametes. Analysis of aneuploidy in gametes from infertile men, coupled with appropriate genetic counselling, is recommended prior to ICSI.

Generic drug maker wins right to sue for anti-competitive practices

In December 2000, the Ontario Court of Appeal upheld the right of generic drug manufacturer Apotex Inc to sue three name-brand pharmaceutical companies for allegedly anti-competitive practices. Apotex's claim had been struck out by a lower court, but the appellate court overturned this judgment and allowed the suit to proceed. The facts alleged by Apotex, if eventually proved true, could support a court finding that the name-brand companies were in fact liable.

Canadian court upholds Glaxo's patent on AZT

In October 2000, the Federal Court of Appeal issued the latest ruling in the ongoing dispute over the validity of Glaxo's Canadian patent for AZT, upholding Glaxo's patent but narrowing the scope of the claims it could validly make. The decision is now on appeal to the Supreme Court of Canada.

Court dismisses constitutional challenge to ban on assisted suicide

On 6 February 2001, the Ontario Superior Court of Justice dismissed a constitutional challenge by Jim Wakeford, a Toronto man with HIV/AIDS and an advocate for access to medical marijuana, to the sections of the Criminal Code that outlaw assisted suicide in Canada.

Canadian court dismisses Pfizer attempt to prevent approval of generic fluconazole

On 10 January 2001, Pfizer lost its bid before the Federal Court of Appeal to prohibit the federal Minister of Health from issuing approvals for two generic versions of the drug fluconazole.

Motion to strike claim dismissed in HIV defamation suit

On 23 April 2001, the Ontario Superior Court of Justice issued the first Canadian ruling on the issue of whether words inputing that a person is HIV-positive or has AIDS can be the basis of a defamation action per se, in the case of Serdar v Metroland Printing, Publishing and Distributing Ltd.

Criminal law and HIV/AIDS: update V

This regular column reviews new developments in the area of criminal prosecutions for HIV transmission or exposure, or developments that have come to our attention since the last issue. Canadian developments are the focus. Cases and legislation from other jurisdictions are only included if they represent a significant development in this area of the law or for the jurisdiction in question.

US files WTO complaints against Brazil over requirement for "local working" of patents

At the end of May 2000, the US (later joined by the European Communities) filed a complaint against Brazil at the World Trade Organization (WTO), alleging Brazil was in violation of its obligations under the Agreement on Trade-Related Aspects of Intellectual Property Rights (the TRIPS Agreement) and the 1994 General Agreement on Tariffs and Trade. Brazilian legislation that came into force in 1997 establishes that, in order to enjoy exclusive patent rights in Brazil, the holder of a patent on an invention must satisfy a "local working" requirement. In other words, the patent holder must "work" the patent in Brazil to enjoy full patent protection. If it fails to do this, the law says it shall be subject to the possibility of the government issuing a compulsory license, allowing someone else to use the invention and pay a royalty fee to the patent holder.