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Thursday, July 14, 2016

The Michigan Daily — michigandaily.com NEWS

Study shows marijuana affects 
user’s pleasure-related cognition

RESEARCH

Drug users feel less 
pleasure to monetary 
rewards compared to 

non-users

By MADELEINE GERSON

Daily Staff Reporter

According to a recent study 

conducted 
by 
University 
of 

Michigan researchers, long-term 
marijuana usage is associated with 
a decrease in the brain’s response 
time. The study, published in 
JAMA Psychiatry medical journal, 
brought forth new information 
about the effect marijuana can 
have on the brain of a young adult 
user.

Marijuana’s reputation as both a 

risky gateway drug and a harmless 
substance with medical benefits is 
a major component in the current 
legislation discussion surrounding 
its 
legalization. 
Currently, 

recreational marijuana is legal in 
four states — Alaska, Colorado, 
Oregon and Washington — and 
Washington, D.C., and medical 
marijuana is legal in 20 states.

According to an article in the 

Los Angeles Times, California will 
vote this November on whether to 
legalize recreational marijuana. 
 

In Michigan, medical marijuana is 
legal and marijuana possession has 
been decriminalized by a total of 14 
cities since November 2014.

The majority of studies on long-

term marijuana usage have been 

associative and limited due to 
the fact that correlation does not 
imply causation. Mary Heitzeg, a 
University assistant professor of 
psychiatry and the senior author 
of the study, said her team’s study 
is the first longitudinal study 
about marijuana usage that is not 
refutable.

“Our study is unique in that we 

actually look at brain activation 
measures over time as opposed to 
cross-sectional studies looking at 
marijuana users and non-users,” 
Heitzeg 
said. 
“Those 
studies 

cannot 
necessarily 
disentangle 

cause and effect.”

The 
participants 
— 
108 

marijuana users in their early 20s 
— were asked to play a game while 
their brains were being scanned in 
a functional magnetic resonance 
imaging scanner. In each round, the 
players were informed they could 
either win money for winning the 
round or no money was at stake.

Dopamine is a neurotransmitter 

that affects the feeling of pleasure 
and 
pleasure-related 
cognition, 

and 
when 
people 
engage 
in 

rewarding 
behavior, 
levels 
of 

dopamine increase in the reward 
centers of the brain — the nucleus 
accumbens. 

The 
neuroimaging 
showed 

that, in participants who reported 
higher usage of marijuana, less 
dopamine was released. This means 
marijuana users felt less pleasure in 
response to the monetary rewards 
presented throughout the game 
compared to non-users.

On 
the 
contrary, 
when 

researchers looked at the same 
participants’ responses to the 
reward of drug anticipation, there 
was a higher amount of dopamine 
in the nucleus accumbens — which 
could be a sign of addiction.

Heitzeg explained that this 

could occur when a drug “hijacks” 
the user’s reward system, referring 
to when a user becomes dependent 
on a drug to experience the feeling 
of reward.

“This means that something 

that would be rewarding to most 
people was no longer rewarding 
to them,” Heitzeg said. “This 
suggests but not proves that their 
reward system has been ‘hijacked’ 
by the drug, and that they need 
the drug to feel reward — or that 
their emotional response has been 
dampened.”

The work of Heitzeg’s team has 

led to the rise of potential future 
research 
questions. 
Rackham 

student 
Meghan 
Martz, 
the 

primary author of the study, 
said 
non-drug-related 
rewards 

other than money could produce 
comparable outcomes.

“This task happens to use 

monetary incentives, but there are 
a number of other non-drug related 
rewards that could also be tested, 
such as food,” Martz said.

Martz added that the study is 

relevant in today’s politics since 
marijuana usage is increasing at 
a high rate, which may lead to a 
belief that the drug does not pose 
any severe consequences to health.

“The legalization of marijuana 

See MARIJUANA, Page 10

Marchers were eager to get more 

people involved, encouraging many 
bystanders to join the protest. Many 
passing-by cars honked in support 
of the protesters, and some drivers 
got out of their vehicles to record 
the protest.

Most bystanders either joined in 

the chants or observed in silence, 
but one woman, in response to 
the chants of “Black lives matter!” 
replied with: “All lives matter!”

The climate between protesters 

and police during the protest was 
friendly, with several protesters 
shaking the hands of police officers 
and speakers calling for the crowd 
to thank the police department. 
However, protest organizer Diante 
Harris, a Kinesiology junior, said 
the department still has work to 
do build relationships with the 
community.

Harris further argued that the 

need for increased civilian oversight 
doesnt necessarily imply the police 
department has been neglecting its 
responsibilities, adding that local 
officers should have nothing to fear. 

“The chief is probably just 

thinking that this is all out of spite, 
or, you know, a quick reaction, but 
as people who pay these officers 
to protect and serve them, and 
as people that are a part of the 
communities that these officers 
work in, I don’t see what bad could 
come out of having a say in some 
of the matters,” Harris said. “Right 
now the police chief doesn’t want to 
hear that in Ann Arbor. He believes 
that this is a local problem, and that 
everyone is overreacting because of 
what happened to Aura (Rosser),” 
he continued, to boos from the 
crowd. 

In front of a crowd of hundreds 

gathered on the Diag, Kinesiology 
senior Nas Ali lamented the death 
of Philando Castile, who was killed 
on the same street Ali lived on as a 
child, where his family still lives.

“Last week, when Philando 

Castile passed away –– I live here, I 
go to school here, but that happened 
half a block from where I grew up,” 
Ali said. “The cop who killed him 
has pulled me over so many times, 
and I can’t even put into words 
the things that he has said to me. 
This time it changed. As much as 
I’ve grieved for everyone who has 
happened before, this time I wasn’t 
removed from it. It wasn’t St. Louis. 
It wasn’t Florida. It was in my 
backyard.”

Harris 
also 
spoke 
to 
the 

experiences he’d had with police.

“Growing up, I only saw them 

when someone in my community 
was being arrested,” Harris said. 
“What do you think that does to you 
when you’re a kid, to your psyche? 
You’re going to not trust the police. 
You’re going to be afraid of the 
police.”

Despite the distrust he described, 

Harris ended by encouraging unity.

“We need more community 

involvement 
with 
our 
police 

officers,” he said. “And that’s the 
truth — I know not everyone wants 
to hear that. A lot of people don’t 
want any unity between the police 
officers and the community, but 
they are part of the communities 
whether we like it or not. And we 
are part of the communities that 
they serve, whether we like it or 
not.”

Protester 
Johnny 
Anderson 

challenged 
stereotypes 
of 

protesters, saying their message 
wasn’t so unpalatable as some 
believed and that demonstrators 
like himself don’t condone violence.

“Everybody has this vision in 

their head, that the revolution’s 
going to be this violent gunfire 
against the government,” Anderson 
said. “No, it’s going to be peace, it’s 
going to be this right here. This is 
the revolution right here. CNN ain’t 
coming here to see this peace, ain’t 
nothing to talk about.”

Ann Arbor resident Brionne 

Fonville said that the revolution 
would require more than protesting 
and marching.

“What I saw here tonight was 

beautiful,” Fonville said. “There’s so 
much power and potential in what 
we did, marching. But we need to 
start thinking about what we’re 
going to do next. You all have the 
same equal power and potential. 
I’m going to paraphrase Dr. King 
for a second, and all I want to say is 
think about what you’re doing with 
your life. Think about what you do 
every day. Think about the people 
you come into contact with and 
think about how you can use that to 
bend the moral arc towards justice.”

AAPD 
Officer 
Thomas 

Hickey, while also encouraging 
communication 
between 
police 

and civilians, argued the AAPD has 
done much to engage its community.

“I can tell you that at the Ann 

Arbor Police Department, we have 
been proactive about diversity and 
multicultural training,” Hickey said. 
“We probably go above the standard 
for training. We pride ourselves on 
staying current with what’s going 
on, and that makes for a better 
police department, and probably 
overall transparent. We have great 
communication with some of the 
folks 
here. 
Communication 
is 

basically the bottom line.”

PROTEST
From Page 1